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aee69d78 PV |
1 | /* |
2 | * Budget Fair Queueing (BFQ) I/O scheduler. | |
3 | * | |
4 | * Based on ideas and code from CFQ: | |
5 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> | |
6 | * | |
7 | * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> | |
8 | * Paolo Valente <paolo.valente@unimore.it> | |
9 | * | |
10 | * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it> | |
11 | * Arianna Avanzini <avanzini@google.com> | |
12 | * | |
13 | * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org> | |
14 | * | |
15 | * This program is free software; you can redistribute it and/or | |
16 | * modify it under the terms of the GNU General Public License as | |
17 | * published by the Free Software Foundation; either version 2 of the | |
18 | * License, or (at your option) any later version. | |
19 | * | |
20 | * This program is distributed in the hope that it will be useful, | |
21 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
22 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
23 | * General Public License for more details. | |
24 | * | |
25 | * BFQ is a proportional-share I/O scheduler, with some extra | |
26 | * low-latency capabilities. BFQ also supports full hierarchical | |
27 | * scheduling through cgroups. Next paragraphs provide an introduction | |
28 | * on BFQ inner workings. Details on BFQ benefits, usage and | |
29 | * limitations can be found in Documentation/block/bfq-iosched.txt. | |
30 | * | |
31 | * BFQ is a proportional-share storage-I/O scheduling algorithm based | |
32 | * on the slice-by-slice service scheme of CFQ. But BFQ assigns | |
33 | * budgets, measured in number of sectors, to processes instead of | |
34 | * time slices. The device is not granted to the in-service process | |
35 | * for a given time slice, but until it has exhausted its assigned | |
36 | * budget. This change from the time to the service domain enables BFQ | |
37 | * to distribute the device throughput among processes as desired, | |
38 | * without any distortion due to throughput fluctuations, or to device | |
39 | * internal queueing. BFQ uses an ad hoc internal scheduler, called | |
40 | * B-WF2Q+, to schedule processes according to their budgets. More | |
41 | * precisely, BFQ schedules queues associated with processes. Each | |
42 | * process/queue is assigned a user-configurable weight, and B-WF2Q+ | |
43 | * guarantees that each queue receives a fraction of the throughput | |
44 | * proportional to its weight. Thanks to the accurate policy of | |
45 | * B-WF2Q+, BFQ can afford to assign high budgets to I/O-bound | |
46 | * processes issuing sequential requests (to boost the throughput), | |
47 | * and yet guarantee a low latency to interactive and soft real-time | |
48 | * applications. | |
49 | * | |
50 | * In particular, to provide these low-latency guarantees, BFQ | |
51 | * explicitly privileges the I/O of two classes of time-sensitive | |
52 | * applications: interactive and soft real-time. This feature enables | |
53 | * BFQ to provide applications in these classes with a very low | |
54 | * latency. Finally, BFQ also features additional heuristics for | |
55 | * preserving both a low latency and a high throughput on NCQ-capable, | |
56 | * rotational or flash-based devices, and to get the job done quickly | |
57 | * for applications consisting in many I/O-bound processes. | |
58 | * | |
59 | * BFQ is described in [1], where also a reference to the initial, more | |
60 | * theoretical paper on BFQ can be found. The interested reader can find | |
61 | * in the latter paper full details on the main algorithm, as well as | |
62 | * formulas of the guarantees and formal proofs of all the properties. | |
63 | * With respect to the version of BFQ presented in these papers, this | |
64 | * implementation adds a few more heuristics, such as the one that | |
65 | * guarantees a low latency to soft real-time applications, and a | |
66 | * hierarchical extension based on H-WF2Q+. | |
67 | * | |
68 | * B-WF2Q+ is based on WF2Q+, which is described in [2], together with | |
69 | * H-WF2Q+, while the augmented tree used here to implement B-WF2Q+ | |
70 | * with O(log N) complexity derives from the one introduced with EEVDF | |
71 | * in [3]. | |
72 | * | |
73 | * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O | |
74 | * Scheduler", Proceedings of the First Workshop on Mobile System | |
75 | * Technologies (MST-2015), May 2015. | |
76 | * http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf | |
77 | * | |
78 | * [2] Jon C.R. Bennett and H. Zhang, "Hierarchical Packet Fair Queueing | |
79 | * Algorithms", IEEE/ACM Transactions on Networking, 5(5):675-689, | |
80 | * Oct 1997. | |
81 | * | |
82 | * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz | |
83 | * | |
84 | * [3] I. Stoica and H. Abdel-Wahab, "Earliest Eligible Virtual Deadline | |
85 | * First: A Flexible and Accurate Mechanism for Proportional Share | |
86 | * Resource Allocation", technical report. | |
87 | * | |
88 | * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf | |
89 | */ | |
90 | #include <linux/module.h> | |
91 | #include <linux/slab.h> | |
92 | #include <linux/blkdev.h> | |
e21b7a0b | 93 | #include <linux/cgroup.h> |
aee69d78 PV |
94 | #include <linux/elevator.h> |
95 | #include <linux/ktime.h> | |
96 | #include <linux/rbtree.h> | |
97 | #include <linux/ioprio.h> | |
98 | #include <linux/sbitmap.h> | |
99 | #include <linux/delay.h> | |
100 | ||
101 | #include "blk.h" | |
102 | #include "blk-mq.h" | |
103 | #include "blk-mq-tag.h" | |
104 | #include "blk-mq-sched.h" | |
105 | #include <linux/blktrace_api.h> | |
106 | #include <linux/hrtimer.h> | |
107 | #include <linux/blk-cgroup.h> | |
108 | ||
109 | #define BFQ_IOPRIO_CLASSES 3 | |
110 | #define BFQ_CL_IDLE_TIMEOUT (HZ/5) | |
111 | ||
112 | #define BFQ_MIN_WEIGHT 1 | |
113 | #define BFQ_MAX_WEIGHT 1000 | |
114 | #define BFQ_WEIGHT_CONVERSION_COEFF 10 | |
115 | ||
116 | #define BFQ_DEFAULT_QUEUE_IOPRIO 4 | |
117 | ||
e21b7a0b | 118 | #define BFQ_WEIGHT_LEGACY_DFL 100 |
aee69d78 PV |
119 | #define BFQ_DEFAULT_GRP_IOPRIO 0 |
120 | #define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE | |
121 | ||
122 | struct bfq_entity; | |
123 | ||
124 | /** | |
125 | * struct bfq_service_tree - per ioprio_class service tree. | |
126 | * | |
127 | * Each service tree represents a B-WF2Q+ scheduler on its own. Each | |
128 | * ioprio_class has its own independent scheduler, and so its own | |
129 | * bfq_service_tree. All the fields are protected by the queue lock | |
130 | * of the containing bfqd. | |
131 | */ | |
132 | struct bfq_service_tree { | |
133 | /* tree for active entities (i.e., those backlogged) */ | |
134 | struct rb_root active; | |
135 | /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/ | |
136 | struct rb_root idle; | |
137 | ||
138 | /* idle entity with minimum F_i */ | |
139 | struct bfq_entity *first_idle; | |
140 | /* idle entity with maximum F_i */ | |
141 | struct bfq_entity *last_idle; | |
142 | ||
143 | /* scheduler virtual time */ | |
144 | u64 vtime; | |
145 | /* scheduler weight sum; active and idle entities contribute to it */ | |
146 | unsigned long wsum; | |
147 | }; | |
148 | ||
149 | /** | |
150 | * struct bfq_sched_data - multi-class scheduler. | |
151 | * | |
152 | * bfq_sched_data is the basic scheduler queue. It supports three | |
e21b7a0b AA |
153 | * ioprio_classes, and can be used either as a toplevel queue or as an |
154 | * intermediate queue on a hierarchical setup. @next_in_service | |
155 | * points to the active entity of the sched_data service trees that | |
156 | * will be scheduled next. It is used to reduce the number of steps | |
157 | * needed for each hierarchical-schedule update. | |
aee69d78 PV |
158 | * |
159 | * The supported ioprio_classes are the same as in CFQ, in descending | |
160 | * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. | |
161 | * Requests from higher priority queues are served before all the | |
162 | * requests from lower priority queues; among requests of the same | |
163 | * queue requests are served according to B-WF2Q+. | |
164 | * All the fields are protected by the queue lock of the containing bfqd. | |
165 | */ | |
166 | struct bfq_sched_data { | |
167 | /* entity in service */ | |
168 | struct bfq_entity *in_service_entity; | |
e21b7a0b | 169 | /* head-of-line entity (see comments above) */ |
aee69d78 PV |
170 | struct bfq_entity *next_in_service; |
171 | /* array of service trees, one per ioprio_class */ | |
172 | struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; | |
e21b7a0b AA |
173 | /* last time CLASS_IDLE was served */ |
174 | unsigned long bfq_class_idle_last_service; | |
175 | ||
aee69d78 PV |
176 | }; |
177 | ||
178 | /** | |
179 | * struct bfq_entity - schedulable entity. | |
180 | * | |
e21b7a0b AA |
181 | * A bfq_entity is used to represent either a bfq_queue (leaf node in the |
182 | * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each | |
183 | * entity belongs to the sched_data of the parent group in the cgroup | |
184 | * hierarchy. Non-leaf entities have also their own sched_data, stored | |
185 | * in @my_sched_data. | |
aee69d78 PV |
186 | * |
187 | * Each entity stores independently its priority values; this would | |
188 | * allow different weights on different devices, but this | |
189 | * functionality is not exported to userspace by now. Priorities and | |
190 | * weights are updated lazily, first storing the new values into the | |
191 | * new_* fields, then setting the @prio_changed flag. As soon as | |
192 | * there is a transition in the entity state that allows the priority | |
193 | * update to take place the effective and the requested priority | |
194 | * values are synchronized. | |
195 | * | |
e21b7a0b AA |
196 | * Unless cgroups are used, the weight value is calculated from the |
197 | * ioprio to export the same interface as CFQ. When dealing with | |
198 | * ``well-behaved'' queues (i.e., queues that do not spend too much | |
199 | * time to consume their budget and have true sequential behavior, and | |
200 | * when there are no external factors breaking anticipation) the | |
201 | * relative weights at each level of the cgroups hierarchy should be | |
202 | * guaranteed. All the fields are protected by the queue lock of the | |
203 | * containing bfqd. | |
aee69d78 PV |
204 | */ |
205 | struct bfq_entity { | |
206 | /* service_tree member */ | |
207 | struct rb_node rb_node; | |
208 | ||
209 | /* | |
e21b7a0b AA |
210 | * Flag, true if the entity is on a tree (either the active or |
211 | * the idle one of its service_tree) or is in service. | |
aee69d78 | 212 | */ |
e21b7a0b | 213 | bool on_st; |
aee69d78 PV |
214 | |
215 | /* B-WF2Q+ start and finish timestamps [sectors/weight] */ | |
216 | u64 start, finish; | |
217 | ||
218 | /* tree the entity is enqueued into; %NULL if not on a tree */ | |
219 | struct rb_root *tree; | |
220 | ||
221 | /* | |
222 | * minimum start time of the (active) subtree rooted at this | |
223 | * entity; used for O(log N) lookups into active trees | |
224 | */ | |
225 | u64 min_start; | |
226 | ||
227 | /* amount of service received during the last service slot */ | |
228 | int service; | |
229 | ||
230 | /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ | |
231 | int budget; | |
232 | ||
233 | /* weight of the queue */ | |
234 | int weight; | |
235 | /* next weight if a change is in progress */ | |
236 | int new_weight; | |
237 | ||
238 | /* original weight, used to implement weight boosting */ | |
239 | int orig_weight; | |
240 | ||
241 | /* parent entity, for hierarchical scheduling */ | |
242 | struct bfq_entity *parent; | |
243 | ||
244 | /* | |
245 | * For non-leaf nodes in the hierarchy, the associated | |
246 | * scheduler queue, %NULL on leaf nodes. | |
247 | */ | |
248 | struct bfq_sched_data *my_sched_data; | |
249 | /* the scheduler queue this entity belongs to */ | |
250 | struct bfq_sched_data *sched_data; | |
251 | ||
252 | /* flag, set to request a weight, ioprio or ioprio_class change */ | |
253 | int prio_changed; | |
254 | }; | |
255 | ||
e21b7a0b AA |
256 | struct bfq_group; |
257 | ||
aee69d78 PV |
258 | /** |
259 | * struct bfq_ttime - per process thinktime stats. | |
260 | */ | |
261 | struct bfq_ttime { | |
262 | /* completion time of the last request */ | |
263 | u64 last_end_request; | |
264 | ||
265 | /* total process thinktime */ | |
266 | u64 ttime_total; | |
267 | /* number of thinktime samples */ | |
268 | unsigned long ttime_samples; | |
269 | /* average process thinktime */ | |
270 | u64 ttime_mean; | |
271 | }; | |
272 | ||
273 | /** | |
274 | * struct bfq_queue - leaf schedulable entity. | |
275 | * | |
276 | * A bfq_queue is a leaf request queue; it can be associated with an | |
e21b7a0b AA |
277 | * io_context or more, if it is async. @cgroup holds a reference to |
278 | * the cgroup, to be sure that it does not disappear while a bfqq | |
279 | * still references it (mostly to avoid races between request issuing | |
280 | * and task migration followed by cgroup destruction). All the fields | |
281 | * are protected by the queue lock of the containing bfqd. | |
aee69d78 PV |
282 | */ |
283 | struct bfq_queue { | |
284 | /* reference counter */ | |
285 | int ref; | |
286 | /* parent bfq_data */ | |
287 | struct bfq_data *bfqd; | |
288 | ||
289 | /* current ioprio and ioprio class */ | |
290 | unsigned short ioprio, ioprio_class; | |
291 | /* next ioprio and ioprio class if a change is in progress */ | |
292 | unsigned short new_ioprio, new_ioprio_class; | |
293 | ||
294 | /* sorted list of pending requests */ | |
295 | struct rb_root sort_list; | |
296 | /* if fifo isn't expired, next request to serve */ | |
297 | struct request *next_rq; | |
298 | /* number of sync and async requests queued */ | |
299 | int queued[2]; | |
300 | /* number of requests currently allocated */ | |
301 | int allocated; | |
302 | /* number of pending metadata requests */ | |
303 | int meta_pending; | |
304 | /* fifo list of requests in sort_list */ | |
305 | struct list_head fifo; | |
306 | ||
307 | /* entity representing this queue in the scheduler */ | |
308 | struct bfq_entity entity; | |
309 | ||
310 | /* maximum budget allowed from the feedback mechanism */ | |
311 | int max_budget; | |
312 | /* budget expiration (in jiffies) */ | |
313 | unsigned long budget_timeout; | |
314 | ||
315 | /* number of requests on the dispatch list or inside driver */ | |
316 | int dispatched; | |
317 | ||
318 | /* status flags */ | |
319 | unsigned long flags; | |
320 | ||
321 | /* node for active/idle bfqq list inside parent bfqd */ | |
322 | struct list_head bfqq_list; | |
323 | ||
324 | /* associated @bfq_ttime struct */ | |
325 | struct bfq_ttime ttime; | |
326 | ||
327 | /* bit vector: a 1 for each seeky requests in history */ | |
328 | u32 seek_history; | |
329 | /* position of the last request enqueued */ | |
330 | sector_t last_request_pos; | |
331 | ||
332 | /* Number of consecutive pairs of request completion and | |
333 | * arrival, such that the queue becomes idle after the | |
334 | * completion, but the next request arrives within an idle | |
335 | * time slice; used only if the queue's IO_bound flag has been | |
336 | * cleared. | |
337 | */ | |
338 | unsigned int requests_within_timer; | |
339 | ||
340 | /* pid of the process owning the queue, used for logging purposes */ | |
341 | pid_t pid; | |
342 | }; | |
343 | ||
344 | /** | |
345 | * struct bfq_io_cq - per (request_queue, io_context) structure. | |
346 | */ | |
347 | struct bfq_io_cq { | |
348 | /* associated io_cq structure */ | |
349 | struct io_cq icq; /* must be the first member */ | |
350 | /* array of two process queues, the sync and the async */ | |
351 | struct bfq_queue *bfqq[2]; | |
352 | /* per (request_queue, blkcg) ioprio */ | |
353 | int ioprio; | |
e21b7a0b AA |
354 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
355 | uint64_t blkcg_serial_nr; /* the current blkcg serial */ | |
356 | #endif | |
aee69d78 PV |
357 | }; |
358 | ||
359 | /** | |
360 | * struct bfq_data - per-device data structure. | |
361 | * | |
362 | * All the fields are protected by @lock. | |
363 | */ | |
364 | struct bfq_data { | |
365 | /* device request queue */ | |
366 | struct request_queue *queue; | |
367 | /* dispatch queue */ | |
368 | struct list_head dispatch; | |
369 | ||
e21b7a0b AA |
370 | /* root bfq_group for the device */ |
371 | struct bfq_group *root_group; | |
aee69d78 PV |
372 | |
373 | /* | |
374 | * Number of bfq_queues containing requests (including the | |
375 | * queue in service, even if it is idling). | |
376 | */ | |
377 | int busy_queues; | |
378 | /* number of queued requests */ | |
379 | int queued; | |
380 | /* number of requests dispatched and waiting for completion */ | |
381 | int rq_in_driver; | |
382 | ||
383 | /* | |
384 | * Maximum number of requests in driver in the last | |
385 | * @hw_tag_samples completed requests. | |
386 | */ | |
387 | int max_rq_in_driver; | |
388 | /* number of samples used to calculate hw_tag */ | |
389 | int hw_tag_samples; | |
390 | /* flag set to one if the driver is showing a queueing behavior */ | |
391 | int hw_tag; | |
392 | ||
393 | /* number of budgets assigned */ | |
394 | int budgets_assigned; | |
395 | ||
396 | /* | |
397 | * Timer set when idling (waiting) for the next request from | |
398 | * the queue in service. | |
399 | */ | |
400 | struct hrtimer idle_slice_timer; | |
401 | ||
402 | /* bfq_queue in service */ | |
403 | struct bfq_queue *in_service_queue; | |
404 | /* bfq_io_cq (bic) associated with the @in_service_queue */ | |
405 | struct bfq_io_cq *in_service_bic; | |
406 | ||
407 | /* on-disk position of the last served request */ | |
408 | sector_t last_position; | |
409 | ||
ab0e43e9 PV |
410 | /* time of last request completion (ns) */ |
411 | u64 last_completion; | |
412 | ||
413 | /* time of first rq dispatch in current observation interval (ns) */ | |
414 | u64 first_dispatch; | |
415 | /* time of last rq dispatch in current observation interval (ns) */ | |
416 | u64 last_dispatch; | |
417 | ||
aee69d78 PV |
418 | /* beginning of the last budget */ |
419 | ktime_t last_budget_start; | |
420 | /* beginning of the last idle slice */ | |
421 | ktime_t last_idling_start; | |
ab0e43e9 PV |
422 | |
423 | /* number of samples in current observation interval */ | |
aee69d78 | 424 | int peak_rate_samples; |
ab0e43e9 PV |
425 | /* num of samples of seq dispatches in current observation interval */ |
426 | u32 sequential_samples; | |
427 | /* total num of sectors transferred in current observation interval */ | |
428 | u64 tot_sectors_dispatched; | |
429 | /* max rq size seen during current observation interval (sectors) */ | |
430 | u32 last_rq_max_size; | |
431 | /* time elapsed from first dispatch in current observ. interval (us) */ | |
432 | u64 delta_from_first; | |
aee69d78 | 433 | /* |
ab0e43e9 PV |
434 | * Current estimate of the device peak rate, measured in |
435 | * [BFQ_RATE_SHIFT * sectors/usec]. The left-shift by | |
436 | * BFQ_RATE_SHIFT is performed to increase precision in | |
aee69d78 PV |
437 | * fixed-point calculations. |
438 | */ | |
ab0e43e9 PV |
439 | u32 peak_rate; |
440 | ||
aee69d78 PV |
441 | /* maximum budget allotted to a bfq_queue before rescheduling */ |
442 | int bfq_max_budget; | |
443 | ||
444 | /* list of all the bfq_queues active on the device */ | |
445 | struct list_head active_list; | |
446 | /* list of all the bfq_queues idle on the device */ | |
447 | struct list_head idle_list; | |
448 | ||
449 | /* | |
450 | * Timeout for async/sync requests; when it fires, requests | |
451 | * are served in fifo order. | |
452 | */ | |
453 | u64 bfq_fifo_expire[2]; | |
454 | /* weight of backward seeks wrt forward ones */ | |
455 | unsigned int bfq_back_penalty; | |
456 | /* maximum allowed backward seek */ | |
457 | unsigned int bfq_back_max; | |
458 | /* maximum idling time */ | |
459 | u32 bfq_slice_idle; | |
aee69d78 PV |
460 | |
461 | /* user-configured max budget value (0 for auto-tuning) */ | |
462 | int bfq_user_max_budget; | |
463 | /* | |
464 | * Timeout for bfq_queues to consume their budget; used to | |
465 | * prevent seeky queues from imposing long latencies to | |
466 | * sequential or quasi-sequential ones (this also implies that | |
467 | * seeky queues cannot receive guarantees in the service | |
468 | * domain; after a timeout they are charged for the time they | |
469 | * have been in service, to preserve fairness among them, but | |
470 | * without service-domain guarantees). | |
471 | */ | |
472 | unsigned int bfq_timeout; | |
473 | ||
474 | /* | |
475 | * Number of consecutive requests that must be issued within | |
476 | * the idle time slice to set again idling to a queue which | |
477 | * was marked as non-I/O-bound (see the definition of the | |
478 | * IO_bound flag for further details). | |
479 | */ | |
480 | unsigned int bfq_requests_within_timer; | |
481 | ||
482 | /* | |
483 | * Force device idling whenever needed to provide accurate | |
484 | * service guarantees, without caring about throughput | |
485 | * issues. CAVEAT: this may even increase latencies, in case | |
486 | * of useless idling for processes that did stop doing I/O. | |
487 | */ | |
488 | bool strict_guarantees; | |
489 | ||
490 | /* fallback dummy bfqq for extreme OOM conditions */ | |
491 | struct bfq_queue oom_bfqq; | |
492 | ||
493 | spinlock_t lock; | |
494 | ||
495 | /* | |
496 | * bic associated with the task issuing current bio for | |
497 | * merging. This and the next field are used as a support to | |
498 | * be able to perform the bic lookup, needed by bio-merge | |
499 | * functions, before the scheduler lock is taken, and thus | |
500 | * avoid taking the request-queue lock while the scheduler | |
501 | * lock is being held. | |
502 | */ | |
503 | struct bfq_io_cq *bio_bic; | |
504 | /* bfqq associated with the task issuing current bio for merging */ | |
505 | struct bfq_queue *bio_bfqq; | |
506 | }; | |
507 | ||
508 | enum bfqq_state_flags { | |
509 | BFQQF_busy = 0, /* has requests or is in service */ | |
510 | BFQQF_wait_request, /* waiting for a request */ | |
511 | BFQQF_non_blocking_wait_rq, /* | |
512 | * waiting for a request | |
513 | * without idling the device | |
514 | */ | |
515 | BFQQF_fifo_expire, /* FIFO checked in this slice */ | |
516 | BFQQF_idle_window, /* slice idling enabled */ | |
517 | BFQQF_sync, /* synchronous queue */ | |
518 | BFQQF_budget_new, /* no completion with this budget */ | |
519 | BFQQF_IO_bound, /* | |
520 | * bfqq has timed-out at least once | |
521 | * having consumed at most 2/10 of | |
522 | * its budget | |
523 | */ | |
524 | }; | |
525 | ||
526 | #define BFQ_BFQQ_FNS(name) \ | |
527 | static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ | |
528 | { \ | |
529 | __set_bit(BFQQF_##name, &(bfqq)->flags); \ | |
530 | } \ | |
531 | static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ | |
532 | { \ | |
533 | __clear_bit(BFQQF_##name, &(bfqq)->flags); \ | |
534 | } \ | |
535 | static int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ | |
536 | { \ | |
537 | return test_bit(BFQQF_##name, &(bfqq)->flags); \ | |
538 | } | |
539 | ||
540 | BFQ_BFQQ_FNS(busy); | |
541 | BFQ_BFQQ_FNS(wait_request); | |
542 | BFQ_BFQQ_FNS(non_blocking_wait_rq); | |
543 | BFQ_BFQQ_FNS(fifo_expire); | |
544 | BFQ_BFQQ_FNS(idle_window); | |
545 | BFQ_BFQQ_FNS(sync); | |
546 | BFQ_BFQQ_FNS(budget_new); | |
547 | BFQ_BFQQ_FNS(IO_bound); | |
548 | #undef BFQ_BFQQ_FNS | |
549 | ||
550 | /* Logging facilities. */ | |
e21b7a0b AA |
551 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
552 | static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); | |
553 | static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); | |
554 | ||
555 | #define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ | |
556 | char __pbuf[128]; \ | |
557 | \ | |
558 | blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \ | |
559 | blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, (bfqq)->pid, \ | |
560 | bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ | |
561 | __pbuf, ##args); \ | |
562 | } while (0) | |
563 | ||
564 | #define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ | |
565 | char __pbuf[128]; \ | |
566 | \ | |
567 | blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \ | |
568 | blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args); \ | |
569 | } while (0) | |
570 | ||
571 | #else /* CONFIG_BFQ_GROUP_IOSCHED */ | |
572 | ||
573 | #define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ | |
574 | blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \ | |
575 | bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ | |
576 | ##args) | |
577 | #define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) | |
578 | ||
579 | #endif /* CONFIG_BFQ_GROUP_IOSCHED */ | |
aee69d78 PV |
580 | |
581 | #define bfq_log(bfqd, fmt, args...) \ | |
582 | blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) | |
583 | ||
584 | /* Expiration reasons. */ | |
585 | enum bfqq_expiration { | |
586 | BFQQE_TOO_IDLE = 0, /* | |
587 | * queue has been idling for | |
588 | * too long | |
589 | */ | |
590 | BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */ | |
591 | BFQQE_BUDGET_EXHAUSTED, /* budget consumed */ | |
592 | BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */ | |
593 | BFQQE_PREEMPTED /* preemption in progress */ | |
594 | }; | |
595 | ||
e21b7a0b AA |
596 | struct bfqg_stats { |
597 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
598 | /* number of ios merged */ | |
599 | struct blkg_rwstat merged; | |
600 | /* total time spent on device in ns, may not be accurate w/ queueing */ | |
601 | struct blkg_rwstat service_time; | |
602 | /* total time spent waiting in scheduler queue in ns */ | |
603 | struct blkg_rwstat wait_time; | |
604 | /* number of IOs queued up */ | |
605 | struct blkg_rwstat queued; | |
606 | /* total disk time and nr sectors dispatched by this group */ | |
607 | struct blkg_stat time; | |
608 | /* sum of number of ios queued across all samples */ | |
609 | struct blkg_stat avg_queue_size_sum; | |
610 | /* count of samples taken for average */ | |
611 | struct blkg_stat avg_queue_size_samples; | |
612 | /* how many times this group has been removed from service tree */ | |
613 | struct blkg_stat dequeue; | |
614 | /* total time spent waiting for it to be assigned a timeslice. */ | |
615 | struct blkg_stat group_wait_time; | |
616 | /* time spent idling for this blkcg_gq */ | |
617 | struct blkg_stat idle_time; | |
618 | /* total time with empty current active q with other requests queued */ | |
619 | struct blkg_stat empty_time; | |
620 | /* fields after this shouldn't be cleared on stat reset */ | |
621 | uint64_t start_group_wait_time; | |
622 | uint64_t start_idle_time; | |
623 | uint64_t start_empty_time; | |
624 | uint16_t flags; | |
625 | #endif /* CONFIG_BFQ_GROUP_IOSCHED */ | |
626 | }; | |
627 | ||
628 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
629 | ||
630 | /* | |
631 | * struct bfq_group_data - per-blkcg storage for the blkio subsystem. | |
632 | * | |
633 | * @ps: @blkcg_policy_storage that this structure inherits | |
634 | * @weight: weight of the bfq_group | |
635 | */ | |
636 | struct bfq_group_data { | |
637 | /* must be the first member */ | |
638 | struct blkcg_policy_data pd; | |
639 | ||
640 | unsigned short weight; | |
641 | }; | |
642 | ||
643 | /** | |
644 | * struct bfq_group - per (device, cgroup) data structure. | |
645 | * @entity: schedulable entity to insert into the parent group sched_data. | |
646 | * @sched_data: own sched_data, to contain child entities (they may be | |
647 | * both bfq_queues and bfq_groups). | |
648 | * @bfqd: the bfq_data for the device this group acts upon. | |
649 | * @async_bfqq: array of async queues for all the tasks belonging to | |
650 | * the group, one queue per ioprio value per ioprio_class, | |
651 | * except for the idle class that has only one queue. | |
652 | * @async_idle_bfqq: async queue for the idle class (ioprio is ignored). | |
653 | * @my_entity: pointer to @entity, %NULL for the toplevel group; used | |
654 | * to avoid too many special cases during group creation/ | |
655 | * migration. | |
656 | * @stats: stats for this bfqg. | |
657 | * | |
658 | * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup | |
659 | * there is a set of bfq_groups, each one collecting the lower-level | |
660 | * entities belonging to the group that are acting on the same device. | |
661 | * | |
662 | * Locking works as follows: | |
663 | * o @bfqd is protected by the queue lock, RCU is used to access it | |
664 | * from the readers. | |
665 | * o All the other fields are protected by the @bfqd queue lock. | |
666 | */ | |
667 | struct bfq_group { | |
668 | /* must be the first member */ | |
669 | struct blkg_policy_data pd; | |
670 | ||
671 | struct bfq_entity entity; | |
672 | struct bfq_sched_data sched_data; | |
673 | ||
674 | void *bfqd; | |
675 | ||
676 | struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; | |
677 | struct bfq_queue *async_idle_bfqq; | |
678 | ||
679 | struct bfq_entity *my_entity; | |
680 | ||
681 | struct bfqg_stats stats; | |
682 | }; | |
683 | ||
684 | #else | |
685 | struct bfq_group { | |
686 | struct bfq_sched_data sched_data; | |
687 | ||
688 | struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; | |
689 | struct bfq_queue *async_idle_bfqq; | |
690 | ||
691 | struct rb_root rq_pos_tree; | |
692 | }; | |
693 | #endif | |
694 | ||
aee69d78 PV |
695 | static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); |
696 | ||
e21b7a0b AA |
697 | static unsigned int bfq_class_idx(struct bfq_entity *entity) |
698 | { | |
699 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
700 | ||
701 | return bfqq ? bfqq->ioprio_class - 1 : | |
702 | BFQ_DEFAULT_GRP_CLASS - 1; | |
703 | } | |
704 | ||
aee69d78 PV |
705 | static struct bfq_service_tree * |
706 | bfq_entity_service_tree(struct bfq_entity *entity) | |
707 | { | |
708 | struct bfq_sched_data *sched_data = entity->sched_data; | |
e21b7a0b | 709 | unsigned int idx = bfq_class_idx(entity); |
aee69d78 PV |
710 | |
711 | return sched_data->service_tree + idx; | |
712 | } | |
713 | ||
714 | static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync) | |
715 | { | |
716 | return bic->bfqq[is_sync]; | |
717 | } | |
718 | ||
719 | static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, | |
720 | bool is_sync) | |
721 | { | |
722 | bic->bfqq[is_sync] = bfqq; | |
723 | } | |
724 | ||
725 | static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) | |
726 | { | |
727 | return bic->icq.q->elevator->elevator_data; | |
728 | } | |
729 | ||
730 | static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio); | |
731 | static void bfq_put_queue(struct bfq_queue *bfqq); | |
732 | static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, | |
733 | struct bio *bio, bool is_sync, | |
734 | struct bfq_io_cq *bic); | |
e21b7a0b | 735 | static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); |
aee69d78 PV |
736 | static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); |
737 | ||
aee69d78 PV |
738 | /* Expiration time of sync (0) and async (1) requests, in ns. */ |
739 | static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 }; | |
740 | ||
741 | /* Maximum backwards seek (magic number lifted from CFQ), in KiB. */ | |
742 | static const int bfq_back_max = 16 * 1024; | |
743 | ||
744 | /* Penalty of a backwards seek, in number of sectors. */ | |
745 | static const int bfq_back_penalty = 2; | |
746 | ||
747 | /* Idling period duration, in ns. */ | |
748 | static u64 bfq_slice_idle = NSEC_PER_SEC / 125; | |
749 | ||
750 | /* Minimum number of assigned budgets for which stats are safe to compute. */ | |
751 | static const int bfq_stats_min_budgets = 194; | |
752 | ||
753 | /* Default maximum budget values, in sectors and number of requests. */ | |
754 | static const int bfq_default_max_budget = 16 * 1024; | |
755 | ||
756 | /* Default timeout values, in jiffies, approximating CFQ defaults. */ | |
757 | static const int bfq_timeout = HZ / 8; | |
758 | ||
759 | static struct kmem_cache *bfq_pool; | |
760 | ||
ab0e43e9 | 761 | /* Below this threshold (in ns), we consider thinktime immediate. */ |
aee69d78 PV |
762 | #define BFQ_MIN_TT (2 * NSEC_PER_MSEC) |
763 | ||
764 | /* hw_tag detection: parallel requests threshold and min samples needed. */ | |
765 | #define BFQ_HW_QUEUE_THRESHOLD 4 | |
766 | #define BFQ_HW_QUEUE_SAMPLES 32 | |
767 | ||
768 | #define BFQQ_SEEK_THR (sector_t)(8 * 100) | |
769 | #define BFQQ_SECT_THR_NONROT (sector_t)(2 * 32) | |
770 | #define BFQQ_CLOSE_THR (sector_t)(8 * 1024) | |
771 | #define BFQQ_SEEKY(bfqq) (hweight32(bfqq->seek_history) > 32/8) | |
772 | ||
ab0e43e9 PV |
773 | /* Min number of samples required to perform peak-rate update */ |
774 | #define BFQ_RATE_MIN_SAMPLES 32 | |
775 | /* Min observation time interval required to perform a peak-rate update (ns) */ | |
776 | #define BFQ_RATE_MIN_INTERVAL (300*NSEC_PER_MSEC) | |
777 | /* Target observation time interval for a peak-rate update (ns) */ | |
778 | #define BFQ_RATE_REF_INTERVAL NSEC_PER_SEC | |
aee69d78 PV |
779 | |
780 | /* Shift used for peak rate fixed precision calculations. */ | |
781 | #define BFQ_RATE_SHIFT 16 | |
782 | ||
783 | #define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ | |
784 | { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) | |
785 | ||
786 | #define RQ_BIC(rq) ((struct bfq_io_cq *) (rq)->elv.priv[0]) | |
787 | #define RQ_BFQQ(rq) ((rq)->elv.priv[1]) | |
788 | ||
789 | /** | |
790 | * icq_to_bic - convert iocontext queue structure to bfq_io_cq. | |
791 | * @icq: the iocontext queue. | |
792 | */ | |
793 | static struct bfq_io_cq *icq_to_bic(struct io_cq *icq) | |
794 | { | |
795 | /* bic->icq is the first member, %NULL will convert to %NULL */ | |
796 | return container_of(icq, struct bfq_io_cq, icq); | |
797 | } | |
798 | ||
799 | /** | |
800 | * bfq_bic_lookup - search into @ioc a bic associated to @bfqd. | |
801 | * @bfqd: the lookup key. | |
802 | * @ioc: the io_context of the process doing I/O. | |
803 | * @q: the request queue. | |
804 | */ | |
805 | static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd, | |
806 | struct io_context *ioc, | |
807 | struct request_queue *q) | |
808 | { | |
809 | if (ioc) { | |
810 | unsigned long flags; | |
811 | struct bfq_io_cq *icq; | |
812 | ||
813 | spin_lock_irqsave(q->queue_lock, flags); | |
814 | icq = icq_to_bic(ioc_lookup_icq(ioc, q)); | |
815 | spin_unlock_irqrestore(q->queue_lock, flags); | |
816 | ||
817 | return icq; | |
818 | } | |
819 | ||
820 | return NULL; | |
821 | } | |
822 | ||
823 | /* | |
e21b7a0b AA |
824 | * Scheduler run of queue, if there are requests pending and no one in the |
825 | * driver that will restart queueing. | |
826 | */ | |
827 | static void bfq_schedule_dispatch(struct bfq_data *bfqd) | |
828 | { | |
829 | if (bfqd->queued != 0) { | |
830 | bfq_log(bfqd, "schedule dispatch"); | |
831 | blk_mq_run_hw_queues(bfqd->queue, true); | |
832 | } | |
833 | } | |
834 | ||
835 | /** | |
836 | * bfq_gt - compare two timestamps. | |
837 | * @a: first ts. | |
838 | * @b: second ts. | |
839 | * | |
840 | * Return @a > @b, dealing with wrapping correctly. | |
841 | */ | |
842 | static int bfq_gt(u64 a, u64 b) | |
843 | { | |
844 | return (s64)(a - b) > 0; | |
845 | } | |
846 | ||
847 | static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree) | |
848 | { | |
849 | struct rb_node *node = tree->rb_node; | |
850 | ||
851 | return rb_entry(node, struct bfq_entity, rb_node); | |
852 | } | |
853 | ||
854 | static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd); | |
855 | ||
856 | static bool bfq_update_parent_budget(struct bfq_entity *next_in_service); | |
857 | ||
858 | /** | |
859 | * bfq_update_next_in_service - update sd->next_in_service | |
860 | * @sd: sched_data for which to perform the update. | |
861 | * @new_entity: if not NULL, pointer to the entity whose activation, | |
862 | * requeueing or repositionig triggered the invocation of | |
863 | * this function. | |
864 | * | |
865 | * This function is called to update sd->next_in_service, which, in | |
866 | * its turn, may change as a consequence of the insertion or | |
867 | * extraction of an entity into/from one of the active trees of | |
868 | * sd. These insertions/extractions occur as a consequence of | |
869 | * activations/deactivations of entities, with some activations being | |
870 | * 'true' activations, and other activations being requeueings (i.e., | |
871 | * implementing the second, requeueing phase of the mechanism used to | |
872 | * reposition an entity in its active tree; see comments on | |
873 | * __bfq_activate_entity and __bfq_requeue_entity for details). In | |
874 | * both the last two activation sub-cases, new_entity points to the | |
875 | * just activated or requeued entity. | |
876 | * | |
877 | * Returns true if sd->next_in_service changes in such a way that | |
878 | * entity->parent may become the next_in_service for its parent | |
879 | * entity. | |
aee69d78 | 880 | */ |
e21b7a0b AA |
881 | static bool bfq_update_next_in_service(struct bfq_sched_data *sd, |
882 | struct bfq_entity *new_entity) | |
883 | { | |
884 | struct bfq_entity *next_in_service = sd->next_in_service; | |
885 | bool parent_sched_may_change = false; | |
886 | ||
887 | /* | |
888 | * If this update is triggered by the activation, requeueing | |
889 | * or repositiong of an entity that does not coincide with | |
890 | * sd->next_in_service, then a full lookup in the active tree | |
891 | * can be avoided. In fact, it is enough to check whether the | |
892 | * just-modified entity has a higher priority than | |
893 | * sd->next_in_service, or, even if it has the same priority | |
894 | * as sd->next_in_service, is eligible and has a lower virtual | |
895 | * finish time than sd->next_in_service. If this compound | |
896 | * condition holds, then the new entity becomes the new | |
897 | * next_in_service. Otherwise no change is needed. | |
898 | */ | |
899 | if (new_entity && new_entity != sd->next_in_service) { | |
900 | /* | |
901 | * Flag used to decide whether to replace | |
902 | * sd->next_in_service with new_entity. Tentatively | |
903 | * set to true, and left as true if | |
904 | * sd->next_in_service is NULL. | |
905 | */ | |
906 | bool replace_next = true; | |
907 | ||
908 | /* | |
909 | * If there is already a next_in_service candidate | |
910 | * entity, then compare class priorities or timestamps | |
911 | * to decide whether to replace sd->service_tree with | |
912 | * new_entity. | |
913 | */ | |
914 | if (next_in_service) { | |
915 | unsigned int new_entity_class_idx = | |
916 | bfq_class_idx(new_entity); | |
917 | struct bfq_service_tree *st = | |
918 | sd->service_tree + new_entity_class_idx; | |
919 | ||
920 | /* | |
921 | * For efficiency, evaluate the most likely | |
922 | * sub-condition first. | |
923 | */ | |
924 | replace_next = | |
925 | (new_entity_class_idx == | |
926 | bfq_class_idx(next_in_service) | |
927 | && | |
928 | !bfq_gt(new_entity->start, st->vtime) | |
929 | && | |
930 | bfq_gt(next_in_service->finish, | |
931 | new_entity->finish)) | |
932 | || | |
933 | new_entity_class_idx < | |
934 | bfq_class_idx(next_in_service); | |
935 | } | |
936 | ||
937 | if (replace_next) | |
938 | next_in_service = new_entity; | |
939 | } else /* invoked because of a deactivation: lookup needed */ | |
940 | next_in_service = bfq_lookup_next_entity(sd); | |
941 | ||
942 | if (next_in_service) { | |
943 | parent_sched_may_change = !sd->next_in_service || | |
944 | bfq_update_parent_budget(next_in_service); | |
945 | } | |
946 | ||
947 | sd->next_in_service = next_in_service; | |
948 | ||
949 | if (!next_in_service) | |
950 | return parent_sched_may_change; | |
951 | ||
952 | return parent_sched_may_change; | |
953 | } | |
954 | ||
955 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
956 | /* both next loops stop at one of the child entities of the root group */ | |
aee69d78 | 957 | #define for_each_entity(entity) \ |
e21b7a0b | 958 | for (; entity ; entity = entity->parent) |
aee69d78 | 959 | |
e21b7a0b AA |
960 | /* |
961 | * For each iteration, compute parent in advance, so as to be safe if | |
962 | * entity is deallocated during the iteration. Such a deallocation may | |
963 | * happen as a consequence of a bfq_put_queue that frees the bfq_queue | |
964 | * containing entity. | |
965 | */ | |
aee69d78 | 966 | #define for_each_entity_safe(entity, parent) \ |
e21b7a0b | 967 | for (; entity && ({ parent = entity->parent; 1; }); entity = parent) |
aee69d78 | 968 | |
e21b7a0b AA |
969 | /* |
970 | * Returns true if this budget changes may let next_in_service->parent | |
971 | * become the next_in_service entity for its parent entity. | |
972 | */ | |
973 | static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) | |
aee69d78 | 974 | { |
e21b7a0b AA |
975 | struct bfq_entity *bfqg_entity; |
976 | struct bfq_group *bfqg; | |
977 | struct bfq_sched_data *group_sd; | |
978 | bool ret = false; | |
979 | ||
980 | group_sd = next_in_service->sched_data; | |
981 | ||
982 | bfqg = container_of(group_sd, struct bfq_group, sched_data); | |
983 | /* | |
984 | * bfq_group's my_entity field is not NULL only if the group | |
985 | * is not the root group. We must not touch the root entity | |
986 | * as it must never become an in-service entity. | |
987 | */ | |
988 | bfqg_entity = bfqg->my_entity; | |
989 | if (bfqg_entity) { | |
990 | if (bfqg_entity->budget > next_in_service->budget) | |
991 | ret = true; | |
992 | bfqg_entity->budget = next_in_service->budget; | |
993 | } | |
994 | ||
995 | return ret; | |
996 | } | |
997 | ||
998 | /* | |
999 | * This function tells whether entity stops being a candidate for next | |
1000 | * service, according to the following logic. | |
1001 | * | |
1002 | * This function is invoked for an entity that is about to be set in | |
1003 | * service. If such an entity is a queue, then the entity is no longer | |
1004 | * a candidate for next service (i.e, a candidate entity to serve | |
1005 | * after the in-service entity is expired). The function then returns | |
1006 | * true. | |
1007 | */ | |
1008 | static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) | |
1009 | { | |
1010 | if (bfq_entity_to_bfqq(entity)) | |
1011 | return true; | |
1012 | ||
1013 | return false; | |
aee69d78 PV |
1014 | } |
1015 | ||
e21b7a0b AA |
1016 | #else /* CONFIG_BFQ_GROUP_IOSCHED */ |
1017 | /* | |
1018 | * Next two macros are fake loops when cgroups support is not | |
1019 | * enabled. I fact, in such a case, there is only one level to go up | |
1020 | * (to reach the root group). | |
1021 | */ | |
1022 | #define for_each_entity(entity) \ | |
1023 | for (; entity ; entity = NULL) | |
1024 | ||
1025 | #define for_each_entity_safe(entity, parent) \ | |
1026 | for (parent = NULL; entity ; entity = parent) | |
1027 | ||
1028 | static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) | |
aee69d78 | 1029 | { |
e21b7a0b | 1030 | return false; |
aee69d78 PV |
1031 | } |
1032 | ||
e21b7a0b | 1033 | static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) |
aee69d78 | 1034 | { |
e21b7a0b | 1035 | return true; |
aee69d78 PV |
1036 | } |
1037 | ||
e21b7a0b AA |
1038 | #endif /* CONFIG_BFQ_GROUP_IOSCHED */ |
1039 | ||
aee69d78 PV |
1040 | /* |
1041 | * Shift for timestamp calculations. This actually limits the maximum | |
1042 | * service allowed in one timestamp delta (small shift values increase it), | |
1043 | * the maximum total weight that can be used for the queues in the system | |
1044 | * (big shift values increase it), and the period of virtual time | |
1045 | * wraparounds. | |
1046 | */ | |
1047 | #define WFQ_SERVICE_SHIFT 22 | |
1048 | ||
aee69d78 PV |
1049 | static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) |
1050 | { | |
1051 | struct bfq_queue *bfqq = NULL; | |
1052 | ||
1053 | if (!entity->my_sched_data) | |
1054 | bfqq = container_of(entity, struct bfq_queue, entity); | |
1055 | ||
1056 | return bfqq; | |
1057 | } | |
1058 | ||
1059 | ||
1060 | /** | |
1061 | * bfq_delta - map service into the virtual time domain. | |
1062 | * @service: amount of service. | |
1063 | * @weight: scale factor (weight of an entity or weight sum). | |
1064 | */ | |
1065 | static u64 bfq_delta(unsigned long service, unsigned long weight) | |
1066 | { | |
1067 | u64 d = (u64)service << WFQ_SERVICE_SHIFT; | |
1068 | ||
1069 | do_div(d, weight); | |
1070 | return d; | |
1071 | } | |
1072 | ||
1073 | /** | |
1074 | * bfq_calc_finish - assign the finish time to an entity. | |
1075 | * @entity: the entity to act upon. | |
1076 | * @service: the service to be charged to the entity. | |
1077 | */ | |
1078 | static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service) | |
1079 | { | |
1080 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1081 | ||
1082 | entity->finish = entity->start + | |
1083 | bfq_delta(service, entity->weight); | |
1084 | ||
1085 | if (bfqq) { | |
1086 | bfq_log_bfqq(bfqq->bfqd, bfqq, | |
1087 | "calc_finish: serv %lu, w %d", | |
1088 | service, entity->weight); | |
1089 | bfq_log_bfqq(bfqq->bfqd, bfqq, | |
1090 | "calc_finish: start %llu, finish %llu, delta %llu", | |
1091 | entity->start, entity->finish, | |
1092 | bfq_delta(service, entity->weight)); | |
1093 | } | |
1094 | } | |
1095 | ||
1096 | /** | |
1097 | * bfq_entity_of - get an entity from a node. | |
1098 | * @node: the node field of the entity. | |
1099 | * | |
1100 | * Convert a node pointer to the relative entity. This is used only | |
1101 | * to simplify the logic of some functions and not as the generic | |
1102 | * conversion mechanism because, e.g., in the tree walking functions, | |
1103 | * the check for a %NULL value would be redundant. | |
1104 | */ | |
1105 | static struct bfq_entity *bfq_entity_of(struct rb_node *node) | |
1106 | { | |
1107 | struct bfq_entity *entity = NULL; | |
1108 | ||
1109 | if (node) | |
1110 | entity = rb_entry(node, struct bfq_entity, rb_node); | |
1111 | ||
1112 | return entity; | |
1113 | } | |
1114 | ||
1115 | /** | |
1116 | * bfq_extract - remove an entity from a tree. | |
1117 | * @root: the tree root. | |
1118 | * @entity: the entity to remove. | |
1119 | */ | |
1120 | static void bfq_extract(struct rb_root *root, struct bfq_entity *entity) | |
1121 | { | |
1122 | entity->tree = NULL; | |
1123 | rb_erase(&entity->rb_node, root); | |
1124 | } | |
1125 | ||
1126 | /** | |
1127 | * bfq_idle_extract - extract an entity from the idle tree. | |
1128 | * @st: the service tree of the owning @entity. | |
1129 | * @entity: the entity being removed. | |
1130 | */ | |
1131 | static void bfq_idle_extract(struct bfq_service_tree *st, | |
1132 | struct bfq_entity *entity) | |
1133 | { | |
1134 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1135 | struct rb_node *next; | |
1136 | ||
1137 | if (entity == st->first_idle) { | |
1138 | next = rb_next(&entity->rb_node); | |
1139 | st->first_idle = bfq_entity_of(next); | |
1140 | } | |
1141 | ||
1142 | if (entity == st->last_idle) { | |
1143 | next = rb_prev(&entity->rb_node); | |
1144 | st->last_idle = bfq_entity_of(next); | |
1145 | } | |
1146 | ||
1147 | bfq_extract(&st->idle, entity); | |
1148 | ||
1149 | if (bfqq) | |
1150 | list_del(&bfqq->bfqq_list); | |
1151 | } | |
1152 | ||
1153 | /** | |
1154 | * bfq_insert - generic tree insertion. | |
1155 | * @root: tree root. | |
1156 | * @entity: entity to insert. | |
1157 | * | |
1158 | * This is used for the idle and the active tree, since they are both | |
1159 | * ordered by finish time. | |
1160 | */ | |
1161 | static void bfq_insert(struct rb_root *root, struct bfq_entity *entity) | |
1162 | { | |
1163 | struct bfq_entity *entry; | |
1164 | struct rb_node **node = &root->rb_node; | |
1165 | struct rb_node *parent = NULL; | |
1166 | ||
1167 | while (*node) { | |
1168 | parent = *node; | |
1169 | entry = rb_entry(parent, struct bfq_entity, rb_node); | |
1170 | ||
1171 | if (bfq_gt(entry->finish, entity->finish)) | |
1172 | node = &parent->rb_left; | |
1173 | else | |
1174 | node = &parent->rb_right; | |
1175 | } | |
1176 | ||
1177 | rb_link_node(&entity->rb_node, parent, node); | |
1178 | rb_insert_color(&entity->rb_node, root); | |
1179 | ||
1180 | entity->tree = root; | |
1181 | } | |
1182 | ||
1183 | /** | |
1184 | * bfq_update_min - update the min_start field of a entity. | |
1185 | * @entity: the entity to update. | |
1186 | * @node: one of its children. | |
1187 | * | |
1188 | * This function is called when @entity may store an invalid value for | |
1189 | * min_start due to updates to the active tree. The function assumes | |
1190 | * that the subtree rooted at @node (which may be its left or its right | |
1191 | * child) has a valid min_start value. | |
1192 | */ | |
1193 | static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node) | |
1194 | { | |
1195 | struct bfq_entity *child; | |
1196 | ||
1197 | if (node) { | |
1198 | child = rb_entry(node, struct bfq_entity, rb_node); | |
1199 | if (bfq_gt(entity->min_start, child->min_start)) | |
1200 | entity->min_start = child->min_start; | |
1201 | } | |
1202 | } | |
1203 | ||
1204 | /** | |
1205 | * bfq_update_active_node - recalculate min_start. | |
1206 | * @node: the node to update. | |
1207 | * | |
1208 | * @node may have changed position or one of its children may have moved, | |
1209 | * this function updates its min_start value. The left and right subtrees | |
1210 | * are assumed to hold a correct min_start value. | |
1211 | */ | |
1212 | static void bfq_update_active_node(struct rb_node *node) | |
1213 | { | |
1214 | struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node); | |
1215 | ||
1216 | entity->min_start = entity->start; | |
1217 | bfq_update_min(entity, node->rb_right); | |
1218 | bfq_update_min(entity, node->rb_left); | |
1219 | } | |
1220 | ||
1221 | /** | |
1222 | * bfq_update_active_tree - update min_start for the whole active tree. | |
1223 | * @node: the starting node. | |
1224 | * | |
1225 | * @node must be the deepest modified node after an update. This function | |
1226 | * updates its min_start using the values held by its children, assuming | |
1227 | * that they did not change, and then updates all the nodes that may have | |
1228 | * changed in the path to the root. The only nodes that may have changed | |
1229 | * are the ones in the path or their siblings. | |
1230 | */ | |
1231 | static void bfq_update_active_tree(struct rb_node *node) | |
1232 | { | |
1233 | struct rb_node *parent; | |
1234 | ||
1235 | up: | |
1236 | bfq_update_active_node(node); | |
1237 | ||
1238 | parent = rb_parent(node); | |
1239 | if (!parent) | |
1240 | return; | |
1241 | ||
1242 | if (node == parent->rb_left && parent->rb_right) | |
1243 | bfq_update_active_node(parent->rb_right); | |
1244 | else if (parent->rb_left) | |
1245 | bfq_update_active_node(parent->rb_left); | |
1246 | ||
1247 | node = parent; | |
1248 | goto up; | |
1249 | } | |
1250 | ||
1251 | /** | |
1252 | * bfq_active_insert - insert an entity in the active tree of its | |
1253 | * group/device. | |
1254 | * @st: the service tree of the entity. | |
1255 | * @entity: the entity being inserted. | |
1256 | * | |
1257 | * The active tree is ordered by finish time, but an extra key is kept | |
1258 | * per each node, containing the minimum value for the start times of | |
1259 | * its children (and the node itself), so it's possible to search for | |
1260 | * the eligible node with the lowest finish time in logarithmic time. | |
1261 | */ | |
1262 | static void bfq_active_insert(struct bfq_service_tree *st, | |
1263 | struct bfq_entity *entity) | |
1264 | { | |
1265 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1266 | struct rb_node *node = &entity->rb_node; | |
e21b7a0b AA |
1267 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
1268 | struct bfq_sched_data *sd = NULL; | |
1269 | struct bfq_group *bfqg = NULL; | |
1270 | struct bfq_data *bfqd = NULL; | |
1271 | #endif | |
aee69d78 PV |
1272 | |
1273 | bfq_insert(&st->active, entity); | |
1274 | ||
1275 | if (node->rb_left) | |
1276 | node = node->rb_left; | |
1277 | else if (node->rb_right) | |
1278 | node = node->rb_right; | |
1279 | ||
1280 | bfq_update_active_tree(node); | |
1281 | ||
e21b7a0b AA |
1282 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
1283 | sd = entity->sched_data; | |
1284 | bfqg = container_of(sd, struct bfq_group, sched_data); | |
1285 | bfqd = (struct bfq_data *)bfqg->bfqd; | |
1286 | #endif | |
aee69d78 PV |
1287 | if (bfqq) |
1288 | list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list); | |
1289 | } | |
1290 | ||
1291 | /** | |
1292 | * bfq_ioprio_to_weight - calc a weight from an ioprio. | |
1293 | * @ioprio: the ioprio value to convert. | |
1294 | */ | |
1295 | static unsigned short bfq_ioprio_to_weight(int ioprio) | |
1296 | { | |
1297 | return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF; | |
1298 | } | |
1299 | ||
1300 | /** | |
1301 | * bfq_weight_to_ioprio - calc an ioprio from a weight. | |
1302 | * @weight: the weight value to convert. | |
1303 | * | |
1304 | * To preserve as much as possible the old only-ioprio user interface, | |
1305 | * 0 is used as an escape ioprio value for weights (numerically) equal or | |
1306 | * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF. | |
1307 | */ | |
1308 | static unsigned short bfq_weight_to_ioprio(int weight) | |
1309 | { | |
1310 | return max_t(int, 0, | |
1311 | IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight); | |
1312 | } | |
1313 | ||
1314 | static void bfq_get_entity(struct bfq_entity *entity) | |
1315 | { | |
1316 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1317 | ||
1318 | if (bfqq) { | |
1319 | bfqq->ref++; | |
1320 | bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", | |
1321 | bfqq, bfqq->ref); | |
1322 | } | |
1323 | } | |
1324 | ||
1325 | /** | |
1326 | * bfq_find_deepest - find the deepest node that an extraction can modify. | |
1327 | * @node: the node being removed. | |
1328 | * | |
1329 | * Do the first step of an extraction in an rb tree, looking for the | |
1330 | * node that will replace @node, and returning the deepest node that | |
1331 | * the following modifications to the tree can touch. If @node is the | |
1332 | * last node in the tree return %NULL. | |
1333 | */ | |
1334 | static struct rb_node *bfq_find_deepest(struct rb_node *node) | |
1335 | { | |
1336 | struct rb_node *deepest; | |
1337 | ||
1338 | if (!node->rb_right && !node->rb_left) | |
1339 | deepest = rb_parent(node); | |
1340 | else if (!node->rb_right) | |
1341 | deepest = node->rb_left; | |
1342 | else if (!node->rb_left) | |
1343 | deepest = node->rb_right; | |
1344 | else { | |
1345 | deepest = rb_next(node); | |
1346 | if (deepest->rb_right) | |
1347 | deepest = deepest->rb_right; | |
1348 | else if (rb_parent(deepest) != node) | |
1349 | deepest = rb_parent(deepest); | |
1350 | } | |
1351 | ||
1352 | return deepest; | |
1353 | } | |
1354 | ||
1355 | /** | |
1356 | * bfq_active_extract - remove an entity from the active tree. | |
1357 | * @st: the service_tree containing the tree. | |
1358 | * @entity: the entity being removed. | |
1359 | */ | |
1360 | static void bfq_active_extract(struct bfq_service_tree *st, | |
1361 | struct bfq_entity *entity) | |
1362 | { | |
1363 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1364 | struct rb_node *node; | |
e21b7a0b AA |
1365 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
1366 | struct bfq_sched_data *sd = NULL; | |
1367 | struct bfq_group *bfqg = NULL; | |
1368 | struct bfq_data *bfqd = NULL; | |
1369 | #endif | |
aee69d78 PV |
1370 | |
1371 | node = bfq_find_deepest(&entity->rb_node); | |
1372 | bfq_extract(&st->active, entity); | |
1373 | ||
1374 | if (node) | |
1375 | bfq_update_active_tree(node); | |
1376 | ||
e21b7a0b AA |
1377 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
1378 | sd = entity->sched_data; | |
1379 | bfqg = container_of(sd, struct bfq_group, sched_data); | |
1380 | bfqd = (struct bfq_data *)bfqg->bfqd; | |
1381 | #endif | |
aee69d78 PV |
1382 | if (bfqq) |
1383 | list_del(&bfqq->bfqq_list); | |
1384 | } | |
1385 | ||
1386 | /** | |
1387 | * bfq_idle_insert - insert an entity into the idle tree. | |
1388 | * @st: the service tree containing the tree. | |
1389 | * @entity: the entity to insert. | |
1390 | */ | |
1391 | static void bfq_idle_insert(struct bfq_service_tree *st, | |
1392 | struct bfq_entity *entity) | |
1393 | { | |
1394 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1395 | struct bfq_entity *first_idle = st->first_idle; | |
1396 | struct bfq_entity *last_idle = st->last_idle; | |
1397 | ||
1398 | if (!first_idle || bfq_gt(first_idle->finish, entity->finish)) | |
1399 | st->first_idle = entity; | |
1400 | if (!last_idle || bfq_gt(entity->finish, last_idle->finish)) | |
1401 | st->last_idle = entity; | |
1402 | ||
1403 | bfq_insert(&st->idle, entity); | |
1404 | ||
1405 | if (bfqq) | |
1406 | list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list); | |
1407 | } | |
1408 | ||
1409 | /** | |
1410 | * bfq_forget_entity - do not consider entity any longer for scheduling | |
1411 | * @st: the service tree. | |
1412 | * @entity: the entity being removed. | |
1413 | * @is_in_service: true if entity is currently the in-service entity. | |
1414 | * | |
1415 | * Forget everything about @entity. In addition, if entity represents | |
1416 | * a queue, and the latter is not in service, then release the service | |
1417 | * reference to the queue (the one taken through bfq_get_entity). In | |
1418 | * fact, in this case, there is really no more service reference to | |
1419 | * the queue, as the latter is also outside any service tree. If, | |
1420 | * instead, the queue is in service, then __bfq_bfqd_reset_in_service | |
1421 | * will take care of putting the reference when the queue finally | |
1422 | * stops being served. | |
1423 | */ | |
1424 | static void bfq_forget_entity(struct bfq_service_tree *st, | |
1425 | struct bfq_entity *entity, | |
1426 | bool is_in_service) | |
1427 | { | |
1428 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1429 | ||
e21b7a0b | 1430 | entity->on_st = false; |
aee69d78 PV |
1431 | st->wsum -= entity->weight; |
1432 | if (bfqq && !is_in_service) | |
1433 | bfq_put_queue(bfqq); | |
1434 | } | |
1435 | ||
1436 | /** | |
1437 | * bfq_put_idle_entity - release the idle tree ref of an entity. | |
1438 | * @st: service tree for the entity. | |
1439 | * @entity: the entity being released. | |
1440 | */ | |
1441 | static void bfq_put_idle_entity(struct bfq_service_tree *st, | |
1442 | struct bfq_entity *entity) | |
1443 | { | |
1444 | bfq_idle_extract(st, entity); | |
1445 | bfq_forget_entity(st, entity, | |
1446 | entity == entity->sched_data->in_service_entity); | |
1447 | } | |
1448 | ||
1449 | /** | |
1450 | * bfq_forget_idle - update the idle tree if necessary. | |
1451 | * @st: the service tree to act upon. | |
1452 | * | |
1453 | * To preserve the global O(log N) complexity we only remove one entry here; | |
1454 | * as the idle tree will not grow indefinitely this can be done safely. | |
1455 | */ | |
1456 | static void bfq_forget_idle(struct bfq_service_tree *st) | |
1457 | { | |
1458 | struct bfq_entity *first_idle = st->first_idle; | |
1459 | struct bfq_entity *last_idle = st->last_idle; | |
1460 | ||
1461 | if (RB_EMPTY_ROOT(&st->active) && last_idle && | |
1462 | !bfq_gt(last_idle->finish, st->vtime)) { | |
1463 | /* | |
1464 | * Forget the whole idle tree, increasing the vtime past | |
1465 | * the last finish time of idle entities. | |
1466 | */ | |
1467 | st->vtime = last_idle->finish; | |
1468 | } | |
1469 | ||
1470 | if (first_idle && !bfq_gt(first_idle->finish, st->vtime)) | |
1471 | bfq_put_idle_entity(st, first_idle); | |
1472 | } | |
1473 | ||
1474 | static struct bfq_service_tree * | |
1475 | __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, | |
e21b7a0b | 1476 | struct bfq_entity *entity) |
aee69d78 PV |
1477 | { |
1478 | struct bfq_service_tree *new_st = old_st; | |
1479 | ||
1480 | if (entity->prio_changed) { | |
1481 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
1482 | unsigned short prev_weight, new_weight; | |
1483 | struct bfq_data *bfqd = NULL; | |
e21b7a0b AA |
1484 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
1485 | struct bfq_sched_data *sd; | |
1486 | struct bfq_group *bfqg; | |
1487 | #endif | |
aee69d78 PV |
1488 | |
1489 | if (bfqq) | |
1490 | bfqd = bfqq->bfqd; | |
e21b7a0b AA |
1491 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
1492 | else { | |
1493 | sd = entity->my_sched_data; | |
1494 | bfqg = container_of(sd, struct bfq_group, sched_data); | |
1495 | bfqd = (struct bfq_data *)bfqg->bfqd; | |
1496 | } | |
1497 | #endif | |
aee69d78 PV |
1498 | |
1499 | old_st->wsum -= entity->weight; | |
1500 | ||
1501 | if (entity->new_weight != entity->orig_weight) { | |
1502 | if (entity->new_weight < BFQ_MIN_WEIGHT || | |
1503 | entity->new_weight > BFQ_MAX_WEIGHT) { | |
1504 | pr_crit("update_weight_prio: new_weight %d\n", | |
1505 | entity->new_weight); | |
1506 | if (entity->new_weight < BFQ_MIN_WEIGHT) | |
1507 | entity->new_weight = BFQ_MIN_WEIGHT; | |
1508 | else | |
1509 | entity->new_weight = BFQ_MAX_WEIGHT; | |
1510 | } | |
1511 | entity->orig_weight = entity->new_weight; | |
1512 | if (bfqq) | |
1513 | bfqq->ioprio = | |
1514 | bfq_weight_to_ioprio(entity->orig_weight); | |
1515 | } | |
1516 | ||
1517 | if (bfqq) | |
1518 | bfqq->ioprio_class = bfqq->new_ioprio_class; | |
1519 | entity->prio_changed = 0; | |
1520 | ||
1521 | /* | |
1522 | * NOTE: here we may be changing the weight too early, | |
1523 | * this will cause unfairness. The correct approach | |
1524 | * would have required additional complexity to defer | |
1525 | * weight changes to the proper time instants (i.e., | |
1526 | * when entity->finish <= old_st->vtime). | |
1527 | */ | |
1528 | new_st = bfq_entity_service_tree(entity); | |
1529 | ||
1530 | prev_weight = entity->weight; | |
1531 | new_weight = entity->orig_weight; | |
1532 | entity->weight = new_weight; | |
1533 | ||
1534 | new_st->wsum += entity->weight; | |
1535 | ||
1536 | if (new_st != old_st) | |
1537 | entity->start = new_st->vtime; | |
1538 | } | |
1539 | ||
1540 | return new_st; | |
1541 | } | |
1542 | ||
e21b7a0b AA |
1543 | static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); |
1544 | static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); | |
1545 | ||
aee69d78 PV |
1546 | /** |
1547 | * bfq_bfqq_served - update the scheduler status after selection for | |
1548 | * service. | |
1549 | * @bfqq: the queue being served. | |
1550 | * @served: bytes to transfer. | |
1551 | * | |
1552 | * NOTE: this can be optimized, as the timestamps of upper level entities | |
1553 | * are synchronized every time a new bfqq is selected for service. By now, | |
1554 | * we keep it to better check consistency. | |
1555 | */ | |
1556 | static void bfq_bfqq_served(struct bfq_queue *bfqq, int served) | |
1557 | { | |
1558 | struct bfq_entity *entity = &bfqq->entity; | |
1559 | struct bfq_service_tree *st; | |
1560 | ||
1561 | for_each_entity(entity) { | |
1562 | st = bfq_entity_service_tree(entity); | |
1563 | ||
1564 | entity->service += served; | |
1565 | ||
1566 | st->vtime += bfq_delta(served, st->wsum); | |
1567 | bfq_forget_idle(st); | |
1568 | } | |
e21b7a0b | 1569 | bfqg_stats_set_start_empty_time(bfqq_group(bfqq)); |
aee69d78 PV |
1570 | bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served); |
1571 | } | |
1572 | ||
1573 | /** | |
1574 | * bfq_bfqq_charge_full_budget - set the service to the entity budget. | |
1575 | * @bfqq: the queue that needs a service update. | |
1576 | * | |
1577 | * When it's not possible to be fair in the service domain, because | |
1578 | * a queue is not consuming its budget fast enough (the meaning of | |
1579 | * fast depends on the timeout parameter), we charge it a full | |
1580 | * budget. In this way we should obtain a sort of time-domain | |
1581 | * fairness among all the seeky/slow queues. | |
1582 | */ | |
1583 | static void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq) | |
1584 | { | |
1585 | struct bfq_entity *entity = &bfqq->entity; | |
1586 | ||
1587 | bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget"); | |
1588 | ||
1589 | bfq_bfqq_served(bfqq, entity->budget - entity->service); | |
1590 | } | |
1591 | ||
e21b7a0b AA |
1592 | static void bfq_update_fin_time_enqueue(struct bfq_entity *entity, |
1593 | struct bfq_service_tree *st, | |
1594 | bool backshifted) | |
aee69d78 | 1595 | { |
aee69d78 PV |
1596 | st = __bfq_entity_update_weight_prio(st, entity); |
1597 | bfq_calc_finish(entity, entity->budget); | |
1598 | ||
1599 | /* | |
1600 | * If some queues enjoy backshifting for a while, then their | |
1601 | * (virtual) finish timestamps may happen to become lower and | |
1602 | * lower than the system virtual time. In particular, if | |
1603 | * these queues often happen to be idle for short time | |
1604 | * periods, and during such time periods other queues with | |
1605 | * higher timestamps happen to be busy, then the backshifted | |
1606 | * timestamps of the former queues can become much lower than | |
1607 | * the system virtual time. In fact, to serve the queues with | |
1608 | * higher timestamps while the ones with lower timestamps are | |
1609 | * idle, the system virtual time may be pushed-up to much | |
1610 | * higher values than the finish timestamps of the idle | |
1611 | * queues. As a consequence, the finish timestamps of all new | |
1612 | * or newly activated queues may end up being much larger than | |
1613 | * those of lucky queues with backshifted timestamps. The | |
1614 | * latter queues may then monopolize the device for a lot of | |
1615 | * time. This would simply break service guarantees. | |
1616 | * | |
1617 | * To reduce this problem, push up a little bit the | |
1618 | * backshifted timestamps of the queue associated with this | |
1619 | * entity (only a queue can happen to have the backshifted | |
1620 | * flag set): just enough to let the finish timestamp of the | |
1621 | * queue be equal to the current value of the system virtual | |
1622 | * time. This may introduce a little unfairness among queues | |
1623 | * with backshifted timestamps, but it does not break | |
1624 | * worst-case fairness guarantees. | |
1625 | */ | |
1626 | if (backshifted && bfq_gt(st->vtime, entity->finish)) { | |
1627 | unsigned long delta = st->vtime - entity->finish; | |
1628 | ||
1629 | entity->start += delta; | |
1630 | entity->finish += delta; | |
1631 | } | |
1632 | ||
1633 | bfq_active_insert(st, entity); | |
1634 | } | |
1635 | ||
1636 | /** | |
e21b7a0b AA |
1637 | * __bfq_activate_entity - handle activation of entity. |
1638 | * @entity: the entity being activated. | |
1639 | * @non_blocking_wait_rq: true if entity was waiting for a request | |
1640 | * | |
1641 | * Called for a 'true' activation, i.e., if entity is not active and | |
1642 | * one of its children receives a new request. | |
1643 | * | |
1644 | * Basically, this function updates the timestamps of entity and | |
1645 | * inserts entity into its active tree, ater possible extracting it | |
1646 | * from its idle tree. | |
1647 | */ | |
1648 | static void __bfq_activate_entity(struct bfq_entity *entity, | |
1649 | bool non_blocking_wait_rq) | |
1650 | { | |
1651 | struct bfq_service_tree *st = bfq_entity_service_tree(entity); | |
1652 | bool backshifted = false; | |
1653 | unsigned long long min_vstart; | |
1654 | ||
1655 | /* See comments on bfq_fqq_update_budg_for_activation */ | |
1656 | if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) { | |
1657 | backshifted = true; | |
1658 | min_vstart = entity->finish; | |
1659 | } else | |
1660 | min_vstart = st->vtime; | |
1661 | ||
1662 | if (entity->tree == &st->idle) { | |
1663 | /* | |
1664 | * Must be on the idle tree, bfq_idle_extract() will | |
1665 | * check for that. | |
1666 | */ | |
1667 | bfq_idle_extract(st, entity); | |
1668 | entity->start = bfq_gt(min_vstart, entity->finish) ? | |
1669 | min_vstart : entity->finish; | |
1670 | } else { | |
1671 | /* | |
1672 | * The finish time of the entity may be invalid, and | |
1673 | * it is in the past for sure, otherwise the queue | |
1674 | * would have been on the idle tree. | |
1675 | */ | |
1676 | entity->start = min_vstart; | |
1677 | st->wsum += entity->weight; | |
1678 | /* | |
1679 | * entity is about to be inserted into a service tree, | |
1680 | * and then set in service: get a reference to make | |
1681 | * sure entity does not disappear until it is no | |
1682 | * longer in service or scheduled for service. | |
1683 | */ | |
1684 | bfq_get_entity(entity); | |
1685 | ||
1686 | entity->on_st = true; | |
1687 | } | |
1688 | ||
1689 | bfq_update_fin_time_enqueue(entity, st, backshifted); | |
1690 | } | |
1691 | ||
1692 | /** | |
1693 | * __bfq_requeue_entity - handle requeueing or repositioning of an entity. | |
1694 | * @entity: the entity being requeued or repositioned. | |
1695 | * | |
1696 | * Requeueing is needed if this entity stops being served, which | |
1697 | * happens if a leaf descendant entity has expired. On the other hand, | |
1698 | * repositioning is needed if the next_inservice_entity for the child | |
1699 | * entity has changed. See the comments inside the function for | |
1700 | * details. | |
1701 | * | |
1702 | * Basically, this function: 1) removes entity from its active tree if | |
1703 | * present there, 2) updates the timestamps of entity and 3) inserts | |
1704 | * entity back into its active tree (in the new, right position for | |
1705 | * the new values of the timestamps). | |
1706 | */ | |
1707 | static void __bfq_requeue_entity(struct bfq_entity *entity) | |
1708 | { | |
1709 | struct bfq_sched_data *sd = entity->sched_data; | |
1710 | struct bfq_service_tree *st = bfq_entity_service_tree(entity); | |
1711 | ||
1712 | if (entity == sd->in_service_entity) { | |
1713 | /* | |
1714 | * We are requeueing the current in-service entity, | |
1715 | * which may have to be done for one of the following | |
1716 | * reasons: | |
1717 | * - entity represents the in-service queue, and the | |
1718 | * in-service queue is being requeued after an | |
1719 | * expiration; | |
1720 | * - entity represents a group, and its budget has | |
1721 | * changed because one of its child entities has | |
1722 | * just been either activated or requeued for some | |
1723 | * reason; the timestamps of the entity need then to | |
1724 | * be updated, and the entity needs to be enqueued | |
1725 | * or repositioned accordingly. | |
1726 | * | |
1727 | * In particular, before requeueing, the start time of | |
1728 | * the entity must be moved forward to account for the | |
1729 | * service that the entity has received while in | |
1730 | * service. This is done by the next instructions. The | |
1731 | * finish time will then be updated according to this | |
1732 | * new value of the start time, and to the budget of | |
1733 | * the entity. | |
1734 | */ | |
1735 | bfq_calc_finish(entity, entity->service); | |
1736 | entity->start = entity->finish; | |
1737 | /* | |
1738 | * In addition, if the entity had more than one child | |
1739 | * when set in service, then was not extracted from | |
1740 | * the active tree. This implies that the position of | |
1741 | * the entity in the active tree may need to be | |
1742 | * changed now, because we have just updated the start | |
1743 | * time of the entity, and we will update its finish | |
1744 | * time in a moment (the requeueing is then, more | |
1745 | * precisely, a repositioning in this case). To | |
1746 | * implement this repositioning, we: 1) dequeue the | |
1747 | * entity here, 2) update the finish time and | |
1748 | * requeue the entity according to the new | |
1749 | * timestamps below. | |
1750 | */ | |
1751 | if (entity->tree) | |
1752 | bfq_active_extract(st, entity); | |
1753 | } else { /* The entity is already active, and not in service */ | |
1754 | /* | |
1755 | * In this case, this function gets called only if the | |
1756 | * next_in_service entity below this entity has | |
1757 | * changed, and this change has caused the budget of | |
1758 | * this entity to change, which, finally implies that | |
1759 | * the finish time of this entity must be | |
1760 | * updated. Such an update may cause the scheduling, | |
1761 | * i.e., the position in the active tree, of this | |
1762 | * entity to change. We handle this change by: 1) | |
1763 | * dequeueing the entity here, 2) updating the finish | |
1764 | * time and requeueing the entity according to the new | |
1765 | * timestamps below. This is the same approach as the | |
1766 | * non-extracted-entity sub-case above. | |
1767 | */ | |
1768 | bfq_active_extract(st, entity); | |
1769 | } | |
1770 | ||
1771 | bfq_update_fin_time_enqueue(entity, st, false); | |
1772 | } | |
1773 | ||
1774 | static void __bfq_activate_requeue_entity(struct bfq_entity *entity, | |
1775 | struct bfq_sched_data *sd, | |
1776 | bool non_blocking_wait_rq) | |
1777 | { | |
1778 | struct bfq_service_tree *st = bfq_entity_service_tree(entity); | |
1779 | ||
1780 | if (sd->in_service_entity == entity || entity->tree == &st->active) | |
1781 | /* | |
1782 | * in service or already queued on the active tree, | |
1783 | * requeue or reposition | |
1784 | */ | |
1785 | __bfq_requeue_entity(entity); | |
1786 | else | |
1787 | /* | |
1788 | * Not in service and not queued on its active tree: | |
1789 | * the activity is idle and this is a true activation. | |
1790 | */ | |
1791 | __bfq_activate_entity(entity, non_blocking_wait_rq); | |
1792 | } | |
1793 | ||
1794 | ||
1795 | /** | |
1796 | * bfq_activate_entity - activate or requeue an entity representing a bfq_queue, | |
1797 | * and activate, requeue or reposition all ancestors | |
1798 | * for which such an update becomes necessary. | |
aee69d78 PV |
1799 | * @entity: the entity to activate. |
1800 | * @non_blocking_wait_rq: true if this entity was waiting for a request | |
e21b7a0b AA |
1801 | * @requeue: true if this is a requeue, which implies that bfqq is |
1802 | * being expired; thus ALL its ancestors stop being served and must | |
1803 | * therefore be requeued | |
aee69d78 | 1804 | */ |
e21b7a0b AA |
1805 | static void bfq_activate_requeue_entity(struct bfq_entity *entity, |
1806 | bool non_blocking_wait_rq, | |
1807 | bool requeue) | |
aee69d78 PV |
1808 | { |
1809 | struct bfq_sched_data *sd; | |
1810 | ||
1811 | for_each_entity(entity) { | |
aee69d78 | 1812 | sd = entity->sched_data; |
e21b7a0b AA |
1813 | __bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq); |
1814 | ||
1815 | if (!bfq_update_next_in_service(sd, entity) && !requeue) | |
aee69d78 PV |
1816 | break; |
1817 | } | |
1818 | } | |
1819 | ||
1820 | /** | |
1821 | * __bfq_deactivate_entity - deactivate an entity from its service tree. | |
1822 | * @entity: the entity to deactivate. | |
e21b7a0b AA |
1823 | * @ins_into_idle_tree: if false, the entity will not be put into the |
1824 | * idle tree. | |
aee69d78 | 1825 | * |
e21b7a0b AA |
1826 | * Deactivates an entity, independently from its previous state. Must |
1827 | * be invoked only if entity is on a service tree. Extracts the entity | |
1828 | * from that tree, and if necessary and allowed, puts it on the idle | |
1829 | * tree. | |
aee69d78 | 1830 | */ |
e21b7a0b AA |
1831 | static bool __bfq_deactivate_entity(struct bfq_entity *entity, |
1832 | bool ins_into_idle_tree) | |
aee69d78 PV |
1833 | { |
1834 | struct bfq_sched_data *sd = entity->sched_data; | |
1835 | struct bfq_service_tree *st = bfq_entity_service_tree(entity); | |
1836 | int is_in_service = entity == sd->in_service_entity; | |
aee69d78 | 1837 | |
e21b7a0b AA |
1838 | if (!entity->on_st) /* entity never activated, or already inactive */ |
1839 | return false; | |
aee69d78 | 1840 | |
e21b7a0b | 1841 | if (is_in_service) |
aee69d78 | 1842 | bfq_calc_finish(entity, entity->service); |
e21b7a0b AA |
1843 | |
1844 | if (entity->tree == &st->active) | |
aee69d78 | 1845 | bfq_active_extract(st, entity); |
e21b7a0b | 1846 | else if (!is_in_service && entity->tree == &st->idle) |
aee69d78 PV |
1847 | bfq_idle_extract(st, entity); |
1848 | ||
e21b7a0b | 1849 | if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime)) |
aee69d78 PV |
1850 | bfq_forget_entity(st, entity, is_in_service); |
1851 | else | |
1852 | bfq_idle_insert(st, entity); | |
1853 | ||
e21b7a0b | 1854 | return true; |
aee69d78 PV |
1855 | } |
1856 | ||
1857 | /** | |
e21b7a0b | 1858 | * bfq_deactivate_entity - deactivate an entity representing a bfq_queue. |
aee69d78 | 1859 | * @entity: the entity to deactivate. |
e21b7a0b | 1860 | * @ins_into_idle_tree: true if the entity can be put on the idle tree |
aee69d78 | 1861 | */ |
e21b7a0b AA |
1862 | static void bfq_deactivate_entity(struct bfq_entity *entity, |
1863 | bool ins_into_idle_tree, | |
1864 | bool expiration) | |
aee69d78 PV |
1865 | { |
1866 | struct bfq_sched_data *sd; | |
1867 | struct bfq_entity *parent = NULL; | |
1868 | ||
1869 | for_each_entity_safe(entity, parent) { | |
1870 | sd = entity->sched_data; | |
1871 | ||
e21b7a0b | 1872 | if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) { |
aee69d78 | 1873 | /* |
e21b7a0b AA |
1874 | * entity is not in any tree any more, so |
1875 | * this deactivation is a no-op, and there is | |
1876 | * nothing to change for upper-level entities | |
1877 | * (in case of expiration, this can never | |
1878 | * happen). | |
aee69d78 | 1879 | */ |
e21b7a0b AA |
1880 | return; |
1881 | } | |
1882 | ||
1883 | if (sd->next_in_service == entity) | |
1884 | /* | |
1885 | * entity was the next_in_service entity, | |
1886 | * then, since entity has just been | |
1887 | * deactivated, a new one must be found. | |
1888 | */ | |
1889 | bfq_update_next_in_service(sd, NULL); | |
aee69d78 PV |
1890 | |
1891 | if (sd->next_in_service) | |
1892 | /* | |
e21b7a0b AA |
1893 | * The parent entity is still backlogged, |
1894 | * because next_in_service is not NULL. So, no | |
1895 | * further upwards deactivation must be | |
1896 | * performed. Yet, next_in_service has | |
1897 | * changed. Then the schedule does need to be | |
1898 | * updated upwards. | |
aee69d78 | 1899 | */ |
e21b7a0b | 1900 | break; |
aee69d78 PV |
1901 | |
1902 | /* | |
e21b7a0b AA |
1903 | * If we get here, then the parent is no more |
1904 | * backlogged and we need to propagate the | |
1905 | * deactivation upwards. Thus let the loop go on. | |
aee69d78 | 1906 | */ |
aee69d78 | 1907 | |
e21b7a0b AA |
1908 | /* |
1909 | * Also let parent be queued into the idle tree on | |
1910 | * deactivation, to preserve service guarantees, and | |
1911 | * assuming that who invoked this function does not | |
1912 | * need parent entities too to be removed completely. | |
1913 | */ | |
1914 | ins_into_idle_tree = true; | |
1915 | } | |
aee69d78 | 1916 | |
e21b7a0b AA |
1917 | /* |
1918 | * If the deactivation loop is fully executed, then there are | |
1919 | * no more entities to touch and next loop is not executed at | |
1920 | * all. Otherwise, requeue remaining entities if they are | |
1921 | * about to stop receiving service, or reposition them if this | |
1922 | * is not the case. | |
1923 | */ | |
aee69d78 PV |
1924 | entity = parent; |
1925 | for_each_entity(entity) { | |
e21b7a0b AA |
1926 | /* |
1927 | * Invoke __bfq_requeue_entity on entity, even if | |
1928 | * already active, to requeue/reposition it in the | |
1929 | * active tree (because sd->next_in_service has | |
1930 | * changed) | |
1931 | */ | |
1932 | __bfq_requeue_entity(entity); | |
aee69d78 PV |
1933 | |
1934 | sd = entity->sched_data; | |
e21b7a0b AA |
1935 | if (!bfq_update_next_in_service(sd, entity) && |
1936 | !expiration) | |
1937 | /* | |
1938 | * next_in_service unchanged or not causing | |
1939 | * any change in entity->parent->sd, and no | |
1940 | * requeueing needed for expiration: stop | |
1941 | * here. | |
1942 | */ | |
aee69d78 PV |
1943 | break; |
1944 | } | |
1945 | } | |
1946 | ||
1947 | /** | |
e21b7a0b AA |
1948 | * bfq_calc_vtime_jump - compute the value to which the vtime should jump, |
1949 | * if needed, to have at least one entity eligible. | |
aee69d78 PV |
1950 | * @st: the service tree to act upon. |
1951 | * | |
e21b7a0b | 1952 | * Assumes that st is not empty. |
aee69d78 | 1953 | */ |
e21b7a0b | 1954 | static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st) |
aee69d78 | 1955 | { |
e21b7a0b AA |
1956 | struct bfq_entity *root_entity = bfq_root_active_entity(&st->active); |
1957 | ||
1958 | if (bfq_gt(root_entity->min_start, st->vtime)) | |
1959 | return root_entity->min_start; | |
1960 | ||
1961 | return st->vtime; | |
1962 | } | |
aee69d78 | 1963 | |
e21b7a0b AA |
1964 | static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value) |
1965 | { | |
1966 | if (new_value > st->vtime) { | |
1967 | st->vtime = new_value; | |
aee69d78 PV |
1968 | bfq_forget_idle(st); |
1969 | } | |
1970 | } | |
1971 | ||
1972 | /** | |
1973 | * bfq_first_active_entity - find the eligible entity with | |
1974 | * the smallest finish time | |
1975 | * @st: the service tree to select from. | |
e21b7a0b | 1976 | * @vtime: the system virtual to use as a reference for eligibility |
aee69d78 PV |
1977 | * |
1978 | * This function searches the first schedulable entity, starting from the | |
1979 | * root of the tree and going on the left every time on this side there is | |
1980 | * a subtree with at least one eligible (start >= vtime) entity. The path on | |
1981 | * the right is followed only if a) the left subtree contains no eligible | |
1982 | * entities and b) no eligible entity has been found yet. | |
1983 | */ | |
e21b7a0b AA |
1984 | static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st, |
1985 | u64 vtime) | |
aee69d78 PV |
1986 | { |
1987 | struct bfq_entity *entry, *first = NULL; | |
1988 | struct rb_node *node = st->active.rb_node; | |
1989 | ||
1990 | while (node) { | |
1991 | entry = rb_entry(node, struct bfq_entity, rb_node); | |
1992 | left: | |
e21b7a0b | 1993 | if (!bfq_gt(entry->start, vtime)) |
aee69d78 PV |
1994 | first = entry; |
1995 | ||
1996 | if (node->rb_left) { | |
1997 | entry = rb_entry(node->rb_left, | |
1998 | struct bfq_entity, rb_node); | |
e21b7a0b | 1999 | if (!bfq_gt(entry->min_start, vtime)) { |
aee69d78 PV |
2000 | node = node->rb_left; |
2001 | goto left; | |
2002 | } | |
2003 | } | |
2004 | if (first) | |
2005 | break; | |
2006 | node = node->rb_right; | |
2007 | } | |
2008 | ||
e21b7a0b AA |
2009 | return first; |
2010 | } | |
2011 | ||
2012 | /** | |
2013 | * __bfq_lookup_next_entity - return the first eligible entity in @st. | |
2014 | * @st: the service tree. | |
2015 | * | |
2016 | * If there is no in-service entity for the sched_data st belongs to, | |
2017 | * then return the entity that will be set in service if: | |
2018 | * 1) the parent entity this st belongs to is set in service; | |
2019 | * 2) no entity belonging to such parent entity undergoes a state change | |
2020 | * that would influence the timestamps of the entity (e.g., becomes idle, | |
2021 | * becomes backlogged, changes its budget, ...). | |
2022 | * | |
2023 | * In this first case, update the virtual time in @st too (see the | |
2024 | * comments on this update inside the function). | |
2025 | * | |
2026 | * In constrast, if there is an in-service entity, then return the | |
2027 | * entity that would be set in service if not only the above | |
2028 | * conditions, but also the next one held true: the currently | |
2029 | * in-service entity, on expiration, | |
2030 | * 1) gets a finish time equal to the current one, or | |
2031 | * 2) is not eligible any more, or | |
2032 | * 3) is idle. | |
2033 | */ | |
2034 | static struct bfq_entity * | |
2035 | __bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service) | |
2036 | { | |
2037 | struct bfq_entity *entity; | |
2038 | u64 new_vtime; | |
2039 | ||
2040 | if (RB_EMPTY_ROOT(&st->active)) | |
2041 | return NULL; | |
2042 | ||
2043 | /* | |
2044 | * Get the value of the system virtual time for which at | |
2045 | * least one entity is eligible. | |
2046 | */ | |
2047 | new_vtime = bfq_calc_vtime_jump(st); | |
2048 | ||
2049 | /* | |
2050 | * If there is no in-service entity for the sched_data this | |
2051 | * active tree belongs to, then push the system virtual time | |
2052 | * up to the value that guarantees that at least one entity is | |
2053 | * eligible. If, instead, there is an in-service entity, then | |
2054 | * do not make any such update, because there is already an | |
2055 | * eligible entity, namely the in-service one (even if the | |
2056 | * entity is not on st, because it was extracted when set in | |
2057 | * service). | |
2058 | */ | |
2059 | if (!in_service) | |
2060 | bfq_update_vtime(st, new_vtime); | |
2061 | ||
2062 | entity = bfq_first_active_entity(st, new_vtime); | |
2063 | ||
2064 | return entity; | |
2065 | } | |
2066 | ||
2067 | /** | |
2068 | * bfq_lookup_next_entity - return the first eligible entity in @sd. | |
2069 | * @sd: the sched_data. | |
2070 | * | |
2071 | * This function is invoked when there has been a change in the trees | |
2072 | * for sd, and we need know what is the new next entity after this | |
2073 | * change. | |
2074 | */ | |
2075 | static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd) | |
2076 | { | |
2077 | struct bfq_service_tree *st = sd->service_tree; | |
2078 | struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1); | |
2079 | struct bfq_entity *entity = NULL; | |
2080 | int class_idx = 0; | |
2081 | ||
2082 | /* | |
2083 | * Choose from idle class, if needed to guarantee a minimum | |
2084 | * bandwidth to this class (and if there is some active entity | |
2085 | * in idle class). This should also mitigate | |
2086 | * priority-inversion problems in case a low priority task is | |
2087 | * holding file system resources. | |
2088 | */ | |
2089 | if (time_is_before_jiffies(sd->bfq_class_idle_last_service + | |
2090 | BFQ_CL_IDLE_TIMEOUT)) { | |
2091 | if (!RB_EMPTY_ROOT(&idle_class_st->active)) | |
2092 | class_idx = BFQ_IOPRIO_CLASSES - 1; | |
2093 | /* About to be served if backlogged, or not yet backlogged */ | |
2094 | sd->bfq_class_idle_last_service = jiffies; | |
2095 | } | |
2096 | ||
2097 | /* | |
2098 | * Find the next entity to serve for the highest-priority | |
2099 | * class, unless the idle class needs to be served. | |
2100 | */ | |
2101 | for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) { | |
2102 | entity = __bfq_lookup_next_entity(st + class_idx, | |
2103 | sd->in_service_entity); | |
2104 | ||
2105 | if (entity) | |
2106 | break; | |
2107 | } | |
2108 | ||
2109 | if (!entity) | |
2110 | return NULL; | |
2111 | ||
2112 | return entity; | |
2113 | } | |
2114 | ||
2115 | static bool next_queue_may_preempt(struct bfq_data *bfqd) | |
2116 | { | |
2117 | struct bfq_sched_data *sd = &bfqd->root_group->sched_data; | |
2118 | ||
2119 | return sd->next_in_service != sd->in_service_entity; | |
2120 | } | |
2121 | ||
2122 | /* | |
2123 | * Get next queue for service. | |
2124 | */ | |
2125 | static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd) | |
2126 | { | |
2127 | struct bfq_entity *entity = NULL; | |
2128 | struct bfq_sched_data *sd; | |
2129 | struct bfq_queue *bfqq; | |
2130 | ||
2131 | if (bfqd->busy_queues == 0) | |
2132 | return NULL; | |
2133 | ||
2134 | /* | |
2135 | * Traverse the path from the root to the leaf entity to | |
2136 | * serve. Set in service all the entities visited along the | |
2137 | * way. | |
2138 | */ | |
2139 | sd = &bfqd->root_group->sched_data; | |
2140 | for (; sd ; sd = entity->my_sched_data) { | |
2141 | /* | |
2142 | * WARNING. We are about to set the in-service entity | |
2143 | * to sd->next_in_service, i.e., to the (cached) value | |
2144 | * returned by bfq_lookup_next_entity(sd) the last | |
2145 | * time it was invoked, i.e., the last time when the | |
2146 | * service order in sd changed as a consequence of the | |
2147 | * activation or deactivation of an entity. In this | |
2148 | * respect, if we execute bfq_lookup_next_entity(sd) | |
2149 | * in this very moment, it may, although with low | |
2150 | * probability, yield a different entity than that | |
2151 | * pointed to by sd->next_in_service. This rare event | |
2152 | * happens in case there was no CLASS_IDLE entity to | |
2153 | * serve for sd when bfq_lookup_next_entity(sd) was | |
2154 | * invoked for the last time, while there is now one | |
2155 | * such entity. | |
2156 | * | |
2157 | * If the above event happens, then the scheduling of | |
2158 | * such entity in CLASS_IDLE is postponed until the | |
2159 | * service of the sd->next_in_service entity | |
2160 | * finishes. In fact, when the latter is expired, | |
2161 | * bfq_lookup_next_entity(sd) gets called again, | |
2162 | * exactly to update sd->next_in_service. | |
2163 | */ | |
2164 | ||
2165 | /* Make next_in_service entity become in_service_entity */ | |
2166 | entity = sd->next_in_service; | |
2167 | sd->in_service_entity = entity; | |
2168 | ||
2169 | /* | |
2170 | * Reset the accumulator of the amount of service that | |
2171 | * the entity is about to receive. | |
2172 | */ | |
2173 | entity->service = 0; | |
2174 | ||
2175 | /* | |
2176 | * If entity is no longer a candidate for next | |
2177 | * service, then we extract it from its active tree, | |
2178 | * for the following reason. To further boost the | |
2179 | * throughput in some special case, BFQ needs to know | |
2180 | * which is the next candidate entity to serve, while | |
2181 | * there is already an entity in service. In this | |
2182 | * respect, to make it easy to compute/update the next | |
2183 | * candidate entity to serve after the current | |
2184 | * candidate has been set in service, there is a case | |
2185 | * where it is necessary to extract the current | |
2186 | * candidate from its service tree. Such a case is | |
2187 | * when the entity just set in service cannot be also | |
2188 | * a candidate for next service. Details about when | |
2189 | * this conditions holds are reported in the comments | |
2190 | * on the function bfq_no_longer_next_in_service() | |
2191 | * invoked below. | |
2192 | */ | |
2193 | if (bfq_no_longer_next_in_service(entity)) | |
2194 | bfq_active_extract(bfq_entity_service_tree(entity), | |
2195 | entity); | |
2196 | ||
2197 | /* | |
2198 | * For the same reason why we may have just extracted | |
2199 | * entity from its active tree, we may need to update | |
2200 | * next_in_service for the sched_data of entity too, | |
2201 | * regardless of whether entity has been extracted. | |
2202 | * In fact, even if entity has not been extracted, a | |
2203 | * descendant entity may get extracted. Such an event | |
2204 | * would cause a change in next_in_service for the | |
2205 | * level of the descendant entity, and thus possibly | |
2206 | * back to upper levels. | |
2207 | * | |
2208 | * We cannot perform the resulting needed update | |
2209 | * before the end of this loop, because, to know which | |
2210 | * is the correct next-to-serve candidate entity for | |
2211 | * each level, we need first to find the leaf entity | |
2212 | * to set in service. In fact, only after we know | |
2213 | * which is the next-to-serve leaf entity, we can | |
2214 | * discover whether the parent entity of the leaf | |
2215 | * entity becomes the next-to-serve, and so on. | |
2216 | */ | |
2217 | ||
2218 | } | |
2219 | ||
2220 | bfqq = bfq_entity_to_bfqq(entity); | |
2221 | ||
2222 | /* | |
2223 | * We can finally update all next-to-serve entities along the | |
2224 | * path from the leaf entity just set in service to the root. | |
2225 | */ | |
2226 | for_each_entity(entity) { | |
2227 | struct bfq_sched_data *sd = entity->sched_data; | |
2228 | ||
2229 | if (!bfq_update_next_in_service(sd, NULL)) | |
2230 | break; | |
2231 | } | |
2232 | ||
2233 | return bfqq; | |
2234 | } | |
2235 | ||
2236 | static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) | |
2237 | { | |
2238 | struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue; | |
2239 | struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity; | |
2240 | struct bfq_entity *entity = in_serv_entity; | |
2241 | ||
2242 | if (bfqd->in_service_bic) { | |
2243 | put_io_context(bfqd->in_service_bic->icq.ioc); | |
2244 | bfqd->in_service_bic = NULL; | |
2245 | } | |
2246 | ||
2247 | bfq_clear_bfqq_wait_request(in_serv_bfqq); | |
2248 | hrtimer_try_to_cancel(&bfqd->idle_slice_timer); | |
2249 | bfqd->in_service_queue = NULL; | |
2250 | ||
2251 | /* | |
2252 | * When this function is called, all in-service entities have | |
2253 | * been properly deactivated or requeued, so we can safely | |
2254 | * execute the final step: reset in_service_entity along the | |
2255 | * path from entity to the root. | |
2256 | */ | |
2257 | for_each_entity(entity) | |
2258 | entity->sched_data->in_service_entity = NULL; | |
2259 | ||
2260 | /* | |
2261 | * in_serv_entity is no longer in service, so, if it is in no | |
2262 | * service tree either, then release the service reference to | |
2263 | * the queue it represents (taken with bfq_get_entity). | |
2264 | */ | |
2265 | if (!in_serv_entity->on_st) | |
2266 | bfq_put_queue(in_serv_bfqq); | |
2267 | } | |
2268 | ||
2269 | static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
2270 | bool ins_into_idle_tree, bool expiration) | |
2271 | { | |
2272 | struct bfq_entity *entity = &bfqq->entity; | |
2273 | ||
2274 | bfq_deactivate_entity(entity, ins_into_idle_tree, expiration); | |
2275 | } | |
2276 | ||
2277 | static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) | |
2278 | { | |
2279 | struct bfq_entity *entity = &bfqq->entity; | |
2280 | ||
2281 | bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq), | |
2282 | false); | |
2283 | bfq_clear_bfqq_non_blocking_wait_rq(bfqq); | |
2284 | } | |
2285 | ||
2286 | static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) | |
2287 | { | |
2288 | struct bfq_entity *entity = &bfqq->entity; | |
2289 | ||
2290 | bfq_activate_requeue_entity(entity, false, | |
2291 | bfqq == bfqd->in_service_queue); | |
2292 | } | |
2293 | ||
2294 | static void bfqg_stats_update_dequeue(struct bfq_group *bfqg); | |
2295 | ||
2296 | /* | |
2297 | * Called when the bfqq no longer has requests pending, remove it from | |
2298 | * the service tree. As a special case, it can be invoked during an | |
2299 | * expiration. | |
2300 | */ | |
2301 | static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
2302 | bool expiration) | |
2303 | { | |
2304 | bfq_log_bfqq(bfqd, bfqq, "del from busy"); | |
2305 | ||
2306 | bfq_clear_bfqq_busy(bfqq); | |
2307 | ||
2308 | bfqd->busy_queues--; | |
2309 | ||
2310 | bfqg_stats_update_dequeue(bfqq_group(bfqq)); | |
2311 | ||
2312 | bfq_deactivate_bfqq(bfqd, bfqq, true, expiration); | |
2313 | } | |
2314 | ||
2315 | /* | |
2316 | * Called when an inactive queue receives a new request. | |
2317 | */ | |
2318 | static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) | |
2319 | { | |
2320 | bfq_log_bfqq(bfqd, bfqq, "add to busy"); | |
2321 | ||
2322 | bfq_activate_bfqq(bfqd, bfqq); | |
2323 | ||
2324 | bfq_mark_bfqq_busy(bfqq); | |
2325 | bfqd->busy_queues++; | |
2326 | } | |
2327 | ||
2328 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
2329 | ||
2330 | /* bfqg stats flags */ | |
2331 | enum bfqg_stats_flags { | |
2332 | BFQG_stats_waiting = 0, | |
2333 | BFQG_stats_idling, | |
2334 | BFQG_stats_empty, | |
2335 | }; | |
2336 | ||
2337 | #define BFQG_FLAG_FNS(name) \ | |
2338 | static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \ | |
2339 | { \ | |
2340 | stats->flags |= (1 << BFQG_stats_##name); \ | |
2341 | } \ | |
2342 | static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \ | |
2343 | { \ | |
2344 | stats->flags &= ~(1 << BFQG_stats_##name); \ | |
2345 | } \ | |
2346 | static int bfqg_stats_##name(struct bfqg_stats *stats) \ | |
2347 | { \ | |
2348 | return (stats->flags & (1 << BFQG_stats_##name)) != 0; \ | |
2349 | } \ | |
2350 | ||
2351 | BFQG_FLAG_FNS(waiting) | |
2352 | BFQG_FLAG_FNS(idling) | |
2353 | BFQG_FLAG_FNS(empty) | |
2354 | #undef BFQG_FLAG_FNS | |
2355 | ||
2356 | /* This should be called with the queue_lock held. */ | |
2357 | static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats) | |
2358 | { | |
2359 | unsigned long long now; | |
2360 | ||
2361 | if (!bfqg_stats_waiting(stats)) | |
2362 | return; | |
2363 | ||
2364 | now = sched_clock(); | |
2365 | if (time_after64(now, stats->start_group_wait_time)) | |
2366 | blkg_stat_add(&stats->group_wait_time, | |
2367 | now - stats->start_group_wait_time); | |
2368 | bfqg_stats_clear_waiting(stats); | |
2369 | } | |
2370 | ||
2371 | /* This should be called with the queue_lock held. */ | |
2372 | static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, | |
2373 | struct bfq_group *curr_bfqg) | |
2374 | { | |
2375 | struct bfqg_stats *stats = &bfqg->stats; | |
2376 | ||
2377 | if (bfqg_stats_waiting(stats)) | |
2378 | return; | |
2379 | if (bfqg == curr_bfqg) | |
2380 | return; | |
2381 | stats->start_group_wait_time = sched_clock(); | |
2382 | bfqg_stats_mark_waiting(stats); | |
2383 | } | |
2384 | ||
2385 | /* This should be called with the queue_lock held. */ | |
2386 | static void bfqg_stats_end_empty_time(struct bfqg_stats *stats) | |
2387 | { | |
2388 | unsigned long long now; | |
2389 | ||
2390 | if (!bfqg_stats_empty(stats)) | |
2391 | return; | |
2392 | ||
2393 | now = sched_clock(); | |
2394 | if (time_after64(now, stats->start_empty_time)) | |
2395 | blkg_stat_add(&stats->empty_time, | |
2396 | now - stats->start_empty_time); | |
2397 | bfqg_stats_clear_empty(stats); | |
2398 | } | |
2399 | ||
2400 | static void bfqg_stats_update_dequeue(struct bfq_group *bfqg) | |
2401 | { | |
2402 | blkg_stat_add(&bfqg->stats.dequeue, 1); | |
2403 | } | |
2404 | ||
2405 | static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) | |
2406 | { | |
2407 | struct bfqg_stats *stats = &bfqg->stats; | |
2408 | ||
2409 | if (blkg_rwstat_total(&stats->queued)) | |
2410 | return; | |
2411 | ||
2412 | /* | |
2413 | * group is already marked empty. This can happen if bfqq got new | |
2414 | * request in parent group and moved to this group while being added | |
2415 | * to service tree. Just ignore the event and move on. | |
2416 | */ | |
2417 | if (bfqg_stats_empty(stats)) | |
2418 | return; | |
2419 | ||
2420 | stats->start_empty_time = sched_clock(); | |
2421 | bfqg_stats_mark_empty(stats); | |
2422 | } | |
2423 | ||
2424 | static void bfqg_stats_update_idle_time(struct bfq_group *bfqg) | |
2425 | { | |
2426 | struct bfqg_stats *stats = &bfqg->stats; | |
2427 | ||
2428 | if (bfqg_stats_idling(stats)) { | |
2429 | unsigned long long now = sched_clock(); | |
2430 | ||
2431 | if (time_after64(now, stats->start_idle_time)) | |
2432 | blkg_stat_add(&stats->idle_time, | |
2433 | now - stats->start_idle_time); | |
2434 | bfqg_stats_clear_idling(stats); | |
2435 | } | |
2436 | } | |
2437 | ||
2438 | static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) | |
2439 | { | |
2440 | struct bfqg_stats *stats = &bfqg->stats; | |
2441 | ||
2442 | stats->start_idle_time = sched_clock(); | |
2443 | bfqg_stats_mark_idling(stats); | |
2444 | } | |
2445 | ||
2446 | static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) | |
2447 | { | |
2448 | struct bfqg_stats *stats = &bfqg->stats; | |
2449 | ||
2450 | blkg_stat_add(&stats->avg_queue_size_sum, | |
2451 | blkg_rwstat_total(&stats->queued)); | |
2452 | blkg_stat_add(&stats->avg_queue_size_samples, 1); | |
2453 | bfqg_stats_update_group_wait_time(stats); | |
2454 | } | |
2455 | ||
2456 | /* | |
2457 | * blk-cgroup policy-related handlers | |
2458 | * The following functions help in converting between blk-cgroup | |
2459 | * internal structures and BFQ-specific structures. | |
2460 | */ | |
2461 | ||
2462 | static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd) | |
2463 | { | |
2464 | return pd ? container_of(pd, struct bfq_group, pd) : NULL; | |
2465 | } | |
2466 | ||
2467 | static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg) | |
2468 | { | |
2469 | return pd_to_blkg(&bfqg->pd); | |
2470 | } | |
2471 | ||
2472 | static struct blkcg_policy blkcg_policy_bfq; | |
2473 | ||
2474 | static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg) | |
2475 | { | |
2476 | return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq)); | |
2477 | } | |
2478 | ||
2479 | /* | |
2480 | * bfq_group handlers | |
2481 | * The following functions help in navigating the bfq_group hierarchy | |
2482 | * by allowing to find the parent of a bfq_group or the bfq_group | |
2483 | * associated to a bfq_queue. | |
2484 | */ | |
2485 | ||
2486 | static struct bfq_group *bfqg_parent(struct bfq_group *bfqg) | |
2487 | { | |
2488 | struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent; | |
2489 | ||
2490 | return pblkg ? blkg_to_bfqg(pblkg) : NULL; | |
2491 | } | |
2492 | ||
2493 | static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) | |
2494 | { | |
2495 | struct bfq_entity *group_entity = bfqq->entity.parent; | |
2496 | ||
2497 | return group_entity ? container_of(group_entity, struct bfq_group, | |
2498 | entity) : | |
2499 | bfqq->bfqd->root_group; | |
2500 | } | |
2501 | ||
2502 | /* | |
2503 | * The following two functions handle get and put of a bfq_group by | |
2504 | * wrapping the related blk-cgroup hooks. | |
2505 | */ | |
2506 | ||
2507 | static void bfqg_get(struct bfq_group *bfqg) | |
2508 | { | |
2509 | return blkg_get(bfqg_to_blkg(bfqg)); | |
2510 | } | |
2511 | ||
2512 | static void bfqg_put(struct bfq_group *bfqg) | |
2513 | { | |
2514 | return blkg_put(bfqg_to_blkg(bfqg)); | |
2515 | } | |
2516 | ||
2517 | static void bfqg_stats_update_io_add(struct bfq_group *bfqg, | |
2518 | struct bfq_queue *bfqq, | |
2519 | unsigned int op) | |
2520 | { | |
2521 | blkg_rwstat_add(&bfqg->stats.queued, op, 1); | |
2522 | bfqg_stats_end_empty_time(&bfqg->stats); | |
2523 | if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue)) | |
2524 | bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq)); | |
2525 | } | |
2526 | ||
2527 | static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) | |
2528 | { | |
2529 | blkg_rwstat_add(&bfqg->stats.queued, op, -1); | |
2530 | } | |
2531 | ||
2532 | static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) | |
2533 | { | |
2534 | blkg_rwstat_add(&bfqg->stats.merged, op, 1); | |
2535 | } | |
2536 | ||
2537 | static void bfqg_stats_update_completion(struct bfq_group *bfqg, | |
2538 | uint64_t start_time, uint64_t io_start_time, | |
2539 | unsigned int op) | |
2540 | { | |
2541 | struct bfqg_stats *stats = &bfqg->stats; | |
2542 | unsigned long long now = sched_clock(); | |
2543 | ||
2544 | if (time_after64(now, io_start_time)) | |
2545 | blkg_rwstat_add(&stats->service_time, op, | |
2546 | now - io_start_time); | |
2547 | if (time_after64(io_start_time, start_time)) | |
2548 | blkg_rwstat_add(&stats->wait_time, op, | |
2549 | io_start_time - start_time); | |
2550 | } | |
2551 | ||
2552 | /* @stats = 0 */ | |
2553 | static void bfqg_stats_reset(struct bfqg_stats *stats) | |
2554 | { | |
2555 | /* queued stats shouldn't be cleared */ | |
2556 | blkg_rwstat_reset(&stats->merged); | |
2557 | blkg_rwstat_reset(&stats->service_time); | |
2558 | blkg_rwstat_reset(&stats->wait_time); | |
2559 | blkg_stat_reset(&stats->time); | |
2560 | blkg_stat_reset(&stats->avg_queue_size_sum); | |
2561 | blkg_stat_reset(&stats->avg_queue_size_samples); | |
2562 | blkg_stat_reset(&stats->dequeue); | |
2563 | blkg_stat_reset(&stats->group_wait_time); | |
2564 | blkg_stat_reset(&stats->idle_time); | |
2565 | blkg_stat_reset(&stats->empty_time); | |
2566 | } | |
2567 | ||
2568 | /* @to += @from */ | |
2569 | static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from) | |
2570 | { | |
2571 | if (!to || !from) | |
2572 | return; | |
2573 | ||
2574 | /* queued stats shouldn't be cleared */ | |
2575 | blkg_rwstat_add_aux(&to->merged, &from->merged); | |
2576 | blkg_rwstat_add_aux(&to->service_time, &from->service_time); | |
2577 | blkg_rwstat_add_aux(&to->wait_time, &from->wait_time); | |
2578 | blkg_stat_add_aux(&from->time, &from->time); | |
2579 | blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum); | |
2580 | blkg_stat_add_aux(&to->avg_queue_size_samples, | |
2581 | &from->avg_queue_size_samples); | |
2582 | blkg_stat_add_aux(&to->dequeue, &from->dequeue); | |
2583 | blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time); | |
2584 | blkg_stat_add_aux(&to->idle_time, &from->idle_time); | |
2585 | blkg_stat_add_aux(&to->empty_time, &from->empty_time); | |
2586 | } | |
2587 | ||
2588 | /* | |
2589 | * Transfer @bfqg's stats to its parent's aux counts so that the ancestors' | |
2590 | * recursive stats can still account for the amount used by this bfqg after | |
2591 | * it's gone. | |
2592 | */ | |
2593 | static void bfqg_stats_xfer_dead(struct bfq_group *bfqg) | |
2594 | { | |
2595 | struct bfq_group *parent; | |
2596 | ||
2597 | if (!bfqg) /* root_group */ | |
2598 | return; | |
2599 | ||
2600 | parent = bfqg_parent(bfqg); | |
2601 | ||
2602 | lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock); | |
2603 | ||
2604 | if (unlikely(!parent)) | |
2605 | return; | |
2606 | ||
2607 | bfqg_stats_add_aux(&parent->stats, &bfqg->stats); | |
2608 | bfqg_stats_reset(&bfqg->stats); | |
2609 | } | |
2610 | ||
2611 | static void bfq_init_entity(struct bfq_entity *entity, | |
2612 | struct bfq_group *bfqg) | |
2613 | { | |
2614 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
2615 | ||
2616 | entity->weight = entity->new_weight; | |
2617 | entity->orig_weight = entity->new_weight; | |
2618 | if (bfqq) { | |
2619 | bfqq->ioprio = bfqq->new_ioprio; | |
2620 | bfqq->ioprio_class = bfqq->new_ioprio_class; | |
2621 | bfqg_get(bfqg); | |
2622 | } | |
2623 | entity->parent = bfqg->my_entity; /* NULL for root group */ | |
2624 | entity->sched_data = &bfqg->sched_data; | |
2625 | } | |
2626 | ||
2627 | static void bfqg_stats_exit(struct bfqg_stats *stats) | |
2628 | { | |
2629 | blkg_rwstat_exit(&stats->merged); | |
2630 | blkg_rwstat_exit(&stats->service_time); | |
2631 | blkg_rwstat_exit(&stats->wait_time); | |
2632 | blkg_rwstat_exit(&stats->queued); | |
2633 | blkg_stat_exit(&stats->time); | |
2634 | blkg_stat_exit(&stats->avg_queue_size_sum); | |
2635 | blkg_stat_exit(&stats->avg_queue_size_samples); | |
2636 | blkg_stat_exit(&stats->dequeue); | |
2637 | blkg_stat_exit(&stats->group_wait_time); | |
2638 | blkg_stat_exit(&stats->idle_time); | |
2639 | blkg_stat_exit(&stats->empty_time); | |
2640 | } | |
2641 | ||
2642 | static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) | |
2643 | { | |
2644 | if (blkg_rwstat_init(&stats->merged, gfp) || | |
2645 | blkg_rwstat_init(&stats->service_time, gfp) || | |
2646 | blkg_rwstat_init(&stats->wait_time, gfp) || | |
2647 | blkg_rwstat_init(&stats->queued, gfp) || | |
2648 | blkg_stat_init(&stats->time, gfp) || | |
2649 | blkg_stat_init(&stats->avg_queue_size_sum, gfp) || | |
2650 | blkg_stat_init(&stats->avg_queue_size_samples, gfp) || | |
2651 | blkg_stat_init(&stats->dequeue, gfp) || | |
2652 | blkg_stat_init(&stats->group_wait_time, gfp) || | |
2653 | blkg_stat_init(&stats->idle_time, gfp) || | |
2654 | blkg_stat_init(&stats->empty_time, gfp)) { | |
2655 | bfqg_stats_exit(stats); | |
2656 | return -ENOMEM; | |
2657 | } | |
2658 | ||
2659 | return 0; | |
2660 | } | |
2661 | ||
2662 | static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) | |
2663 | { | |
2664 | return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; | |
2665 | } | |
2666 | ||
2667 | static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) | |
2668 | { | |
2669 | return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); | |
2670 | } | |
2671 | ||
2672 | static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) | |
2673 | { | |
2674 | struct bfq_group_data *bgd; | |
2675 | ||
2676 | bgd = kzalloc(sizeof(*bgd), gfp); | |
2677 | if (!bgd) | |
2678 | return NULL; | |
2679 | return &bgd->pd; | |
2680 | } | |
2681 | ||
2682 | static void bfq_cpd_init(struct blkcg_policy_data *cpd) | |
2683 | { | |
2684 | struct bfq_group_data *d = cpd_to_bfqgd(cpd); | |
2685 | ||
2686 | d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ? | |
2687 | CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL; | |
2688 | } | |
2689 | ||
2690 | static void bfq_cpd_free(struct blkcg_policy_data *cpd) | |
2691 | { | |
2692 | kfree(cpd_to_bfqgd(cpd)); | |
2693 | } | |
2694 | ||
2695 | static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) | |
2696 | { | |
2697 | struct bfq_group *bfqg; | |
2698 | ||
2699 | bfqg = kzalloc_node(sizeof(*bfqg), gfp, node); | |
2700 | if (!bfqg) | |
2701 | return NULL; | |
2702 | ||
2703 | if (bfqg_stats_init(&bfqg->stats, gfp)) { | |
2704 | kfree(bfqg); | |
2705 | return NULL; | |
2706 | } | |
2707 | ||
2708 | return &bfqg->pd; | |
2709 | } | |
2710 | ||
2711 | static void bfq_pd_init(struct blkg_policy_data *pd) | |
2712 | { | |
2713 | struct blkcg_gq *blkg = pd_to_blkg(pd); | |
2714 | struct bfq_group *bfqg = blkg_to_bfqg(blkg); | |
2715 | struct bfq_data *bfqd = blkg->q->elevator->elevator_data; | |
2716 | struct bfq_entity *entity = &bfqg->entity; | |
2717 | struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg); | |
2718 | ||
2719 | entity->orig_weight = entity->weight = entity->new_weight = d->weight; | |
2720 | entity->my_sched_data = &bfqg->sched_data; | |
2721 | bfqg->my_entity = entity; /* | |
2722 | * the root_group's will be set to NULL | |
2723 | * in bfq_init_queue() | |
2724 | */ | |
2725 | bfqg->bfqd = bfqd; | |
2726 | } | |
2727 | ||
2728 | static void bfq_pd_free(struct blkg_policy_data *pd) | |
2729 | { | |
2730 | struct bfq_group *bfqg = pd_to_bfqg(pd); | |
2731 | ||
2732 | bfqg_stats_exit(&bfqg->stats); | |
2733 | return kfree(bfqg); | |
2734 | } | |
2735 | ||
2736 | static void bfq_pd_reset_stats(struct blkg_policy_data *pd) | |
2737 | { | |
2738 | struct bfq_group *bfqg = pd_to_bfqg(pd); | |
2739 | ||
2740 | bfqg_stats_reset(&bfqg->stats); | |
2741 | } | |
2742 | ||
2743 | static void bfq_group_set_parent(struct bfq_group *bfqg, | |
2744 | struct bfq_group *parent) | |
2745 | { | |
2746 | struct bfq_entity *entity; | |
2747 | ||
2748 | entity = &bfqg->entity; | |
2749 | entity->parent = parent->my_entity; | |
2750 | entity->sched_data = &parent->sched_data; | |
2751 | } | |
2752 | ||
2753 | static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd, | |
2754 | struct blkcg *blkcg) | |
2755 | { | |
2756 | struct blkcg_gq *blkg; | |
2757 | ||
2758 | blkg = blkg_lookup(blkcg, bfqd->queue); | |
2759 | if (likely(blkg)) | |
2760 | return blkg_to_bfqg(blkg); | |
2761 | return NULL; | |
2762 | } | |
2763 | ||
2764 | static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, | |
2765 | struct blkcg *blkcg) | |
2766 | { | |
2767 | struct bfq_group *bfqg, *parent; | |
2768 | struct bfq_entity *entity; | |
2769 | ||
2770 | bfqg = bfq_lookup_bfqg(bfqd, blkcg); | |
2771 | ||
2772 | if (unlikely(!bfqg)) | |
2773 | return NULL; | |
2774 | ||
2775 | /* | |
2776 | * Update chain of bfq_groups as we might be handling a leaf group | |
2777 | * which, along with some of its relatives, has not been hooked yet | |
2778 | * to the private hierarchy of BFQ. | |
2779 | */ | |
2780 | entity = &bfqg->entity; | |
2781 | for_each_entity(entity) { | |
2782 | bfqg = container_of(entity, struct bfq_group, entity); | |
2783 | if (bfqg != bfqd->root_group) { | |
2784 | parent = bfqg_parent(bfqg); | |
2785 | if (!parent) | |
2786 | parent = bfqd->root_group; | |
2787 | bfq_group_set_parent(bfqg, parent); | |
2788 | } | |
2789 | } | |
2790 | ||
2791 | return bfqg; | |
2792 | } | |
2793 | ||
2794 | static void bfq_bfqq_expire(struct bfq_data *bfqd, | |
2795 | struct bfq_queue *bfqq, | |
2796 | bool compensate, | |
2797 | enum bfqq_expiration reason); | |
2798 | ||
2799 | /** | |
2800 | * bfq_bfqq_move - migrate @bfqq to @bfqg. | |
2801 | * @bfqd: queue descriptor. | |
2802 | * @bfqq: the queue to move. | |
2803 | * @bfqg: the group to move to. | |
2804 | * | |
2805 | * Move @bfqq to @bfqg, deactivating it from its old group and reactivating | |
2806 | * it on the new one. Avoid putting the entity on the old group idle tree. | |
2807 | * | |
2808 | * Must be called under the queue lock; the cgroup owning @bfqg must | |
2809 | * not disappear (by now this just means that we are called under | |
2810 | * rcu_read_lock()). | |
2811 | */ | |
2812 | static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
2813 | struct bfq_group *bfqg) | |
2814 | { | |
2815 | struct bfq_entity *entity = &bfqq->entity; | |
2816 | ||
2817 | /* If bfqq is empty, then bfq_bfqq_expire also invokes | |
2818 | * bfq_del_bfqq_busy, thereby removing bfqq and its entity | |
2819 | * from data structures related to current group. Otherwise we | |
2820 | * need to remove bfqq explicitly with bfq_deactivate_bfqq, as | |
2821 | * we do below. | |
2822 | */ | |
2823 | if (bfqq == bfqd->in_service_queue) | |
2824 | bfq_bfqq_expire(bfqd, bfqd->in_service_queue, | |
2825 | false, BFQQE_PREEMPTED); | |
2826 | ||
2827 | if (bfq_bfqq_busy(bfqq)) | |
2828 | bfq_deactivate_bfqq(bfqd, bfqq, false, false); | |
2829 | else if (entity->on_st) | |
2830 | bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); | |
2831 | bfqg_put(bfqq_group(bfqq)); | |
2832 | ||
2833 | /* | |
2834 | * Here we use a reference to bfqg. We don't need a refcounter | |
2835 | * as the cgroup reference will not be dropped, so that its | |
2836 | * destroy() callback will not be invoked. | |
2837 | */ | |
2838 | entity->parent = bfqg->my_entity; | |
2839 | entity->sched_data = &bfqg->sched_data; | |
2840 | bfqg_get(bfqg); | |
2841 | ||
2842 | if (bfq_bfqq_busy(bfqq)) | |
2843 | bfq_activate_bfqq(bfqd, bfqq); | |
2844 | ||
2845 | if (!bfqd->in_service_queue && !bfqd->rq_in_driver) | |
2846 | bfq_schedule_dispatch(bfqd); | |
2847 | } | |
2848 | ||
2849 | /** | |
2850 | * __bfq_bic_change_cgroup - move @bic to @cgroup. | |
2851 | * @bfqd: the queue descriptor. | |
2852 | * @bic: the bic to move. | |
2853 | * @blkcg: the blk-cgroup to move to. | |
2854 | * | |
2855 | * Move bic to blkcg, assuming that bfqd->queue is locked; the caller | |
2856 | * has to make sure that the reference to cgroup is valid across the call. | |
2857 | * | |
2858 | * NOTE: an alternative approach might have been to store the current | |
2859 | * cgroup in bfqq and getting a reference to it, reducing the lookup | |
2860 | * time here, at the price of slightly more complex code. | |
2861 | */ | |
2862 | static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, | |
2863 | struct bfq_io_cq *bic, | |
2864 | struct blkcg *blkcg) | |
2865 | { | |
2866 | struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); | |
2867 | struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); | |
2868 | struct bfq_group *bfqg; | |
2869 | struct bfq_entity *entity; | |
2870 | ||
2871 | bfqg = bfq_find_set_group(bfqd, blkcg); | |
2872 | ||
2873 | if (unlikely(!bfqg)) | |
2874 | bfqg = bfqd->root_group; | |
2875 | ||
2876 | if (async_bfqq) { | |
2877 | entity = &async_bfqq->entity; | |
2878 | ||
2879 | if (entity->sched_data != &bfqg->sched_data) { | |
2880 | bic_set_bfqq(bic, NULL, 0); | |
2881 | bfq_log_bfqq(bfqd, async_bfqq, | |
2882 | "bic_change_group: %p %d", | |
2883 | async_bfqq, | |
2884 | async_bfqq->ref); | |
2885 | bfq_put_queue(async_bfqq); | |
2886 | } | |
2887 | } | |
2888 | ||
2889 | if (sync_bfqq) { | |
2890 | entity = &sync_bfqq->entity; | |
2891 | if (entity->sched_data != &bfqg->sched_data) | |
2892 | bfq_bfqq_move(bfqd, sync_bfqq, bfqg); | |
2893 | } | |
2894 | ||
2895 | return bfqg; | |
2896 | } | |
2897 | ||
2898 | static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) | |
2899 | { | |
2900 | struct bfq_data *bfqd = bic_to_bfqd(bic); | |
2901 | struct bfq_group *bfqg = NULL; | |
2902 | uint64_t serial_nr; | |
2903 | ||
2904 | rcu_read_lock(); | |
2905 | serial_nr = bio_blkcg(bio)->css.serial_nr; | |
2906 | ||
2907 | /* | |
2908 | * Check whether blkcg has changed. The condition may trigger | |
2909 | * spuriously on a newly created cic but there's no harm. | |
2910 | */ | |
2911 | if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr)) | |
2912 | goto out; | |
2913 | ||
2914 | bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio)); | |
2915 | bic->blkcg_serial_nr = serial_nr; | |
2916 | out: | |
2917 | rcu_read_unlock(); | |
2918 | } | |
2919 | ||
2920 | /** | |
2921 | * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st. | |
2922 | * @st: the service tree being flushed. | |
2923 | */ | |
2924 | static void bfq_flush_idle_tree(struct bfq_service_tree *st) | |
2925 | { | |
2926 | struct bfq_entity *entity = st->first_idle; | |
2927 | ||
2928 | for (; entity ; entity = st->first_idle) | |
2929 | __bfq_deactivate_entity(entity, false); | |
2930 | } | |
2931 | ||
2932 | /** | |
2933 | * bfq_reparent_leaf_entity - move leaf entity to the root_group. | |
2934 | * @bfqd: the device data structure with the root group. | |
2935 | * @entity: the entity to move. | |
2936 | */ | |
2937 | static void bfq_reparent_leaf_entity(struct bfq_data *bfqd, | |
2938 | struct bfq_entity *entity) | |
2939 | { | |
2940 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
2941 | ||
2942 | bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); | |
aee69d78 PV |
2943 | } |
2944 | ||
2945 | /** | |
e21b7a0b AA |
2946 | * bfq_reparent_active_entities - move to the root group all active |
2947 | * entities. | |
2948 | * @bfqd: the device data structure with the root group. | |
2949 | * @bfqg: the group to move from. | |
2950 | * @st: the service tree with the entities. | |
aee69d78 | 2951 | * |
e21b7a0b | 2952 | * Needs queue_lock to be taken and reference to be valid over the call. |
aee69d78 | 2953 | */ |
e21b7a0b AA |
2954 | static void bfq_reparent_active_entities(struct bfq_data *bfqd, |
2955 | struct bfq_group *bfqg, | |
2956 | struct bfq_service_tree *st) | |
aee69d78 | 2957 | { |
e21b7a0b AA |
2958 | struct rb_root *active = &st->active; |
2959 | struct bfq_entity *entity = NULL; | |
aee69d78 | 2960 | |
e21b7a0b AA |
2961 | if (!RB_EMPTY_ROOT(&st->active)) |
2962 | entity = bfq_entity_of(rb_first(active)); | |
aee69d78 | 2963 | |
e21b7a0b AA |
2964 | for (; entity ; entity = bfq_entity_of(rb_first(active))) |
2965 | bfq_reparent_leaf_entity(bfqd, entity); | |
aee69d78 | 2966 | |
e21b7a0b AA |
2967 | if (bfqg->sched_data.in_service_entity) |
2968 | bfq_reparent_leaf_entity(bfqd, | |
2969 | bfqg->sched_data.in_service_entity); | |
aee69d78 PV |
2970 | } |
2971 | ||
2972 | /** | |
e21b7a0b AA |
2973 | * bfq_pd_offline - deactivate the entity associated with @pd, |
2974 | * and reparent its children entities. | |
2975 | * @pd: descriptor of the policy going offline. | |
aee69d78 | 2976 | * |
e21b7a0b AA |
2977 | * blkio already grabs the queue_lock for us, so no need to use |
2978 | * RCU-based magic | |
aee69d78 | 2979 | */ |
e21b7a0b | 2980 | static void bfq_pd_offline(struct blkg_policy_data *pd) |
aee69d78 | 2981 | { |
e21b7a0b AA |
2982 | struct bfq_service_tree *st; |
2983 | struct bfq_group *bfqg = pd_to_bfqg(pd); | |
2984 | struct bfq_data *bfqd = bfqg->bfqd; | |
2985 | struct bfq_entity *entity = bfqg->my_entity; | |
2986 | unsigned long flags; | |
2987 | int i; | |
aee69d78 | 2988 | |
e21b7a0b AA |
2989 | if (!entity) /* root group */ |
2990 | return; | |
2991 | ||
2992 | spin_lock_irqsave(&bfqd->lock, flags); | |
aee69d78 | 2993 | /* |
e21b7a0b AA |
2994 | * Empty all service_trees belonging to this group before |
2995 | * deactivating the group itself. | |
aee69d78 | 2996 | */ |
e21b7a0b AA |
2997 | for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) { |
2998 | st = bfqg->sched_data.service_tree + i; | |
2999 | ||
3000 | /* | |
3001 | * The idle tree may still contain bfq_queues belonging | |
3002 | * to exited task because they never migrated to a different | |
3003 | * cgroup from the one being destroyed now. No one else | |
3004 | * can access them so it's safe to act without any lock. | |
3005 | */ | |
3006 | bfq_flush_idle_tree(st); | |
3007 | ||
3008 | /* | |
3009 | * It may happen that some queues are still active | |
3010 | * (busy) upon group destruction (if the corresponding | |
3011 | * processes have been forced to terminate). We move | |
3012 | * all the leaf entities corresponding to these queues | |
3013 | * to the root_group. | |
3014 | * Also, it may happen that the group has an entity | |
3015 | * in service, which is disconnected from the active | |
3016 | * tree: it must be moved, too. | |
3017 | * There is no need to put the sync queues, as the | |
3018 | * scheduler has taken no reference. | |
3019 | */ | |
3020 | bfq_reparent_active_entities(bfqd, bfqg, st); | |
aee69d78 PV |
3021 | } |
3022 | ||
e21b7a0b AA |
3023 | __bfq_deactivate_entity(entity, false); |
3024 | bfq_put_async_queues(bfqd, bfqg); | |
3025 | ||
3026 | spin_unlock_irqrestore(&bfqd->lock, flags); | |
3027 | /* | |
3028 | * @blkg is going offline and will be ignored by | |
3029 | * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so | |
3030 | * that they don't get lost. If IOs complete after this point, the | |
3031 | * stats for them will be lost. Oh well... | |
3032 | */ | |
3033 | bfqg_stats_xfer_dead(bfqg); | |
aee69d78 PV |
3034 | } |
3035 | ||
e21b7a0b | 3036 | static int bfq_io_show_weight(struct seq_file *sf, void *v) |
aee69d78 | 3037 | { |
e21b7a0b AA |
3038 | struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); |
3039 | struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); | |
3040 | unsigned int val = 0; | |
aee69d78 | 3041 | |
e21b7a0b AA |
3042 | if (bfqgd) |
3043 | val = bfqgd->weight; | |
aee69d78 | 3044 | |
e21b7a0b | 3045 | seq_printf(sf, "%u\n", val); |
aee69d78 | 3046 | |
e21b7a0b AA |
3047 | return 0; |
3048 | } | |
3049 | ||
3050 | static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, | |
3051 | struct cftype *cftype, | |
3052 | u64 val) | |
aee69d78 | 3053 | { |
e21b7a0b AA |
3054 | struct blkcg *blkcg = css_to_blkcg(css); |
3055 | struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); | |
3056 | struct blkcg_gq *blkg; | |
3057 | int ret = -ERANGE; | |
aee69d78 | 3058 | |
e21b7a0b AA |
3059 | if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) |
3060 | return ret; | |
aee69d78 | 3061 | |
e21b7a0b AA |
3062 | ret = 0; |
3063 | spin_lock_irq(&blkcg->lock); | |
3064 | bfqgd->weight = (unsigned short)val; | |
3065 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { | |
3066 | struct bfq_group *bfqg = blkg_to_bfqg(blkg); | |
3067 | ||
3068 | if (!bfqg) | |
3069 | continue; | |
3070 | /* | |
3071 | * Setting the prio_changed flag of the entity | |
3072 | * to 1 with new_weight == weight would re-set | |
3073 | * the value of the weight to its ioprio mapping. | |
3074 | * Set the flag only if necessary. | |
3075 | */ | |
3076 | if ((unsigned short)val != bfqg->entity.new_weight) { | |
3077 | bfqg->entity.new_weight = (unsigned short)val; | |
3078 | /* | |
3079 | * Make sure that the above new value has been | |
3080 | * stored in bfqg->entity.new_weight before | |
3081 | * setting the prio_changed flag. In fact, | |
3082 | * this flag may be read asynchronously (in | |
3083 | * critical sections protected by a different | |
3084 | * lock than that held here), and finding this | |
3085 | * flag set may cause the execution of the code | |
3086 | * for updating parameters whose value may | |
3087 | * depend also on bfqg->entity.new_weight (in | |
3088 | * __bfq_entity_update_weight_prio). | |
3089 | * This barrier makes sure that the new value | |
3090 | * of bfqg->entity.new_weight is correctly | |
3091 | * seen in that code. | |
3092 | */ | |
3093 | smp_wmb(); | |
3094 | bfqg->entity.prio_changed = 1; | |
3095 | } | |
aee69d78 | 3096 | } |
e21b7a0b | 3097 | spin_unlock_irq(&blkcg->lock); |
aee69d78 | 3098 | |
e21b7a0b AA |
3099 | return ret; |
3100 | } | |
aee69d78 | 3101 | |
e21b7a0b AA |
3102 | static ssize_t bfq_io_set_weight(struct kernfs_open_file *of, |
3103 | char *buf, size_t nbytes, | |
3104 | loff_t off) | |
3105 | { | |
3106 | u64 weight; | |
3107 | /* First unsigned long found in the file is used */ | |
3108 | int ret = kstrtoull(strim(buf), 0, &weight); | |
3109 | ||
3110 | if (ret) | |
3111 | return ret; | |
3112 | ||
3113 | return bfq_io_set_weight_legacy(of_css(of), NULL, weight); | |
aee69d78 PV |
3114 | } |
3115 | ||
e21b7a0b | 3116 | static int bfqg_print_stat(struct seq_file *sf, void *v) |
aee69d78 | 3117 | { |
e21b7a0b AA |
3118 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat, |
3119 | &blkcg_policy_bfq, seq_cft(sf)->private, false); | |
3120 | return 0; | |
3121 | } | |
aee69d78 | 3122 | |
e21b7a0b AA |
3123 | static int bfqg_print_rwstat(struct seq_file *sf, void *v) |
3124 | { | |
3125 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, | |
3126 | &blkcg_policy_bfq, seq_cft(sf)->private, true); | |
3127 | return 0; | |
3128 | } | |
aee69d78 | 3129 | |
e21b7a0b AA |
3130 | static u64 bfqg_prfill_stat_recursive(struct seq_file *sf, |
3131 | struct blkg_policy_data *pd, int off) | |
3132 | { | |
3133 | u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd), | |
3134 | &blkcg_policy_bfq, off); | |
3135 | return __blkg_prfill_u64(sf, pd, sum); | |
3136 | } | |
aee69d78 | 3137 | |
e21b7a0b AA |
3138 | static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, |
3139 | struct blkg_policy_data *pd, int off) | |
3140 | { | |
3141 | struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd), | |
3142 | &blkcg_policy_bfq, | |
3143 | off); | |
3144 | return __blkg_prfill_rwstat(sf, pd, &sum); | |
aee69d78 PV |
3145 | } |
3146 | ||
e21b7a0b | 3147 | static int bfqg_print_stat_recursive(struct seq_file *sf, void *v) |
aee69d78 | 3148 | { |
e21b7a0b AA |
3149 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), |
3150 | bfqg_prfill_stat_recursive, &blkcg_policy_bfq, | |
3151 | seq_cft(sf)->private, false); | |
3152 | return 0; | |
3153 | } | |
aee69d78 | 3154 | |
e21b7a0b AA |
3155 | static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v) |
3156 | { | |
3157 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
3158 | bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq, | |
3159 | seq_cft(sf)->private, true); | |
3160 | return 0; | |
aee69d78 PV |
3161 | } |
3162 | ||
e21b7a0b AA |
3163 | static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd, |
3164 | int off) | |
aee69d78 | 3165 | { |
e21b7a0b | 3166 | u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes); |
aee69d78 | 3167 | |
e21b7a0b | 3168 | return __blkg_prfill_u64(sf, pd, sum >> 9); |
aee69d78 PV |
3169 | } |
3170 | ||
e21b7a0b | 3171 | static int bfqg_print_stat_sectors(struct seq_file *sf, void *v) |
aee69d78 | 3172 | { |
e21b7a0b AA |
3173 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), |
3174 | bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false); | |
3175 | return 0; | |
3176 | } | |
aee69d78 | 3177 | |
e21b7a0b AA |
3178 | static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf, |
3179 | struct blkg_policy_data *pd, int off) | |
3180 | { | |
3181 | struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL, | |
3182 | offsetof(struct blkcg_gq, stat_bytes)); | |
3183 | u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) + | |
3184 | atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]); | |
aee69d78 | 3185 | |
e21b7a0b AA |
3186 | return __blkg_prfill_u64(sf, pd, sum >> 9); |
3187 | } | |
aee69d78 | 3188 | |
e21b7a0b AA |
3189 | static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v) |
3190 | { | |
3191 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
3192 | bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0, | |
3193 | false); | |
3194 | return 0; | |
aee69d78 PV |
3195 | } |
3196 | ||
e21b7a0b AA |
3197 | static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf, |
3198 | struct blkg_policy_data *pd, int off) | |
aee69d78 | 3199 | { |
e21b7a0b AA |
3200 | struct bfq_group *bfqg = pd_to_bfqg(pd); |
3201 | u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples); | |
3202 | u64 v = 0; | |
aee69d78 | 3203 | |
e21b7a0b AA |
3204 | if (samples) { |
3205 | v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum); | |
3206 | v = div64_u64(v, samples); | |
3207 | } | |
3208 | __blkg_prfill_u64(sf, pd, v); | |
3209 | return 0; | |
3210 | } | |
aee69d78 | 3211 | |
e21b7a0b AA |
3212 | /* print avg_queue_size */ |
3213 | static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v) | |
3214 | { | |
3215 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
3216 | bfqg_prfill_avg_queue_size, &blkcg_policy_bfq, | |
3217 | 0, false); | |
3218 | return 0; | |
3219 | } | |
3220 | ||
3221 | static struct bfq_group * | |
3222 | bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) | |
3223 | { | |
3224 | int ret; | |
3225 | ||
3226 | ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq); | |
3227 | if (ret) | |
3228 | return NULL; | |
3229 | ||
3230 | return blkg_to_bfqg(bfqd->queue->root_blkg); | |
aee69d78 PV |
3231 | } |
3232 | ||
e21b7a0b AA |
3233 | static struct cftype bfq_blkcg_legacy_files[] = { |
3234 | { | |
3235 | .name = "bfq.weight", | |
3236 | .flags = CFTYPE_NOT_ON_ROOT, | |
3237 | .seq_show = bfq_io_show_weight, | |
3238 | .write_u64 = bfq_io_set_weight_legacy, | |
3239 | }, | |
3240 | ||
3241 | /* statistics, covers only the tasks in the bfqg */ | |
3242 | { | |
3243 | .name = "bfq.time", | |
3244 | .private = offsetof(struct bfq_group, stats.time), | |
3245 | .seq_show = bfqg_print_stat, | |
3246 | }, | |
3247 | { | |
3248 | .name = "bfq.sectors", | |
3249 | .seq_show = bfqg_print_stat_sectors, | |
3250 | }, | |
3251 | { | |
3252 | .name = "bfq.io_service_bytes", | |
3253 | .private = (unsigned long)&blkcg_policy_bfq, | |
3254 | .seq_show = blkg_print_stat_bytes, | |
3255 | }, | |
3256 | { | |
3257 | .name = "bfq.io_serviced", | |
3258 | .private = (unsigned long)&blkcg_policy_bfq, | |
3259 | .seq_show = blkg_print_stat_ios, | |
3260 | }, | |
3261 | { | |
3262 | .name = "bfq.io_service_time", | |
3263 | .private = offsetof(struct bfq_group, stats.service_time), | |
3264 | .seq_show = bfqg_print_rwstat, | |
3265 | }, | |
3266 | { | |
3267 | .name = "bfq.io_wait_time", | |
3268 | .private = offsetof(struct bfq_group, stats.wait_time), | |
3269 | .seq_show = bfqg_print_rwstat, | |
3270 | }, | |
3271 | { | |
3272 | .name = "bfq.io_merged", | |
3273 | .private = offsetof(struct bfq_group, stats.merged), | |
3274 | .seq_show = bfqg_print_rwstat, | |
3275 | }, | |
3276 | { | |
3277 | .name = "bfq.io_queued", | |
3278 | .private = offsetof(struct bfq_group, stats.queued), | |
3279 | .seq_show = bfqg_print_rwstat, | |
3280 | }, | |
3281 | ||
3282 | /* the same statictics which cover the bfqg and its descendants */ | |
3283 | { | |
3284 | .name = "bfq.time_recursive", | |
3285 | .private = offsetof(struct bfq_group, stats.time), | |
3286 | .seq_show = bfqg_print_stat_recursive, | |
3287 | }, | |
3288 | { | |
3289 | .name = "bfq.sectors_recursive", | |
3290 | .seq_show = bfqg_print_stat_sectors_recursive, | |
3291 | }, | |
3292 | { | |
3293 | .name = "bfq.io_service_bytes_recursive", | |
3294 | .private = (unsigned long)&blkcg_policy_bfq, | |
3295 | .seq_show = blkg_print_stat_bytes_recursive, | |
3296 | }, | |
3297 | { | |
3298 | .name = "bfq.io_serviced_recursive", | |
3299 | .private = (unsigned long)&blkcg_policy_bfq, | |
3300 | .seq_show = blkg_print_stat_ios_recursive, | |
3301 | }, | |
3302 | { | |
3303 | .name = "bfq.io_service_time_recursive", | |
3304 | .private = offsetof(struct bfq_group, stats.service_time), | |
3305 | .seq_show = bfqg_print_rwstat_recursive, | |
3306 | }, | |
3307 | { | |
3308 | .name = "bfq.io_wait_time_recursive", | |
3309 | .private = offsetof(struct bfq_group, stats.wait_time), | |
3310 | .seq_show = bfqg_print_rwstat_recursive, | |
3311 | }, | |
3312 | { | |
3313 | .name = "bfq.io_merged_recursive", | |
3314 | .private = offsetof(struct bfq_group, stats.merged), | |
3315 | .seq_show = bfqg_print_rwstat_recursive, | |
3316 | }, | |
3317 | { | |
3318 | .name = "bfq.io_queued_recursive", | |
3319 | .private = offsetof(struct bfq_group, stats.queued), | |
3320 | .seq_show = bfqg_print_rwstat_recursive, | |
3321 | }, | |
3322 | { | |
3323 | .name = "bfq.avg_queue_size", | |
3324 | .seq_show = bfqg_print_avg_queue_size, | |
3325 | }, | |
3326 | { | |
3327 | .name = "bfq.group_wait_time", | |
3328 | .private = offsetof(struct bfq_group, stats.group_wait_time), | |
3329 | .seq_show = bfqg_print_stat, | |
3330 | }, | |
3331 | { | |
3332 | .name = "bfq.idle_time", | |
3333 | .private = offsetof(struct bfq_group, stats.idle_time), | |
3334 | .seq_show = bfqg_print_stat, | |
3335 | }, | |
3336 | { | |
3337 | .name = "bfq.empty_time", | |
3338 | .private = offsetof(struct bfq_group, stats.empty_time), | |
3339 | .seq_show = bfqg_print_stat, | |
3340 | }, | |
3341 | { | |
3342 | .name = "bfq.dequeue", | |
3343 | .private = offsetof(struct bfq_group, stats.dequeue), | |
3344 | .seq_show = bfqg_print_stat, | |
3345 | }, | |
3346 | { } /* terminate */ | |
3347 | }; | |
3348 | ||
3349 | static struct cftype bfq_blkg_files[] = { | |
3350 | { | |
3351 | .name = "bfq.weight", | |
3352 | .flags = CFTYPE_NOT_ON_ROOT, | |
3353 | .seq_show = bfq_io_show_weight, | |
3354 | .write = bfq_io_set_weight, | |
3355 | }, | |
3356 | {} /* terminate */ | |
3357 | }; | |
3358 | ||
3359 | #else /* CONFIG_BFQ_GROUP_IOSCHED */ | |
3360 | ||
3361 | static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg, | |
3362 | struct bfq_queue *bfqq, unsigned int op) { } | |
3363 | static inline void | |
3364 | bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { } | |
3365 | static inline void | |
3366 | bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { } | |
3367 | static inline void bfqg_stats_update_completion(struct bfq_group *bfqg, | |
3368 | uint64_t start_time, uint64_t io_start_time, | |
3369 | unsigned int op) { } | |
3370 | static inline void | |
3371 | bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, | |
3372 | struct bfq_group *curr_bfqg) { } | |
3373 | static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { } | |
3374 | static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { } | |
3375 | static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { } | |
3376 | static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { } | |
3377 | static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { } | |
3378 | static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { } | |
3379 | ||
3380 | static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
3381 | struct bfq_group *bfqg) {} | |
3382 | ||
3383 | static void bfq_init_entity(struct bfq_entity *entity, | |
3384 | struct bfq_group *bfqg) | |
aee69d78 PV |
3385 | { |
3386 | struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); | |
3387 | ||
3388 | entity->weight = entity->new_weight; | |
3389 | entity->orig_weight = entity->new_weight; | |
e21b7a0b AA |
3390 | if (bfqq) { |
3391 | bfqq->ioprio = bfqq->new_ioprio; | |
3392 | bfqq->ioprio_class = bfqq->new_ioprio_class; | |
3393 | } | |
3394 | entity->sched_data = &bfqg->sched_data; | |
3395 | } | |
3396 | ||
3397 | static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {} | |
3398 | ||
3399 | static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, | |
3400 | struct blkcg *blkcg) | |
3401 | { | |
3402 | return bfqd->root_group; | |
3403 | } | |
3404 | ||
3405 | static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) | |
3406 | { | |
3407 | return bfqq->bfqd->root_group; | |
3408 | } | |
aee69d78 | 3409 | |
e21b7a0b AA |
3410 | static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, |
3411 | int node) | |
3412 | { | |
3413 | struct bfq_group *bfqg; | |
3414 | int i; | |
3415 | ||
3416 | bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node); | |
3417 | if (!bfqg) | |
3418 | return NULL; | |
aee69d78 | 3419 | |
e21b7a0b AA |
3420 | for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) |
3421 | bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; | |
3422 | ||
3423 | return bfqg; | |
aee69d78 | 3424 | } |
e21b7a0b | 3425 | #endif /* CONFIG_BFQ_GROUP_IOSCHED */ |
aee69d78 PV |
3426 | |
3427 | #define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
3428 | #define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT) | |
3429 | ||
3430 | #define bfq_sample_valid(samples) ((samples) > 80) | |
3431 | ||
aee69d78 PV |
3432 | /* |
3433 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. | |
3434 | * We choose the request that is closesr to the head right now. Distance | |
3435 | * behind the head is penalized and only allowed to a certain extent. | |
3436 | */ | |
3437 | static struct request *bfq_choose_req(struct bfq_data *bfqd, | |
3438 | struct request *rq1, | |
3439 | struct request *rq2, | |
3440 | sector_t last) | |
3441 | { | |
3442 | sector_t s1, s2, d1 = 0, d2 = 0; | |
3443 | unsigned long back_max; | |
3444 | #define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */ | |
3445 | #define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
3446 | unsigned int wrap = 0; /* bit mask: requests behind the disk head? */ | |
3447 | ||
3448 | if (!rq1 || rq1 == rq2) | |
3449 | return rq2; | |
3450 | if (!rq2) | |
3451 | return rq1; | |
3452 | ||
3453 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) | |
3454 | return rq1; | |
3455 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
3456 | return rq2; | |
3457 | if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META)) | |
3458 | return rq1; | |
3459 | else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META)) | |
3460 | return rq2; | |
3461 | ||
3462 | s1 = blk_rq_pos(rq1); | |
3463 | s2 = blk_rq_pos(rq2); | |
3464 | ||
3465 | /* | |
3466 | * By definition, 1KiB is 2 sectors. | |
3467 | */ | |
3468 | back_max = bfqd->bfq_back_max * 2; | |
3469 | ||
3470 | /* | |
3471 | * Strict one way elevator _except_ in the case where we allow | |
3472 | * short backward seeks which are biased as twice the cost of a | |
3473 | * similar forward seek. | |
3474 | */ | |
3475 | if (s1 >= last) | |
3476 | d1 = s1 - last; | |
3477 | else if (s1 + back_max >= last) | |
3478 | d1 = (last - s1) * bfqd->bfq_back_penalty; | |
3479 | else | |
3480 | wrap |= BFQ_RQ1_WRAP; | |
3481 | ||
3482 | if (s2 >= last) | |
3483 | d2 = s2 - last; | |
3484 | else if (s2 + back_max >= last) | |
3485 | d2 = (last - s2) * bfqd->bfq_back_penalty; | |
3486 | else | |
3487 | wrap |= BFQ_RQ2_WRAP; | |
3488 | ||
3489 | /* Found required data */ | |
3490 | ||
3491 | /* | |
3492 | * By doing switch() on the bit mask "wrap" we avoid having to | |
3493 | * check two variables for all permutations: --> faster! | |
3494 | */ | |
3495 | switch (wrap) { | |
3496 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ | |
3497 | if (d1 < d2) | |
3498 | return rq1; | |
3499 | else if (d2 < d1) | |
3500 | return rq2; | |
3501 | ||
3502 | if (s1 >= s2) | |
3503 | return rq1; | |
3504 | else | |
3505 | return rq2; | |
3506 | ||
3507 | case BFQ_RQ2_WRAP: | |
3508 | return rq1; | |
3509 | case BFQ_RQ1_WRAP: | |
3510 | return rq2; | |
3511 | case BFQ_RQ1_WRAP|BFQ_RQ2_WRAP: /* both rqs wrapped */ | |
3512 | default: | |
3513 | /* | |
3514 | * Since both rqs are wrapped, | |
3515 | * start with the one that's further behind head | |
3516 | * (--> only *one* back seek required), | |
3517 | * since back seek takes more time than forward. | |
3518 | */ | |
3519 | if (s1 <= s2) | |
3520 | return rq1; | |
3521 | else | |
3522 | return rq2; | |
3523 | } | |
3524 | } | |
3525 | ||
3526 | /* | |
3527 | * Return expired entry, or NULL to just start from scratch in rbtree. | |
3528 | */ | |
3529 | static struct request *bfq_check_fifo(struct bfq_queue *bfqq, | |
3530 | struct request *last) | |
3531 | { | |
3532 | struct request *rq; | |
3533 | ||
3534 | if (bfq_bfqq_fifo_expire(bfqq)) | |
3535 | return NULL; | |
3536 | ||
3537 | bfq_mark_bfqq_fifo_expire(bfqq); | |
3538 | ||
3539 | rq = rq_entry_fifo(bfqq->fifo.next); | |
3540 | ||
3541 | if (rq == last || ktime_get_ns() < rq->fifo_time) | |
3542 | return NULL; | |
3543 | ||
3544 | bfq_log_bfqq(bfqq->bfqd, bfqq, "check_fifo: returned %p", rq); | |
3545 | return rq; | |
3546 | } | |
3547 | ||
3548 | static struct request *bfq_find_next_rq(struct bfq_data *bfqd, | |
3549 | struct bfq_queue *bfqq, | |
3550 | struct request *last) | |
3551 | { | |
3552 | struct rb_node *rbnext = rb_next(&last->rb_node); | |
3553 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
3554 | struct request *next, *prev = NULL; | |
3555 | ||
3556 | /* Follow expired path, else get first next available. */ | |
3557 | next = bfq_check_fifo(bfqq, last); | |
3558 | if (next) | |
3559 | return next; | |
3560 | ||
3561 | if (rbprev) | |
3562 | prev = rb_entry_rq(rbprev); | |
3563 | ||
3564 | if (rbnext) | |
3565 | next = rb_entry_rq(rbnext); | |
3566 | else { | |
3567 | rbnext = rb_first(&bfqq->sort_list); | |
3568 | if (rbnext && rbnext != &last->rb_node) | |
3569 | next = rb_entry_rq(rbnext); | |
3570 | } | |
3571 | ||
3572 | return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last)); | |
3573 | } | |
3574 | ||
3575 | static unsigned long bfq_serv_to_charge(struct request *rq, | |
3576 | struct bfq_queue *bfqq) | |
3577 | { | |
3578 | return blk_rq_sectors(rq); | |
3579 | } | |
3580 | ||
3581 | /** | |
3582 | * bfq_updated_next_req - update the queue after a new next_rq selection. | |
3583 | * @bfqd: the device data the queue belongs to. | |
3584 | * @bfqq: the queue to update. | |
3585 | * | |
3586 | * If the first request of a queue changes we make sure that the queue | |
3587 | * has enough budget to serve at least its first request (if the | |
3588 | * request has grown). We do this because if the queue has not enough | |
3589 | * budget for its first request, it has to go through two dispatch | |
3590 | * rounds to actually get it dispatched. | |
3591 | */ | |
3592 | static void bfq_updated_next_req(struct bfq_data *bfqd, | |
3593 | struct bfq_queue *bfqq) | |
3594 | { | |
3595 | struct bfq_entity *entity = &bfqq->entity; | |
3596 | struct request *next_rq = bfqq->next_rq; | |
3597 | unsigned long new_budget; | |
3598 | ||
3599 | if (!next_rq) | |
3600 | return; | |
3601 | ||
3602 | if (bfqq == bfqd->in_service_queue) | |
3603 | /* | |
3604 | * In order not to break guarantees, budgets cannot be | |
3605 | * changed after an entity has been selected. | |
3606 | */ | |
3607 | return; | |
3608 | ||
3609 | new_budget = max_t(unsigned long, bfqq->max_budget, | |
3610 | bfq_serv_to_charge(next_rq, bfqq)); | |
3611 | if (entity->budget != new_budget) { | |
3612 | entity->budget = new_budget; | |
3613 | bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu", | |
3614 | new_budget); | |
e21b7a0b | 3615 | bfq_requeue_bfqq(bfqd, bfqq); |
aee69d78 PV |
3616 | } |
3617 | } | |
3618 | ||
3619 | static int bfq_bfqq_budget_left(struct bfq_queue *bfqq) | |
3620 | { | |
3621 | struct bfq_entity *entity = &bfqq->entity; | |
3622 | ||
3623 | return entity->budget - entity->service; | |
3624 | } | |
3625 | ||
3626 | /* | |
3627 | * If enough samples have been computed, return the current max budget | |
3628 | * stored in bfqd, which is dynamically updated according to the | |
3629 | * estimated disk peak rate; otherwise return the default max budget | |
3630 | */ | |
3631 | static int bfq_max_budget(struct bfq_data *bfqd) | |
3632 | { | |
3633 | if (bfqd->budgets_assigned < bfq_stats_min_budgets) | |
3634 | return bfq_default_max_budget; | |
3635 | else | |
3636 | return bfqd->bfq_max_budget; | |
3637 | } | |
3638 | ||
3639 | /* | |
3640 | * Return min budget, which is a fraction of the current or default | |
3641 | * max budget (trying with 1/32) | |
3642 | */ | |
3643 | static int bfq_min_budget(struct bfq_data *bfqd) | |
3644 | { | |
3645 | if (bfqd->budgets_assigned < bfq_stats_min_budgets) | |
3646 | return bfq_default_max_budget / 32; | |
3647 | else | |
3648 | return bfqd->bfq_max_budget / 32; | |
3649 | } | |
3650 | ||
3651 | static void bfq_bfqq_expire(struct bfq_data *bfqd, | |
3652 | struct bfq_queue *bfqq, | |
3653 | bool compensate, | |
3654 | enum bfqq_expiration reason); | |
3655 | ||
3656 | /* | |
3657 | * The next function, invoked after the input queue bfqq switches from | |
3658 | * idle to busy, updates the budget of bfqq. The function also tells | |
3659 | * whether the in-service queue should be expired, by returning | |
3660 | * true. The purpose of expiring the in-service queue is to give bfqq | |
3661 | * the chance to possibly preempt the in-service queue, and the reason | |
3662 | * for preempting the in-service queue is to achieve the following | |
3663 | * goal: guarantee to bfqq its reserved bandwidth even if bfqq has | |
3664 | * expired because it has remained idle. | |
3665 | * | |
3666 | * In particular, bfqq may have expired for one of the following two | |
3667 | * reasons: | |
3668 | * | |
3669 | * - BFQQE_NO_MORE_REQUESTS bfqq did not enjoy any device idling | |
3670 | * and did not make it to issue a new request before its last | |
3671 | * request was served; | |
3672 | * | |
3673 | * - BFQQE_TOO_IDLE bfqq did enjoy device idling, but did not issue | |
3674 | * a new request before the expiration of the idling-time. | |
3675 | * | |
3676 | * Even if bfqq has expired for one of the above reasons, the process | |
3677 | * associated with the queue may be however issuing requests greedily, | |
3678 | * and thus be sensitive to the bandwidth it receives (bfqq may have | |
3679 | * remained idle for other reasons: CPU high load, bfqq not enjoying | |
3680 | * idling, I/O throttling somewhere in the path from the process to | |
3681 | * the I/O scheduler, ...). But if, after every expiration for one of | |
3682 | * the above two reasons, bfqq has to wait for the service of at least | |
3683 | * one full budget of another queue before being served again, then | |
3684 | * bfqq is likely to get a much lower bandwidth or resource time than | |
3685 | * its reserved ones. To address this issue, two countermeasures need | |
3686 | * to be taken. | |
3687 | * | |
3688 | * First, the budget and the timestamps of bfqq need to be updated in | |
3689 | * a special way on bfqq reactivation: they need to be updated as if | |
3690 | * bfqq did not remain idle and did not expire. In fact, if they are | |
3691 | * computed as if bfqq expired and remained idle until reactivation, | |
3692 | * then the process associated with bfqq is treated as if, instead of | |
3693 | * being greedy, it stopped issuing requests when bfqq remained idle, | |
3694 | * and restarts issuing requests only on this reactivation. In other | |
3695 | * words, the scheduler does not help the process recover the "service | |
3696 | * hole" between bfqq expiration and reactivation. As a consequence, | |
3697 | * the process receives a lower bandwidth than its reserved one. In | |
3698 | * contrast, to recover this hole, the budget must be updated as if | |
3699 | * bfqq was not expired at all before this reactivation, i.e., it must | |
3700 | * be set to the value of the remaining budget when bfqq was | |
3701 | * expired. Along the same line, timestamps need to be assigned the | |
3702 | * value they had the last time bfqq was selected for service, i.e., | |
3703 | * before last expiration. Thus timestamps need to be back-shifted | |
3704 | * with respect to their normal computation (see [1] for more details | |
3705 | * on this tricky aspect). | |
3706 | * | |
3707 | * Secondly, to allow the process to recover the hole, the in-service | |
3708 | * queue must be expired too, to give bfqq the chance to preempt it | |
3709 | * immediately. In fact, if bfqq has to wait for a full budget of the | |
3710 | * in-service queue to be completed, then it may become impossible to | |
3711 | * let the process recover the hole, even if the back-shifted | |
3712 | * timestamps of bfqq are lower than those of the in-service queue. If | |
3713 | * this happens for most or all of the holes, then the process may not | |
3714 | * receive its reserved bandwidth. In this respect, it is worth noting | |
3715 | * that, being the service of outstanding requests unpreemptible, a | |
3716 | * little fraction of the holes may however be unrecoverable, thereby | |
3717 | * causing a little loss of bandwidth. | |
3718 | * | |
3719 | * The last important point is detecting whether bfqq does need this | |
3720 | * bandwidth recovery. In this respect, the next function deems the | |
3721 | * process associated with bfqq greedy, and thus allows it to recover | |
3722 | * the hole, if: 1) the process is waiting for the arrival of a new | |
3723 | * request (which implies that bfqq expired for one of the above two | |
3724 | * reasons), and 2) such a request has arrived soon. The first | |
3725 | * condition is controlled through the flag non_blocking_wait_rq, | |
3726 | * while the second through the flag arrived_in_time. If both | |
3727 | * conditions hold, then the function computes the budget in the | |
3728 | * above-described special way, and signals that the in-service queue | |
3729 | * should be expired. Timestamp back-shifting is done later in | |
3730 | * __bfq_activate_entity. | |
3731 | */ | |
3732 | static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd, | |
3733 | struct bfq_queue *bfqq, | |
3734 | bool arrived_in_time) | |
3735 | { | |
3736 | struct bfq_entity *entity = &bfqq->entity; | |
3737 | ||
3738 | if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) { | |
3739 | /* | |
3740 | * We do not clear the flag non_blocking_wait_rq here, as | |
3741 | * the latter is used in bfq_activate_bfqq to signal | |
3742 | * that timestamps need to be back-shifted (and is | |
3743 | * cleared right after). | |
3744 | */ | |
3745 | ||
3746 | /* | |
3747 | * In next assignment we rely on that either | |
3748 | * entity->service or entity->budget are not updated | |
3749 | * on expiration if bfqq is empty (see | |
3750 | * __bfq_bfqq_recalc_budget). Thus both quantities | |
3751 | * remain unchanged after such an expiration, and the | |
3752 | * following statement therefore assigns to | |
3753 | * entity->budget the remaining budget on such an | |
3754 | * expiration. For clarity, entity->service is not | |
3755 | * updated on expiration in any case, and, in normal | |
3756 | * operation, is reset only when bfqq is selected for | |
3757 | * service (see bfq_get_next_queue). | |
3758 | */ | |
3759 | entity->budget = min_t(unsigned long, | |
3760 | bfq_bfqq_budget_left(bfqq), | |
3761 | bfqq->max_budget); | |
3762 | ||
3763 | return true; | |
3764 | } | |
3765 | ||
3766 | entity->budget = max_t(unsigned long, bfqq->max_budget, | |
3767 | bfq_serv_to_charge(bfqq->next_rq, bfqq)); | |
3768 | bfq_clear_bfqq_non_blocking_wait_rq(bfqq); | |
3769 | return false; | |
3770 | } | |
3771 | ||
3772 | static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, | |
3773 | struct bfq_queue *bfqq, | |
3774 | struct request *rq) | |
3775 | { | |
3776 | bool bfqq_wants_to_preempt, | |
3777 | /* | |
3778 | * See the comments on | |
3779 | * bfq_bfqq_update_budg_for_activation for | |
3780 | * details on the usage of the next variable. | |
3781 | */ | |
3782 | arrived_in_time = ktime_get_ns() <= | |
3783 | bfqq->ttime.last_end_request + | |
3784 | bfqd->bfq_slice_idle * 3; | |
3785 | ||
e21b7a0b AA |
3786 | bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags); |
3787 | ||
aee69d78 PV |
3788 | /* |
3789 | * Update budget and check whether bfqq may want to preempt | |
3790 | * the in-service queue. | |
3791 | */ | |
3792 | bfqq_wants_to_preempt = | |
3793 | bfq_bfqq_update_budg_for_activation(bfqd, bfqq, | |
3794 | arrived_in_time); | |
3795 | ||
3796 | if (!bfq_bfqq_IO_bound(bfqq)) { | |
3797 | if (arrived_in_time) { | |
3798 | bfqq->requests_within_timer++; | |
3799 | if (bfqq->requests_within_timer >= | |
3800 | bfqd->bfq_requests_within_timer) | |
3801 | bfq_mark_bfqq_IO_bound(bfqq); | |
3802 | } else | |
3803 | bfqq->requests_within_timer = 0; | |
3804 | } | |
3805 | ||
3806 | bfq_add_bfqq_busy(bfqd, bfqq); | |
3807 | ||
3808 | /* | |
3809 | * Expire in-service queue only if preemption may be needed | |
3810 | * for guarantees. In this respect, the function | |
3811 | * next_queue_may_preempt just checks a simple, necessary | |
3812 | * condition, and not a sufficient condition based on | |
3813 | * timestamps. In fact, for the latter condition to be | |
3814 | * evaluated, timestamps would need first to be updated, and | |
3815 | * this operation is quite costly (see the comments on the | |
3816 | * function bfq_bfqq_update_budg_for_activation). | |
3817 | */ | |
3818 | if (bfqd->in_service_queue && bfqq_wants_to_preempt && | |
3819 | next_queue_may_preempt(bfqd)) | |
3820 | bfq_bfqq_expire(bfqd, bfqd->in_service_queue, | |
3821 | false, BFQQE_PREEMPTED); | |
3822 | } | |
3823 | ||
3824 | static void bfq_add_request(struct request *rq) | |
3825 | { | |
3826 | struct bfq_queue *bfqq = RQ_BFQQ(rq); | |
3827 | struct bfq_data *bfqd = bfqq->bfqd; | |
3828 | struct request *next_rq, *prev; | |
3829 | ||
3830 | bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq)); | |
3831 | bfqq->queued[rq_is_sync(rq)]++; | |
3832 | bfqd->queued++; | |
3833 | ||
3834 | elv_rb_add(&bfqq->sort_list, rq); | |
3835 | ||
3836 | /* | |
3837 | * Check if this request is a better next-serve candidate. | |
3838 | */ | |
3839 | prev = bfqq->next_rq; | |
3840 | next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position); | |
3841 | bfqq->next_rq = next_rq; | |
3842 | ||
3843 | if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */ | |
3844 | bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, rq); | |
3845 | else if (prev != bfqq->next_rq) | |
3846 | bfq_updated_next_req(bfqd, bfqq); | |
3847 | } | |
3848 | ||
3849 | static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd, | |
3850 | struct bio *bio, | |
3851 | struct request_queue *q) | |
3852 | { | |
3853 | struct bfq_queue *bfqq = bfqd->bio_bfqq; | |
3854 | ||
3855 | ||
3856 | if (bfqq) | |
3857 | return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio)); | |
3858 | ||
3859 | return NULL; | |
3860 | } | |
3861 | ||
ab0e43e9 PV |
3862 | static sector_t get_sdist(sector_t last_pos, struct request *rq) |
3863 | { | |
3864 | if (last_pos) | |
3865 | return abs(blk_rq_pos(rq) - last_pos); | |
3866 | ||
3867 | return 0; | |
3868 | } | |
3869 | ||
aee69d78 PV |
3870 | #if 0 /* Still not clear if we can do without next two functions */ |
3871 | static void bfq_activate_request(struct request_queue *q, struct request *rq) | |
3872 | { | |
3873 | struct bfq_data *bfqd = q->elevator->elevator_data; | |
3874 | ||
3875 | bfqd->rq_in_driver++; | |
aee69d78 PV |
3876 | } |
3877 | ||
3878 | static void bfq_deactivate_request(struct request_queue *q, struct request *rq) | |
3879 | { | |
3880 | struct bfq_data *bfqd = q->elevator->elevator_data; | |
3881 | ||
3882 | bfqd->rq_in_driver--; | |
3883 | } | |
3884 | #endif | |
3885 | ||
3886 | static void bfq_remove_request(struct request_queue *q, | |
3887 | struct request *rq) | |
3888 | { | |
3889 | struct bfq_queue *bfqq = RQ_BFQQ(rq); | |
3890 | struct bfq_data *bfqd = bfqq->bfqd; | |
3891 | const int sync = rq_is_sync(rq); | |
3892 | ||
3893 | if (bfqq->next_rq == rq) { | |
3894 | bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq); | |
3895 | bfq_updated_next_req(bfqd, bfqq); | |
3896 | } | |
3897 | ||
3898 | if (rq->queuelist.prev != &rq->queuelist) | |
3899 | list_del_init(&rq->queuelist); | |
3900 | bfqq->queued[sync]--; | |
3901 | bfqd->queued--; | |
3902 | elv_rb_del(&bfqq->sort_list, rq); | |
3903 | ||
3904 | elv_rqhash_del(q, rq); | |
3905 | if (q->last_merge == rq) | |
3906 | q->last_merge = NULL; | |
3907 | ||
3908 | if (RB_EMPTY_ROOT(&bfqq->sort_list)) { | |
3909 | bfqq->next_rq = NULL; | |
3910 | ||
3911 | if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) { | |
e21b7a0b | 3912 | bfq_del_bfqq_busy(bfqd, bfqq, false); |
aee69d78 PV |
3913 | /* |
3914 | * bfqq emptied. In normal operation, when | |
3915 | * bfqq is empty, bfqq->entity.service and | |
3916 | * bfqq->entity.budget must contain, | |
3917 | * respectively, the service received and the | |
3918 | * budget used last time bfqq emptied. These | |
3919 | * facts do not hold in this case, as at least | |
3920 | * this last removal occurred while bfqq is | |
3921 | * not in service. To avoid inconsistencies, | |
3922 | * reset both bfqq->entity.service and | |
3923 | * bfqq->entity.budget, if bfqq has still a | |
3924 | * process that may issue I/O requests to it. | |
3925 | */ | |
3926 | bfqq->entity.budget = bfqq->entity.service = 0; | |
3927 | } | |
3928 | } | |
3929 | ||
3930 | if (rq->cmd_flags & REQ_META) | |
3931 | bfqq->meta_pending--; | |
e21b7a0b AA |
3932 | |
3933 | bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags); | |
aee69d78 PV |
3934 | } |
3935 | ||
3936 | static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio) | |
3937 | { | |
3938 | struct request_queue *q = hctx->queue; | |
3939 | struct bfq_data *bfqd = q->elevator->elevator_data; | |
3940 | struct request *free = NULL; | |
3941 | /* | |
3942 | * bfq_bic_lookup grabs the queue_lock: invoke it now and | |
3943 | * store its return value for later use, to avoid nesting | |
3944 | * queue_lock inside the bfqd->lock. We assume that the bic | |
3945 | * returned by bfq_bic_lookup does not go away before | |
3946 | * bfqd->lock is taken. | |
3947 | */ | |
3948 | struct bfq_io_cq *bic = bfq_bic_lookup(bfqd, current->io_context, q); | |
3949 | bool ret; | |
3950 | ||
3951 | spin_lock_irq(&bfqd->lock); | |
3952 | ||
3953 | if (bic) | |
3954 | bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf)); | |
3955 | else | |
3956 | bfqd->bio_bfqq = NULL; | |
3957 | bfqd->bio_bic = bic; | |
3958 | ||
3959 | ret = blk_mq_sched_try_merge(q, bio, &free); | |
3960 | ||
3961 | if (free) | |
3962 | blk_mq_free_request(free); | |
3963 | spin_unlock_irq(&bfqd->lock); | |
3964 | ||
3965 | return ret; | |
3966 | } | |
3967 | ||
3968 | static int bfq_request_merge(struct request_queue *q, struct request **req, | |
3969 | struct bio *bio) | |
3970 | { | |
3971 | struct bfq_data *bfqd = q->elevator->elevator_data; | |
3972 | struct request *__rq; | |
3973 | ||
3974 | __rq = bfq_find_rq_fmerge(bfqd, bio, q); | |
3975 | if (__rq && elv_bio_merge_ok(__rq, bio)) { | |
3976 | *req = __rq; | |
3977 | return ELEVATOR_FRONT_MERGE; | |
3978 | } | |
3979 | ||
3980 | return ELEVATOR_NO_MERGE; | |
3981 | } | |
3982 | ||
3983 | static void bfq_request_merged(struct request_queue *q, struct request *req, | |
3984 | enum elv_merge type) | |
3985 | { | |
3986 | if (type == ELEVATOR_FRONT_MERGE && | |
3987 | rb_prev(&req->rb_node) && | |
3988 | blk_rq_pos(req) < | |
3989 | blk_rq_pos(container_of(rb_prev(&req->rb_node), | |
3990 | struct request, rb_node))) { | |
3991 | struct bfq_queue *bfqq = RQ_BFQQ(req); | |
3992 | struct bfq_data *bfqd = bfqq->bfqd; | |
3993 | struct request *prev, *next_rq; | |
3994 | ||
3995 | /* Reposition request in its sort_list */ | |
3996 | elv_rb_del(&bfqq->sort_list, req); | |
3997 | elv_rb_add(&bfqq->sort_list, req); | |
3998 | ||
3999 | /* Choose next request to be served for bfqq */ | |
4000 | prev = bfqq->next_rq; | |
4001 | next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req, | |
4002 | bfqd->last_position); | |
4003 | bfqq->next_rq = next_rq; | |
4004 | /* | |
4005 | * If next_rq changes, update the queue's budget to fit | |
4006 | * the new request. | |
4007 | */ | |
4008 | if (prev != bfqq->next_rq) | |
4009 | bfq_updated_next_req(bfqd, bfqq); | |
4010 | } | |
4011 | } | |
4012 | ||
4013 | static void bfq_requests_merged(struct request_queue *q, struct request *rq, | |
4014 | struct request *next) | |
4015 | { | |
4016 | struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next); | |
4017 | ||
4018 | if (!RB_EMPTY_NODE(&rq->rb_node)) | |
e21b7a0b | 4019 | goto end; |
aee69d78 PV |
4020 | spin_lock_irq(&bfqq->bfqd->lock); |
4021 | ||
4022 | /* | |
4023 | * If next and rq belong to the same bfq_queue and next is older | |
4024 | * than rq, then reposition rq in the fifo (by substituting next | |
4025 | * with rq). Otherwise, if next and rq belong to different | |
4026 | * bfq_queues, never reposition rq: in fact, we would have to | |
4027 | * reposition it with respect to next's position in its own fifo, | |
4028 | * which would most certainly be too expensive with respect to | |
4029 | * the benefits. | |
4030 | */ | |
4031 | if (bfqq == next_bfqq && | |
4032 | !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
4033 | next->fifo_time < rq->fifo_time) { | |
4034 | list_del_init(&rq->queuelist); | |
4035 | list_replace_init(&next->queuelist, &rq->queuelist); | |
4036 | rq->fifo_time = next->fifo_time; | |
4037 | } | |
4038 | ||
4039 | if (bfqq->next_rq == next) | |
4040 | bfqq->next_rq = rq; | |
4041 | ||
4042 | bfq_remove_request(q, next); | |
4043 | ||
4044 | spin_unlock_irq(&bfqq->bfqd->lock); | |
e21b7a0b AA |
4045 | end: |
4046 | bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags); | |
aee69d78 PV |
4047 | } |
4048 | ||
4049 | static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq, | |
4050 | struct bio *bio) | |
4051 | { | |
4052 | struct bfq_data *bfqd = q->elevator->elevator_data; | |
4053 | bool is_sync = op_is_sync(bio->bi_opf); | |
4054 | struct bfq_queue *bfqq = bfqd->bio_bfqq; | |
4055 | ||
4056 | /* | |
4057 | * Disallow merge of a sync bio into an async request. | |
4058 | */ | |
4059 | if (is_sync && !rq_is_sync(rq)) | |
4060 | return false; | |
4061 | ||
4062 | /* | |
4063 | * Lookup the bfqq that this bio will be queued with. Allow | |
4064 | * merge only if rq is queued there. | |
4065 | */ | |
4066 | if (!bfqq) | |
4067 | return false; | |
4068 | ||
4069 | return bfqq == RQ_BFQQ(rq); | |
4070 | } | |
4071 | ||
4072 | static void __bfq_set_in_service_queue(struct bfq_data *bfqd, | |
4073 | struct bfq_queue *bfqq) | |
4074 | { | |
4075 | if (bfqq) { | |
e21b7a0b | 4076 | bfqg_stats_update_avg_queue_size(bfqq_group(bfqq)); |
aee69d78 PV |
4077 | bfq_mark_bfqq_budget_new(bfqq); |
4078 | bfq_clear_bfqq_fifo_expire(bfqq); | |
4079 | ||
4080 | bfqd->budgets_assigned = (bfqd->budgets_assigned * 7 + 256) / 8; | |
4081 | ||
4082 | bfq_log_bfqq(bfqd, bfqq, | |
4083 | "set_in_service_queue, cur-budget = %d", | |
4084 | bfqq->entity.budget); | |
4085 | } | |
4086 | ||
4087 | bfqd->in_service_queue = bfqq; | |
4088 | } | |
4089 | ||
4090 | /* | |
4091 | * Get and set a new queue for service. | |
4092 | */ | |
4093 | static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd) | |
4094 | { | |
4095 | struct bfq_queue *bfqq = bfq_get_next_queue(bfqd); | |
4096 | ||
4097 | __bfq_set_in_service_queue(bfqd, bfqq); | |
4098 | return bfqq; | |
4099 | } | |
4100 | ||
aee69d78 PV |
4101 | static void bfq_arm_slice_timer(struct bfq_data *bfqd) |
4102 | { | |
4103 | struct bfq_queue *bfqq = bfqd->in_service_queue; | |
4104 | struct bfq_io_cq *bic; | |
4105 | u32 sl; | |
4106 | ||
4107 | /* Processes have exited, don't wait. */ | |
4108 | bic = bfqd->in_service_bic; | |
4109 | if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0) | |
4110 | return; | |
4111 | ||
4112 | bfq_mark_bfqq_wait_request(bfqq); | |
4113 | ||
4114 | /* | |
4115 | * We don't want to idle for seeks, but we do want to allow | |
4116 | * fair distribution of slice time for a process doing back-to-back | |
4117 | * seeks. So allow a little bit of time for him to submit a new rq. | |
4118 | */ | |
4119 | sl = bfqd->bfq_slice_idle; | |
4120 | /* | |
4121 | * Grant only minimum idle time if the queue is seeky. | |
4122 | */ | |
4123 | if (BFQQ_SEEKY(bfqq)) | |
4124 | sl = min_t(u64, sl, BFQ_MIN_TT); | |
4125 | ||
4126 | bfqd->last_idling_start = ktime_get(); | |
4127 | hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl), | |
4128 | HRTIMER_MODE_REL); | |
e21b7a0b | 4129 | bfqg_stats_set_start_idle_time(bfqq_group(bfqq)); |
aee69d78 PV |
4130 | } |
4131 | ||
4132 | /* | |
4133 | * Set the maximum time for the in-service queue to consume its | |
4134 | * budget. This prevents seeky processes from lowering the disk | |
4135 | * throughput (always guaranteed with a time slice scheme as in CFQ). | |
4136 | */ | |
4137 | static void bfq_set_budget_timeout(struct bfq_data *bfqd) | |
4138 | { | |
4139 | struct bfq_queue *bfqq = bfqd->in_service_queue; | |
4140 | unsigned int timeout_coeff = bfqq->entity.weight / | |
4141 | bfqq->entity.orig_weight; | |
4142 | ||
4143 | bfqd->last_budget_start = ktime_get(); | |
4144 | ||
4145 | bfq_clear_bfqq_budget_new(bfqq); | |
4146 | bfqq->budget_timeout = jiffies + | |
4147 | bfqd->bfq_timeout * timeout_coeff; | |
4148 | ||
4149 | bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u", | |
4150 | jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff)); | |
4151 | } | |
4152 | ||
ab0e43e9 PV |
4153 | /* |
4154 | * In autotuning mode, max_budget is dynamically recomputed as the | |
4155 | * amount of sectors transferred in timeout at the estimated peak | |
4156 | * rate. This enables BFQ to utilize a full timeslice with a full | |
4157 | * budget, even if the in-service queue is served at peak rate. And | |
4158 | * this maximises throughput with sequential workloads. | |
4159 | */ | |
4160 | static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd) | |
4161 | { | |
4162 | return (u64)bfqd->peak_rate * USEC_PER_MSEC * | |
4163 | jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT; | |
4164 | } | |
4165 | ||
4166 | static void bfq_reset_rate_computation(struct bfq_data *bfqd, | |
4167 | struct request *rq) | |
4168 | { | |
4169 | if (rq != NULL) { /* new rq dispatch now, reset accordingly */ | |
4170 | bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns(); | |
4171 | bfqd->peak_rate_samples = 1; | |
4172 | bfqd->sequential_samples = 0; | |
4173 | bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size = | |
4174 | blk_rq_sectors(rq); | |
4175 | } else /* no new rq dispatched, just reset the number of samples */ | |
4176 | bfqd->peak_rate_samples = 0; /* full re-init on next disp. */ | |
4177 | ||
4178 | bfq_log(bfqd, | |
4179 | "reset_rate_computation at end, sample %u/%u tot_sects %llu", | |
4180 | bfqd->peak_rate_samples, bfqd->sequential_samples, | |
4181 | bfqd->tot_sectors_dispatched); | |
4182 | } | |
4183 | ||
4184 | static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq) | |
4185 | { | |
4186 | u32 rate, weight, divisor; | |
4187 | ||
4188 | /* | |
4189 | * For the convergence property to hold (see comments on | |
4190 | * bfq_update_peak_rate()) and for the assessment to be | |
4191 | * reliable, a minimum number of samples must be present, and | |
4192 | * a minimum amount of time must have elapsed. If not so, do | |
4193 | * not compute new rate. Just reset parameters, to get ready | |
4194 | * for a new evaluation attempt. | |
4195 | */ | |
4196 | if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES || | |
4197 | bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) | |
4198 | goto reset_computation; | |
4199 | ||
4200 | /* | |
4201 | * If a new request completion has occurred after last | |
4202 | * dispatch, then, to approximate the rate at which requests | |
4203 | * have been served by the device, it is more precise to | |
4204 | * extend the observation interval to the last completion. | |
4205 | */ | |
4206 | bfqd->delta_from_first = | |
4207 | max_t(u64, bfqd->delta_from_first, | |
4208 | bfqd->last_completion - bfqd->first_dispatch); | |
4209 | ||
4210 | /* | |
4211 | * Rate computed in sects/usec, and not sects/nsec, for | |
4212 | * precision issues. | |
4213 | */ | |
4214 | rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT, | |
4215 | div_u64(bfqd->delta_from_first, NSEC_PER_USEC)); | |
4216 | ||
4217 | /* | |
4218 | * Peak rate not updated if: | |
4219 | * - the percentage of sequential dispatches is below 3/4 of the | |
4220 | * total, and rate is below the current estimated peak rate | |
4221 | * - rate is unreasonably high (> 20M sectors/sec) | |
4222 | */ | |
4223 | if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 && | |
4224 | rate <= bfqd->peak_rate) || | |
4225 | rate > 20<<BFQ_RATE_SHIFT) | |
4226 | goto reset_computation; | |
4227 | ||
4228 | /* | |
4229 | * We have to update the peak rate, at last! To this purpose, | |
4230 | * we use a low-pass filter. We compute the smoothing constant | |
4231 | * of the filter as a function of the 'weight' of the new | |
4232 | * measured rate. | |
4233 | * | |
4234 | * As can be seen in next formulas, we define this weight as a | |
4235 | * quantity proportional to how sequential the workload is, | |
4236 | * and to how long the observation time interval is. | |
4237 | * | |
4238 | * The weight runs from 0 to 8. The maximum value of the | |
4239 | * weight, 8, yields the minimum value for the smoothing | |
4240 | * constant. At this minimum value for the smoothing constant, | |
4241 | * the measured rate contributes for half of the next value of | |
4242 | * the estimated peak rate. | |
4243 | * | |
4244 | * So, the first step is to compute the weight as a function | |
4245 | * of how sequential the workload is. Note that the weight | |
4246 | * cannot reach 9, because bfqd->sequential_samples cannot | |
4247 | * become equal to bfqd->peak_rate_samples, which, in its | |
4248 | * turn, holds true because bfqd->sequential_samples is not | |
4249 | * incremented for the first sample. | |
4250 | */ | |
4251 | weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples; | |
4252 | ||
4253 | /* | |
4254 | * Second step: further refine the weight as a function of the | |
4255 | * duration of the observation interval. | |
4256 | */ | |
4257 | weight = min_t(u32, 8, | |
4258 | div_u64(weight * bfqd->delta_from_first, | |
4259 | BFQ_RATE_REF_INTERVAL)); | |
4260 | ||
4261 | /* | |
4262 | * Divisor ranging from 10, for minimum weight, to 2, for | |
4263 | * maximum weight. | |
4264 | */ | |
4265 | divisor = 10 - weight; | |
4266 | ||
4267 | /* | |
4268 | * Finally, update peak rate: | |
4269 | * | |
4270 | * peak_rate = peak_rate * (divisor-1) / divisor + rate / divisor | |
4271 | */ | |
4272 | bfqd->peak_rate *= divisor-1; | |
4273 | bfqd->peak_rate /= divisor; | |
4274 | rate /= divisor; /* smoothing constant alpha = 1/divisor */ | |
4275 | ||
4276 | bfqd->peak_rate += rate; | |
4277 | if (bfqd->bfq_user_max_budget == 0) | |
4278 | bfqd->bfq_max_budget = | |
4279 | bfq_calc_max_budget(bfqd); | |
4280 | ||
4281 | reset_computation: | |
4282 | bfq_reset_rate_computation(bfqd, rq); | |
4283 | } | |
4284 | ||
4285 | /* | |
4286 | * Update the read/write peak rate (the main quantity used for | |
4287 | * auto-tuning, see update_thr_responsiveness_params()). | |
4288 | * | |
4289 | * It is not trivial to estimate the peak rate (correctly): because of | |
4290 | * the presence of sw and hw queues between the scheduler and the | |
4291 | * device components that finally serve I/O requests, it is hard to | |
4292 | * say exactly when a given dispatched request is served inside the | |
4293 | * device, and for how long. As a consequence, it is hard to know | |
4294 | * precisely at what rate a given set of requests is actually served | |
4295 | * by the device. | |
4296 | * | |
4297 | * On the opposite end, the dispatch time of any request is trivially | |
4298 | * available, and, from this piece of information, the "dispatch rate" | |
4299 | * of requests can be immediately computed. So, the idea in the next | |
4300 | * function is to use what is known, namely request dispatch times | |
4301 | * (plus, when useful, request completion times), to estimate what is | |
4302 | * unknown, namely in-device request service rate. | |
4303 | * | |
4304 | * The main issue is that, because of the above facts, the rate at | |
4305 | * which a certain set of requests is dispatched over a certain time | |
4306 | * interval can vary greatly with respect to the rate at which the | |
4307 | * same requests are then served. But, since the size of any | |
4308 | * intermediate queue is limited, and the service scheme is lossless | |
4309 | * (no request is silently dropped), the following obvious convergence | |
4310 | * property holds: the number of requests dispatched MUST become | |
4311 | * closer and closer to the number of requests completed as the | |
4312 | * observation interval grows. This is the key property used in | |
4313 | * the next function to estimate the peak service rate as a function | |
4314 | * of the observed dispatch rate. The function assumes to be invoked | |
4315 | * on every request dispatch. | |
4316 | */ | |
4317 | static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq) | |
4318 | { | |
4319 | u64 now_ns = ktime_get_ns(); | |
4320 | ||
4321 | if (bfqd->peak_rate_samples == 0) { /* first dispatch */ | |
4322 | bfq_log(bfqd, "update_peak_rate: goto reset, samples %d", | |
4323 | bfqd->peak_rate_samples); | |
4324 | bfq_reset_rate_computation(bfqd, rq); | |
4325 | goto update_last_values; /* will add one sample */ | |
4326 | } | |
4327 | ||
4328 | /* | |
4329 | * Device idle for very long: the observation interval lasting | |
4330 | * up to this dispatch cannot be a valid observation interval | |
4331 | * for computing a new peak rate (similarly to the late- | |
4332 | * completion event in bfq_completed_request()). Go to | |
4333 | * update_rate_and_reset to have the following three steps | |
4334 | * taken: | |
4335 | * - close the observation interval at the last (previous) | |
4336 | * request dispatch or completion | |
4337 | * - compute rate, if possible, for that observation interval | |
4338 | * - start a new observation interval with this dispatch | |
4339 | */ | |
4340 | if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC && | |
4341 | bfqd->rq_in_driver == 0) | |
4342 | goto update_rate_and_reset; | |
4343 | ||
4344 | /* Update sampling information */ | |
4345 | bfqd->peak_rate_samples++; | |
4346 | ||
4347 | if ((bfqd->rq_in_driver > 0 || | |
4348 | now_ns - bfqd->last_completion < BFQ_MIN_TT) | |
4349 | && get_sdist(bfqd->last_position, rq) < BFQQ_SEEK_THR) | |
4350 | bfqd->sequential_samples++; | |
4351 | ||
4352 | bfqd->tot_sectors_dispatched += blk_rq_sectors(rq); | |
4353 | ||
4354 | /* Reset max observed rq size every 32 dispatches */ | |
4355 | if (likely(bfqd->peak_rate_samples % 32)) | |
4356 | bfqd->last_rq_max_size = | |
4357 | max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size); | |
4358 | else | |
4359 | bfqd->last_rq_max_size = blk_rq_sectors(rq); | |
4360 | ||
4361 | bfqd->delta_from_first = now_ns - bfqd->first_dispatch; | |
4362 | ||
4363 | /* Target observation interval not yet reached, go on sampling */ | |
4364 | if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL) | |
4365 | goto update_last_values; | |
4366 | ||
4367 | update_rate_and_reset: | |
4368 | bfq_update_rate_reset(bfqd, rq); | |
4369 | update_last_values: | |
4370 | bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); | |
4371 | bfqd->last_dispatch = now_ns; | |
4372 | } | |
4373 | ||
aee69d78 PV |
4374 | /* |
4375 | * Remove request from internal lists. | |
4376 | */ | |
4377 | static void bfq_dispatch_remove(struct request_queue *q, struct request *rq) | |
4378 | { | |
4379 | struct bfq_queue *bfqq = RQ_BFQQ(rq); | |
4380 | ||
4381 | /* | |
4382 | * For consistency, the next instruction should have been | |
4383 | * executed after removing the request from the queue and | |
4384 | * dispatching it. We execute instead this instruction before | |
4385 | * bfq_remove_request() (and hence introduce a temporary | |
4386 | * inconsistency), for efficiency. In fact, should this | |
4387 | * dispatch occur for a non in-service bfqq, this anticipated | |
4388 | * increment prevents two counters related to bfqq->dispatched | |
4389 | * from risking to be, first, uselessly decremented, and then | |
4390 | * incremented again when the (new) value of bfqq->dispatched | |
4391 | * happens to be taken into account. | |
4392 | */ | |
4393 | bfqq->dispatched++; | |
ab0e43e9 | 4394 | bfq_update_peak_rate(q->elevator->elevator_data, rq); |
aee69d78 PV |
4395 | |
4396 | bfq_remove_request(q, rq); | |
4397 | } | |
4398 | ||
4399 | static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) | |
4400 | { | |
aee69d78 | 4401 | if (RB_EMPTY_ROOT(&bfqq->sort_list)) |
e21b7a0b | 4402 | bfq_del_bfqq_busy(bfqd, bfqq, true); |
aee69d78 | 4403 | else |
e21b7a0b AA |
4404 | bfq_requeue_bfqq(bfqd, bfqq); |
4405 | ||
4406 | /* | |
4407 | * All in-service entities must have been properly deactivated | |
4408 | * or requeued before executing the next function, which | |
4409 | * resets all in-service entites as no more in service. | |
4410 | */ | |
4411 | __bfq_bfqd_reset_in_service(bfqd); | |
aee69d78 PV |
4412 | } |
4413 | ||
4414 | /** | |
4415 | * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior. | |
4416 | * @bfqd: device data. | |
4417 | * @bfqq: queue to update. | |
4418 | * @reason: reason for expiration. | |
4419 | * | |
4420 | * Handle the feedback on @bfqq budget at queue expiration. | |
4421 | * See the body for detailed comments. | |
4422 | */ | |
4423 | static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, | |
4424 | struct bfq_queue *bfqq, | |
4425 | enum bfqq_expiration reason) | |
4426 | { | |
4427 | struct request *next_rq; | |
4428 | int budget, min_budget; | |
4429 | ||
4430 | budget = bfqq->max_budget; | |
4431 | min_budget = bfq_min_budget(bfqd); | |
4432 | ||
4433 | bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d", | |
4434 | bfqq->entity.budget, bfq_bfqq_budget_left(bfqq)); | |
4435 | bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d", | |
4436 | budget, bfq_min_budget(bfqd)); | |
4437 | bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d", | |
4438 | bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue)); | |
4439 | ||
4440 | if (bfq_bfqq_sync(bfqq)) { | |
4441 | switch (reason) { | |
4442 | /* | |
4443 | * Caveat: in all the following cases we trade latency | |
4444 | * for throughput. | |
4445 | */ | |
4446 | case BFQQE_TOO_IDLE: | |
54b60456 PV |
4447 | /* |
4448 | * This is the only case where we may reduce | |
4449 | * the budget: if there is no request of the | |
4450 | * process still waiting for completion, then | |
4451 | * we assume (tentatively) that the timer has | |
4452 | * expired because the batch of requests of | |
4453 | * the process could have been served with a | |
4454 | * smaller budget. Hence, betting that | |
4455 | * process will behave in the same way when it | |
4456 | * becomes backlogged again, we reduce its | |
4457 | * next budget. As long as we guess right, | |
4458 | * this budget cut reduces the latency | |
4459 | * experienced by the process. | |
4460 | * | |
4461 | * However, if there are still outstanding | |
4462 | * requests, then the process may have not yet | |
4463 | * issued its next request just because it is | |
4464 | * still waiting for the completion of some of | |
4465 | * the still outstanding ones. So in this | |
4466 | * subcase we do not reduce its budget, on the | |
4467 | * contrary we increase it to possibly boost | |
4468 | * the throughput, as discussed in the | |
4469 | * comments to the BUDGET_TIMEOUT case. | |
4470 | */ | |
4471 | if (bfqq->dispatched > 0) /* still outstanding reqs */ | |
4472 | budget = min(budget * 2, bfqd->bfq_max_budget); | |
4473 | else { | |
4474 | if (budget > 5 * min_budget) | |
4475 | budget -= 4 * min_budget; | |
4476 | else | |
4477 | budget = min_budget; | |
4478 | } | |
aee69d78 PV |
4479 | break; |
4480 | case BFQQE_BUDGET_TIMEOUT: | |
54b60456 PV |
4481 | /* |
4482 | * We double the budget here because it gives | |
4483 | * the chance to boost the throughput if this | |
4484 | * is not a seeky process (and has bumped into | |
4485 | * this timeout because of, e.g., ZBR). | |
4486 | */ | |
4487 | budget = min(budget * 2, bfqd->bfq_max_budget); | |
aee69d78 PV |
4488 | break; |
4489 | case BFQQE_BUDGET_EXHAUSTED: | |
4490 | /* | |
4491 | * The process still has backlog, and did not | |
4492 | * let either the budget timeout or the disk | |
4493 | * idling timeout expire. Hence it is not | |
4494 | * seeky, has a short thinktime and may be | |
4495 | * happy with a higher budget too. So | |
4496 | * definitely increase the budget of this good | |
4497 | * candidate to boost the disk throughput. | |
4498 | */ | |
54b60456 | 4499 | budget = min(budget * 4, bfqd->bfq_max_budget); |
aee69d78 PV |
4500 | break; |
4501 | case BFQQE_NO_MORE_REQUESTS: | |
4502 | /* | |
4503 | * For queues that expire for this reason, it | |
4504 | * is particularly important to keep the | |
4505 | * budget close to the actual service they | |
4506 | * need. Doing so reduces the timestamp | |
4507 | * misalignment problem described in the | |
4508 | * comments in the body of | |
4509 | * __bfq_activate_entity. In fact, suppose | |
4510 | * that a queue systematically expires for | |
4511 | * BFQQE_NO_MORE_REQUESTS and presents a | |
4512 | * new request in time to enjoy timestamp | |
4513 | * back-shifting. The larger the budget of the | |
4514 | * queue is with respect to the service the | |
4515 | * queue actually requests in each service | |
4516 | * slot, the more times the queue can be | |
4517 | * reactivated with the same virtual finish | |
4518 | * time. It follows that, even if this finish | |
4519 | * time is pushed to the system virtual time | |
4520 | * to reduce the consequent timestamp | |
4521 | * misalignment, the queue unjustly enjoys for | |
4522 | * many re-activations a lower finish time | |
4523 | * than all newly activated queues. | |
4524 | * | |
4525 | * The service needed by bfqq is measured | |
4526 | * quite precisely by bfqq->entity.service. | |
4527 | * Since bfqq does not enjoy device idling, | |
4528 | * bfqq->entity.service is equal to the number | |
4529 | * of sectors that the process associated with | |
4530 | * bfqq requested to read/write before waiting | |
4531 | * for request completions, or blocking for | |
4532 | * other reasons. | |
4533 | */ | |
4534 | budget = max_t(int, bfqq->entity.service, min_budget); | |
4535 | break; | |
4536 | default: | |
4537 | return; | |
4538 | } | |
4539 | } else { | |
4540 | /* | |
4541 | * Async queues get always the maximum possible | |
4542 | * budget, as for them we do not care about latency | |
4543 | * (in addition, their ability to dispatch is limited | |
4544 | * by the charging factor). | |
4545 | */ | |
4546 | budget = bfqd->bfq_max_budget; | |
4547 | } | |
4548 | ||
4549 | bfqq->max_budget = budget; | |
4550 | ||
4551 | if (bfqd->budgets_assigned >= bfq_stats_min_budgets && | |
4552 | !bfqd->bfq_user_max_budget) | |
4553 | bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget); | |
4554 | ||
4555 | /* | |
4556 | * If there is still backlog, then assign a new budget, making | |
4557 | * sure that it is large enough for the next request. Since | |
4558 | * the finish time of bfqq must be kept in sync with the | |
4559 | * budget, be sure to call __bfq_bfqq_expire() *after* this | |
4560 | * update. | |
4561 | * | |
4562 | * If there is no backlog, then no need to update the budget; | |
4563 | * it will be updated on the arrival of a new request. | |
4564 | */ | |
4565 | next_rq = bfqq->next_rq; | |
4566 | if (next_rq) | |
4567 | bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget, | |
4568 | bfq_serv_to_charge(next_rq, bfqq)); | |
4569 | ||
4570 | bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d", | |
4571 | next_rq ? blk_rq_sectors(next_rq) : 0, | |
4572 | bfqq->entity.budget); | |
4573 | } | |
4574 | ||
aee69d78 | 4575 | /* |
ab0e43e9 PV |
4576 | * Return true if the process associated with bfqq is "slow". The slow |
4577 | * flag is used, in addition to the budget timeout, to reduce the | |
4578 | * amount of service provided to seeky processes, and thus reduce | |
4579 | * their chances to lower the throughput. More details in the comments | |
4580 | * on the function bfq_bfqq_expire(). | |
4581 | * | |
4582 | * An important observation is in order: as discussed in the comments | |
4583 | * on the function bfq_update_peak_rate(), with devices with internal | |
4584 | * queues, it is hard if ever possible to know when and for how long | |
4585 | * an I/O request is processed by the device (apart from the trivial | |
4586 | * I/O pattern where a new request is dispatched only after the | |
4587 | * previous one has been completed). This makes it hard to evaluate | |
4588 | * the real rate at which the I/O requests of each bfq_queue are | |
4589 | * served. In fact, for an I/O scheduler like BFQ, serving a | |
4590 | * bfq_queue means just dispatching its requests during its service | |
4591 | * slot (i.e., until the budget of the queue is exhausted, or the | |
4592 | * queue remains idle, or, finally, a timeout fires). But, during the | |
4593 | * service slot of a bfq_queue, around 100 ms at most, the device may | |
4594 | * be even still processing requests of bfq_queues served in previous | |
4595 | * service slots. On the opposite end, the requests of the in-service | |
4596 | * bfq_queue may be completed after the service slot of the queue | |
4597 | * finishes. | |
4598 | * | |
4599 | * Anyway, unless more sophisticated solutions are used | |
4600 | * (where possible), the sum of the sizes of the requests dispatched | |
4601 | * during the service slot of a bfq_queue is probably the only | |
4602 | * approximation available for the service received by the bfq_queue | |
4603 | * during its service slot. And this sum is the quantity used in this | |
4604 | * function to evaluate the I/O speed of a process. | |
aee69d78 | 4605 | */ |
ab0e43e9 PV |
4606 | static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq, |
4607 | bool compensate, enum bfqq_expiration reason, | |
4608 | unsigned long *delta_ms) | |
aee69d78 | 4609 | { |
ab0e43e9 PV |
4610 | ktime_t delta_ktime; |
4611 | u32 delta_usecs; | |
4612 | bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */ | |
aee69d78 | 4613 | |
ab0e43e9 | 4614 | if (!bfq_bfqq_sync(bfqq)) |
aee69d78 PV |
4615 | return false; |
4616 | ||
4617 | if (compensate) | |
ab0e43e9 | 4618 | delta_ktime = bfqd->last_idling_start; |
aee69d78 | 4619 | else |
ab0e43e9 PV |
4620 | delta_ktime = ktime_get(); |
4621 | delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start); | |
4622 | delta_usecs = ktime_to_us(delta_ktime); | |
aee69d78 PV |
4623 | |
4624 | /* don't use too short time intervals */ | |
ab0e43e9 PV |
4625 | if (delta_usecs < 1000) { |
4626 | if (blk_queue_nonrot(bfqd->queue)) | |
4627 | /* | |
4628 | * give same worst-case guarantees as idling | |
4629 | * for seeky | |
4630 | */ | |
4631 | *delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC; | |
4632 | else /* charge at least one seek */ | |
4633 | *delta_ms = bfq_slice_idle / NSEC_PER_MSEC; | |
4634 | ||
4635 | return slow; | |
4636 | } | |
aee69d78 | 4637 | |
ab0e43e9 | 4638 | *delta_ms = delta_usecs / USEC_PER_MSEC; |
aee69d78 PV |
4639 | |
4640 | /* | |
ab0e43e9 PV |
4641 | * Use only long (> 20ms) intervals to filter out excessive |
4642 | * spikes in service rate estimation. | |
aee69d78 | 4643 | */ |
ab0e43e9 PV |
4644 | if (delta_usecs > 20000) { |
4645 | /* | |
4646 | * Caveat for rotational devices: processes doing I/O | |
4647 | * in the slower disk zones tend to be slow(er) even | |
4648 | * if not seeky. In this respect, the estimated peak | |
4649 | * rate is likely to be an average over the disk | |
4650 | * surface. Accordingly, to not be too harsh with | |
4651 | * unlucky processes, a process is deemed slow only if | |
4652 | * its rate has been lower than half of the estimated | |
4653 | * peak rate. | |
4654 | */ | |
4655 | slow = bfqq->entity.service < bfqd->bfq_max_budget / 2; | |
aee69d78 PV |
4656 | } |
4657 | ||
ab0e43e9 | 4658 | bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow); |
aee69d78 | 4659 | |
ab0e43e9 | 4660 | return slow; |
aee69d78 PV |
4661 | } |
4662 | ||
4663 | /* | |
4664 | * Return the farthest past time instant according to jiffies | |
4665 | * macros. | |
4666 | */ | |
4667 | static unsigned long bfq_smallest_from_now(void) | |
4668 | { | |
4669 | return jiffies - MAX_JIFFY_OFFSET; | |
4670 | } | |
4671 | ||
4672 | /** | |
4673 | * bfq_bfqq_expire - expire a queue. | |
4674 | * @bfqd: device owning the queue. | |
4675 | * @bfqq: the queue to expire. | |
4676 | * @compensate: if true, compensate for the time spent idling. | |
4677 | * @reason: the reason causing the expiration. | |
4678 | * | |
4679 | * | |
4680 | * If the process associated with the queue is slow (i.e., seeky), or | |
4681 | * in case of budget timeout, or, finally, if it is async, we | |
4682 | * artificially charge it an entire budget (independently of the | |
4683 | * actual service it received). As a consequence, the queue will get | |
4684 | * higher timestamps than the correct ones upon reactivation, and | |
4685 | * hence it will be rescheduled as if it had received more service | |
4686 | * than what it actually received. In the end, this class of processes | |
4687 | * will receive less service in proportion to how slowly they consume | |
4688 | * their budgets (and hence how seriously they tend to lower the | |
4689 | * throughput). | |
4690 | * | |
4691 | * In contrast, when a queue expires because it has been idling for | |
4692 | * too much or because it exhausted its budget, we do not touch the | |
4693 | * amount of service it has received. Hence when the queue will be | |
4694 | * reactivated and its timestamps updated, the latter will be in sync | |
4695 | * with the actual service received by the queue until expiration. | |
4696 | * | |
4697 | * Charging a full budget to the first type of queues and the exact | |
4698 | * service to the others has the effect of using the WF2Q+ policy to | |
4699 | * schedule the former on a timeslice basis, without violating the | |
4700 | * service domain guarantees of the latter. | |
4701 | */ | |
4702 | static void bfq_bfqq_expire(struct bfq_data *bfqd, | |
4703 | struct bfq_queue *bfqq, | |
4704 | bool compensate, | |
4705 | enum bfqq_expiration reason) | |
4706 | { | |
4707 | bool slow; | |
ab0e43e9 PV |
4708 | unsigned long delta = 0; |
4709 | struct bfq_entity *entity = &bfqq->entity; | |
aee69d78 PV |
4710 | int ref; |
4711 | ||
4712 | /* | |
ab0e43e9 | 4713 | * Check whether the process is slow (see bfq_bfqq_is_slow). |
aee69d78 | 4714 | */ |
ab0e43e9 | 4715 | slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta); |
aee69d78 PV |
4716 | |
4717 | /* | |
4718 | * As above explained, 'punish' slow (i.e., seeky), timed-out | |
4719 | * and async queues, to favor sequential sync workloads. | |
4720 | */ | |
4721 | if (slow || reason == BFQQE_BUDGET_TIMEOUT) | |
4722 | bfq_bfqq_charge_full_budget(bfqq); | |
4723 | ||
4724 | if (reason == BFQQE_TOO_IDLE && | |
ab0e43e9 | 4725 | entity->service <= 2 * entity->budget / 10) |
aee69d78 PV |
4726 | bfq_clear_bfqq_IO_bound(bfqq); |
4727 | ||
4728 | bfq_log_bfqq(bfqd, bfqq, | |
4729 | "expire (%d, slow %d, num_disp %d, idle_win %d)", reason, | |
4730 | slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq)); | |
4731 | ||
4732 | /* | |
4733 | * Increase, decrease or leave budget unchanged according to | |
4734 | * reason. | |
4735 | */ | |
4736 | __bfq_bfqq_recalc_budget(bfqd, bfqq, reason); | |
4737 | ref = bfqq->ref; | |
4738 | __bfq_bfqq_expire(bfqd, bfqq); | |
4739 | ||
4740 | /* mark bfqq as waiting a request only if a bic still points to it */ | |
4741 | if (ref > 1 && !bfq_bfqq_busy(bfqq) && | |
4742 | reason != BFQQE_BUDGET_TIMEOUT && | |
4743 | reason != BFQQE_BUDGET_EXHAUSTED) | |
4744 | bfq_mark_bfqq_non_blocking_wait_rq(bfqq); | |
4745 | } | |
4746 | ||
4747 | /* | |
4748 | * Budget timeout is not implemented through a dedicated timer, but | |
4749 | * just checked on request arrivals and completions, as well as on | |
4750 | * idle timer expirations. | |
4751 | */ | |
4752 | static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) | |
4753 | { | |
4754 | if (bfq_bfqq_budget_new(bfqq) || | |
4755 | time_is_after_jiffies(bfqq->budget_timeout)) | |
4756 | return false; | |
4757 | return true; | |
4758 | } | |
4759 | ||
4760 | /* | |
4761 | * If we expire a queue that is actively waiting (i.e., with the | |
4762 | * device idled) for the arrival of a new request, then we may incur | |
4763 | * the timestamp misalignment problem described in the body of the | |
4764 | * function __bfq_activate_entity. Hence we return true only if this | |
4765 | * condition does not hold, or if the queue is slow enough to deserve | |
4766 | * only to be kicked off for preserving a high throughput. | |
4767 | */ | |
4768 | static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) | |
4769 | { | |
4770 | bfq_log_bfqq(bfqq->bfqd, bfqq, | |
4771 | "may_budget_timeout: wait_request %d left %d timeout %d", | |
4772 | bfq_bfqq_wait_request(bfqq), | |
4773 | bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3, | |
4774 | bfq_bfqq_budget_timeout(bfqq)); | |
4775 | ||
4776 | return (!bfq_bfqq_wait_request(bfqq) || | |
4777 | bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3) | |
4778 | && | |
4779 | bfq_bfqq_budget_timeout(bfqq); | |
4780 | } | |
4781 | ||
4782 | /* | |
4783 | * For a queue that becomes empty, device idling is allowed only if | |
4784 | * this function returns true for the queue. And this function returns | |
4785 | * true only if idling is beneficial for throughput. | |
4786 | */ | |
4787 | static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) | |
4788 | { | |
4789 | struct bfq_data *bfqd = bfqq->bfqd; | |
4790 | bool idling_boosts_thr; | |
4791 | ||
4792 | if (bfqd->strict_guarantees) | |
4793 | return true; | |
4794 | ||
4795 | /* | |
4796 | * The value of the next variable is computed considering that | |
4797 | * idling is usually beneficial for the throughput if: | |
4798 | * (a) the device is not NCQ-capable, or | |
4799 | * (b) regardless of the presence of NCQ, the request pattern | |
4800 | * for bfqq is I/O-bound (possible throughput losses | |
4801 | * caused by granting idling to seeky queues are mitigated | |
4802 | * by the fact that, in all scenarios where boosting | |
4803 | * throughput is the best thing to do, i.e., in all | |
4804 | * symmetric scenarios, only a minimal idle time is | |
4805 | * allowed to seeky queues). | |
4806 | */ | |
4807 | idling_boosts_thr = !bfqd->hw_tag || bfq_bfqq_IO_bound(bfqq); | |
4808 | ||
4809 | /* | |
4810 | * We have now the components we need to compute the return | |
4811 | * value of the function, which is true only if both the | |
4812 | * following conditions hold: | |
4813 | * 1) bfqq is sync, because idling make sense only for sync queues; | |
4814 | * 2) idling boosts the throughput. | |
4815 | */ | |
4816 | return bfq_bfqq_sync(bfqq) && idling_boosts_thr; | |
4817 | } | |
4818 | ||
4819 | /* | |
4820 | * If the in-service queue is empty but the function bfq_bfqq_may_idle | |
4821 | * returns true, then: | |
4822 | * 1) the queue must remain in service and cannot be expired, and | |
4823 | * 2) the device must be idled to wait for the possible arrival of a new | |
4824 | * request for the queue. | |
4825 | * See the comments on the function bfq_bfqq_may_idle for the reasons | |
4826 | * why performing device idling is the best choice to boost the throughput | |
4827 | * and preserve service guarantees when bfq_bfqq_may_idle itself | |
4828 | * returns true. | |
4829 | */ | |
4830 | static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) | |
4831 | { | |
4832 | struct bfq_data *bfqd = bfqq->bfqd; | |
4833 | ||
4834 | return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 && | |
4835 | bfq_bfqq_may_idle(bfqq); | |
4836 | } | |
4837 | ||
4838 | /* | |
4839 | * Select a queue for service. If we have a current queue in service, | |
4840 | * check whether to continue servicing it, or retrieve and set a new one. | |
4841 | */ | |
4842 | static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) | |
4843 | { | |
4844 | struct bfq_queue *bfqq; | |
4845 | struct request *next_rq; | |
4846 | enum bfqq_expiration reason = BFQQE_BUDGET_TIMEOUT; | |
4847 | ||
4848 | bfqq = bfqd->in_service_queue; | |
4849 | if (!bfqq) | |
4850 | goto new_queue; | |
4851 | ||
4852 | bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue"); | |
4853 | ||
4854 | if (bfq_may_expire_for_budg_timeout(bfqq) && | |
4855 | !bfq_bfqq_wait_request(bfqq) && | |
4856 | !bfq_bfqq_must_idle(bfqq)) | |
4857 | goto expire; | |
4858 | ||
4859 | check_queue: | |
4860 | /* | |
4861 | * This loop is rarely executed more than once. Even when it | |
4862 | * happens, it is much more convenient to re-execute this loop | |
4863 | * than to return NULL and trigger a new dispatch to get a | |
4864 | * request served. | |
4865 | */ | |
4866 | next_rq = bfqq->next_rq; | |
4867 | /* | |
4868 | * If bfqq has requests queued and it has enough budget left to | |
4869 | * serve them, keep the queue, otherwise expire it. | |
4870 | */ | |
4871 | if (next_rq) { | |
4872 | if (bfq_serv_to_charge(next_rq, bfqq) > | |
4873 | bfq_bfqq_budget_left(bfqq)) { | |
4874 | /* | |
4875 | * Expire the queue for budget exhaustion, | |
4876 | * which makes sure that the next budget is | |
4877 | * enough to serve the next request, even if | |
4878 | * it comes from the fifo expired path. | |
4879 | */ | |
4880 | reason = BFQQE_BUDGET_EXHAUSTED; | |
4881 | goto expire; | |
4882 | } else { | |
4883 | /* | |
4884 | * The idle timer may be pending because we may | |
4885 | * not disable disk idling even when a new request | |
4886 | * arrives. | |
4887 | */ | |
4888 | if (bfq_bfqq_wait_request(bfqq)) { | |
4889 | /* | |
4890 | * If we get here: 1) at least a new request | |
4891 | * has arrived but we have not disabled the | |
4892 | * timer because the request was too small, | |
4893 | * 2) then the block layer has unplugged | |
4894 | * the device, causing the dispatch to be | |
4895 | * invoked. | |
4896 | * | |
4897 | * Since the device is unplugged, now the | |
4898 | * requests are probably large enough to | |
4899 | * provide a reasonable throughput. | |
4900 | * So we disable idling. | |
4901 | */ | |
4902 | bfq_clear_bfqq_wait_request(bfqq); | |
4903 | hrtimer_try_to_cancel(&bfqd->idle_slice_timer); | |
e21b7a0b | 4904 | bfqg_stats_update_idle_time(bfqq_group(bfqq)); |
aee69d78 PV |
4905 | } |
4906 | goto keep_queue; | |
4907 | } | |
4908 | } | |
4909 | ||
4910 | /* | |
4911 | * No requests pending. However, if the in-service queue is idling | |
4912 | * for a new request, or has requests waiting for a completion and | |
4913 | * may idle after their completion, then keep it anyway. | |
4914 | */ | |
4915 | if (bfq_bfqq_wait_request(bfqq) || | |
4916 | (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) { | |
4917 | bfqq = NULL; | |
4918 | goto keep_queue; | |
4919 | } | |
4920 | ||
4921 | reason = BFQQE_NO_MORE_REQUESTS; | |
4922 | expire: | |
4923 | bfq_bfqq_expire(bfqd, bfqq, false, reason); | |
4924 | new_queue: | |
4925 | bfqq = bfq_set_in_service_queue(bfqd); | |
4926 | if (bfqq) { | |
4927 | bfq_log_bfqq(bfqd, bfqq, "select_queue: checking new queue"); | |
4928 | goto check_queue; | |
4929 | } | |
4930 | keep_queue: | |
4931 | if (bfqq) | |
4932 | bfq_log_bfqq(bfqd, bfqq, "select_queue: returned this queue"); | |
4933 | else | |
4934 | bfq_log(bfqd, "select_queue: no queue returned"); | |
4935 | ||
4936 | return bfqq; | |
4937 | } | |
4938 | ||
4939 | /* | |
4940 | * Dispatch next request from bfqq. | |
4941 | */ | |
4942 | static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd, | |
4943 | struct bfq_queue *bfqq) | |
4944 | { | |
4945 | struct request *rq = bfqq->next_rq; | |
4946 | unsigned long service_to_charge; | |
4947 | ||
4948 | service_to_charge = bfq_serv_to_charge(rq, bfqq); | |
4949 | ||
4950 | bfq_bfqq_served(bfqq, service_to_charge); | |
4951 | ||
4952 | bfq_dispatch_remove(bfqd->queue, rq); | |
4953 | ||
4954 | if (!bfqd->in_service_bic) { | |
4955 | atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount); | |
4956 | bfqd->in_service_bic = RQ_BIC(rq); | |
4957 | } | |
4958 | ||
4959 | /* | |
4960 | * Expire bfqq, pretending that its budget expired, if bfqq | |
4961 | * belongs to CLASS_IDLE and other queues are waiting for | |
4962 | * service. | |
4963 | */ | |
4964 | if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq)) | |
4965 | goto expire; | |
4966 | ||
4967 | return rq; | |
4968 | ||
4969 | expire: | |
4970 | bfq_bfqq_expire(bfqd, bfqq, false, BFQQE_BUDGET_EXHAUSTED); | |
4971 | return rq; | |
4972 | } | |
4973 | ||
4974 | static bool bfq_has_work(struct blk_mq_hw_ctx *hctx) | |
4975 | { | |
4976 | struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; | |
4977 | ||
4978 | /* | |
4979 | * Avoiding lock: a race on bfqd->busy_queues should cause at | |
4980 | * most a call to dispatch for nothing | |
4981 | */ | |
4982 | return !list_empty_careful(&bfqd->dispatch) || | |
4983 | bfqd->busy_queues > 0; | |
4984 | } | |
4985 | ||
4986 | static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) | |
4987 | { | |
4988 | struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; | |
4989 | struct request *rq = NULL; | |
4990 | struct bfq_queue *bfqq = NULL; | |
4991 | ||
4992 | if (!list_empty(&bfqd->dispatch)) { | |
4993 | rq = list_first_entry(&bfqd->dispatch, struct request, | |
4994 | queuelist); | |
4995 | list_del_init(&rq->queuelist); | |
4996 | ||
4997 | bfqq = RQ_BFQQ(rq); | |
4998 | ||
4999 | if (bfqq) { | |
5000 | /* | |
5001 | * Increment counters here, because this | |
5002 | * dispatch does not follow the standard | |
5003 | * dispatch flow (where counters are | |
5004 | * incremented) | |
5005 | */ | |
5006 | bfqq->dispatched++; | |
5007 | ||
5008 | goto inc_in_driver_start_rq; | |
5009 | } | |
5010 | ||
5011 | /* | |
5012 | * We exploit the put_rq_private hook to decrement | |
5013 | * rq_in_driver, but put_rq_private will not be | |
5014 | * invoked on this request. So, to avoid unbalance, | |
5015 | * just start this request, without incrementing | |
5016 | * rq_in_driver. As a negative consequence, | |
5017 | * rq_in_driver is deceptively lower than it should be | |
5018 | * while this request is in service. This may cause | |
5019 | * bfq_schedule_dispatch to be invoked uselessly. | |
5020 | * | |
5021 | * As for implementing an exact solution, the | |
5022 | * put_request hook, if defined, is probably invoked | |
5023 | * also on this request. So, by exploiting this hook, | |
5024 | * we could 1) increment rq_in_driver here, and 2) | |
5025 | * decrement it in put_request. Such a solution would | |
5026 | * let the value of the counter be always accurate, | |
5027 | * but it would entail using an extra interface | |
5028 | * function. This cost seems higher than the benefit, | |
5029 | * being the frequency of non-elevator-private | |
5030 | * requests very low. | |
5031 | */ | |
5032 | goto start_rq; | |
5033 | } | |
5034 | ||
5035 | bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues); | |
5036 | ||
5037 | if (bfqd->busy_queues == 0) | |
5038 | goto exit; | |
5039 | ||
5040 | /* | |
5041 | * Force device to serve one request at a time if | |
5042 | * strict_guarantees is true. Forcing this service scheme is | |
5043 | * currently the ONLY way to guarantee that the request | |
5044 | * service order enforced by the scheduler is respected by a | |
5045 | * queueing device. Otherwise the device is free even to make | |
5046 | * some unlucky request wait for as long as the device | |
5047 | * wishes. | |
5048 | * | |
5049 | * Of course, serving one request at at time may cause loss of | |
5050 | * throughput. | |
5051 | */ | |
5052 | if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0) | |
5053 | goto exit; | |
5054 | ||
5055 | bfqq = bfq_select_queue(bfqd); | |
5056 | if (!bfqq) | |
5057 | goto exit; | |
5058 | ||
5059 | rq = bfq_dispatch_rq_from_bfqq(bfqd, bfqq); | |
5060 | ||
5061 | if (rq) { | |
5062 | inc_in_driver_start_rq: | |
5063 | bfqd->rq_in_driver++; | |
5064 | start_rq: | |
5065 | rq->rq_flags |= RQF_STARTED; | |
5066 | } | |
5067 | exit: | |
5068 | return rq; | |
5069 | } | |
5070 | ||
5071 | static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) | |
5072 | { | |
5073 | struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; | |
5074 | struct request *rq; | |
5075 | ||
5076 | spin_lock_irq(&bfqd->lock); | |
5077 | rq = __bfq_dispatch_request(hctx); | |
5078 | spin_unlock_irq(&bfqd->lock); | |
5079 | ||
5080 | return rq; | |
5081 | } | |
5082 | ||
5083 | /* | |
5084 | * Task holds one reference to the queue, dropped when task exits. Each rq | |
5085 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
5086 | * | |
5087 | * Scheduler lock must be held here. Recall not to use bfqq after calling | |
5088 | * this function on it. | |
5089 | */ | |
5090 | static void bfq_put_queue(struct bfq_queue *bfqq) | |
5091 | { | |
e21b7a0b AA |
5092 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
5093 | struct bfq_group *bfqg = bfqq_group(bfqq); | |
5094 | #endif | |
5095 | ||
aee69d78 PV |
5096 | if (bfqq->bfqd) |
5097 | bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", | |
5098 | bfqq, bfqq->ref); | |
5099 | ||
5100 | bfqq->ref--; | |
5101 | if (bfqq->ref) | |
5102 | return; | |
5103 | ||
e21b7a0b AA |
5104 | bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq); |
5105 | ||
aee69d78 | 5106 | kmem_cache_free(bfq_pool, bfqq); |
e21b7a0b AA |
5107 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
5108 | bfqg_put(bfqg); | |
5109 | #endif | |
aee69d78 PV |
5110 | } |
5111 | ||
5112 | static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) | |
5113 | { | |
5114 | if (bfqq == bfqd->in_service_queue) { | |
5115 | __bfq_bfqq_expire(bfqd, bfqq); | |
5116 | bfq_schedule_dispatch(bfqd); | |
5117 | } | |
5118 | ||
5119 | bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref); | |
5120 | ||
5121 | bfq_put_queue(bfqq); /* release process reference */ | |
5122 | } | |
5123 | ||
5124 | static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync) | |
5125 | { | |
5126 | struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync); | |
5127 | struct bfq_data *bfqd; | |
5128 | ||
5129 | if (bfqq) | |
5130 | bfqd = bfqq->bfqd; /* NULL if scheduler already exited */ | |
5131 | ||
5132 | if (bfqq && bfqd) { | |
5133 | unsigned long flags; | |
5134 | ||
5135 | spin_lock_irqsave(&bfqd->lock, flags); | |
5136 | bfq_exit_bfqq(bfqd, bfqq); | |
5137 | bic_set_bfqq(bic, NULL, is_sync); | |
5138 | spin_unlock_irq(&bfqd->lock); | |
5139 | } | |
5140 | } | |
5141 | ||
5142 | static void bfq_exit_icq(struct io_cq *icq) | |
5143 | { | |
5144 | struct bfq_io_cq *bic = icq_to_bic(icq); | |
5145 | ||
5146 | bfq_exit_icq_bfqq(bic, true); | |
5147 | bfq_exit_icq_bfqq(bic, false); | |
5148 | } | |
5149 | ||
5150 | /* | |
5151 | * Update the entity prio values; note that the new values will not | |
5152 | * be used until the next (re)activation. | |
5153 | */ | |
5154 | static void | |
5155 | bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic) | |
5156 | { | |
5157 | struct task_struct *tsk = current; | |
5158 | int ioprio_class; | |
5159 | struct bfq_data *bfqd = bfqq->bfqd; | |
5160 | ||
5161 | if (!bfqd) | |
5162 | return; | |
5163 | ||
5164 | ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); | |
5165 | switch (ioprio_class) { | |
5166 | default: | |
5167 | dev_err(bfqq->bfqd->queue->backing_dev_info->dev, | |
5168 | "bfq: bad prio class %d\n", ioprio_class); | |
5169 | case IOPRIO_CLASS_NONE: | |
5170 | /* | |
5171 | * No prio set, inherit CPU scheduling settings. | |
5172 | */ | |
5173 | bfqq->new_ioprio = task_nice_ioprio(tsk); | |
5174 | bfqq->new_ioprio_class = task_nice_ioclass(tsk); | |
5175 | break; | |
5176 | case IOPRIO_CLASS_RT: | |
5177 | bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); | |
5178 | bfqq->new_ioprio_class = IOPRIO_CLASS_RT; | |
5179 | break; | |
5180 | case IOPRIO_CLASS_BE: | |
5181 | bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); | |
5182 | bfqq->new_ioprio_class = IOPRIO_CLASS_BE; | |
5183 | break; | |
5184 | case IOPRIO_CLASS_IDLE: | |
5185 | bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE; | |
5186 | bfqq->new_ioprio = 7; | |
5187 | bfq_clear_bfqq_idle_window(bfqq); | |
5188 | break; | |
5189 | } | |
5190 | ||
5191 | if (bfqq->new_ioprio >= IOPRIO_BE_NR) { | |
5192 | pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n", | |
5193 | bfqq->new_ioprio); | |
5194 | bfqq->new_ioprio = IOPRIO_BE_NR; | |
5195 | } | |
5196 | ||
5197 | bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio); | |
5198 | bfqq->entity.prio_changed = 1; | |
5199 | } | |
5200 | ||
5201 | static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) | |
5202 | { | |
5203 | struct bfq_data *bfqd = bic_to_bfqd(bic); | |
5204 | struct bfq_queue *bfqq; | |
5205 | int ioprio = bic->icq.ioc->ioprio; | |
5206 | ||
5207 | /* | |
5208 | * This condition may trigger on a newly created bic, be sure to | |
5209 | * drop the lock before returning. | |
5210 | */ | |
5211 | if (unlikely(!bfqd) || likely(bic->ioprio == ioprio)) | |
5212 | return; | |
5213 | ||
5214 | bic->ioprio = ioprio; | |
5215 | ||
5216 | bfqq = bic_to_bfqq(bic, false); | |
5217 | if (bfqq) { | |
5218 | /* release process reference on this queue */ | |
5219 | bfq_put_queue(bfqq); | |
5220 | bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic); | |
5221 | bic_set_bfqq(bic, bfqq, false); | |
5222 | } | |
5223 | ||
5224 | bfqq = bic_to_bfqq(bic, true); | |
5225 | if (bfqq) | |
5226 | bfq_set_next_ioprio_data(bfqq, bic); | |
5227 | } | |
5228 | ||
5229 | static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
5230 | struct bfq_io_cq *bic, pid_t pid, int is_sync) | |
5231 | { | |
5232 | RB_CLEAR_NODE(&bfqq->entity.rb_node); | |
5233 | INIT_LIST_HEAD(&bfqq->fifo); | |
5234 | ||
5235 | bfqq->ref = 0; | |
5236 | bfqq->bfqd = bfqd; | |
5237 | ||
5238 | if (bic) | |
5239 | bfq_set_next_ioprio_data(bfqq, bic); | |
5240 | ||
5241 | if (is_sync) { | |
5242 | if (!bfq_class_idle(bfqq)) | |
5243 | bfq_mark_bfqq_idle_window(bfqq); | |
5244 | bfq_mark_bfqq_sync(bfqq); | |
5245 | } else | |
5246 | bfq_clear_bfqq_sync(bfqq); | |
5247 | ||
5248 | /* set end request to minus infinity from now */ | |
5249 | bfqq->ttime.last_end_request = ktime_get_ns() + 1; | |
5250 | ||
5251 | bfq_mark_bfqq_IO_bound(bfqq); | |
5252 | ||
5253 | bfqq->pid = pid; | |
5254 | ||
5255 | /* Tentative initial value to trade off between thr and lat */ | |
54b60456 | 5256 | bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3; |
aee69d78 | 5257 | bfqq->budget_timeout = bfq_smallest_from_now(); |
aee69d78 PV |
5258 | |
5259 | /* first request is almost certainly seeky */ | |
5260 | bfqq->seek_history = 1; | |
5261 | } | |
5262 | ||
5263 | static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, | |
e21b7a0b | 5264 | struct bfq_group *bfqg, |
aee69d78 PV |
5265 | int ioprio_class, int ioprio) |
5266 | { | |
5267 | switch (ioprio_class) { | |
5268 | case IOPRIO_CLASS_RT: | |
e21b7a0b | 5269 | return &bfqg->async_bfqq[0][ioprio]; |
aee69d78 PV |
5270 | case IOPRIO_CLASS_NONE: |
5271 | ioprio = IOPRIO_NORM; | |
5272 | /* fall through */ | |
5273 | case IOPRIO_CLASS_BE: | |
e21b7a0b | 5274 | return &bfqg->async_bfqq[1][ioprio]; |
aee69d78 | 5275 | case IOPRIO_CLASS_IDLE: |
e21b7a0b | 5276 | return &bfqg->async_idle_bfqq; |
aee69d78 PV |
5277 | default: |
5278 | return NULL; | |
5279 | } | |
5280 | } | |
5281 | ||
5282 | static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, | |
5283 | struct bio *bio, bool is_sync, | |
5284 | struct bfq_io_cq *bic) | |
5285 | { | |
5286 | const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio); | |
5287 | const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); | |
5288 | struct bfq_queue **async_bfqq = NULL; | |
5289 | struct bfq_queue *bfqq; | |
e21b7a0b | 5290 | struct bfq_group *bfqg; |
aee69d78 PV |
5291 | |
5292 | rcu_read_lock(); | |
5293 | ||
e21b7a0b AA |
5294 | bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio)); |
5295 | if (!bfqg) { | |
5296 | bfqq = &bfqd->oom_bfqq; | |
5297 | goto out; | |
5298 | } | |
5299 | ||
aee69d78 | 5300 | if (!is_sync) { |
e21b7a0b | 5301 | async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class, |
aee69d78 PV |
5302 | ioprio); |
5303 | bfqq = *async_bfqq; | |
5304 | if (bfqq) | |
5305 | goto out; | |
5306 | } | |
5307 | ||
5308 | bfqq = kmem_cache_alloc_node(bfq_pool, | |
5309 | GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN, | |
5310 | bfqd->queue->node); | |
5311 | ||
5312 | if (bfqq) { | |
5313 | bfq_init_bfqq(bfqd, bfqq, bic, current->pid, | |
5314 | is_sync); | |
e21b7a0b | 5315 | bfq_init_entity(&bfqq->entity, bfqg); |
aee69d78 PV |
5316 | bfq_log_bfqq(bfqd, bfqq, "allocated"); |
5317 | } else { | |
5318 | bfqq = &bfqd->oom_bfqq; | |
5319 | bfq_log_bfqq(bfqd, bfqq, "using oom bfqq"); | |
5320 | goto out; | |
5321 | } | |
5322 | ||
5323 | /* | |
5324 | * Pin the queue now that it's allocated, scheduler exit will | |
5325 | * prune it. | |
5326 | */ | |
5327 | if (async_bfqq) { | |
e21b7a0b AA |
5328 | bfqq->ref++; /* |
5329 | * Extra group reference, w.r.t. sync | |
5330 | * queue. This extra reference is removed | |
5331 | * only if bfqq->bfqg disappears, to | |
5332 | * guarantee that this queue is not freed | |
5333 | * until its group goes away. | |
5334 | */ | |
5335 | bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d", | |
aee69d78 PV |
5336 | bfqq, bfqq->ref); |
5337 | *async_bfqq = bfqq; | |
5338 | } | |
5339 | ||
5340 | out: | |
5341 | bfqq->ref++; /* get a process reference to this queue */ | |
5342 | bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref); | |
5343 | rcu_read_unlock(); | |
5344 | return bfqq; | |
5345 | } | |
5346 | ||
5347 | static void bfq_update_io_thinktime(struct bfq_data *bfqd, | |
5348 | struct bfq_queue *bfqq) | |
5349 | { | |
5350 | struct bfq_ttime *ttime = &bfqq->ttime; | |
5351 | u64 elapsed = ktime_get_ns() - bfqq->ttime.last_end_request; | |
5352 | ||
5353 | elapsed = min_t(u64, elapsed, 2ULL * bfqd->bfq_slice_idle); | |
5354 | ||
5355 | ttime->ttime_samples = (7*bfqq->ttime.ttime_samples + 256) / 8; | |
5356 | ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed, 8); | |
5357 | ttime->ttime_mean = div64_ul(ttime->ttime_total + 128, | |
5358 | ttime->ttime_samples); | |
5359 | } | |
5360 | ||
5361 | static void | |
5362 | bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
5363 | struct request *rq) | |
5364 | { | |
aee69d78 | 5365 | bfqq->seek_history <<= 1; |
ab0e43e9 PV |
5366 | bfqq->seek_history |= |
5367 | get_sdist(bfqq->last_request_pos, rq) > BFQQ_SEEK_THR && | |
aee69d78 PV |
5368 | (!blk_queue_nonrot(bfqd->queue) || |
5369 | blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT); | |
5370 | } | |
5371 | ||
5372 | /* | |
5373 | * Disable idle window if the process thinks too long or seeks so much that | |
5374 | * it doesn't matter. | |
5375 | */ | |
5376 | static void bfq_update_idle_window(struct bfq_data *bfqd, | |
5377 | struct bfq_queue *bfqq, | |
5378 | struct bfq_io_cq *bic) | |
5379 | { | |
5380 | int enable_idle; | |
5381 | ||
5382 | /* Don't idle for async or idle io prio class. */ | |
5383 | if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq)) | |
5384 | return; | |
5385 | ||
5386 | enable_idle = bfq_bfqq_idle_window(bfqq); | |
5387 | ||
5388 | if (atomic_read(&bic->icq.ioc->active_ref) == 0 || | |
5389 | bfqd->bfq_slice_idle == 0 || | |
5390 | (bfqd->hw_tag && BFQQ_SEEKY(bfqq))) | |
5391 | enable_idle = 0; | |
5392 | else if (bfq_sample_valid(bfqq->ttime.ttime_samples)) { | |
5393 | if (bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle) | |
5394 | enable_idle = 0; | |
5395 | else | |
5396 | enable_idle = 1; | |
5397 | } | |
5398 | bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d", | |
5399 | enable_idle); | |
5400 | ||
5401 | if (enable_idle) | |
5402 | bfq_mark_bfqq_idle_window(bfqq); | |
5403 | else | |
5404 | bfq_clear_bfqq_idle_window(bfqq); | |
5405 | } | |
5406 | ||
5407 | /* | |
5408 | * Called when a new fs request (rq) is added to bfqq. Check if there's | |
5409 | * something we should do about it. | |
5410 | */ | |
5411 | static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
5412 | struct request *rq) | |
5413 | { | |
5414 | struct bfq_io_cq *bic = RQ_BIC(rq); | |
5415 | ||
5416 | if (rq->cmd_flags & REQ_META) | |
5417 | bfqq->meta_pending++; | |
5418 | ||
5419 | bfq_update_io_thinktime(bfqd, bfqq); | |
5420 | bfq_update_io_seektime(bfqd, bfqq, rq); | |
5421 | if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 || | |
5422 | !BFQQ_SEEKY(bfqq)) | |
5423 | bfq_update_idle_window(bfqd, bfqq, bic); | |
5424 | ||
5425 | bfq_log_bfqq(bfqd, bfqq, | |
5426 | "rq_enqueued: idle_window=%d (seeky %d)", | |
5427 | bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq)); | |
5428 | ||
5429 | bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); | |
5430 | ||
5431 | if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) { | |
5432 | bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 && | |
5433 | blk_rq_sectors(rq) < 32; | |
5434 | bool budget_timeout = bfq_bfqq_budget_timeout(bfqq); | |
5435 | ||
5436 | /* | |
5437 | * There is just this request queued: if the request | |
5438 | * is small and the queue is not to be expired, then | |
5439 | * just exit. | |
5440 | * | |
5441 | * In this way, if the device is being idled to wait | |
5442 | * for a new request from the in-service queue, we | |
5443 | * avoid unplugging the device and committing the | |
5444 | * device to serve just a small request. On the | |
5445 | * contrary, we wait for the block layer to decide | |
5446 | * when to unplug the device: hopefully, new requests | |
5447 | * will be merged to this one quickly, then the device | |
5448 | * will be unplugged and larger requests will be | |
5449 | * dispatched. | |
5450 | */ | |
5451 | if (small_req && !budget_timeout) | |
5452 | return; | |
5453 | ||
5454 | /* | |
5455 | * A large enough request arrived, or the queue is to | |
5456 | * be expired: in both cases disk idling is to be | |
5457 | * stopped, so clear wait_request flag and reset | |
5458 | * timer. | |
5459 | */ | |
5460 | bfq_clear_bfqq_wait_request(bfqq); | |
5461 | hrtimer_try_to_cancel(&bfqd->idle_slice_timer); | |
e21b7a0b | 5462 | bfqg_stats_update_idle_time(bfqq_group(bfqq)); |
aee69d78 PV |
5463 | |
5464 | /* | |
5465 | * The queue is not empty, because a new request just | |
5466 | * arrived. Hence we can safely expire the queue, in | |
5467 | * case of budget timeout, without risking that the | |
5468 | * timestamps of the queue are not updated correctly. | |
5469 | * See [1] for more details. | |
5470 | */ | |
5471 | if (budget_timeout) | |
5472 | bfq_bfqq_expire(bfqd, bfqq, false, | |
5473 | BFQQE_BUDGET_TIMEOUT); | |
5474 | } | |
5475 | } | |
5476 | ||
5477 | static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq) | |
5478 | { | |
5479 | struct bfq_queue *bfqq = RQ_BFQQ(rq); | |
5480 | ||
5481 | bfq_add_request(rq); | |
5482 | ||
5483 | rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; | |
5484 | list_add_tail(&rq->queuelist, &bfqq->fifo); | |
5485 | ||
5486 | bfq_rq_enqueued(bfqd, bfqq, rq); | |
5487 | } | |
5488 | ||
5489 | static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, | |
5490 | bool at_head) | |
5491 | { | |
5492 | struct request_queue *q = hctx->queue; | |
5493 | struct bfq_data *bfqd = q->elevator->elevator_data; | |
5494 | ||
5495 | spin_lock_irq(&bfqd->lock); | |
5496 | if (blk_mq_sched_try_insert_merge(q, rq)) { | |
5497 | spin_unlock_irq(&bfqd->lock); | |
5498 | return; | |
5499 | } | |
5500 | ||
5501 | spin_unlock_irq(&bfqd->lock); | |
5502 | ||
5503 | blk_mq_sched_request_inserted(rq); | |
5504 | ||
5505 | spin_lock_irq(&bfqd->lock); | |
5506 | if (at_head || blk_rq_is_passthrough(rq)) { | |
5507 | if (at_head) | |
5508 | list_add(&rq->queuelist, &bfqd->dispatch); | |
5509 | else | |
5510 | list_add_tail(&rq->queuelist, &bfqd->dispatch); | |
5511 | } else { | |
5512 | __bfq_insert_request(bfqd, rq); | |
5513 | ||
5514 | if (rq_mergeable(rq)) { | |
5515 | elv_rqhash_add(q, rq); | |
5516 | if (!q->last_merge) | |
5517 | q->last_merge = rq; | |
5518 | } | |
5519 | } | |
5520 | ||
5521 | spin_unlock_irq(&bfqd->lock); | |
5522 | } | |
5523 | ||
5524 | static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx, | |
5525 | struct list_head *list, bool at_head) | |
5526 | { | |
5527 | while (!list_empty(list)) { | |
5528 | struct request *rq; | |
5529 | ||
5530 | rq = list_first_entry(list, struct request, queuelist); | |
5531 | list_del_init(&rq->queuelist); | |
5532 | bfq_insert_request(hctx, rq, at_head); | |
5533 | } | |
5534 | } | |
5535 | ||
5536 | static void bfq_update_hw_tag(struct bfq_data *bfqd) | |
5537 | { | |
5538 | bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver, | |
5539 | bfqd->rq_in_driver); | |
5540 | ||
5541 | if (bfqd->hw_tag == 1) | |
5542 | return; | |
5543 | ||
5544 | /* | |
5545 | * This sample is valid if the number of outstanding requests | |
5546 | * is large enough to allow a queueing behavior. Note that the | |
5547 | * sum is not exact, as it's not taking into account deactivated | |
5548 | * requests. | |
5549 | */ | |
5550 | if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD) | |
5551 | return; | |
5552 | ||
5553 | if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES) | |
5554 | return; | |
5555 | ||
5556 | bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD; | |
5557 | bfqd->max_rq_in_driver = 0; | |
5558 | bfqd->hw_tag_samples = 0; | |
5559 | } | |
5560 | ||
5561 | static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd) | |
5562 | { | |
ab0e43e9 PV |
5563 | u64 now_ns; |
5564 | u32 delta_us; | |
5565 | ||
aee69d78 PV |
5566 | bfq_update_hw_tag(bfqd); |
5567 | ||
5568 | bfqd->rq_in_driver--; | |
5569 | bfqq->dispatched--; | |
5570 | ||
ab0e43e9 PV |
5571 | now_ns = ktime_get_ns(); |
5572 | ||
5573 | bfqq->ttime.last_end_request = now_ns; | |
5574 | ||
5575 | /* | |
5576 | * Using us instead of ns, to get a reasonable precision in | |
5577 | * computing rate in next check. | |
5578 | */ | |
5579 | delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC); | |
5580 | ||
5581 | /* | |
5582 | * If the request took rather long to complete, and, according | |
5583 | * to the maximum request size recorded, this completion latency | |
5584 | * implies that the request was certainly served at a very low | |
5585 | * rate (less than 1M sectors/sec), then the whole observation | |
5586 | * interval that lasts up to this time instant cannot be a | |
5587 | * valid time interval for computing a new peak rate. Invoke | |
5588 | * bfq_update_rate_reset to have the following three steps | |
5589 | * taken: | |
5590 | * - close the observation interval at the last (previous) | |
5591 | * request dispatch or completion | |
5592 | * - compute rate, if possible, for that observation interval | |
5593 | * - reset to zero samples, which will trigger a proper | |
5594 | * re-initialization of the observation interval on next | |
5595 | * dispatch | |
5596 | */ | |
5597 | if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC && | |
5598 | (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us < | |
5599 | 1UL<<(BFQ_RATE_SHIFT - 10)) | |
5600 | bfq_update_rate_reset(bfqd, NULL); | |
5601 | bfqd->last_completion = now_ns; | |
aee69d78 PV |
5602 | |
5603 | /* | |
5604 | * If this is the in-service queue, check if it needs to be expired, | |
5605 | * or if we want to idle in case it has no pending requests. | |
5606 | */ | |
5607 | if (bfqd->in_service_queue == bfqq) { | |
5608 | if (bfq_bfqq_budget_new(bfqq)) | |
5609 | bfq_set_budget_timeout(bfqd); | |
5610 | ||
5611 | if (bfq_bfqq_must_idle(bfqq)) { | |
5612 | bfq_arm_slice_timer(bfqd); | |
5613 | return; | |
5614 | } else if (bfq_may_expire_for_budg_timeout(bfqq)) | |
5615 | bfq_bfqq_expire(bfqd, bfqq, false, | |
5616 | BFQQE_BUDGET_TIMEOUT); | |
5617 | else if (RB_EMPTY_ROOT(&bfqq->sort_list) && | |
5618 | (bfqq->dispatched == 0 || | |
5619 | !bfq_bfqq_may_idle(bfqq))) | |
5620 | bfq_bfqq_expire(bfqd, bfqq, false, | |
5621 | BFQQE_NO_MORE_REQUESTS); | |
5622 | } | |
5623 | } | |
5624 | ||
5625 | static void bfq_put_rq_priv_body(struct bfq_queue *bfqq) | |
5626 | { | |
5627 | bfqq->allocated--; | |
5628 | ||
5629 | bfq_put_queue(bfqq); | |
5630 | } | |
5631 | ||
5632 | static void bfq_put_rq_private(struct request_queue *q, struct request *rq) | |
5633 | { | |
5634 | struct bfq_queue *bfqq = RQ_BFQQ(rq); | |
5635 | struct bfq_data *bfqd = bfqq->bfqd; | |
5636 | ||
e21b7a0b AA |
5637 | if (rq->rq_flags & RQF_STARTED) |
5638 | bfqg_stats_update_completion(bfqq_group(bfqq), | |
5639 | rq_start_time_ns(rq), | |
5640 | rq_io_start_time_ns(rq), | |
5641 | rq->cmd_flags); | |
aee69d78 PV |
5642 | |
5643 | if (likely(rq->rq_flags & RQF_STARTED)) { | |
5644 | unsigned long flags; | |
5645 | ||
5646 | spin_lock_irqsave(&bfqd->lock, flags); | |
5647 | ||
5648 | bfq_completed_request(bfqq, bfqd); | |
5649 | bfq_put_rq_priv_body(bfqq); | |
5650 | ||
5651 | spin_unlock_irqrestore(&bfqd->lock, flags); | |
5652 | } else { | |
5653 | /* | |
5654 | * Request rq may be still/already in the scheduler, | |
5655 | * in which case we need to remove it. And we cannot | |
5656 | * defer such a check and removal, to avoid | |
5657 | * inconsistencies in the time interval from the end | |
5658 | * of this function to the start of the deferred work. | |
5659 | * This situation seems to occur only in process | |
5660 | * context, as a consequence of a merge. In the | |
5661 | * current version of the code, this implies that the | |
5662 | * lock is held. | |
5663 | */ | |
5664 | ||
5665 | if (!RB_EMPTY_NODE(&rq->rb_node)) | |
5666 | bfq_remove_request(q, rq); | |
5667 | bfq_put_rq_priv_body(bfqq); | |
5668 | } | |
5669 | ||
5670 | rq->elv.priv[0] = NULL; | |
5671 | rq->elv.priv[1] = NULL; | |
5672 | } | |
5673 | ||
5674 | /* | |
5675 | * Allocate bfq data structures associated with this request. | |
5676 | */ | |
5677 | static int bfq_get_rq_private(struct request_queue *q, struct request *rq, | |
5678 | struct bio *bio) | |
5679 | { | |
5680 | struct bfq_data *bfqd = q->elevator->elevator_data; | |
5681 | struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq); | |
5682 | const int is_sync = rq_is_sync(rq); | |
5683 | struct bfq_queue *bfqq; | |
5684 | ||
5685 | spin_lock_irq(&bfqd->lock); | |
5686 | ||
5687 | bfq_check_ioprio_change(bic, bio); | |
5688 | ||
5689 | if (!bic) | |
5690 | goto queue_fail; | |
5691 | ||
e21b7a0b AA |
5692 | bfq_bic_update_cgroup(bic, bio); |
5693 | ||
aee69d78 PV |
5694 | bfqq = bic_to_bfqq(bic, is_sync); |
5695 | if (!bfqq || bfqq == &bfqd->oom_bfqq) { | |
5696 | if (bfqq) | |
5697 | bfq_put_queue(bfqq); | |
5698 | bfqq = bfq_get_queue(bfqd, bio, is_sync, bic); | |
5699 | bic_set_bfqq(bic, bfqq, is_sync); | |
5700 | } | |
5701 | ||
5702 | bfqq->allocated++; | |
5703 | bfqq->ref++; | |
5704 | bfq_log_bfqq(bfqd, bfqq, "get_request %p: bfqq %p, %d", | |
5705 | rq, bfqq, bfqq->ref); | |
5706 | ||
5707 | rq->elv.priv[0] = bic; | |
5708 | rq->elv.priv[1] = bfqq; | |
5709 | ||
5710 | spin_unlock_irq(&bfqd->lock); | |
5711 | ||
5712 | return 0; | |
5713 | ||
5714 | queue_fail: | |
5715 | spin_unlock_irq(&bfqd->lock); | |
5716 | ||
5717 | return 1; | |
5718 | } | |
5719 | ||
5720 | static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq) | |
5721 | { | |
5722 | struct bfq_data *bfqd = bfqq->bfqd; | |
5723 | enum bfqq_expiration reason; | |
5724 | unsigned long flags; | |
5725 | ||
5726 | spin_lock_irqsave(&bfqd->lock, flags); | |
5727 | bfq_clear_bfqq_wait_request(bfqq); | |
5728 | ||
5729 | if (bfqq != bfqd->in_service_queue) { | |
5730 | spin_unlock_irqrestore(&bfqd->lock, flags); | |
5731 | return; | |
5732 | } | |
5733 | ||
5734 | if (bfq_bfqq_budget_timeout(bfqq)) | |
5735 | /* | |
5736 | * Also here the queue can be safely expired | |
5737 | * for budget timeout without wasting | |
5738 | * guarantees | |
5739 | */ | |
5740 | reason = BFQQE_BUDGET_TIMEOUT; | |
5741 | else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0) | |
5742 | /* | |
5743 | * The queue may not be empty upon timer expiration, | |
5744 | * because we may not disable the timer when the | |
5745 | * first request of the in-service queue arrives | |
5746 | * during disk idling. | |
5747 | */ | |
5748 | reason = BFQQE_TOO_IDLE; | |
5749 | else | |
5750 | goto schedule_dispatch; | |
5751 | ||
5752 | bfq_bfqq_expire(bfqd, bfqq, true, reason); | |
5753 | ||
5754 | schedule_dispatch: | |
5755 | spin_unlock_irqrestore(&bfqd->lock, flags); | |
5756 | bfq_schedule_dispatch(bfqd); | |
5757 | } | |
5758 | ||
5759 | /* | |
5760 | * Handler of the expiration of the timer running if the in-service queue | |
5761 | * is idling inside its time slice. | |
5762 | */ | |
5763 | static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer) | |
5764 | { | |
5765 | struct bfq_data *bfqd = container_of(timer, struct bfq_data, | |
5766 | idle_slice_timer); | |
5767 | struct bfq_queue *bfqq = bfqd->in_service_queue; | |
5768 | ||
5769 | /* | |
5770 | * Theoretical race here: the in-service queue can be NULL or | |
5771 | * different from the queue that was idling if a new request | |
5772 | * arrives for the current queue and there is a full dispatch | |
5773 | * cycle that changes the in-service queue. This can hardly | |
5774 | * happen, but in the worst case we just expire a queue too | |
5775 | * early. | |
5776 | */ | |
5777 | if (bfqq) | |
5778 | bfq_idle_slice_timer_body(bfqq); | |
5779 | ||
5780 | return HRTIMER_NORESTART; | |
5781 | } | |
5782 | ||
5783 | static void __bfq_put_async_bfqq(struct bfq_data *bfqd, | |
5784 | struct bfq_queue **bfqq_ptr) | |
5785 | { | |
5786 | struct bfq_queue *bfqq = *bfqq_ptr; | |
5787 | ||
5788 | bfq_log(bfqd, "put_async_bfqq: %p", bfqq); | |
5789 | if (bfqq) { | |
e21b7a0b AA |
5790 | bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); |
5791 | ||
aee69d78 PV |
5792 | bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d", |
5793 | bfqq, bfqq->ref); | |
5794 | bfq_put_queue(bfqq); | |
5795 | *bfqq_ptr = NULL; | |
5796 | } | |
5797 | } | |
5798 | ||
5799 | /* | |
e21b7a0b AA |
5800 | * Release all the bfqg references to its async queues. If we are |
5801 | * deallocating the group these queues may still contain requests, so | |
5802 | * we reparent them to the root cgroup (i.e., the only one that will | |
5803 | * exist for sure until all the requests on a device are gone). | |
aee69d78 | 5804 | */ |
e21b7a0b | 5805 | static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) |
aee69d78 PV |
5806 | { |
5807 | int i, j; | |
5808 | ||
5809 | for (i = 0; i < 2; i++) | |
5810 | for (j = 0; j < IOPRIO_BE_NR; j++) | |
e21b7a0b | 5811 | __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]); |
aee69d78 | 5812 | |
e21b7a0b | 5813 | __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq); |
aee69d78 PV |
5814 | } |
5815 | ||
5816 | static void bfq_exit_queue(struct elevator_queue *e) | |
5817 | { | |
5818 | struct bfq_data *bfqd = e->elevator_data; | |
5819 | struct bfq_queue *bfqq, *n; | |
5820 | ||
5821 | hrtimer_cancel(&bfqd->idle_slice_timer); | |
5822 | ||
5823 | spin_lock_irq(&bfqd->lock); | |
5824 | list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) | |
e21b7a0b | 5825 | bfq_deactivate_bfqq(bfqd, bfqq, false, false); |
aee69d78 PV |
5826 | spin_unlock_irq(&bfqd->lock); |
5827 | ||
5828 | hrtimer_cancel(&bfqd->idle_slice_timer); | |
5829 | ||
e21b7a0b AA |
5830 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
5831 | blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq); | |
5832 | #else | |
5833 | spin_lock_irq(&bfqd->lock); | |
5834 | bfq_put_async_queues(bfqd, bfqd->root_group); | |
5835 | kfree(bfqd->root_group); | |
5836 | spin_unlock_irq(&bfqd->lock); | |
5837 | #endif | |
5838 | ||
aee69d78 PV |
5839 | kfree(bfqd); |
5840 | } | |
5841 | ||
e21b7a0b AA |
5842 | static void bfq_init_root_group(struct bfq_group *root_group, |
5843 | struct bfq_data *bfqd) | |
5844 | { | |
5845 | int i; | |
5846 | ||
5847 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
5848 | root_group->entity.parent = NULL; | |
5849 | root_group->my_entity = NULL; | |
5850 | root_group->bfqd = bfqd; | |
5851 | #endif | |
5852 | for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) | |
5853 | root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; | |
5854 | root_group->sched_data.bfq_class_idle_last_service = jiffies; | |
5855 | } | |
5856 | ||
aee69d78 PV |
5857 | static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) |
5858 | { | |
5859 | struct bfq_data *bfqd; | |
5860 | struct elevator_queue *eq; | |
aee69d78 PV |
5861 | |
5862 | eq = elevator_alloc(q, e); | |
5863 | if (!eq) | |
5864 | return -ENOMEM; | |
5865 | ||
5866 | bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node); | |
5867 | if (!bfqd) { | |
5868 | kobject_put(&eq->kobj); | |
5869 | return -ENOMEM; | |
5870 | } | |
5871 | eq->elevator_data = bfqd; | |
5872 | ||
e21b7a0b AA |
5873 | spin_lock_irq(q->queue_lock); |
5874 | q->elevator = eq; | |
5875 | spin_unlock_irq(q->queue_lock); | |
5876 | ||
aee69d78 PV |
5877 | /* |
5878 | * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues. | |
5879 | * Grab a permanent reference to it, so that the normal code flow | |
5880 | * will not attempt to free it. | |
5881 | */ | |
5882 | bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0); | |
5883 | bfqd->oom_bfqq.ref++; | |
5884 | bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; | |
5885 | bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE; | |
5886 | bfqd->oom_bfqq.entity.new_weight = | |
5887 | bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio); | |
5888 | /* | |
5889 | * Trigger weight initialization, according to ioprio, at the | |
5890 | * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio | |
5891 | * class won't be changed any more. | |
5892 | */ | |
5893 | bfqd->oom_bfqq.entity.prio_changed = 1; | |
5894 | ||
5895 | bfqd->queue = q; | |
5896 | ||
e21b7a0b | 5897 | INIT_LIST_HEAD(&bfqd->dispatch); |
aee69d78 PV |
5898 | |
5899 | hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC, | |
5900 | HRTIMER_MODE_REL); | |
5901 | bfqd->idle_slice_timer.function = bfq_idle_slice_timer; | |
5902 | ||
5903 | INIT_LIST_HEAD(&bfqd->active_list); | |
5904 | INIT_LIST_HEAD(&bfqd->idle_list); | |
5905 | ||
5906 | bfqd->hw_tag = -1; | |
5907 | ||
5908 | bfqd->bfq_max_budget = bfq_default_max_budget; | |
5909 | ||
5910 | bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0]; | |
5911 | bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1]; | |
5912 | bfqd->bfq_back_max = bfq_back_max; | |
5913 | bfqd->bfq_back_penalty = bfq_back_penalty; | |
5914 | bfqd->bfq_slice_idle = bfq_slice_idle; | |
aee69d78 PV |
5915 | bfqd->bfq_timeout = bfq_timeout; |
5916 | ||
5917 | bfqd->bfq_requests_within_timer = 120; | |
5918 | ||
5919 | spin_lock_init(&bfqd->lock); | |
aee69d78 | 5920 | |
e21b7a0b AA |
5921 | /* |
5922 | * The invocation of the next bfq_create_group_hierarchy | |
5923 | * function is the head of a chain of function calls | |
5924 | * (bfq_create_group_hierarchy->blkcg_activate_policy-> | |
5925 | * blk_mq_freeze_queue) that may lead to the invocation of the | |
5926 | * has_work hook function. For this reason, | |
5927 | * bfq_create_group_hierarchy is invoked only after all | |
5928 | * scheduler data has been initialized, apart from the fields | |
5929 | * that can be initialized only after invoking | |
5930 | * bfq_create_group_hierarchy. This, in particular, enables | |
5931 | * has_work to correctly return false. Of course, to avoid | |
5932 | * other inconsistencies, the blk-mq stack must then refrain | |
5933 | * from invoking further scheduler hooks before this init | |
5934 | * function is finished. | |
5935 | */ | |
5936 | bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node); | |
5937 | if (!bfqd->root_group) | |
5938 | goto out_free; | |
5939 | bfq_init_root_group(bfqd->root_group, bfqd); | |
5940 | bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group); | |
5941 | ||
aee69d78 PV |
5942 | |
5943 | return 0; | |
e21b7a0b AA |
5944 | |
5945 | out_free: | |
5946 | kfree(bfqd); | |
5947 | kobject_put(&eq->kobj); | |
5948 | return -ENOMEM; | |
aee69d78 PV |
5949 | } |
5950 | ||
5951 | static void bfq_slab_kill(void) | |
5952 | { | |
5953 | kmem_cache_destroy(bfq_pool); | |
5954 | } | |
5955 | ||
5956 | static int __init bfq_slab_setup(void) | |
5957 | { | |
5958 | bfq_pool = KMEM_CACHE(bfq_queue, 0); | |
5959 | if (!bfq_pool) | |
5960 | return -ENOMEM; | |
5961 | return 0; | |
5962 | } | |
5963 | ||
5964 | static ssize_t bfq_var_show(unsigned int var, char *page) | |
5965 | { | |
5966 | return sprintf(page, "%u\n", var); | |
5967 | } | |
5968 | ||
5969 | static ssize_t bfq_var_store(unsigned long *var, const char *page, | |
5970 | size_t count) | |
5971 | { | |
5972 | unsigned long new_val; | |
5973 | int ret = kstrtoul(page, 10, &new_val); | |
5974 | ||
5975 | if (ret == 0) | |
5976 | *var = new_val; | |
5977 | ||
5978 | return count; | |
5979 | } | |
5980 | ||
5981 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ | |
5982 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ | |
5983 | { \ | |
5984 | struct bfq_data *bfqd = e->elevator_data; \ | |
5985 | u64 __data = __VAR; \ | |
5986 | if (__CONV == 1) \ | |
5987 | __data = jiffies_to_msecs(__data); \ | |
5988 | else if (__CONV == 2) \ | |
5989 | __data = div_u64(__data, NSEC_PER_MSEC); \ | |
5990 | return bfq_var_show(__data, (page)); \ | |
5991 | } | |
5992 | SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2); | |
5993 | SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2); | |
5994 | SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0); | |
5995 | SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0); | |
5996 | SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2); | |
5997 | SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0); | |
5998 | SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1); | |
5999 | SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0); | |
6000 | #undef SHOW_FUNCTION | |
6001 | ||
6002 | #define USEC_SHOW_FUNCTION(__FUNC, __VAR) \ | |
6003 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ | |
6004 | { \ | |
6005 | struct bfq_data *bfqd = e->elevator_data; \ | |
6006 | u64 __data = __VAR; \ | |
6007 | __data = div_u64(__data, NSEC_PER_USEC); \ | |
6008 | return bfq_var_show(__data, (page)); \ | |
6009 | } | |
6010 | USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle); | |
6011 | #undef USEC_SHOW_FUNCTION | |
6012 | ||
6013 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
6014 | static ssize_t \ | |
6015 | __FUNC(struct elevator_queue *e, const char *page, size_t count) \ | |
6016 | { \ | |
6017 | struct bfq_data *bfqd = e->elevator_data; \ | |
6018 | unsigned long uninitialized_var(__data); \ | |
6019 | int ret = bfq_var_store(&__data, (page), count); \ | |
6020 | if (__data < (MIN)) \ | |
6021 | __data = (MIN); \ | |
6022 | else if (__data > (MAX)) \ | |
6023 | __data = (MAX); \ | |
6024 | if (__CONV == 1) \ | |
6025 | *(__PTR) = msecs_to_jiffies(__data); \ | |
6026 | else if (__CONV == 2) \ | |
6027 | *(__PTR) = (u64)__data * NSEC_PER_MSEC; \ | |
6028 | else \ | |
6029 | *(__PTR) = __data; \ | |
6030 | return ret; \ | |
6031 | } | |
6032 | STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1, | |
6033 | INT_MAX, 2); | |
6034 | STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1, | |
6035 | INT_MAX, 2); | |
6036 | STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0); | |
6037 | STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1, | |
6038 | INT_MAX, 0); | |
6039 | STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2); | |
6040 | #undef STORE_FUNCTION | |
6041 | ||
6042 | #define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \ | |
6043 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\ | |
6044 | { \ | |
6045 | struct bfq_data *bfqd = e->elevator_data; \ | |
6046 | unsigned long uninitialized_var(__data); \ | |
6047 | int ret = bfq_var_store(&__data, (page), count); \ | |
6048 | if (__data < (MIN)) \ | |
6049 | __data = (MIN); \ | |
6050 | else if (__data > (MAX)) \ | |
6051 | __data = (MAX); \ | |
6052 | *(__PTR) = (u64)__data * NSEC_PER_USEC; \ | |
6053 | return ret; \ | |
6054 | } | |
6055 | USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0, | |
6056 | UINT_MAX); | |
6057 | #undef USEC_STORE_FUNCTION | |
6058 | ||
aee69d78 PV |
6059 | static ssize_t bfq_max_budget_store(struct elevator_queue *e, |
6060 | const char *page, size_t count) | |
6061 | { | |
6062 | struct bfq_data *bfqd = e->elevator_data; | |
6063 | unsigned long uninitialized_var(__data); | |
6064 | int ret = bfq_var_store(&__data, (page), count); | |
6065 | ||
6066 | if (__data == 0) | |
ab0e43e9 | 6067 | bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd); |
aee69d78 PV |
6068 | else { |
6069 | if (__data > INT_MAX) | |
6070 | __data = INT_MAX; | |
6071 | bfqd->bfq_max_budget = __data; | |
6072 | } | |
6073 | ||
6074 | bfqd->bfq_user_max_budget = __data; | |
6075 | ||
6076 | return ret; | |
6077 | } | |
6078 | ||
6079 | /* | |
6080 | * Leaving this name to preserve name compatibility with cfq | |
6081 | * parameters, but this timeout is used for both sync and async. | |
6082 | */ | |
6083 | static ssize_t bfq_timeout_sync_store(struct elevator_queue *e, | |
6084 | const char *page, size_t count) | |
6085 | { | |
6086 | struct bfq_data *bfqd = e->elevator_data; | |
6087 | unsigned long uninitialized_var(__data); | |
6088 | int ret = bfq_var_store(&__data, (page), count); | |
6089 | ||
6090 | if (__data < 1) | |
6091 | __data = 1; | |
6092 | else if (__data > INT_MAX) | |
6093 | __data = INT_MAX; | |
6094 | ||
6095 | bfqd->bfq_timeout = msecs_to_jiffies(__data); | |
6096 | if (bfqd->bfq_user_max_budget == 0) | |
ab0e43e9 | 6097 | bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd); |
aee69d78 PV |
6098 | |
6099 | return ret; | |
6100 | } | |
6101 | ||
6102 | static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e, | |
6103 | const char *page, size_t count) | |
6104 | { | |
6105 | struct bfq_data *bfqd = e->elevator_data; | |
6106 | unsigned long uninitialized_var(__data); | |
6107 | int ret = bfq_var_store(&__data, (page), count); | |
6108 | ||
6109 | if (__data > 1) | |
6110 | __data = 1; | |
6111 | if (!bfqd->strict_guarantees && __data == 1 | |
6112 | && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC) | |
6113 | bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC; | |
6114 | ||
6115 | bfqd->strict_guarantees = __data; | |
6116 | ||
6117 | return ret; | |
6118 | } | |
6119 | ||
6120 | #define BFQ_ATTR(name) \ | |
6121 | __ATTR(name, 0644, bfq_##name##_show, bfq_##name##_store) | |
6122 | ||
6123 | static struct elv_fs_entry bfq_attrs[] = { | |
6124 | BFQ_ATTR(fifo_expire_sync), | |
6125 | BFQ_ATTR(fifo_expire_async), | |
6126 | BFQ_ATTR(back_seek_max), | |
6127 | BFQ_ATTR(back_seek_penalty), | |
6128 | BFQ_ATTR(slice_idle), | |
6129 | BFQ_ATTR(slice_idle_us), | |
6130 | BFQ_ATTR(max_budget), | |
6131 | BFQ_ATTR(timeout_sync), | |
6132 | BFQ_ATTR(strict_guarantees), | |
6133 | __ATTR_NULL | |
6134 | }; | |
6135 | ||
6136 | static struct elevator_type iosched_bfq_mq = { | |
6137 | .ops.mq = { | |
6138 | .get_rq_priv = bfq_get_rq_private, | |
6139 | .put_rq_priv = bfq_put_rq_private, | |
6140 | .exit_icq = bfq_exit_icq, | |
6141 | .insert_requests = bfq_insert_requests, | |
6142 | .dispatch_request = bfq_dispatch_request, | |
6143 | .next_request = elv_rb_latter_request, | |
6144 | .former_request = elv_rb_former_request, | |
6145 | .allow_merge = bfq_allow_bio_merge, | |
6146 | .bio_merge = bfq_bio_merge, | |
6147 | .request_merge = bfq_request_merge, | |
6148 | .requests_merged = bfq_requests_merged, | |
6149 | .request_merged = bfq_request_merged, | |
6150 | .has_work = bfq_has_work, | |
6151 | .init_sched = bfq_init_queue, | |
6152 | .exit_sched = bfq_exit_queue, | |
6153 | }, | |
6154 | ||
6155 | .uses_mq = true, | |
6156 | .icq_size = sizeof(struct bfq_io_cq), | |
6157 | .icq_align = __alignof__(struct bfq_io_cq), | |
6158 | .elevator_attrs = bfq_attrs, | |
6159 | .elevator_name = "bfq", | |
6160 | .elevator_owner = THIS_MODULE, | |
6161 | }; | |
6162 | ||
e21b7a0b AA |
6163 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
6164 | static struct blkcg_policy blkcg_policy_bfq = { | |
6165 | .dfl_cftypes = bfq_blkg_files, | |
6166 | .legacy_cftypes = bfq_blkcg_legacy_files, | |
6167 | ||
6168 | .cpd_alloc_fn = bfq_cpd_alloc, | |
6169 | .cpd_init_fn = bfq_cpd_init, | |
6170 | .cpd_bind_fn = bfq_cpd_init, | |
6171 | .cpd_free_fn = bfq_cpd_free, | |
6172 | ||
6173 | .pd_alloc_fn = bfq_pd_alloc, | |
6174 | .pd_init_fn = bfq_pd_init, | |
6175 | .pd_offline_fn = bfq_pd_offline, | |
6176 | .pd_free_fn = bfq_pd_free, | |
6177 | .pd_reset_stats_fn = bfq_pd_reset_stats, | |
6178 | }; | |
6179 | #endif | |
6180 | ||
aee69d78 PV |
6181 | static int __init bfq_init(void) |
6182 | { | |
6183 | int ret; | |
6184 | ||
e21b7a0b AA |
6185 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
6186 | ret = blkcg_policy_register(&blkcg_policy_bfq); | |
6187 | if (ret) | |
6188 | return ret; | |
6189 | #endif | |
6190 | ||
aee69d78 PV |
6191 | ret = -ENOMEM; |
6192 | if (bfq_slab_setup()) | |
6193 | goto err_pol_unreg; | |
6194 | ||
6195 | ret = elv_register(&iosched_bfq_mq); | |
6196 | if (ret) | |
6197 | goto err_pol_unreg; | |
6198 | ||
6199 | return 0; | |
6200 | ||
6201 | err_pol_unreg: | |
e21b7a0b AA |
6202 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
6203 | blkcg_policy_unregister(&blkcg_policy_bfq); | |
6204 | #endif | |
aee69d78 PV |
6205 | return ret; |
6206 | } | |
6207 | ||
6208 | static void __exit bfq_exit(void) | |
6209 | { | |
6210 | elv_unregister(&iosched_bfq_mq); | |
e21b7a0b AA |
6211 | #ifdef CONFIG_BFQ_GROUP_IOSCHED |
6212 | blkcg_policy_unregister(&blkcg_policy_bfq); | |
6213 | #endif | |
aee69d78 PV |
6214 | bfq_slab_kill(); |
6215 | } | |
6216 | ||
6217 | module_init(bfq_init); | |
6218 | module_exit(bfq_exit); | |
6219 | ||
6220 | MODULE_AUTHOR("Paolo Valente"); | |
6221 | MODULE_LICENSE("GPL"); | |
6222 | MODULE_DESCRIPTION("MQ Budget Fair Queueing I/O Scheduler"); |