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1 | /* | |
2 | * CFQ, or complete fairness queueing, disk scheduler. | |
3 | * | |
4 | * Based on ideas from a previously unfinished io | |
5 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. | |
6 | * | |
7 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> | |
8 | */ | |
9 | #include <linux/module.h> | |
10 | #include <linux/slab.h> | |
11 | #include <linux/blkdev.h> | |
12 | #include <linux/elevator.h> | |
13 | #include <linux/jiffies.h> | |
14 | #include <linux/rbtree.h> | |
15 | #include <linux/ioprio.h> | |
16 | #include <linux/blktrace_api.h> | |
17 | #include "cfq.h" | |
18 | ||
19 | /* | |
20 | * tunables | |
21 | */ | |
22 | /* max queue in one round of service */ | |
23 | static const int cfq_quantum = 8; | |
24 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; | |
25 | /* maximum backwards seek, in KiB */ | |
26 | static const int cfq_back_max = 16 * 1024; | |
27 | /* penalty of a backwards seek */ | |
28 | static const int cfq_back_penalty = 2; | |
29 | static const int cfq_slice_sync = HZ / 10; | |
30 | static int cfq_slice_async = HZ / 25; | |
31 | static const int cfq_slice_async_rq = 2; | |
32 | static int cfq_slice_idle = HZ / 125; | |
33 | static int cfq_group_idle = HZ / 125; | |
34 | static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ | |
35 | static const int cfq_hist_divisor = 4; | |
36 | ||
37 | /* | |
38 | * offset from end of service tree | |
39 | */ | |
40 | #define CFQ_IDLE_DELAY (HZ / 5) | |
41 | ||
42 | /* | |
43 | * below this threshold, we consider thinktime immediate | |
44 | */ | |
45 | #define CFQ_MIN_TT (2) | |
46 | ||
47 | #define CFQ_SLICE_SCALE (5) | |
48 | #define CFQ_HW_QUEUE_MIN (5) | |
49 | #define CFQ_SERVICE_SHIFT 12 | |
50 | ||
51 | #define CFQQ_SEEK_THR (sector_t)(8 * 100) | |
52 | #define CFQQ_CLOSE_THR (sector_t)(8 * 1024) | |
53 | #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) | |
54 | #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) | |
55 | ||
56 | #define RQ_CIC(rq) \ | |
57 | ((struct cfq_io_context *) (rq)->elevator_private[0]) | |
58 | #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1]) | |
59 | #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2]) | |
60 | ||
61 | static struct kmem_cache *cfq_pool; | |
62 | static struct kmem_cache *cfq_ioc_pool; | |
63 | ||
64 | static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); | |
65 | static struct completion *ioc_gone; | |
66 | static DEFINE_SPINLOCK(ioc_gone_lock); | |
67 | ||
68 | static DEFINE_SPINLOCK(cic_index_lock); | |
69 | static DEFINE_IDA(cic_index_ida); | |
70 | ||
71 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR | |
72 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
73 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) | |
74 | ||
75 | #define sample_valid(samples) ((samples) > 80) | |
76 | #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) | |
77 | ||
78 | /* | |
79 | * Most of our rbtree usage is for sorting with min extraction, so | |
80 | * if we cache the leftmost node we don't have to walk down the tree | |
81 | * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should | |
82 | * move this into the elevator for the rq sorting as well. | |
83 | */ | |
84 | struct cfq_rb_root { | |
85 | struct rb_root rb; | |
86 | struct rb_node *left; | |
87 | unsigned count; | |
88 | unsigned total_weight; | |
89 | u64 min_vdisktime; | |
90 | }; | |
91 | #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \ | |
92 | .count = 0, .min_vdisktime = 0, } | |
93 | ||
94 | /* | |
95 | * Per process-grouping structure | |
96 | */ | |
97 | struct cfq_queue { | |
98 | /* reference count */ | |
99 | int ref; | |
100 | /* various state flags, see below */ | |
101 | unsigned int flags; | |
102 | /* parent cfq_data */ | |
103 | struct cfq_data *cfqd; | |
104 | /* service_tree member */ | |
105 | struct rb_node rb_node; | |
106 | /* service_tree key */ | |
107 | unsigned long rb_key; | |
108 | /* prio tree member */ | |
109 | struct rb_node p_node; | |
110 | /* prio tree root we belong to, if any */ | |
111 | struct rb_root *p_root; | |
112 | /* sorted list of pending requests */ | |
113 | struct rb_root sort_list; | |
114 | /* if fifo isn't expired, next request to serve */ | |
115 | struct request *next_rq; | |
116 | /* requests queued in sort_list */ | |
117 | int queued[2]; | |
118 | /* currently allocated requests */ | |
119 | int allocated[2]; | |
120 | /* fifo list of requests in sort_list */ | |
121 | struct list_head fifo; | |
122 | ||
123 | /* time when queue got scheduled in to dispatch first request. */ | |
124 | unsigned long dispatch_start; | |
125 | unsigned int allocated_slice; | |
126 | unsigned int slice_dispatch; | |
127 | /* time when first request from queue completed and slice started. */ | |
128 | unsigned long slice_start; | |
129 | unsigned long slice_end; | |
130 | long slice_resid; | |
131 | ||
132 | /* pending metadata requests */ | |
133 | int meta_pending; | |
134 | /* number of requests that are on the dispatch list or inside driver */ | |
135 | int dispatched; | |
136 | ||
137 | /* io prio of this group */ | |
138 | unsigned short ioprio, org_ioprio; | |
139 | unsigned short ioprio_class, org_ioprio_class; | |
140 | ||
141 | pid_t pid; | |
142 | ||
143 | u32 seek_history; | |
144 | sector_t last_request_pos; | |
145 | ||
146 | struct cfq_rb_root *service_tree; | |
147 | struct cfq_queue *new_cfqq; | |
148 | struct cfq_group *cfqg; | |
149 | /* Number of sectors dispatched from queue in single dispatch round */ | |
150 | unsigned long nr_sectors; | |
151 | }; | |
152 | ||
153 | /* | |
154 | * First index in the service_trees. | |
155 | * IDLE is handled separately, so it has negative index | |
156 | */ | |
157 | enum wl_prio_t { | |
158 | BE_WORKLOAD = 0, | |
159 | RT_WORKLOAD = 1, | |
160 | IDLE_WORKLOAD = 2, | |
161 | CFQ_PRIO_NR, | |
162 | }; | |
163 | ||
164 | /* | |
165 | * Second index in the service_trees. | |
166 | */ | |
167 | enum wl_type_t { | |
168 | ASYNC_WORKLOAD = 0, | |
169 | SYNC_NOIDLE_WORKLOAD = 1, | |
170 | SYNC_WORKLOAD = 2 | |
171 | }; | |
172 | ||
173 | /* This is per cgroup per device grouping structure */ | |
174 | struct cfq_group { | |
175 | /* group service_tree member */ | |
176 | struct rb_node rb_node; | |
177 | ||
178 | /* group service_tree key */ | |
179 | u64 vdisktime; | |
180 | unsigned int weight; | |
181 | ||
182 | /* number of cfqq currently on this group */ | |
183 | int nr_cfqq; | |
184 | ||
185 | /* | |
186 | * Per group busy queus average. Useful for workload slice calc. We | |
187 | * create the array for each prio class but at run time it is used | |
188 | * only for RT and BE class and slot for IDLE class remains unused. | |
189 | * This is primarily done to avoid confusion and a gcc warning. | |
190 | */ | |
191 | unsigned int busy_queues_avg[CFQ_PRIO_NR]; | |
192 | /* | |
193 | * rr lists of queues with requests. We maintain service trees for | |
194 | * RT and BE classes. These trees are subdivided in subclasses | |
195 | * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE | |
196 | * class there is no subclassification and all the cfq queues go on | |
197 | * a single tree service_tree_idle. | |
198 | * Counts are embedded in the cfq_rb_root | |
199 | */ | |
200 | struct cfq_rb_root service_trees[2][3]; | |
201 | struct cfq_rb_root service_tree_idle; | |
202 | ||
203 | unsigned long saved_workload_slice; | |
204 | enum wl_type_t saved_workload; | |
205 | enum wl_prio_t saved_serving_prio; | |
206 | struct blkio_group blkg; | |
207 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
208 | struct hlist_node cfqd_node; | |
209 | int ref; | |
210 | #endif | |
211 | /* number of requests that are on the dispatch list or inside driver */ | |
212 | int dispatched; | |
213 | }; | |
214 | ||
215 | /* | |
216 | * Per block device queue structure | |
217 | */ | |
218 | struct cfq_data { | |
219 | struct request_queue *queue; | |
220 | /* Root service tree for cfq_groups */ | |
221 | struct cfq_rb_root grp_service_tree; | |
222 | struct cfq_group root_group; | |
223 | ||
224 | /* | |
225 | * The priority currently being served | |
226 | */ | |
227 | enum wl_prio_t serving_prio; | |
228 | enum wl_type_t serving_type; | |
229 | unsigned long workload_expires; | |
230 | struct cfq_group *serving_group; | |
231 | ||
232 | /* | |
233 | * Each priority tree is sorted by next_request position. These | |
234 | * trees are used when determining if two or more queues are | |
235 | * interleaving requests (see cfq_close_cooperator). | |
236 | */ | |
237 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; | |
238 | ||
239 | unsigned int busy_queues; | |
240 | ||
241 | int rq_in_driver; | |
242 | int rq_in_flight[2]; | |
243 | ||
244 | /* | |
245 | * queue-depth detection | |
246 | */ | |
247 | int rq_queued; | |
248 | int hw_tag; | |
249 | /* | |
250 | * hw_tag can be | |
251 | * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) | |
252 | * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) | |
253 | * 0 => no NCQ | |
254 | */ | |
255 | int hw_tag_est_depth; | |
256 | unsigned int hw_tag_samples; | |
257 | ||
258 | /* | |
259 | * idle window management | |
260 | */ | |
261 | struct timer_list idle_slice_timer; | |
262 | struct work_struct unplug_work; | |
263 | ||
264 | struct cfq_queue *active_queue; | |
265 | struct cfq_io_context *active_cic; | |
266 | ||
267 | /* | |
268 | * async queue for each priority case | |
269 | */ | |
270 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; | |
271 | struct cfq_queue *async_idle_cfqq; | |
272 | ||
273 | sector_t last_position; | |
274 | ||
275 | /* | |
276 | * tunables, see top of file | |
277 | */ | |
278 | unsigned int cfq_quantum; | |
279 | unsigned int cfq_fifo_expire[2]; | |
280 | unsigned int cfq_back_penalty; | |
281 | unsigned int cfq_back_max; | |
282 | unsigned int cfq_slice[2]; | |
283 | unsigned int cfq_slice_async_rq; | |
284 | unsigned int cfq_slice_idle; | |
285 | unsigned int cfq_group_idle; | |
286 | unsigned int cfq_latency; | |
287 | ||
288 | unsigned int cic_index; | |
289 | struct list_head cic_list; | |
290 | ||
291 | /* | |
292 | * Fallback dummy cfqq for extreme OOM conditions | |
293 | */ | |
294 | struct cfq_queue oom_cfqq; | |
295 | ||
296 | unsigned long last_delayed_sync; | |
297 | ||
298 | /* List of cfq groups being managed on this device*/ | |
299 | struct hlist_head cfqg_list; | |
300 | struct rcu_head rcu; | |
301 | }; | |
302 | ||
303 | static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); | |
304 | ||
305 | static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, | |
306 | enum wl_prio_t prio, | |
307 | enum wl_type_t type) | |
308 | { | |
309 | if (!cfqg) | |
310 | return NULL; | |
311 | ||
312 | if (prio == IDLE_WORKLOAD) | |
313 | return &cfqg->service_tree_idle; | |
314 | ||
315 | return &cfqg->service_trees[prio][type]; | |
316 | } | |
317 | ||
318 | enum cfqq_state_flags { | |
319 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ | |
320 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
321 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ | |
322 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ | |
323 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ | |
324 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
325 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
326 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ | |
327 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ | |
328 | CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ | |
329 | CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ | |
330 | CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ | |
331 | CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ | |
332 | }; | |
333 | ||
334 | #define CFQ_CFQQ_FNS(name) \ | |
335 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
336 | { \ | |
337 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ | |
338 | } \ | |
339 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
340 | { \ | |
341 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ | |
342 | } \ | |
343 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
344 | { \ | |
345 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ | |
346 | } | |
347 | ||
348 | CFQ_CFQQ_FNS(on_rr); | |
349 | CFQ_CFQQ_FNS(wait_request); | |
350 | CFQ_CFQQ_FNS(must_dispatch); | |
351 | CFQ_CFQQ_FNS(must_alloc_slice); | |
352 | CFQ_CFQQ_FNS(fifo_expire); | |
353 | CFQ_CFQQ_FNS(idle_window); | |
354 | CFQ_CFQQ_FNS(prio_changed); | |
355 | CFQ_CFQQ_FNS(slice_new); | |
356 | CFQ_CFQQ_FNS(sync); | |
357 | CFQ_CFQQ_FNS(coop); | |
358 | CFQ_CFQQ_FNS(split_coop); | |
359 | CFQ_CFQQ_FNS(deep); | |
360 | CFQ_CFQQ_FNS(wait_busy); | |
361 | #undef CFQ_CFQQ_FNS | |
362 | ||
363 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
364 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ | |
365 | blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ | |
366 | cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ | |
367 | blkg_path(&(cfqq)->cfqg->blkg), ##args); | |
368 | ||
369 | #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ | |
370 | blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ | |
371 | blkg_path(&(cfqg)->blkg), ##args); \ | |
372 | ||
373 | #else | |
374 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ | |
375 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) | |
376 | #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0); | |
377 | #endif | |
378 | #define cfq_log(cfqd, fmt, args...) \ | |
379 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) | |
380 | ||
381 | /* Traverses through cfq group service trees */ | |
382 | #define for_each_cfqg_st(cfqg, i, j, st) \ | |
383 | for (i = 0; i <= IDLE_WORKLOAD; i++) \ | |
384 | for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ | |
385 | : &cfqg->service_tree_idle; \ | |
386 | (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ | |
387 | (i == IDLE_WORKLOAD && j == 0); \ | |
388 | j++, st = i < IDLE_WORKLOAD ? \ | |
389 | &cfqg->service_trees[i][j]: NULL) \ | |
390 | ||
391 | ||
392 | static inline bool iops_mode(struct cfq_data *cfqd) | |
393 | { | |
394 | /* | |
395 | * If we are not idling on queues and it is a NCQ drive, parallel | |
396 | * execution of requests is on and measuring time is not possible | |
397 | * in most of the cases until and unless we drive shallower queue | |
398 | * depths and that becomes a performance bottleneck. In such cases | |
399 | * switch to start providing fairness in terms of number of IOs. | |
400 | */ | |
401 | if (!cfqd->cfq_slice_idle && cfqd->hw_tag) | |
402 | return true; | |
403 | else | |
404 | return false; | |
405 | } | |
406 | ||
407 | static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) | |
408 | { | |
409 | if (cfq_class_idle(cfqq)) | |
410 | return IDLE_WORKLOAD; | |
411 | if (cfq_class_rt(cfqq)) | |
412 | return RT_WORKLOAD; | |
413 | return BE_WORKLOAD; | |
414 | } | |
415 | ||
416 | ||
417 | static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) | |
418 | { | |
419 | if (!cfq_cfqq_sync(cfqq)) | |
420 | return ASYNC_WORKLOAD; | |
421 | if (!cfq_cfqq_idle_window(cfqq)) | |
422 | return SYNC_NOIDLE_WORKLOAD; | |
423 | return SYNC_WORKLOAD; | |
424 | } | |
425 | ||
426 | static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, | |
427 | struct cfq_data *cfqd, | |
428 | struct cfq_group *cfqg) | |
429 | { | |
430 | if (wl == IDLE_WORKLOAD) | |
431 | return cfqg->service_tree_idle.count; | |
432 | ||
433 | return cfqg->service_trees[wl][ASYNC_WORKLOAD].count | |
434 | + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count | |
435 | + cfqg->service_trees[wl][SYNC_WORKLOAD].count; | |
436 | } | |
437 | ||
438 | static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, | |
439 | struct cfq_group *cfqg) | |
440 | { | |
441 | return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count | |
442 | + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; | |
443 | } | |
444 | ||
445 | static void cfq_dispatch_insert(struct request_queue *, struct request *); | |
446 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, | |
447 | struct io_context *, gfp_t); | |
448 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, | |
449 | struct io_context *); | |
450 | ||
451 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, | |
452 | bool is_sync) | |
453 | { | |
454 | return cic->cfqq[is_sync]; | |
455 | } | |
456 | ||
457 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
458 | struct cfq_queue *cfqq, bool is_sync) | |
459 | { | |
460 | cic->cfqq[is_sync] = cfqq; | |
461 | } | |
462 | ||
463 | #define CIC_DEAD_KEY 1ul | |
464 | #define CIC_DEAD_INDEX_SHIFT 1 | |
465 | ||
466 | static inline void *cfqd_dead_key(struct cfq_data *cfqd) | |
467 | { | |
468 | return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY); | |
469 | } | |
470 | ||
471 | static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic) | |
472 | { | |
473 | struct cfq_data *cfqd = cic->key; | |
474 | ||
475 | if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY)) | |
476 | return NULL; | |
477 | ||
478 | return cfqd; | |
479 | } | |
480 | ||
481 | /* | |
482 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
483 | * set (in which case it could also be direct WRITE). | |
484 | */ | |
485 | static inline bool cfq_bio_sync(struct bio *bio) | |
486 | { | |
487 | return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); | |
488 | } | |
489 | ||
490 | /* | |
491 | * scheduler run of queue, if there are requests pending and no one in the | |
492 | * driver that will restart queueing | |
493 | */ | |
494 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) | |
495 | { | |
496 | if (cfqd->busy_queues) { | |
497 | cfq_log(cfqd, "schedule dispatch"); | |
498 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); | |
499 | } | |
500 | } | |
501 | ||
502 | static int cfq_queue_empty(struct request_queue *q) | |
503 | { | |
504 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
505 | ||
506 | return !cfqd->rq_queued; | |
507 | } | |
508 | ||
509 | /* | |
510 | * Scale schedule slice based on io priority. Use the sync time slice only | |
511 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
512 | * io only, should not get full sync slice length. | |
513 | */ | |
514 | static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, | |
515 | unsigned short prio) | |
516 | { | |
517 | const int base_slice = cfqd->cfq_slice[sync]; | |
518 | ||
519 | WARN_ON(prio >= IOPRIO_BE_NR); | |
520 | ||
521 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
522 | } | |
523 | ||
524 | static inline int | |
525 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
526 | { | |
527 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
528 | } | |
529 | ||
530 | static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) | |
531 | { | |
532 | u64 d = delta << CFQ_SERVICE_SHIFT; | |
533 | ||
534 | d = d * BLKIO_WEIGHT_DEFAULT; | |
535 | do_div(d, cfqg->weight); | |
536 | return d; | |
537 | } | |
538 | ||
539 | static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) | |
540 | { | |
541 | s64 delta = (s64)(vdisktime - min_vdisktime); | |
542 | if (delta > 0) | |
543 | min_vdisktime = vdisktime; | |
544 | ||
545 | return min_vdisktime; | |
546 | } | |
547 | ||
548 | static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) | |
549 | { | |
550 | s64 delta = (s64)(vdisktime - min_vdisktime); | |
551 | if (delta < 0) | |
552 | min_vdisktime = vdisktime; | |
553 | ||
554 | return min_vdisktime; | |
555 | } | |
556 | ||
557 | static void update_min_vdisktime(struct cfq_rb_root *st) | |
558 | { | |
559 | u64 vdisktime = st->min_vdisktime; | |
560 | struct cfq_group *cfqg; | |
561 | ||
562 | if (st->left) { | |
563 | cfqg = rb_entry_cfqg(st->left); | |
564 | vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime); | |
565 | } | |
566 | ||
567 | st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime); | |
568 | } | |
569 | ||
570 | /* | |
571 | * get averaged number of queues of RT/BE priority. | |
572 | * average is updated, with a formula that gives more weight to higher numbers, | |
573 | * to quickly follows sudden increases and decrease slowly | |
574 | */ | |
575 | ||
576 | static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, | |
577 | struct cfq_group *cfqg, bool rt) | |
578 | { | |
579 | unsigned min_q, max_q; | |
580 | unsigned mult = cfq_hist_divisor - 1; | |
581 | unsigned round = cfq_hist_divisor / 2; | |
582 | unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); | |
583 | ||
584 | min_q = min(cfqg->busy_queues_avg[rt], busy); | |
585 | max_q = max(cfqg->busy_queues_avg[rt], busy); | |
586 | cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / | |
587 | cfq_hist_divisor; | |
588 | return cfqg->busy_queues_avg[rt]; | |
589 | } | |
590 | ||
591 | static inline unsigned | |
592 | cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) | |
593 | { | |
594 | struct cfq_rb_root *st = &cfqd->grp_service_tree; | |
595 | ||
596 | return cfq_target_latency * cfqg->weight / st->total_weight; | |
597 | } | |
598 | ||
599 | static inline unsigned | |
600 | cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
601 | { | |
602 | unsigned slice = cfq_prio_to_slice(cfqd, cfqq); | |
603 | if (cfqd->cfq_latency) { | |
604 | /* | |
605 | * interested queues (we consider only the ones with the same | |
606 | * priority class in the cfq group) | |
607 | */ | |
608 | unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, | |
609 | cfq_class_rt(cfqq)); | |
610 | unsigned sync_slice = cfqd->cfq_slice[1]; | |
611 | unsigned expect_latency = sync_slice * iq; | |
612 | unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); | |
613 | ||
614 | if (expect_latency > group_slice) { | |
615 | unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; | |
616 | /* scale low_slice according to IO priority | |
617 | * and sync vs async */ | |
618 | unsigned low_slice = | |
619 | min(slice, base_low_slice * slice / sync_slice); | |
620 | /* the adapted slice value is scaled to fit all iqs | |
621 | * into the target latency */ | |
622 | slice = max(slice * group_slice / expect_latency, | |
623 | low_slice); | |
624 | } | |
625 | } | |
626 | return slice; | |
627 | } | |
628 | ||
629 | static inline void | |
630 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
631 | { | |
632 | unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); | |
633 | ||
634 | cfqq->slice_start = jiffies; | |
635 | cfqq->slice_end = jiffies + slice; | |
636 | cfqq->allocated_slice = slice; | |
637 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); | |
638 | } | |
639 | ||
640 | /* | |
641 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
642 | * isn't valid until the first request from the dispatch is activated | |
643 | * and the slice time set. | |
644 | */ | |
645 | static inline bool cfq_slice_used(struct cfq_queue *cfqq) | |
646 | { | |
647 | if (cfq_cfqq_slice_new(cfqq)) | |
648 | return false; | |
649 | if (time_before(jiffies, cfqq->slice_end)) | |
650 | return false; | |
651 | ||
652 | return true; | |
653 | } | |
654 | ||
655 | /* | |
656 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. | |
657 | * We choose the request that is closest to the head right now. Distance | |
658 | * behind the head is penalized and only allowed to a certain extent. | |
659 | */ | |
660 | static struct request * | |
661 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) | |
662 | { | |
663 | sector_t s1, s2, d1 = 0, d2 = 0; | |
664 | unsigned long back_max; | |
665 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ | |
666 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
667 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
668 | ||
669 | if (rq1 == NULL || rq1 == rq2) | |
670 | return rq2; | |
671 | if (rq2 == NULL) | |
672 | return rq1; | |
673 | ||
674 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) | |
675 | return rq1; | |
676 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
677 | return rq2; | |
678 | if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META)) | |
679 | return rq1; | |
680 | else if ((rq2->cmd_flags & REQ_META) && | |
681 | !(rq1->cmd_flags & REQ_META)) | |
682 | return rq2; | |
683 | ||
684 | s1 = blk_rq_pos(rq1); | |
685 | s2 = blk_rq_pos(rq2); | |
686 | ||
687 | /* | |
688 | * by definition, 1KiB is 2 sectors | |
689 | */ | |
690 | back_max = cfqd->cfq_back_max * 2; | |
691 | ||
692 | /* | |
693 | * Strict one way elevator _except_ in the case where we allow | |
694 | * short backward seeks which are biased as twice the cost of a | |
695 | * similar forward seek. | |
696 | */ | |
697 | if (s1 >= last) | |
698 | d1 = s1 - last; | |
699 | else if (s1 + back_max >= last) | |
700 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
701 | else | |
702 | wrap |= CFQ_RQ1_WRAP; | |
703 | ||
704 | if (s2 >= last) | |
705 | d2 = s2 - last; | |
706 | else if (s2 + back_max >= last) | |
707 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
708 | else | |
709 | wrap |= CFQ_RQ2_WRAP; | |
710 | ||
711 | /* Found required data */ | |
712 | ||
713 | /* | |
714 | * By doing switch() on the bit mask "wrap" we avoid having to | |
715 | * check two variables for all permutations: --> faster! | |
716 | */ | |
717 | switch (wrap) { | |
718 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ | |
719 | if (d1 < d2) | |
720 | return rq1; | |
721 | else if (d2 < d1) | |
722 | return rq2; | |
723 | else { | |
724 | if (s1 >= s2) | |
725 | return rq1; | |
726 | else | |
727 | return rq2; | |
728 | } | |
729 | ||
730 | case CFQ_RQ2_WRAP: | |
731 | return rq1; | |
732 | case CFQ_RQ1_WRAP: | |
733 | return rq2; | |
734 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
735 | default: | |
736 | /* | |
737 | * Since both rqs are wrapped, | |
738 | * start with the one that's further behind head | |
739 | * (--> only *one* back seek required), | |
740 | * since back seek takes more time than forward. | |
741 | */ | |
742 | if (s1 <= s2) | |
743 | return rq1; | |
744 | else | |
745 | return rq2; | |
746 | } | |
747 | } | |
748 | ||
749 | /* | |
750 | * The below is leftmost cache rbtree addon | |
751 | */ | |
752 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) | |
753 | { | |
754 | /* Service tree is empty */ | |
755 | if (!root->count) | |
756 | return NULL; | |
757 | ||
758 | if (!root->left) | |
759 | root->left = rb_first(&root->rb); | |
760 | ||
761 | if (root->left) | |
762 | return rb_entry(root->left, struct cfq_queue, rb_node); | |
763 | ||
764 | return NULL; | |
765 | } | |
766 | ||
767 | static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) | |
768 | { | |
769 | if (!root->left) | |
770 | root->left = rb_first(&root->rb); | |
771 | ||
772 | if (root->left) | |
773 | return rb_entry_cfqg(root->left); | |
774 | ||
775 | return NULL; | |
776 | } | |
777 | ||
778 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) | |
779 | { | |
780 | rb_erase(n, root); | |
781 | RB_CLEAR_NODE(n); | |
782 | } | |
783 | ||
784 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) | |
785 | { | |
786 | if (root->left == n) | |
787 | root->left = NULL; | |
788 | rb_erase_init(n, &root->rb); | |
789 | --root->count; | |
790 | } | |
791 | ||
792 | /* | |
793 | * would be nice to take fifo expire time into account as well | |
794 | */ | |
795 | static struct request * | |
796 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
797 | struct request *last) | |
798 | { | |
799 | struct rb_node *rbnext = rb_next(&last->rb_node); | |
800 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
801 | struct request *next = NULL, *prev = NULL; | |
802 | ||
803 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); | |
804 | ||
805 | if (rbprev) | |
806 | prev = rb_entry_rq(rbprev); | |
807 | ||
808 | if (rbnext) | |
809 | next = rb_entry_rq(rbnext); | |
810 | else { | |
811 | rbnext = rb_first(&cfqq->sort_list); | |
812 | if (rbnext && rbnext != &last->rb_node) | |
813 | next = rb_entry_rq(rbnext); | |
814 | } | |
815 | ||
816 | return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); | |
817 | } | |
818 | ||
819 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, | |
820 | struct cfq_queue *cfqq) | |
821 | { | |
822 | /* | |
823 | * just an approximation, should be ok. | |
824 | */ | |
825 | return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - | |
826 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); | |
827 | } | |
828 | ||
829 | static inline s64 | |
830 | cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) | |
831 | { | |
832 | return cfqg->vdisktime - st->min_vdisktime; | |
833 | } | |
834 | ||
835 | static void | |
836 | __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) | |
837 | { | |
838 | struct rb_node **node = &st->rb.rb_node; | |
839 | struct rb_node *parent = NULL; | |
840 | struct cfq_group *__cfqg; | |
841 | s64 key = cfqg_key(st, cfqg); | |
842 | int left = 1; | |
843 | ||
844 | while (*node != NULL) { | |
845 | parent = *node; | |
846 | __cfqg = rb_entry_cfqg(parent); | |
847 | ||
848 | if (key < cfqg_key(st, __cfqg)) | |
849 | node = &parent->rb_left; | |
850 | else { | |
851 | node = &parent->rb_right; | |
852 | left = 0; | |
853 | } | |
854 | } | |
855 | ||
856 | if (left) | |
857 | st->left = &cfqg->rb_node; | |
858 | ||
859 | rb_link_node(&cfqg->rb_node, parent, node); | |
860 | rb_insert_color(&cfqg->rb_node, &st->rb); | |
861 | } | |
862 | ||
863 | static void | |
864 | cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg) | |
865 | { | |
866 | struct cfq_rb_root *st = &cfqd->grp_service_tree; | |
867 | struct cfq_group *__cfqg; | |
868 | struct rb_node *n; | |
869 | ||
870 | cfqg->nr_cfqq++; | |
871 | if (!RB_EMPTY_NODE(&cfqg->rb_node)) | |
872 | return; | |
873 | ||
874 | /* | |
875 | * Currently put the group at the end. Later implement something | |
876 | * so that groups get lesser vtime based on their weights, so that | |
877 | * if group does not loose all if it was not continously backlogged. | |
878 | */ | |
879 | n = rb_last(&st->rb); | |
880 | if (n) { | |
881 | __cfqg = rb_entry_cfqg(n); | |
882 | cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; | |
883 | } else | |
884 | cfqg->vdisktime = st->min_vdisktime; | |
885 | ||
886 | __cfq_group_service_tree_add(st, cfqg); | |
887 | st->total_weight += cfqg->weight; | |
888 | } | |
889 | ||
890 | static void | |
891 | cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg) | |
892 | { | |
893 | struct cfq_rb_root *st = &cfqd->grp_service_tree; | |
894 | ||
895 | BUG_ON(cfqg->nr_cfqq < 1); | |
896 | cfqg->nr_cfqq--; | |
897 | ||
898 | /* If there are other cfq queues under this group, don't delete it */ | |
899 | if (cfqg->nr_cfqq) | |
900 | return; | |
901 | ||
902 | cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); | |
903 | st->total_weight -= cfqg->weight; | |
904 | if (!RB_EMPTY_NODE(&cfqg->rb_node)) | |
905 | cfq_rb_erase(&cfqg->rb_node, st); | |
906 | cfqg->saved_workload_slice = 0; | |
907 | cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); | |
908 | } | |
909 | ||
910 | static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq) | |
911 | { | |
912 | unsigned int slice_used; | |
913 | ||
914 | /* | |
915 | * Queue got expired before even a single request completed or | |
916 | * got expired immediately after first request completion. | |
917 | */ | |
918 | if (!cfqq->slice_start || cfqq->slice_start == jiffies) { | |
919 | /* | |
920 | * Also charge the seek time incurred to the group, otherwise | |
921 | * if there are mutiple queues in the group, each can dispatch | |
922 | * a single request on seeky media and cause lots of seek time | |
923 | * and group will never know it. | |
924 | */ | |
925 | slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), | |
926 | 1); | |
927 | } else { | |
928 | slice_used = jiffies - cfqq->slice_start; | |
929 | if (slice_used > cfqq->allocated_slice) | |
930 | slice_used = cfqq->allocated_slice; | |
931 | } | |
932 | ||
933 | return slice_used; | |
934 | } | |
935 | ||
936 | static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, | |
937 | struct cfq_queue *cfqq) | |
938 | { | |
939 | struct cfq_rb_root *st = &cfqd->grp_service_tree; | |
940 | unsigned int used_sl, charge; | |
941 | int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) | |
942 | - cfqg->service_tree_idle.count; | |
943 | ||
944 | BUG_ON(nr_sync < 0); | |
945 | used_sl = charge = cfq_cfqq_slice_usage(cfqq); | |
946 | ||
947 | if (iops_mode(cfqd)) | |
948 | charge = cfqq->slice_dispatch; | |
949 | else if (!cfq_cfqq_sync(cfqq) && !nr_sync) | |
950 | charge = cfqq->allocated_slice; | |
951 | ||
952 | /* Can't update vdisktime while group is on service tree */ | |
953 | cfq_rb_erase(&cfqg->rb_node, st); | |
954 | cfqg->vdisktime += cfq_scale_slice(charge, cfqg); | |
955 | __cfq_group_service_tree_add(st, cfqg); | |
956 | ||
957 | /* This group is being expired. Save the context */ | |
958 | if (time_after(cfqd->workload_expires, jiffies)) { | |
959 | cfqg->saved_workload_slice = cfqd->workload_expires | |
960 | - jiffies; | |
961 | cfqg->saved_workload = cfqd->serving_type; | |
962 | cfqg->saved_serving_prio = cfqd->serving_prio; | |
963 | } else | |
964 | cfqg->saved_workload_slice = 0; | |
965 | ||
966 | cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, | |
967 | st->min_vdisktime); | |
968 | cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u" | |
969 | " sect=%u", used_sl, cfqq->slice_dispatch, charge, | |
970 | iops_mode(cfqd), cfqq->nr_sectors); | |
971 | cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl); | |
972 | cfq_blkiocg_set_start_empty_time(&cfqg->blkg); | |
973 | } | |
974 | ||
975 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
976 | static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) | |
977 | { | |
978 | if (blkg) | |
979 | return container_of(blkg, struct cfq_group, blkg); | |
980 | return NULL; | |
981 | } | |
982 | ||
983 | void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, | |
984 | unsigned int weight) | |
985 | { | |
986 | cfqg_of_blkg(blkg)->weight = weight; | |
987 | } | |
988 | ||
989 | static struct cfq_group * | |
990 | cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create) | |
991 | { | |
992 | struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); | |
993 | struct cfq_group *cfqg = NULL; | |
994 | void *key = cfqd; | |
995 | int i, j; | |
996 | struct cfq_rb_root *st; | |
997 | struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; | |
998 | unsigned int major, minor; | |
999 | ||
1000 | cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); | |
1001 | if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { | |
1002 | sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); | |
1003 | cfqg->blkg.dev = MKDEV(major, minor); | |
1004 | goto done; | |
1005 | } | |
1006 | if (cfqg || !create) | |
1007 | goto done; | |
1008 | ||
1009 | cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); | |
1010 | if (!cfqg) | |
1011 | goto done; | |
1012 | ||
1013 | for_each_cfqg_st(cfqg, i, j, st) | |
1014 | *st = CFQ_RB_ROOT; | |
1015 | RB_CLEAR_NODE(&cfqg->rb_node); | |
1016 | ||
1017 | /* | |
1018 | * Take the initial reference that will be released on destroy | |
1019 | * This can be thought of a joint reference by cgroup and | |
1020 | * elevator which will be dropped by either elevator exit | |
1021 | * or cgroup deletion path depending on who is exiting first. | |
1022 | */ | |
1023 | cfqg->ref = 1; | |
1024 | ||
1025 | /* | |
1026 | * Add group onto cgroup list. It might happen that bdi->dev is | |
1027 | * not initialized yet. Initialize this new group without major | |
1028 | * and minor info and this info will be filled in once a new thread | |
1029 | * comes for IO. See code above. | |
1030 | */ | |
1031 | if (bdi->dev) { | |
1032 | sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); | |
1033 | cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd, | |
1034 | MKDEV(major, minor)); | |
1035 | } else | |
1036 | cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd, | |
1037 | 0); | |
1038 | ||
1039 | cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); | |
1040 | ||
1041 | /* Add group on cfqd list */ | |
1042 | hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); | |
1043 | ||
1044 | done: | |
1045 | return cfqg; | |
1046 | } | |
1047 | ||
1048 | /* | |
1049 | * Search for the cfq group current task belongs to. If create = 1, then also | |
1050 | * create the cfq group if it does not exist. request_queue lock must be held. | |
1051 | */ | |
1052 | static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) | |
1053 | { | |
1054 | struct cgroup *cgroup; | |
1055 | struct cfq_group *cfqg = NULL; | |
1056 | ||
1057 | rcu_read_lock(); | |
1058 | cgroup = task_cgroup(current, blkio_subsys_id); | |
1059 | cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create); | |
1060 | if (!cfqg && create) | |
1061 | cfqg = &cfqd->root_group; | |
1062 | rcu_read_unlock(); | |
1063 | return cfqg; | |
1064 | } | |
1065 | ||
1066 | static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) | |
1067 | { | |
1068 | cfqg->ref++; | |
1069 | return cfqg; | |
1070 | } | |
1071 | ||
1072 | static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) | |
1073 | { | |
1074 | /* Currently, all async queues are mapped to root group */ | |
1075 | if (!cfq_cfqq_sync(cfqq)) | |
1076 | cfqg = &cfqq->cfqd->root_group; | |
1077 | ||
1078 | cfqq->cfqg = cfqg; | |
1079 | /* cfqq reference on cfqg */ | |
1080 | cfqq->cfqg->ref++; | |
1081 | } | |
1082 | ||
1083 | static void cfq_put_cfqg(struct cfq_group *cfqg) | |
1084 | { | |
1085 | struct cfq_rb_root *st; | |
1086 | int i, j; | |
1087 | ||
1088 | BUG_ON(cfqg->ref <= 0); | |
1089 | cfqg->ref--; | |
1090 | if (cfqg->ref) | |
1091 | return; | |
1092 | for_each_cfqg_st(cfqg, i, j, st) | |
1093 | BUG_ON(!RB_EMPTY_ROOT(&st->rb)); | |
1094 | kfree(cfqg); | |
1095 | } | |
1096 | ||
1097 | static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) | |
1098 | { | |
1099 | /* Something wrong if we are trying to remove same group twice */ | |
1100 | BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); | |
1101 | ||
1102 | hlist_del_init(&cfqg->cfqd_node); | |
1103 | ||
1104 | /* | |
1105 | * Put the reference taken at the time of creation so that when all | |
1106 | * queues are gone, group can be destroyed. | |
1107 | */ | |
1108 | cfq_put_cfqg(cfqg); | |
1109 | } | |
1110 | ||
1111 | static void cfq_release_cfq_groups(struct cfq_data *cfqd) | |
1112 | { | |
1113 | struct hlist_node *pos, *n; | |
1114 | struct cfq_group *cfqg; | |
1115 | ||
1116 | hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { | |
1117 | /* | |
1118 | * If cgroup removal path got to blk_group first and removed | |
1119 | * it from cgroup list, then it will take care of destroying | |
1120 | * cfqg also. | |
1121 | */ | |
1122 | if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg)) | |
1123 | cfq_destroy_cfqg(cfqd, cfqg); | |
1124 | } | |
1125 | } | |
1126 | ||
1127 | /* | |
1128 | * Blk cgroup controller notification saying that blkio_group object is being | |
1129 | * delinked as associated cgroup object is going away. That also means that | |
1130 | * no new IO will come in this group. So get rid of this group as soon as | |
1131 | * any pending IO in the group is finished. | |
1132 | * | |
1133 | * This function is called under rcu_read_lock(). key is the rcu protected | |
1134 | * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu | |
1135 | * read lock. | |
1136 | * | |
1137 | * "key" was fetched from blkio_group under blkio_cgroup->lock. That means | |
1138 | * it should not be NULL as even if elevator was exiting, cgroup deltion | |
1139 | * path got to it first. | |
1140 | */ | |
1141 | void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) | |
1142 | { | |
1143 | unsigned long flags; | |
1144 | struct cfq_data *cfqd = key; | |
1145 | ||
1146 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
1147 | cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); | |
1148 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
1149 | } | |
1150 | ||
1151 | #else /* GROUP_IOSCHED */ | |
1152 | static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) | |
1153 | { | |
1154 | return &cfqd->root_group; | |
1155 | } | |
1156 | ||
1157 | static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) | |
1158 | { | |
1159 | return cfqg; | |
1160 | } | |
1161 | ||
1162 | static inline void | |
1163 | cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { | |
1164 | cfqq->cfqg = cfqg; | |
1165 | } | |
1166 | ||
1167 | static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} | |
1168 | static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} | |
1169 | ||
1170 | #endif /* GROUP_IOSCHED */ | |
1171 | ||
1172 | /* | |
1173 | * The cfqd->service_trees holds all pending cfq_queue's that have | |
1174 | * requests waiting to be processed. It is sorted in the order that | |
1175 | * we will service the queues. | |
1176 | */ | |
1177 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1178 | bool add_front) | |
1179 | { | |
1180 | struct rb_node **p, *parent; | |
1181 | struct cfq_queue *__cfqq; | |
1182 | unsigned long rb_key; | |
1183 | struct cfq_rb_root *service_tree; | |
1184 | int left; | |
1185 | int new_cfqq = 1; | |
1186 | int group_changed = 0; | |
1187 | ||
1188 | service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), | |
1189 | cfqq_type(cfqq)); | |
1190 | if (cfq_class_idle(cfqq)) { | |
1191 | rb_key = CFQ_IDLE_DELAY; | |
1192 | parent = rb_last(&service_tree->rb); | |
1193 | if (parent && parent != &cfqq->rb_node) { | |
1194 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
1195 | rb_key += __cfqq->rb_key; | |
1196 | } else | |
1197 | rb_key += jiffies; | |
1198 | } else if (!add_front) { | |
1199 | /* | |
1200 | * Get our rb key offset. Subtract any residual slice | |
1201 | * value carried from last service. A negative resid | |
1202 | * count indicates slice overrun, and this should position | |
1203 | * the next service time further away in the tree. | |
1204 | */ | |
1205 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; | |
1206 | rb_key -= cfqq->slice_resid; | |
1207 | cfqq->slice_resid = 0; | |
1208 | } else { | |
1209 | rb_key = -HZ; | |
1210 | __cfqq = cfq_rb_first(service_tree); | |
1211 | rb_key += __cfqq ? __cfqq->rb_key : jiffies; | |
1212 | } | |
1213 | ||
1214 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { | |
1215 | new_cfqq = 0; | |
1216 | /* | |
1217 | * same position, nothing more to do | |
1218 | */ | |
1219 | if (rb_key == cfqq->rb_key && | |
1220 | cfqq->service_tree == service_tree) | |
1221 | return; | |
1222 | ||
1223 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); | |
1224 | cfqq->service_tree = NULL; | |
1225 | } | |
1226 | ||
1227 | left = 1; | |
1228 | parent = NULL; | |
1229 | cfqq->service_tree = service_tree; | |
1230 | p = &service_tree->rb.rb_node; | |
1231 | while (*p) { | |
1232 | struct rb_node **n; | |
1233 | ||
1234 | parent = *p; | |
1235 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
1236 | ||
1237 | /* | |
1238 | * sort by key, that represents service time. | |
1239 | */ | |
1240 | if (time_before(rb_key, __cfqq->rb_key)) | |
1241 | n = &(*p)->rb_left; | |
1242 | else { | |
1243 | n = &(*p)->rb_right; | |
1244 | left = 0; | |
1245 | } | |
1246 | ||
1247 | p = n; | |
1248 | } | |
1249 | ||
1250 | if (left) | |
1251 | service_tree->left = &cfqq->rb_node; | |
1252 | ||
1253 | cfqq->rb_key = rb_key; | |
1254 | rb_link_node(&cfqq->rb_node, parent, p); | |
1255 | rb_insert_color(&cfqq->rb_node, &service_tree->rb); | |
1256 | service_tree->count++; | |
1257 | if ((add_front || !new_cfqq) && !group_changed) | |
1258 | return; | |
1259 | cfq_group_service_tree_add(cfqd, cfqq->cfqg); | |
1260 | } | |
1261 | ||
1262 | static struct cfq_queue * | |
1263 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, | |
1264 | sector_t sector, struct rb_node **ret_parent, | |
1265 | struct rb_node ***rb_link) | |
1266 | { | |
1267 | struct rb_node **p, *parent; | |
1268 | struct cfq_queue *cfqq = NULL; | |
1269 | ||
1270 | parent = NULL; | |
1271 | p = &root->rb_node; | |
1272 | while (*p) { | |
1273 | struct rb_node **n; | |
1274 | ||
1275 | parent = *p; | |
1276 | cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
1277 | ||
1278 | /* | |
1279 | * Sort strictly based on sector. Smallest to the left, | |
1280 | * largest to the right. | |
1281 | */ | |
1282 | if (sector > blk_rq_pos(cfqq->next_rq)) | |
1283 | n = &(*p)->rb_right; | |
1284 | else if (sector < blk_rq_pos(cfqq->next_rq)) | |
1285 | n = &(*p)->rb_left; | |
1286 | else | |
1287 | break; | |
1288 | p = n; | |
1289 | cfqq = NULL; | |
1290 | } | |
1291 | ||
1292 | *ret_parent = parent; | |
1293 | if (rb_link) | |
1294 | *rb_link = p; | |
1295 | return cfqq; | |
1296 | } | |
1297 | ||
1298 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1299 | { | |
1300 | struct rb_node **p, *parent; | |
1301 | struct cfq_queue *__cfqq; | |
1302 | ||
1303 | if (cfqq->p_root) { | |
1304 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
1305 | cfqq->p_root = NULL; | |
1306 | } | |
1307 | ||
1308 | if (cfq_class_idle(cfqq)) | |
1309 | return; | |
1310 | if (!cfqq->next_rq) | |
1311 | return; | |
1312 | ||
1313 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; | |
1314 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, | |
1315 | blk_rq_pos(cfqq->next_rq), &parent, &p); | |
1316 | if (!__cfqq) { | |
1317 | rb_link_node(&cfqq->p_node, parent, p); | |
1318 | rb_insert_color(&cfqq->p_node, cfqq->p_root); | |
1319 | } else | |
1320 | cfqq->p_root = NULL; | |
1321 | } | |
1322 | ||
1323 | /* | |
1324 | * Update cfqq's position in the service tree. | |
1325 | */ | |
1326 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1327 | { | |
1328 | /* | |
1329 | * Resorting requires the cfqq to be on the RR list already. | |
1330 | */ | |
1331 | if (cfq_cfqq_on_rr(cfqq)) { | |
1332 | cfq_service_tree_add(cfqd, cfqq, 0); | |
1333 | cfq_prio_tree_add(cfqd, cfqq); | |
1334 | } | |
1335 | } | |
1336 | ||
1337 | /* | |
1338 | * add to busy list of queues for service, trying to be fair in ordering | |
1339 | * the pending list according to last request service | |
1340 | */ | |
1341 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1342 | { | |
1343 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); | |
1344 | BUG_ON(cfq_cfqq_on_rr(cfqq)); | |
1345 | cfq_mark_cfqq_on_rr(cfqq); | |
1346 | cfqd->busy_queues++; | |
1347 | ||
1348 | cfq_resort_rr_list(cfqd, cfqq); | |
1349 | } | |
1350 | ||
1351 | /* | |
1352 | * Called when the cfqq no longer has requests pending, remove it from | |
1353 | * the service tree. | |
1354 | */ | |
1355 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1356 | { | |
1357 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); | |
1358 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
1359 | cfq_clear_cfqq_on_rr(cfqq); | |
1360 | ||
1361 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { | |
1362 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); | |
1363 | cfqq->service_tree = NULL; | |
1364 | } | |
1365 | if (cfqq->p_root) { | |
1366 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
1367 | cfqq->p_root = NULL; | |
1368 | } | |
1369 | ||
1370 | cfq_group_service_tree_del(cfqd, cfqq->cfqg); | |
1371 | BUG_ON(!cfqd->busy_queues); | |
1372 | cfqd->busy_queues--; | |
1373 | } | |
1374 | ||
1375 | /* | |
1376 | * rb tree support functions | |
1377 | */ | |
1378 | static void cfq_del_rq_rb(struct request *rq) | |
1379 | { | |
1380 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1381 | const int sync = rq_is_sync(rq); | |
1382 | ||
1383 | BUG_ON(!cfqq->queued[sync]); | |
1384 | cfqq->queued[sync]--; | |
1385 | ||
1386 | elv_rb_del(&cfqq->sort_list, rq); | |
1387 | ||
1388 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { | |
1389 | /* | |
1390 | * Queue will be deleted from service tree when we actually | |
1391 | * expire it later. Right now just remove it from prio tree | |
1392 | * as it is empty. | |
1393 | */ | |
1394 | if (cfqq->p_root) { | |
1395 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
1396 | cfqq->p_root = NULL; | |
1397 | } | |
1398 | } | |
1399 | } | |
1400 | ||
1401 | static void cfq_add_rq_rb(struct request *rq) | |
1402 | { | |
1403 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1404 | struct cfq_data *cfqd = cfqq->cfqd; | |
1405 | struct request *__alias, *prev; | |
1406 | ||
1407 | cfqq->queued[rq_is_sync(rq)]++; | |
1408 | ||
1409 | /* | |
1410 | * looks a little odd, but the first insert might return an alias. | |
1411 | * if that happens, put the alias on the dispatch list | |
1412 | */ | |
1413 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) | |
1414 | cfq_dispatch_insert(cfqd->queue, __alias); | |
1415 | ||
1416 | if (!cfq_cfqq_on_rr(cfqq)) | |
1417 | cfq_add_cfqq_rr(cfqd, cfqq); | |
1418 | ||
1419 | /* | |
1420 | * check if this request is a better next-serve candidate | |
1421 | */ | |
1422 | prev = cfqq->next_rq; | |
1423 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); | |
1424 | ||
1425 | /* | |
1426 | * adjust priority tree position, if ->next_rq changes | |
1427 | */ | |
1428 | if (prev != cfqq->next_rq) | |
1429 | cfq_prio_tree_add(cfqd, cfqq); | |
1430 | ||
1431 | BUG_ON(!cfqq->next_rq); | |
1432 | } | |
1433 | ||
1434 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) | |
1435 | { | |
1436 | elv_rb_del(&cfqq->sort_list, rq); | |
1437 | cfqq->queued[rq_is_sync(rq)]--; | |
1438 | cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, | |
1439 | rq_data_dir(rq), rq_is_sync(rq)); | |
1440 | cfq_add_rq_rb(rq); | |
1441 | cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, | |
1442 | &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), | |
1443 | rq_is_sync(rq)); | |
1444 | } | |
1445 | ||
1446 | static struct request * | |
1447 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1448 | { | |
1449 | struct task_struct *tsk = current; | |
1450 | struct cfq_io_context *cic; | |
1451 | struct cfq_queue *cfqq; | |
1452 | ||
1453 | cic = cfq_cic_lookup(cfqd, tsk->io_context); | |
1454 | if (!cic) | |
1455 | return NULL; | |
1456 | ||
1457 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
1458 | if (cfqq) { | |
1459 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
1460 | ||
1461 | return elv_rb_find(&cfqq->sort_list, sector); | |
1462 | } | |
1463 | ||
1464 | return NULL; | |
1465 | } | |
1466 | ||
1467 | static void cfq_activate_request(struct request_queue *q, struct request *rq) | |
1468 | { | |
1469 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1470 | ||
1471 | cfqd->rq_in_driver++; | |
1472 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", | |
1473 | cfqd->rq_in_driver); | |
1474 | ||
1475 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); | |
1476 | } | |
1477 | ||
1478 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) | |
1479 | { | |
1480 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1481 | ||
1482 | WARN_ON(!cfqd->rq_in_driver); | |
1483 | cfqd->rq_in_driver--; | |
1484 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", | |
1485 | cfqd->rq_in_driver); | |
1486 | } | |
1487 | ||
1488 | static void cfq_remove_request(struct request *rq) | |
1489 | { | |
1490 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1491 | ||
1492 | if (cfqq->next_rq == rq) | |
1493 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1494 | ||
1495 | list_del_init(&rq->queuelist); | |
1496 | cfq_del_rq_rb(rq); | |
1497 | ||
1498 | cfqq->cfqd->rq_queued--; | |
1499 | cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, | |
1500 | rq_data_dir(rq), rq_is_sync(rq)); | |
1501 | if (rq->cmd_flags & REQ_META) { | |
1502 | WARN_ON(!cfqq->meta_pending); | |
1503 | cfqq->meta_pending--; | |
1504 | } | |
1505 | } | |
1506 | ||
1507 | static int cfq_merge(struct request_queue *q, struct request **req, | |
1508 | struct bio *bio) | |
1509 | { | |
1510 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1511 | struct request *__rq; | |
1512 | ||
1513 | __rq = cfq_find_rq_fmerge(cfqd, bio); | |
1514 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
1515 | *req = __rq; | |
1516 | return ELEVATOR_FRONT_MERGE; | |
1517 | } | |
1518 | ||
1519 | return ELEVATOR_NO_MERGE; | |
1520 | } | |
1521 | ||
1522 | static void cfq_merged_request(struct request_queue *q, struct request *req, | |
1523 | int type) | |
1524 | { | |
1525 | if (type == ELEVATOR_FRONT_MERGE) { | |
1526 | struct cfq_queue *cfqq = RQ_CFQQ(req); | |
1527 | ||
1528 | cfq_reposition_rq_rb(cfqq, req); | |
1529 | } | |
1530 | } | |
1531 | ||
1532 | static void cfq_bio_merged(struct request_queue *q, struct request *req, | |
1533 | struct bio *bio) | |
1534 | { | |
1535 | cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, | |
1536 | bio_data_dir(bio), cfq_bio_sync(bio)); | |
1537 | } | |
1538 | ||
1539 | static void | |
1540 | cfq_merged_requests(struct request_queue *q, struct request *rq, | |
1541 | struct request *next) | |
1542 | { | |
1543 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1544 | /* | |
1545 | * reposition in fifo if next is older than rq | |
1546 | */ | |
1547 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
1548 | time_before(rq_fifo_time(next), rq_fifo_time(rq))) { | |
1549 | list_move(&rq->queuelist, &next->queuelist); | |
1550 | rq_set_fifo_time(rq, rq_fifo_time(next)); | |
1551 | } | |
1552 | ||
1553 | if (cfqq->next_rq == next) | |
1554 | cfqq->next_rq = rq; | |
1555 | cfq_remove_request(next); | |
1556 | cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, | |
1557 | rq_data_dir(next), rq_is_sync(next)); | |
1558 | } | |
1559 | ||
1560 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, | |
1561 | struct bio *bio) | |
1562 | { | |
1563 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1564 | struct cfq_io_context *cic; | |
1565 | struct cfq_queue *cfqq; | |
1566 | ||
1567 | /* | |
1568 | * Disallow merge of a sync bio into an async request. | |
1569 | */ | |
1570 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) | |
1571 | return false; | |
1572 | ||
1573 | /* | |
1574 | * Lookup the cfqq that this bio will be queued with. Allow | |
1575 | * merge only if rq is queued there. | |
1576 | */ | |
1577 | cic = cfq_cic_lookup(cfqd, current->io_context); | |
1578 | if (!cic) | |
1579 | return false; | |
1580 | ||
1581 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
1582 | return cfqq == RQ_CFQQ(rq); | |
1583 | } | |
1584 | ||
1585 | static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1586 | { | |
1587 | del_timer(&cfqd->idle_slice_timer); | |
1588 | cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); | |
1589 | } | |
1590 | ||
1591 | static void __cfq_set_active_queue(struct cfq_data *cfqd, | |
1592 | struct cfq_queue *cfqq) | |
1593 | { | |
1594 | if (cfqq) { | |
1595 | cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", | |
1596 | cfqd->serving_prio, cfqd->serving_type); | |
1597 | cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); | |
1598 | cfqq->slice_start = 0; | |
1599 | cfqq->dispatch_start = jiffies; | |
1600 | cfqq->allocated_slice = 0; | |
1601 | cfqq->slice_end = 0; | |
1602 | cfqq->slice_dispatch = 0; | |
1603 | cfqq->nr_sectors = 0; | |
1604 | ||
1605 | cfq_clear_cfqq_wait_request(cfqq); | |
1606 | cfq_clear_cfqq_must_dispatch(cfqq); | |
1607 | cfq_clear_cfqq_must_alloc_slice(cfqq); | |
1608 | cfq_clear_cfqq_fifo_expire(cfqq); | |
1609 | cfq_mark_cfqq_slice_new(cfqq); | |
1610 | ||
1611 | cfq_del_timer(cfqd, cfqq); | |
1612 | } | |
1613 | ||
1614 | cfqd->active_queue = cfqq; | |
1615 | } | |
1616 | ||
1617 | /* | |
1618 | * current cfqq expired its slice (or was too idle), select new one | |
1619 | */ | |
1620 | static void | |
1621 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1622 | bool timed_out) | |
1623 | { | |
1624 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); | |
1625 | ||
1626 | if (cfq_cfqq_wait_request(cfqq)) | |
1627 | cfq_del_timer(cfqd, cfqq); | |
1628 | ||
1629 | cfq_clear_cfqq_wait_request(cfqq); | |
1630 | cfq_clear_cfqq_wait_busy(cfqq); | |
1631 | ||
1632 | /* | |
1633 | * If this cfqq is shared between multiple processes, check to | |
1634 | * make sure that those processes are still issuing I/Os within | |
1635 | * the mean seek distance. If not, it may be time to break the | |
1636 | * queues apart again. | |
1637 | */ | |
1638 | if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) | |
1639 | cfq_mark_cfqq_split_coop(cfqq); | |
1640 | ||
1641 | /* | |
1642 | * store what was left of this slice, if the queue idled/timed out | |
1643 | */ | |
1644 | if (timed_out) { | |
1645 | if (cfq_cfqq_slice_new(cfqq)) | |
1646 | cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); | |
1647 | else | |
1648 | cfqq->slice_resid = cfqq->slice_end - jiffies; | |
1649 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); | |
1650 | } | |
1651 | ||
1652 | cfq_group_served(cfqd, cfqq->cfqg, cfqq); | |
1653 | ||
1654 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) | |
1655 | cfq_del_cfqq_rr(cfqd, cfqq); | |
1656 | ||
1657 | cfq_resort_rr_list(cfqd, cfqq); | |
1658 | ||
1659 | if (cfqq == cfqd->active_queue) | |
1660 | cfqd->active_queue = NULL; | |
1661 | ||
1662 | if (cfqd->active_cic) { | |
1663 | put_io_context(cfqd->active_cic->ioc); | |
1664 | cfqd->active_cic = NULL; | |
1665 | } | |
1666 | } | |
1667 | ||
1668 | static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) | |
1669 | { | |
1670 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1671 | ||
1672 | if (cfqq) | |
1673 | __cfq_slice_expired(cfqd, cfqq, timed_out); | |
1674 | } | |
1675 | ||
1676 | /* | |
1677 | * Get next queue for service. Unless we have a queue preemption, | |
1678 | * we'll simply select the first cfqq in the service tree. | |
1679 | */ | |
1680 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) | |
1681 | { | |
1682 | struct cfq_rb_root *service_tree = | |
1683 | service_tree_for(cfqd->serving_group, cfqd->serving_prio, | |
1684 | cfqd->serving_type); | |
1685 | ||
1686 | if (!cfqd->rq_queued) | |
1687 | return NULL; | |
1688 | ||
1689 | /* There is nothing to dispatch */ | |
1690 | if (!service_tree) | |
1691 | return NULL; | |
1692 | if (RB_EMPTY_ROOT(&service_tree->rb)) | |
1693 | return NULL; | |
1694 | return cfq_rb_first(service_tree); | |
1695 | } | |
1696 | ||
1697 | static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) | |
1698 | { | |
1699 | struct cfq_group *cfqg; | |
1700 | struct cfq_queue *cfqq; | |
1701 | int i, j; | |
1702 | struct cfq_rb_root *st; | |
1703 | ||
1704 | if (!cfqd->rq_queued) | |
1705 | return NULL; | |
1706 | ||
1707 | cfqg = cfq_get_next_cfqg(cfqd); | |
1708 | if (!cfqg) | |
1709 | return NULL; | |
1710 | ||
1711 | for_each_cfqg_st(cfqg, i, j, st) | |
1712 | if ((cfqq = cfq_rb_first(st)) != NULL) | |
1713 | return cfqq; | |
1714 | return NULL; | |
1715 | } | |
1716 | ||
1717 | /* | |
1718 | * Get and set a new active queue for service. | |
1719 | */ | |
1720 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, | |
1721 | struct cfq_queue *cfqq) | |
1722 | { | |
1723 | if (!cfqq) | |
1724 | cfqq = cfq_get_next_queue(cfqd); | |
1725 | ||
1726 | __cfq_set_active_queue(cfqd, cfqq); | |
1727 | return cfqq; | |
1728 | } | |
1729 | ||
1730 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, | |
1731 | struct request *rq) | |
1732 | { | |
1733 | if (blk_rq_pos(rq) >= cfqd->last_position) | |
1734 | return blk_rq_pos(rq) - cfqd->last_position; | |
1735 | else | |
1736 | return cfqd->last_position - blk_rq_pos(rq); | |
1737 | } | |
1738 | ||
1739 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
1740 | struct request *rq) | |
1741 | { | |
1742 | return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; | |
1743 | } | |
1744 | ||
1745 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, | |
1746 | struct cfq_queue *cur_cfqq) | |
1747 | { | |
1748 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; | |
1749 | struct rb_node *parent, *node; | |
1750 | struct cfq_queue *__cfqq; | |
1751 | sector_t sector = cfqd->last_position; | |
1752 | ||
1753 | if (RB_EMPTY_ROOT(root)) | |
1754 | return NULL; | |
1755 | ||
1756 | /* | |
1757 | * First, if we find a request starting at the end of the last | |
1758 | * request, choose it. | |
1759 | */ | |
1760 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); | |
1761 | if (__cfqq) | |
1762 | return __cfqq; | |
1763 | ||
1764 | /* | |
1765 | * If the exact sector wasn't found, the parent of the NULL leaf | |
1766 | * will contain the closest sector. | |
1767 | */ | |
1768 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
1769 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) | |
1770 | return __cfqq; | |
1771 | ||
1772 | if (blk_rq_pos(__cfqq->next_rq) < sector) | |
1773 | node = rb_next(&__cfqq->p_node); | |
1774 | else | |
1775 | node = rb_prev(&__cfqq->p_node); | |
1776 | if (!node) | |
1777 | return NULL; | |
1778 | ||
1779 | __cfqq = rb_entry(node, struct cfq_queue, p_node); | |
1780 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) | |
1781 | return __cfqq; | |
1782 | ||
1783 | return NULL; | |
1784 | } | |
1785 | ||
1786 | /* | |
1787 | * cfqd - obvious | |
1788 | * cur_cfqq - passed in so that we don't decide that the current queue is | |
1789 | * closely cooperating with itself. | |
1790 | * | |
1791 | * So, basically we're assuming that that cur_cfqq has dispatched at least | |
1792 | * one request, and that cfqd->last_position reflects a position on the disk | |
1793 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid | |
1794 | * assumption. | |
1795 | */ | |
1796 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, | |
1797 | struct cfq_queue *cur_cfqq) | |
1798 | { | |
1799 | struct cfq_queue *cfqq; | |
1800 | ||
1801 | if (cfq_class_idle(cur_cfqq)) | |
1802 | return NULL; | |
1803 | if (!cfq_cfqq_sync(cur_cfqq)) | |
1804 | return NULL; | |
1805 | if (CFQQ_SEEKY(cur_cfqq)) | |
1806 | return NULL; | |
1807 | ||
1808 | /* | |
1809 | * Don't search priority tree if it's the only queue in the group. | |
1810 | */ | |
1811 | if (cur_cfqq->cfqg->nr_cfqq == 1) | |
1812 | return NULL; | |
1813 | ||
1814 | /* | |
1815 | * We should notice if some of the queues are cooperating, eg | |
1816 | * working closely on the same area of the disk. In that case, | |
1817 | * we can group them together and don't waste time idling. | |
1818 | */ | |
1819 | cfqq = cfqq_close(cfqd, cur_cfqq); | |
1820 | if (!cfqq) | |
1821 | return NULL; | |
1822 | ||
1823 | /* If new queue belongs to different cfq_group, don't choose it */ | |
1824 | if (cur_cfqq->cfqg != cfqq->cfqg) | |
1825 | return NULL; | |
1826 | ||
1827 | /* | |
1828 | * It only makes sense to merge sync queues. | |
1829 | */ | |
1830 | if (!cfq_cfqq_sync(cfqq)) | |
1831 | return NULL; | |
1832 | if (CFQQ_SEEKY(cfqq)) | |
1833 | return NULL; | |
1834 | ||
1835 | /* | |
1836 | * Do not merge queues of different priority classes | |
1837 | */ | |
1838 | if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) | |
1839 | return NULL; | |
1840 | ||
1841 | return cfqq; | |
1842 | } | |
1843 | ||
1844 | /* | |
1845 | * Determine whether we should enforce idle window for this queue. | |
1846 | */ | |
1847 | ||
1848 | static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1849 | { | |
1850 | enum wl_prio_t prio = cfqq_prio(cfqq); | |
1851 | struct cfq_rb_root *service_tree = cfqq->service_tree; | |
1852 | ||
1853 | BUG_ON(!service_tree); | |
1854 | BUG_ON(!service_tree->count); | |
1855 | ||
1856 | if (!cfqd->cfq_slice_idle) | |
1857 | return false; | |
1858 | ||
1859 | /* We never do for idle class queues. */ | |
1860 | if (prio == IDLE_WORKLOAD) | |
1861 | return false; | |
1862 | ||
1863 | /* We do for queues that were marked with idle window flag. */ | |
1864 | if (cfq_cfqq_idle_window(cfqq) && | |
1865 | !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) | |
1866 | return true; | |
1867 | ||
1868 | /* | |
1869 | * Otherwise, we do only if they are the last ones | |
1870 | * in their service tree. | |
1871 | */ | |
1872 | if (service_tree->count == 1 && cfq_cfqq_sync(cfqq)) | |
1873 | return true; | |
1874 | cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", | |
1875 | service_tree->count); | |
1876 | return false; | |
1877 | } | |
1878 | ||
1879 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) | |
1880 | { | |
1881 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1882 | struct cfq_io_context *cic; | |
1883 | unsigned long sl, group_idle = 0; | |
1884 | ||
1885 | /* | |
1886 | * SSD device without seek penalty, disable idling. But only do so | |
1887 | * for devices that support queuing, otherwise we still have a problem | |
1888 | * with sync vs async workloads. | |
1889 | */ | |
1890 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) | |
1891 | return; | |
1892 | ||
1893 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); | |
1894 | WARN_ON(cfq_cfqq_slice_new(cfqq)); | |
1895 | ||
1896 | /* | |
1897 | * idle is disabled, either manually or by past process history | |
1898 | */ | |
1899 | if (!cfq_should_idle(cfqd, cfqq)) { | |
1900 | /* no queue idling. Check for group idling */ | |
1901 | if (cfqd->cfq_group_idle) | |
1902 | group_idle = cfqd->cfq_group_idle; | |
1903 | else | |
1904 | return; | |
1905 | } | |
1906 | ||
1907 | /* | |
1908 | * still active requests from this queue, don't idle | |
1909 | */ | |
1910 | if (cfqq->dispatched) | |
1911 | return; | |
1912 | ||
1913 | /* | |
1914 | * task has exited, don't wait | |
1915 | */ | |
1916 | cic = cfqd->active_cic; | |
1917 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) | |
1918 | return; | |
1919 | ||
1920 | /* | |
1921 | * If our average think time is larger than the remaining time | |
1922 | * slice, then don't idle. This avoids overrunning the allotted | |
1923 | * time slice. | |
1924 | */ | |
1925 | if (sample_valid(cic->ttime_samples) && | |
1926 | (cfqq->slice_end - jiffies < cic->ttime_mean)) { | |
1927 | cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d", | |
1928 | cic->ttime_mean); | |
1929 | return; | |
1930 | } | |
1931 | ||
1932 | /* There are other queues in the group, don't do group idle */ | |
1933 | if (group_idle && cfqq->cfqg->nr_cfqq > 1) | |
1934 | return; | |
1935 | ||
1936 | cfq_mark_cfqq_wait_request(cfqq); | |
1937 | ||
1938 | if (group_idle) | |
1939 | sl = cfqd->cfq_group_idle; | |
1940 | else | |
1941 | sl = cfqd->cfq_slice_idle; | |
1942 | ||
1943 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); | |
1944 | cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); | |
1945 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, | |
1946 | group_idle ? 1 : 0); | |
1947 | } | |
1948 | ||
1949 | /* | |
1950 | * Move request from internal lists to the request queue dispatch list. | |
1951 | */ | |
1952 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) | |
1953 | { | |
1954 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1955 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
1956 | ||
1957 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); | |
1958 | ||
1959 | cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); | |
1960 | cfq_remove_request(rq); | |
1961 | cfqq->dispatched++; | |
1962 | (RQ_CFQG(rq))->dispatched++; | |
1963 | elv_dispatch_sort(q, rq); | |
1964 | ||
1965 | cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; | |
1966 | cfqq->nr_sectors += blk_rq_sectors(rq); | |
1967 | cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), | |
1968 | rq_data_dir(rq), rq_is_sync(rq)); | |
1969 | } | |
1970 | ||
1971 | /* | |
1972 | * return expired entry, or NULL to just start from scratch in rbtree | |
1973 | */ | |
1974 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) | |
1975 | { | |
1976 | struct request *rq = NULL; | |
1977 | ||
1978 | if (cfq_cfqq_fifo_expire(cfqq)) | |
1979 | return NULL; | |
1980 | ||
1981 | cfq_mark_cfqq_fifo_expire(cfqq); | |
1982 | ||
1983 | if (list_empty(&cfqq->fifo)) | |
1984 | return NULL; | |
1985 | ||
1986 | rq = rq_entry_fifo(cfqq->fifo.next); | |
1987 | if (time_before(jiffies, rq_fifo_time(rq))) | |
1988 | rq = NULL; | |
1989 | ||
1990 | cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); | |
1991 | return rq; | |
1992 | } | |
1993 | ||
1994 | static inline int | |
1995 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1996 | { | |
1997 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1998 | ||
1999 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); | |
2000 | ||
2001 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); | |
2002 | } | |
2003 | ||
2004 | /* | |
2005 | * Must be called with the queue_lock held. | |
2006 | */ | |
2007 | static int cfqq_process_refs(struct cfq_queue *cfqq) | |
2008 | { | |
2009 | int process_refs, io_refs; | |
2010 | ||
2011 | io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; | |
2012 | process_refs = cfqq->ref - io_refs; | |
2013 | BUG_ON(process_refs < 0); | |
2014 | return process_refs; | |
2015 | } | |
2016 | ||
2017 | static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) | |
2018 | { | |
2019 | int process_refs, new_process_refs; | |
2020 | struct cfq_queue *__cfqq; | |
2021 | ||
2022 | /* | |
2023 | * If there are no process references on the new_cfqq, then it is | |
2024 | * unsafe to follow the ->new_cfqq chain as other cfqq's in the | |
2025 | * chain may have dropped their last reference (not just their | |
2026 | * last process reference). | |
2027 | */ | |
2028 | if (!cfqq_process_refs(new_cfqq)) | |
2029 | return; | |
2030 | ||
2031 | /* Avoid a circular list and skip interim queue merges */ | |
2032 | while ((__cfqq = new_cfqq->new_cfqq)) { | |
2033 | if (__cfqq == cfqq) | |
2034 | return; | |
2035 | new_cfqq = __cfqq; | |
2036 | } | |
2037 | ||
2038 | process_refs = cfqq_process_refs(cfqq); | |
2039 | new_process_refs = cfqq_process_refs(new_cfqq); | |
2040 | /* | |
2041 | * If the process for the cfqq has gone away, there is no | |
2042 | * sense in merging the queues. | |
2043 | */ | |
2044 | if (process_refs == 0 || new_process_refs == 0) | |
2045 | return; | |
2046 | ||
2047 | /* | |
2048 | * Merge in the direction of the lesser amount of work. | |
2049 | */ | |
2050 | if (new_process_refs >= process_refs) { | |
2051 | cfqq->new_cfqq = new_cfqq; | |
2052 | new_cfqq->ref += process_refs; | |
2053 | } else { | |
2054 | new_cfqq->new_cfqq = cfqq; | |
2055 | cfqq->ref += new_process_refs; | |
2056 | } | |
2057 | } | |
2058 | ||
2059 | static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, | |
2060 | struct cfq_group *cfqg, enum wl_prio_t prio) | |
2061 | { | |
2062 | struct cfq_queue *queue; | |
2063 | int i; | |
2064 | bool key_valid = false; | |
2065 | unsigned long lowest_key = 0; | |
2066 | enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; | |
2067 | ||
2068 | for (i = 0; i <= SYNC_WORKLOAD; ++i) { | |
2069 | /* select the one with lowest rb_key */ | |
2070 | queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); | |
2071 | if (queue && | |
2072 | (!key_valid || time_before(queue->rb_key, lowest_key))) { | |
2073 | lowest_key = queue->rb_key; | |
2074 | cur_best = i; | |
2075 | key_valid = true; | |
2076 | } | |
2077 | } | |
2078 | ||
2079 | return cur_best; | |
2080 | } | |
2081 | ||
2082 | static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) | |
2083 | { | |
2084 | unsigned slice; | |
2085 | unsigned count; | |
2086 | struct cfq_rb_root *st; | |
2087 | unsigned group_slice; | |
2088 | enum wl_prio_t original_prio = cfqd->serving_prio; | |
2089 | ||
2090 | /* Choose next priority. RT > BE > IDLE */ | |
2091 | if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) | |
2092 | cfqd->serving_prio = RT_WORKLOAD; | |
2093 | else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) | |
2094 | cfqd->serving_prio = BE_WORKLOAD; | |
2095 | else { | |
2096 | cfqd->serving_prio = IDLE_WORKLOAD; | |
2097 | cfqd->workload_expires = jiffies + 1; | |
2098 | return; | |
2099 | } | |
2100 | ||
2101 | if (original_prio != cfqd->serving_prio) | |
2102 | goto new_workload; | |
2103 | ||
2104 | /* | |
2105 | * For RT and BE, we have to choose also the type | |
2106 | * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload | |
2107 | * expiration time | |
2108 | */ | |
2109 | st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); | |
2110 | count = st->count; | |
2111 | ||
2112 | /* | |
2113 | * check workload expiration, and that we still have other queues ready | |
2114 | */ | |
2115 | if (count && !time_after(jiffies, cfqd->workload_expires)) | |
2116 | return; | |
2117 | ||
2118 | new_workload: | |
2119 | /* otherwise select new workload type */ | |
2120 | cfqd->serving_type = | |
2121 | cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); | |
2122 | st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); | |
2123 | count = st->count; | |
2124 | ||
2125 | /* | |
2126 | * the workload slice is computed as a fraction of target latency | |
2127 | * proportional to the number of queues in that workload, over | |
2128 | * all the queues in the same priority class | |
2129 | */ | |
2130 | group_slice = cfq_group_slice(cfqd, cfqg); | |
2131 | ||
2132 | slice = group_slice * count / | |
2133 | max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], | |
2134 | cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); | |
2135 | ||
2136 | if (cfqd->serving_type == ASYNC_WORKLOAD) { | |
2137 | unsigned int tmp; | |
2138 | ||
2139 | /* | |
2140 | * Async queues are currently system wide. Just taking | |
2141 | * proportion of queues with-in same group will lead to higher | |
2142 | * async ratio system wide as generally root group is going | |
2143 | * to have higher weight. A more accurate thing would be to | |
2144 | * calculate system wide asnc/sync ratio. | |
2145 | */ | |
2146 | tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); | |
2147 | tmp = tmp/cfqd->busy_queues; | |
2148 | slice = min_t(unsigned, slice, tmp); | |
2149 | ||
2150 | /* async workload slice is scaled down according to | |
2151 | * the sync/async slice ratio. */ | |
2152 | slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; | |
2153 | } else | |
2154 | /* sync workload slice is at least 2 * cfq_slice_idle */ | |
2155 | slice = max(slice, 2 * cfqd->cfq_slice_idle); | |
2156 | ||
2157 | slice = max_t(unsigned, slice, CFQ_MIN_TT); | |
2158 | cfq_log(cfqd, "workload slice:%d", slice); | |
2159 | cfqd->workload_expires = jiffies + slice; | |
2160 | } | |
2161 | ||
2162 | static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) | |
2163 | { | |
2164 | struct cfq_rb_root *st = &cfqd->grp_service_tree; | |
2165 | struct cfq_group *cfqg; | |
2166 | ||
2167 | if (RB_EMPTY_ROOT(&st->rb)) | |
2168 | return NULL; | |
2169 | cfqg = cfq_rb_first_group(st); | |
2170 | update_min_vdisktime(st); | |
2171 | return cfqg; | |
2172 | } | |
2173 | ||
2174 | static void cfq_choose_cfqg(struct cfq_data *cfqd) | |
2175 | { | |
2176 | struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); | |
2177 | ||
2178 | cfqd->serving_group = cfqg; | |
2179 | ||
2180 | /* Restore the workload type data */ | |
2181 | if (cfqg->saved_workload_slice) { | |
2182 | cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; | |
2183 | cfqd->serving_type = cfqg->saved_workload; | |
2184 | cfqd->serving_prio = cfqg->saved_serving_prio; | |
2185 | } else | |
2186 | cfqd->workload_expires = jiffies - 1; | |
2187 | ||
2188 | choose_service_tree(cfqd, cfqg); | |
2189 | } | |
2190 | ||
2191 | /* | |
2192 | * Select a queue for service. If we have a current active queue, | |
2193 | * check whether to continue servicing it, or retrieve and set a new one. | |
2194 | */ | |
2195 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) | |
2196 | { | |
2197 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
2198 | ||
2199 | cfqq = cfqd->active_queue; | |
2200 | if (!cfqq) | |
2201 | goto new_queue; | |
2202 | ||
2203 | if (!cfqd->rq_queued) | |
2204 | return NULL; | |
2205 | ||
2206 | /* | |
2207 | * We were waiting for group to get backlogged. Expire the queue | |
2208 | */ | |
2209 | if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) | |
2210 | goto expire; | |
2211 | ||
2212 | /* | |
2213 | * The active queue has run out of time, expire it and select new. | |
2214 | */ | |
2215 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { | |
2216 | /* | |
2217 | * If slice had not expired at the completion of last request | |
2218 | * we might not have turned on wait_busy flag. Don't expire | |
2219 | * the queue yet. Allow the group to get backlogged. | |
2220 | * | |
2221 | * The very fact that we have used the slice, that means we | |
2222 | * have been idling all along on this queue and it should be | |
2223 | * ok to wait for this request to complete. | |
2224 | */ | |
2225 | if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) | |
2226 | && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { | |
2227 | cfqq = NULL; | |
2228 | goto keep_queue; | |
2229 | } else | |
2230 | goto check_group_idle; | |
2231 | } | |
2232 | ||
2233 | /* | |
2234 | * The active queue has requests and isn't expired, allow it to | |
2235 | * dispatch. | |
2236 | */ | |
2237 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) | |
2238 | goto keep_queue; | |
2239 | ||
2240 | /* | |
2241 | * If another queue has a request waiting within our mean seek | |
2242 | * distance, let it run. The expire code will check for close | |
2243 | * cooperators and put the close queue at the front of the service | |
2244 | * tree. If possible, merge the expiring queue with the new cfqq. | |
2245 | */ | |
2246 | new_cfqq = cfq_close_cooperator(cfqd, cfqq); | |
2247 | if (new_cfqq) { | |
2248 | if (!cfqq->new_cfqq) | |
2249 | cfq_setup_merge(cfqq, new_cfqq); | |
2250 | goto expire; | |
2251 | } | |
2252 | ||
2253 | /* | |
2254 | * No requests pending. If the active queue still has requests in | |
2255 | * flight or is idling for a new request, allow either of these | |
2256 | * conditions to happen (or time out) before selecting a new queue. | |
2257 | */ | |
2258 | if (timer_pending(&cfqd->idle_slice_timer)) { | |
2259 | cfqq = NULL; | |
2260 | goto keep_queue; | |
2261 | } | |
2262 | ||
2263 | /* | |
2264 | * This is a deep seek queue, but the device is much faster than | |
2265 | * the queue can deliver, don't idle | |
2266 | **/ | |
2267 | if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && | |
2268 | (cfq_cfqq_slice_new(cfqq) || | |
2269 | (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { | |
2270 | cfq_clear_cfqq_deep(cfqq); | |
2271 | cfq_clear_cfqq_idle_window(cfqq); | |
2272 | } | |
2273 | ||
2274 | if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { | |
2275 | cfqq = NULL; | |
2276 | goto keep_queue; | |
2277 | } | |
2278 | ||
2279 | /* | |
2280 | * If group idle is enabled and there are requests dispatched from | |
2281 | * this group, wait for requests to complete. | |
2282 | */ | |
2283 | check_group_idle: | |
2284 | if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 | |
2285 | && cfqq->cfqg->dispatched) { | |
2286 | cfqq = NULL; | |
2287 | goto keep_queue; | |
2288 | } | |
2289 | ||
2290 | expire: | |
2291 | cfq_slice_expired(cfqd, 0); | |
2292 | new_queue: | |
2293 | /* | |
2294 | * Current queue expired. Check if we have to switch to a new | |
2295 | * service tree | |
2296 | */ | |
2297 | if (!new_cfqq) | |
2298 | cfq_choose_cfqg(cfqd); | |
2299 | ||
2300 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); | |
2301 | keep_queue: | |
2302 | return cfqq; | |
2303 | } | |
2304 | ||
2305 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) | |
2306 | { | |
2307 | int dispatched = 0; | |
2308 | ||
2309 | while (cfqq->next_rq) { | |
2310 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
2311 | dispatched++; | |
2312 | } | |
2313 | ||
2314 | BUG_ON(!list_empty(&cfqq->fifo)); | |
2315 | ||
2316 | /* By default cfqq is not expired if it is empty. Do it explicitly */ | |
2317 | __cfq_slice_expired(cfqq->cfqd, cfqq, 0); | |
2318 | return dispatched; | |
2319 | } | |
2320 | ||
2321 | /* | |
2322 | * Drain our current requests. Used for barriers and when switching | |
2323 | * io schedulers on-the-fly. | |
2324 | */ | |
2325 | static int cfq_forced_dispatch(struct cfq_data *cfqd) | |
2326 | { | |
2327 | struct cfq_queue *cfqq; | |
2328 | int dispatched = 0; | |
2329 | ||
2330 | /* Expire the timeslice of the current active queue first */ | |
2331 | cfq_slice_expired(cfqd, 0); | |
2332 | while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { | |
2333 | __cfq_set_active_queue(cfqd, cfqq); | |
2334 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); | |
2335 | } | |
2336 | ||
2337 | BUG_ON(cfqd->busy_queues); | |
2338 | ||
2339 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); | |
2340 | return dispatched; | |
2341 | } | |
2342 | ||
2343 | static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, | |
2344 | struct cfq_queue *cfqq) | |
2345 | { | |
2346 | /* the queue hasn't finished any request, can't estimate */ | |
2347 | if (cfq_cfqq_slice_new(cfqq)) | |
2348 | return true; | |
2349 | if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, | |
2350 | cfqq->slice_end)) | |
2351 | return true; | |
2352 | ||
2353 | return false; | |
2354 | } | |
2355 | ||
2356 | static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2357 | { | |
2358 | unsigned int max_dispatch; | |
2359 | ||
2360 | /* | |
2361 | * Drain async requests before we start sync IO | |
2362 | */ | |
2363 | if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) | |
2364 | return false; | |
2365 | ||
2366 | /* | |
2367 | * If this is an async queue and we have sync IO in flight, let it wait | |
2368 | */ | |
2369 | if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) | |
2370 | return false; | |
2371 | ||
2372 | max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); | |
2373 | if (cfq_class_idle(cfqq)) | |
2374 | max_dispatch = 1; | |
2375 | ||
2376 | /* | |
2377 | * Does this cfqq already have too much IO in flight? | |
2378 | */ | |
2379 | if (cfqq->dispatched >= max_dispatch) { | |
2380 | /* | |
2381 | * idle queue must always only have a single IO in flight | |
2382 | */ | |
2383 | if (cfq_class_idle(cfqq)) | |
2384 | return false; | |
2385 | ||
2386 | /* | |
2387 | * We have other queues, don't allow more IO from this one | |
2388 | */ | |
2389 | if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq)) | |
2390 | return false; | |
2391 | ||
2392 | /* | |
2393 | * Sole queue user, no limit | |
2394 | */ | |
2395 | if (cfqd->busy_queues == 1) | |
2396 | max_dispatch = -1; | |
2397 | else | |
2398 | /* | |
2399 | * Normally we start throttling cfqq when cfq_quantum/2 | |
2400 | * requests have been dispatched. But we can drive | |
2401 | * deeper queue depths at the beginning of slice | |
2402 | * subjected to upper limit of cfq_quantum. | |
2403 | * */ | |
2404 | max_dispatch = cfqd->cfq_quantum; | |
2405 | } | |
2406 | ||
2407 | /* | |
2408 | * Async queues must wait a bit before being allowed dispatch. | |
2409 | * We also ramp up the dispatch depth gradually for async IO, | |
2410 | * based on the last sync IO we serviced | |
2411 | */ | |
2412 | if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { | |
2413 | unsigned long last_sync = jiffies - cfqd->last_delayed_sync; | |
2414 | unsigned int depth; | |
2415 | ||
2416 | depth = last_sync / cfqd->cfq_slice[1]; | |
2417 | if (!depth && !cfqq->dispatched) | |
2418 | depth = 1; | |
2419 | if (depth < max_dispatch) | |
2420 | max_dispatch = depth; | |
2421 | } | |
2422 | ||
2423 | /* | |
2424 | * If we're below the current max, allow a dispatch | |
2425 | */ | |
2426 | return cfqq->dispatched < max_dispatch; | |
2427 | } | |
2428 | ||
2429 | /* | |
2430 | * Dispatch a request from cfqq, moving them to the request queue | |
2431 | * dispatch list. | |
2432 | */ | |
2433 | static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2434 | { | |
2435 | struct request *rq; | |
2436 | ||
2437 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); | |
2438 | ||
2439 | if (!cfq_may_dispatch(cfqd, cfqq)) | |
2440 | return false; | |
2441 | ||
2442 | /* | |
2443 | * follow expired path, else get first next available | |
2444 | */ | |
2445 | rq = cfq_check_fifo(cfqq); | |
2446 | if (!rq) | |
2447 | rq = cfqq->next_rq; | |
2448 | ||
2449 | /* | |
2450 | * insert request into driver dispatch list | |
2451 | */ | |
2452 | cfq_dispatch_insert(cfqd->queue, rq); | |
2453 | ||
2454 | if (!cfqd->active_cic) { | |
2455 | struct cfq_io_context *cic = RQ_CIC(rq); | |
2456 | ||
2457 | atomic_long_inc(&cic->ioc->refcount); | |
2458 | cfqd->active_cic = cic; | |
2459 | } | |
2460 | ||
2461 | return true; | |
2462 | } | |
2463 | ||
2464 | /* | |
2465 | * Find the cfqq that we need to service and move a request from that to the | |
2466 | * dispatch list | |
2467 | */ | |
2468 | static int cfq_dispatch_requests(struct request_queue *q, int force) | |
2469 | { | |
2470 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2471 | struct cfq_queue *cfqq; | |
2472 | ||
2473 | if (!cfqd->busy_queues) | |
2474 | return 0; | |
2475 | ||
2476 | if (unlikely(force)) | |
2477 | return cfq_forced_dispatch(cfqd); | |
2478 | ||
2479 | cfqq = cfq_select_queue(cfqd); | |
2480 | if (!cfqq) | |
2481 | return 0; | |
2482 | ||
2483 | /* | |
2484 | * Dispatch a request from this cfqq, if it is allowed | |
2485 | */ | |
2486 | if (!cfq_dispatch_request(cfqd, cfqq)) | |
2487 | return 0; | |
2488 | ||
2489 | cfqq->slice_dispatch++; | |
2490 | cfq_clear_cfqq_must_dispatch(cfqq); | |
2491 | ||
2492 | /* | |
2493 | * expire an async queue immediately if it has used up its slice. idle | |
2494 | * queue always expire after 1 dispatch round. | |
2495 | */ | |
2496 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && | |
2497 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
2498 | cfq_class_idle(cfqq))) { | |
2499 | cfqq->slice_end = jiffies + 1; | |
2500 | cfq_slice_expired(cfqd, 0); | |
2501 | } | |
2502 | ||
2503 | cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); | |
2504 | return 1; | |
2505 | } | |
2506 | ||
2507 | /* | |
2508 | * task holds one reference to the queue, dropped when task exits. each rq | |
2509 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
2510 | * | |
2511 | * Each cfq queue took a reference on the parent group. Drop it now. | |
2512 | * queue lock must be held here. | |
2513 | */ | |
2514 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
2515 | { | |
2516 | struct cfq_data *cfqd = cfqq->cfqd; | |
2517 | struct cfq_group *cfqg; | |
2518 | ||
2519 | BUG_ON(cfqq->ref <= 0); | |
2520 | ||
2521 | cfqq->ref--; | |
2522 | if (cfqq->ref) | |
2523 | return; | |
2524 | ||
2525 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); | |
2526 | BUG_ON(rb_first(&cfqq->sort_list)); | |
2527 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); | |
2528 | cfqg = cfqq->cfqg; | |
2529 | ||
2530 | if (unlikely(cfqd->active_queue == cfqq)) { | |
2531 | __cfq_slice_expired(cfqd, cfqq, 0); | |
2532 | cfq_schedule_dispatch(cfqd); | |
2533 | } | |
2534 | ||
2535 | BUG_ON(cfq_cfqq_on_rr(cfqq)); | |
2536 | kmem_cache_free(cfq_pool, cfqq); | |
2537 | cfq_put_cfqg(cfqg); | |
2538 | } | |
2539 | ||
2540 | /* | |
2541 | * Must always be called with the rcu_read_lock() held | |
2542 | */ | |
2543 | static void | |
2544 | __call_for_each_cic(struct io_context *ioc, | |
2545 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
2546 | { | |
2547 | struct cfq_io_context *cic; | |
2548 | struct hlist_node *n; | |
2549 | ||
2550 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) | |
2551 | func(ioc, cic); | |
2552 | } | |
2553 | ||
2554 | /* | |
2555 | * Call func for each cic attached to this ioc. | |
2556 | */ | |
2557 | static void | |
2558 | call_for_each_cic(struct io_context *ioc, | |
2559 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
2560 | { | |
2561 | rcu_read_lock(); | |
2562 | __call_for_each_cic(ioc, func); | |
2563 | rcu_read_unlock(); | |
2564 | } | |
2565 | ||
2566 | static void cfq_cic_free_rcu(struct rcu_head *head) | |
2567 | { | |
2568 | struct cfq_io_context *cic; | |
2569 | ||
2570 | cic = container_of(head, struct cfq_io_context, rcu_head); | |
2571 | ||
2572 | kmem_cache_free(cfq_ioc_pool, cic); | |
2573 | elv_ioc_count_dec(cfq_ioc_count); | |
2574 | ||
2575 | if (ioc_gone) { | |
2576 | /* | |
2577 | * CFQ scheduler is exiting, grab exit lock and check | |
2578 | * the pending io context count. If it hits zero, | |
2579 | * complete ioc_gone and set it back to NULL | |
2580 | */ | |
2581 | spin_lock(&ioc_gone_lock); | |
2582 | if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { | |
2583 | complete(ioc_gone); | |
2584 | ioc_gone = NULL; | |
2585 | } | |
2586 | spin_unlock(&ioc_gone_lock); | |
2587 | } | |
2588 | } | |
2589 | ||
2590 | static void cfq_cic_free(struct cfq_io_context *cic) | |
2591 | { | |
2592 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); | |
2593 | } | |
2594 | ||
2595 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) | |
2596 | { | |
2597 | unsigned long flags; | |
2598 | unsigned long dead_key = (unsigned long) cic->key; | |
2599 | ||
2600 | BUG_ON(!(dead_key & CIC_DEAD_KEY)); | |
2601 | ||
2602 | spin_lock_irqsave(&ioc->lock, flags); | |
2603 | radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT); | |
2604 | hlist_del_rcu(&cic->cic_list); | |
2605 | spin_unlock_irqrestore(&ioc->lock, flags); | |
2606 | ||
2607 | cfq_cic_free(cic); | |
2608 | } | |
2609 | ||
2610 | /* | |
2611 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. | |
2612 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), | |
2613 | * and ->trim() which is called with the task lock held | |
2614 | */ | |
2615 | static void cfq_free_io_context(struct io_context *ioc) | |
2616 | { | |
2617 | /* | |
2618 | * ioc->refcount is zero here, or we are called from elv_unregister(), | |
2619 | * so no more cic's are allowed to be linked into this ioc. So it | |
2620 | * should be ok to iterate over the known list, we will see all cic's | |
2621 | * since no new ones are added. | |
2622 | */ | |
2623 | __call_for_each_cic(ioc, cic_free_func); | |
2624 | } | |
2625 | ||
2626 | static void cfq_put_cooperator(struct cfq_queue *cfqq) | |
2627 | { | |
2628 | struct cfq_queue *__cfqq, *next; | |
2629 | ||
2630 | /* | |
2631 | * If this queue was scheduled to merge with another queue, be | |
2632 | * sure to drop the reference taken on that queue (and others in | |
2633 | * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. | |
2634 | */ | |
2635 | __cfqq = cfqq->new_cfqq; | |
2636 | while (__cfqq) { | |
2637 | if (__cfqq == cfqq) { | |
2638 | WARN(1, "cfqq->new_cfqq loop detected\n"); | |
2639 | break; | |
2640 | } | |
2641 | next = __cfqq->new_cfqq; | |
2642 | cfq_put_queue(__cfqq); | |
2643 | __cfqq = next; | |
2644 | } | |
2645 | } | |
2646 | ||
2647 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2648 | { | |
2649 | if (unlikely(cfqq == cfqd->active_queue)) { | |
2650 | __cfq_slice_expired(cfqd, cfqq, 0); | |
2651 | cfq_schedule_dispatch(cfqd); | |
2652 | } | |
2653 | ||
2654 | cfq_put_cooperator(cfqq); | |
2655 | ||
2656 | cfq_put_queue(cfqq); | |
2657 | } | |
2658 | ||
2659 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, | |
2660 | struct cfq_io_context *cic) | |
2661 | { | |
2662 | struct io_context *ioc = cic->ioc; | |
2663 | ||
2664 | list_del_init(&cic->queue_list); | |
2665 | ||
2666 | /* | |
2667 | * Make sure dead mark is seen for dead queues | |
2668 | */ | |
2669 | smp_wmb(); | |
2670 | cic->key = cfqd_dead_key(cfqd); | |
2671 | ||
2672 | if (ioc->ioc_data == cic) | |
2673 | rcu_assign_pointer(ioc->ioc_data, NULL); | |
2674 | ||
2675 | if (cic->cfqq[BLK_RW_ASYNC]) { | |
2676 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); | |
2677 | cic->cfqq[BLK_RW_ASYNC] = NULL; | |
2678 | } | |
2679 | ||
2680 | if (cic->cfqq[BLK_RW_SYNC]) { | |
2681 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); | |
2682 | cic->cfqq[BLK_RW_SYNC] = NULL; | |
2683 | } | |
2684 | } | |
2685 | ||
2686 | static void cfq_exit_single_io_context(struct io_context *ioc, | |
2687 | struct cfq_io_context *cic) | |
2688 | { | |
2689 | struct cfq_data *cfqd = cic_to_cfqd(cic); | |
2690 | ||
2691 | if (cfqd) { | |
2692 | struct request_queue *q = cfqd->queue; | |
2693 | unsigned long flags; | |
2694 | ||
2695 | spin_lock_irqsave(q->queue_lock, flags); | |
2696 | ||
2697 | /* | |
2698 | * Ensure we get a fresh copy of the ->key to prevent | |
2699 | * race between exiting task and queue | |
2700 | */ | |
2701 | smp_read_barrier_depends(); | |
2702 | if (cic->key == cfqd) | |
2703 | __cfq_exit_single_io_context(cfqd, cic); | |
2704 | ||
2705 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2706 | } | |
2707 | } | |
2708 | ||
2709 | /* | |
2710 | * The process that ioc belongs to has exited, we need to clean up | |
2711 | * and put the internal structures we have that belongs to that process. | |
2712 | */ | |
2713 | static void cfq_exit_io_context(struct io_context *ioc) | |
2714 | { | |
2715 | call_for_each_cic(ioc, cfq_exit_single_io_context); | |
2716 | } | |
2717 | ||
2718 | static struct cfq_io_context * | |
2719 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) | |
2720 | { | |
2721 | struct cfq_io_context *cic; | |
2722 | ||
2723 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, | |
2724 | cfqd->queue->node); | |
2725 | if (cic) { | |
2726 | cic->last_end_request = jiffies; | |
2727 | INIT_LIST_HEAD(&cic->queue_list); | |
2728 | INIT_HLIST_NODE(&cic->cic_list); | |
2729 | cic->dtor = cfq_free_io_context; | |
2730 | cic->exit = cfq_exit_io_context; | |
2731 | elv_ioc_count_inc(cfq_ioc_count); | |
2732 | } | |
2733 | ||
2734 | return cic; | |
2735 | } | |
2736 | ||
2737 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) | |
2738 | { | |
2739 | struct task_struct *tsk = current; | |
2740 | int ioprio_class; | |
2741 | ||
2742 | if (!cfq_cfqq_prio_changed(cfqq)) | |
2743 | return; | |
2744 | ||
2745 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); | |
2746 | switch (ioprio_class) { | |
2747 | default: | |
2748 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
2749 | case IOPRIO_CLASS_NONE: | |
2750 | /* | |
2751 | * no prio set, inherit CPU scheduling settings | |
2752 | */ | |
2753 | cfqq->ioprio = task_nice_ioprio(tsk); | |
2754 | cfqq->ioprio_class = task_nice_ioclass(tsk); | |
2755 | break; | |
2756 | case IOPRIO_CLASS_RT: | |
2757 | cfqq->ioprio = task_ioprio(ioc); | |
2758 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
2759 | break; | |
2760 | case IOPRIO_CLASS_BE: | |
2761 | cfqq->ioprio = task_ioprio(ioc); | |
2762 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
2763 | break; | |
2764 | case IOPRIO_CLASS_IDLE: | |
2765 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
2766 | cfqq->ioprio = 7; | |
2767 | cfq_clear_cfqq_idle_window(cfqq); | |
2768 | break; | |
2769 | } | |
2770 | ||
2771 | /* | |
2772 | * keep track of original prio settings in case we have to temporarily | |
2773 | * elevate the priority of this queue | |
2774 | */ | |
2775 | cfqq->org_ioprio = cfqq->ioprio; | |
2776 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
2777 | cfq_clear_cfqq_prio_changed(cfqq); | |
2778 | } | |
2779 | ||
2780 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) | |
2781 | { | |
2782 | struct cfq_data *cfqd = cic_to_cfqd(cic); | |
2783 | struct cfq_queue *cfqq; | |
2784 | unsigned long flags; | |
2785 | ||
2786 | if (unlikely(!cfqd)) | |
2787 | return; | |
2788 | ||
2789 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2790 | ||
2791 | cfqq = cic->cfqq[BLK_RW_ASYNC]; | |
2792 | if (cfqq) { | |
2793 | struct cfq_queue *new_cfqq; | |
2794 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, | |
2795 | GFP_ATOMIC); | |
2796 | if (new_cfqq) { | |
2797 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; | |
2798 | cfq_put_queue(cfqq); | |
2799 | } | |
2800 | } | |
2801 | ||
2802 | cfqq = cic->cfqq[BLK_RW_SYNC]; | |
2803 | if (cfqq) | |
2804 | cfq_mark_cfqq_prio_changed(cfqq); | |
2805 | ||
2806 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2807 | } | |
2808 | ||
2809 | static void cfq_ioc_set_ioprio(struct io_context *ioc) | |
2810 | { | |
2811 | call_for_each_cic(ioc, changed_ioprio); | |
2812 | ioc->ioprio_changed = 0; | |
2813 | } | |
2814 | ||
2815 | static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
2816 | pid_t pid, bool is_sync) | |
2817 | { | |
2818 | RB_CLEAR_NODE(&cfqq->rb_node); | |
2819 | RB_CLEAR_NODE(&cfqq->p_node); | |
2820 | INIT_LIST_HEAD(&cfqq->fifo); | |
2821 | ||
2822 | cfqq->ref = 0; | |
2823 | cfqq->cfqd = cfqd; | |
2824 | ||
2825 | cfq_mark_cfqq_prio_changed(cfqq); | |
2826 | ||
2827 | if (is_sync) { | |
2828 | if (!cfq_class_idle(cfqq)) | |
2829 | cfq_mark_cfqq_idle_window(cfqq); | |
2830 | cfq_mark_cfqq_sync(cfqq); | |
2831 | } | |
2832 | cfqq->pid = pid; | |
2833 | } | |
2834 | ||
2835 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
2836 | static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic) | |
2837 | { | |
2838 | struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); | |
2839 | struct cfq_data *cfqd = cic_to_cfqd(cic); | |
2840 | unsigned long flags; | |
2841 | struct request_queue *q; | |
2842 | ||
2843 | if (unlikely(!cfqd)) | |
2844 | return; | |
2845 | ||
2846 | q = cfqd->queue; | |
2847 | ||
2848 | spin_lock_irqsave(q->queue_lock, flags); | |
2849 | ||
2850 | if (sync_cfqq) { | |
2851 | /* | |
2852 | * Drop reference to sync queue. A new sync queue will be | |
2853 | * assigned in new group upon arrival of a fresh request. | |
2854 | */ | |
2855 | cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); | |
2856 | cic_set_cfqq(cic, NULL, 1); | |
2857 | cfq_put_queue(sync_cfqq); | |
2858 | } | |
2859 | ||
2860 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2861 | } | |
2862 | ||
2863 | static void cfq_ioc_set_cgroup(struct io_context *ioc) | |
2864 | { | |
2865 | call_for_each_cic(ioc, changed_cgroup); | |
2866 | ioc->cgroup_changed = 0; | |
2867 | } | |
2868 | #endif /* CONFIG_CFQ_GROUP_IOSCHED */ | |
2869 | ||
2870 | static struct cfq_queue * | |
2871 | cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, | |
2872 | struct io_context *ioc, gfp_t gfp_mask) | |
2873 | { | |
2874 | struct cfq_queue *cfqq, *new_cfqq = NULL; | |
2875 | struct cfq_io_context *cic; | |
2876 | struct cfq_group *cfqg; | |
2877 | ||
2878 | retry: | |
2879 | cfqg = cfq_get_cfqg(cfqd, 1); | |
2880 | cic = cfq_cic_lookup(cfqd, ioc); | |
2881 | /* cic always exists here */ | |
2882 | cfqq = cic_to_cfqq(cic, is_sync); | |
2883 | ||
2884 | /* | |
2885 | * Always try a new alloc if we fell back to the OOM cfqq | |
2886 | * originally, since it should just be a temporary situation. | |
2887 | */ | |
2888 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { | |
2889 | cfqq = NULL; | |
2890 | if (new_cfqq) { | |
2891 | cfqq = new_cfqq; | |
2892 | new_cfqq = NULL; | |
2893 | } else if (gfp_mask & __GFP_WAIT) { | |
2894 | spin_unlock_irq(cfqd->queue->queue_lock); | |
2895 | new_cfqq = kmem_cache_alloc_node(cfq_pool, | |
2896 | gfp_mask | __GFP_ZERO, | |
2897 | cfqd->queue->node); | |
2898 | spin_lock_irq(cfqd->queue->queue_lock); | |
2899 | if (new_cfqq) | |
2900 | goto retry; | |
2901 | } else { | |
2902 | cfqq = kmem_cache_alloc_node(cfq_pool, | |
2903 | gfp_mask | __GFP_ZERO, | |
2904 | cfqd->queue->node); | |
2905 | } | |
2906 | ||
2907 | if (cfqq) { | |
2908 | cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); | |
2909 | cfq_init_prio_data(cfqq, ioc); | |
2910 | cfq_link_cfqq_cfqg(cfqq, cfqg); | |
2911 | cfq_log_cfqq(cfqd, cfqq, "alloced"); | |
2912 | } else | |
2913 | cfqq = &cfqd->oom_cfqq; | |
2914 | } | |
2915 | ||
2916 | if (new_cfqq) | |
2917 | kmem_cache_free(cfq_pool, new_cfqq); | |
2918 | ||
2919 | return cfqq; | |
2920 | } | |
2921 | ||
2922 | static struct cfq_queue ** | |
2923 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
2924 | { | |
2925 | switch (ioprio_class) { | |
2926 | case IOPRIO_CLASS_RT: | |
2927 | return &cfqd->async_cfqq[0][ioprio]; | |
2928 | case IOPRIO_CLASS_BE: | |
2929 | return &cfqd->async_cfqq[1][ioprio]; | |
2930 | case IOPRIO_CLASS_IDLE: | |
2931 | return &cfqd->async_idle_cfqq; | |
2932 | default: | |
2933 | BUG(); | |
2934 | } | |
2935 | } | |
2936 | ||
2937 | static struct cfq_queue * | |
2938 | cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, | |
2939 | gfp_t gfp_mask) | |
2940 | { | |
2941 | const int ioprio = task_ioprio(ioc); | |
2942 | const int ioprio_class = task_ioprio_class(ioc); | |
2943 | struct cfq_queue **async_cfqq = NULL; | |
2944 | struct cfq_queue *cfqq = NULL; | |
2945 | ||
2946 | if (!is_sync) { | |
2947 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
2948 | cfqq = *async_cfqq; | |
2949 | } | |
2950 | ||
2951 | if (!cfqq) | |
2952 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); | |
2953 | ||
2954 | /* | |
2955 | * pin the queue now that it's allocated, scheduler exit will prune it | |
2956 | */ | |
2957 | if (!is_sync && !(*async_cfqq)) { | |
2958 | cfqq->ref++; | |
2959 | *async_cfqq = cfqq; | |
2960 | } | |
2961 | ||
2962 | cfqq->ref++; | |
2963 | return cfqq; | |
2964 | } | |
2965 | ||
2966 | /* | |
2967 | * We drop cfq io contexts lazily, so we may find a dead one. | |
2968 | */ | |
2969 | static void | |
2970 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, | |
2971 | struct cfq_io_context *cic) | |
2972 | { | |
2973 | unsigned long flags; | |
2974 | ||
2975 | WARN_ON(!list_empty(&cic->queue_list)); | |
2976 | BUG_ON(cic->key != cfqd_dead_key(cfqd)); | |
2977 | ||
2978 | spin_lock_irqsave(&ioc->lock, flags); | |
2979 | ||
2980 | BUG_ON(ioc->ioc_data == cic); | |
2981 | ||
2982 | radix_tree_delete(&ioc->radix_root, cfqd->cic_index); | |
2983 | hlist_del_rcu(&cic->cic_list); | |
2984 | spin_unlock_irqrestore(&ioc->lock, flags); | |
2985 | ||
2986 | cfq_cic_free(cic); | |
2987 | } | |
2988 | ||
2989 | static struct cfq_io_context * | |
2990 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) | |
2991 | { | |
2992 | struct cfq_io_context *cic; | |
2993 | unsigned long flags; | |
2994 | ||
2995 | if (unlikely(!ioc)) | |
2996 | return NULL; | |
2997 | ||
2998 | rcu_read_lock(); | |
2999 | ||
3000 | /* | |
3001 | * we maintain a last-hit cache, to avoid browsing over the tree | |
3002 | */ | |
3003 | cic = rcu_dereference(ioc->ioc_data); | |
3004 | if (cic && cic->key == cfqd) { | |
3005 | rcu_read_unlock(); | |
3006 | return cic; | |
3007 | } | |
3008 | ||
3009 | do { | |
3010 | cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index); | |
3011 | rcu_read_unlock(); | |
3012 | if (!cic) | |
3013 | break; | |
3014 | if (unlikely(cic->key != cfqd)) { | |
3015 | cfq_drop_dead_cic(cfqd, ioc, cic); | |
3016 | rcu_read_lock(); | |
3017 | continue; | |
3018 | } | |
3019 | ||
3020 | spin_lock_irqsave(&ioc->lock, flags); | |
3021 | rcu_assign_pointer(ioc->ioc_data, cic); | |
3022 | spin_unlock_irqrestore(&ioc->lock, flags); | |
3023 | break; | |
3024 | } while (1); | |
3025 | ||
3026 | return cic; | |
3027 | } | |
3028 | ||
3029 | /* | |
3030 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup | |
3031 | * the process specific cfq io context when entered from the block layer. | |
3032 | * Also adds the cic to a per-cfqd list, used when this queue is removed. | |
3033 | */ | |
3034 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, | |
3035 | struct cfq_io_context *cic, gfp_t gfp_mask) | |
3036 | { | |
3037 | unsigned long flags; | |
3038 | int ret; | |
3039 | ||
3040 | ret = radix_tree_preload(gfp_mask); | |
3041 | if (!ret) { | |
3042 | cic->ioc = ioc; | |
3043 | cic->key = cfqd; | |
3044 | ||
3045 | spin_lock_irqsave(&ioc->lock, flags); | |
3046 | ret = radix_tree_insert(&ioc->radix_root, | |
3047 | cfqd->cic_index, cic); | |
3048 | if (!ret) | |
3049 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); | |
3050 | spin_unlock_irqrestore(&ioc->lock, flags); | |
3051 | ||
3052 | radix_tree_preload_end(); | |
3053 | ||
3054 | if (!ret) { | |
3055 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
3056 | list_add(&cic->queue_list, &cfqd->cic_list); | |
3057 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
3058 | } | |
3059 | } | |
3060 | ||
3061 | if (ret) | |
3062 | printk(KERN_ERR "cfq: cic link failed!\n"); | |
3063 | ||
3064 | return ret; | |
3065 | } | |
3066 | ||
3067 | /* | |
3068 | * Setup general io context and cfq io context. There can be several cfq | |
3069 | * io contexts per general io context, if this process is doing io to more | |
3070 | * than one device managed by cfq. | |
3071 | */ | |
3072 | static struct cfq_io_context * | |
3073 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) | |
3074 | { | |
3075 | struct io_context *ioc = NULL; | |
3076 | struct cfq_io_context *cic; | |
3077 | ||
3078 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
3079 | ||
3080 | ioc = get_io_context(gfp_mask, cfqd->queue->node); | |
3081 | if (!ioc) | |
3082 | return NULL; | |
3083 | ||
3084 | cic = cfq_cic_lookup(cfqd, ioc); | |
3085 | if (cic) | |
3086 | goto out; | |
3087 | ||
3088 | cic = cfq_alloc_io_context(cfqd, gfp_mask); | |
3089 | if (cic == NULL) | |
3090 | goto err; | |
3091 | ||
3092 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) | |
3093 | goto err_free; | |
3094 | ||
3095 | out: | |
3096 | smp_read_barrier_depends(); | |
3097 | if (unlikely(ioc->ioprio_changed)) | |
3098 | cfq_ioc_set_ioprio(ioc); | |
3099 | ||
3100 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
3101 | if (unlikely(ioc->cgroup_changed)) | |
3102 | cfq_ioc_set_cgroup(ioc); | |
3103 | #endif | |
3104 | return cic; | |
3105 | err_free: | |
3106 | cfq_cic_free(cic); | |
3107 | err: | |
3108 | put_io_context(ioc); | |
3109 | return NULL; | |
3110 | } | |
3111 | ||
3112 | static void | |
3113 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
3114 | { | |
3115 | unsigned long elapsed = jiffies - cic->last_end_request; | |
3116 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
3117 | ||
3118 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; | |
3119 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
3120 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
3121 | } | |
3122 | ||
3123 | static void | |
3124 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
3125 | struct request *rq) | |
3126 | { | |
3127 | sector_t sdist = 0; | |
3128 | sector_t n_sec = blk_rq_sectors(rq); | |
3129 | if (cfqq->last_request_pos) { | |
3130 | if (cfqq->last_request_pos < blk_rq_pos(rq)) | |
3131 | sdist = blk_rq_pos(rq) - cfqq->last_request_pos; | |
3132 | else | |
3133 | sdist = cfqq->last_request_pos - blk_rq_pos(rq); | |
3134 | } | |
3135 | ||
3136 | cfqq->seek_history <<= 1; | |
3137 | if (blk_queue_nonrot(cfqd->queue)) | |
3138 | cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); | |
3139 | else | |
3140 | cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); | |
3141 | } | |
3142 | ||
3143 | /* | |
3144 | * Disable idle window if the process thinks too long or seeks so much that | |
3145 | * it doesn't matter | |
3146 | */ | |
3147 | static void | |
3148 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
3149 | struct cfq_io_context *cic) | |
3150 | { | |
3151 | int old_idle, enable_idle; | |
3152 | ||
3153 | /* | |
3154 | * Don't idle for async or idle io prio class | |
3155 | */ | |
3156 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) | |
3157 | return; | |
3158 | ||
3159 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); | |
3160 | ||
3161 | if (cfqq->queued[0] + cfqq->queued[1] >= 4) | |
3162 | cfq_mark_cfqq_deep(cfqq); | |
3163 | ||
3164 | if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) | |
3165 | enable_idle = 0; | |
3166 | else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || | |
3167 | (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) | |
3168 | enable_idle = 0; | |
3169 | else if (sample_valid(cic->ttime_samples)) { | |
3170 | if (cic->ttime_mean > cfqd->cfq_slice_idle) | |
3171 | enable_idle = 0; | |
3172 | else | |
3173 | enable_idle = 1; | |
3174 | } | |
3175 | ||
3176 | if (old_idle != enable_idle) { | |
3177 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); | |
3178 | if (enable_idle) | |
3179 | cfq_mark_cfqq_idle_window(cfqq); | |
3180 | else | |
3181 | cfq_clear_cfqq_idle_window(cfqq); | |
3182 | } | |
3183 | } | |
3184 | ||
3185 | /* | |
3186 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
3187 | * no or if we aren't sure, a 1 will cause a preempt. | |
3188 | */ | |
3189 | static bool | |
3190 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, | |
3191 | struct request *rq) | |
3192 | { | |
3193 | struct cfq_queue *cfqq; | |
3194 | ||
3195 | cfqq = cfqd->active_queue; | |
3196 | if (!cfqq) | |
3197 | return false; | |
3198 | ||
3199 | if (cfq_class_idle(new_cfqq)) | |
3200 | return false; | |
3201 | ||
3202 | if (cfq_class_idle(cfqq)) | |
3203 | return true; | |
3204 | ||
3205 | /* | |
3206 | * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. | |
3207 | */ | |
3208 | if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) | |
3209 | return false; | |
3210 | ||
3211 | /* | |
3212 | * if the new request is sync, but the currently running queue is | |
3213 | * not, let the sync request have priority. | |
3214 | */ | |
3215 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) | |
3216 | return true; | |
3217 | ||
3218 | if (new_cfqq->cfqg != cfqq->cfqg) | |
3219 | return false; | |
3220 | ||
3221 | if (cfq_slice_used(cfqq)) | |
3222 | return true; | |
3223 | ||
3224 | /* Allow preemption only if we are idling on sync-noidle tree */ | |
3225 | if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && | |
3226 | cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && | |
3227 | new_cfqq->service_tree->count == 2 && | |
3228 | RB_EMPTY_ROOT(&cfqq->sort_list)) | |
3229 | return true; | |
3230 | ||
3231 | /* | |
3232 | * So both queues are sync. Let the new request get disk time if | |
3233 | * it's a metadata request and the current queue is doing regular IO. | |
3234 | */ | |
3235 | if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending) | |
3236 | return true; | |
3237 | ||
3238 | /* | |
3239 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. | |
3240 | */ | |
3241 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) | |
3242 | return true; | |
3243 | ||
3244 | /* An idle queue should not be idle now for some reason */ | |
3245 | if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) | |
3246 | return true; | |
3247 | ||
3248 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) | |
3249 | return false; | |
3250 | ||
3251 | /* | |
3252 | * if this request is as-good as one we would expect from the | |
3253 | * current cfqq, let it preempt | |
3254 | */ | |
3255 | if (cfq_rq_close(cfqd, cfqq, rq)) | |
3256 | return true; | |
3257 | ||
3258 | return false; | |
3259 | } | |
3260 | ||
3261 | /* | |
3262 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
3263 | * let it have half of its nominal slice. | |
3264 | */ | |
3265 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
3266 | { | |
3267 | struct cfq_queue *old_cfqq = cfqd->active_queue; | |
3268 | ||
3269 | cfq_log_cfqq(cfqd, cfqq, "preempt"); | |
3270 | cfq_slice_expired(cfqd, 1); | |
3271 | ||
3272 | /* | |
3273 | * workload type is changed, don't save slice, otherwise preempt | |
3274 | * doesn't happen | |
3275 | */ | |
3276 | if (cfqq_type(old_cfqq) != cfqq_type(cfqq)) | |
3277 | cfqq->cfqg->saved_workload_slice = 0; | |
3278 | ||
3279 | /* | |
3280 | * Put the new queue at the front of the of the current list, | |
3281 | * so we know that it will be selected next. | |
3282 | */ | |
3283 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
3284 | ||
3285 | cfq_service_tree_add(cfqd, cfqq, 1); | |
3286 | ||
3287 | cfqq->slice_end = 0; | |
3288 | cfq_mark_cfqq_slice_new(cfqq); | |
3289 | } | |
3290 | ||
3291 | /* | |
3292 | * Called when a new fs request (rq) is added (to cfqq). Check if there's | |
3293 | * something we should do about it | |
3294 | */ | |
3295 | static void | |
3296 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
3297 | struct request *rq) | |
3298 | { | |
3299 | struct cfq_io_context *cic = RQ_CIC(rq); | |
3300 | ||
3301 | cfqd->rq_queued++; | |
3302 | if (rq->cmd_flags & REQ_META) | |
3303 | cfqq->meta_pending++; | |
3304 | ||
3305 | cfq_update_io_thinktime(cfqd, cic); | |
3306 | cfq_update_io_seektime(cfqd, cfqq, rq); | |
3307 | cfq_update_idle_window(cfqd, cfqq, cic); | |
3308 | ||
3309 | cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); | |
3310 | ||
3311 | if (cfqq == cfqd->active_queue) { | |
3312 | /* | |
3313 | * Remember that we saw a request from this process, but | |
3314 | * don't start queuing just yet. Otherwise we risk seeing lots | |
3315 | * of tiny requests, because we disrupt the normal plugging | |
3316 | * and merging. If the request is already larger than a single | |
3317 | * page, let it rip immediately. For that case we assume that | |
3318 | * merging is already done. Ditto for a busy system that | |
3319 | * has other work pending, don't risk delaying until the | |
3320 | * idle timer unplug to continue working. | |
3321 | */ | |
3322 | if (cfq_cfqq_wait_request(cfqq)) { | |
3323 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || | |
3324 | cfqd->busy_queues > 1) { | |
3325 | cfq_del_timer(cfqd, cfqq); | |
3326 | cfq_clear_cfqq_wait_request(cfqq); | |
3327 | __blk_run_queue(cfqd->queue); | |
3328 | } else { | |
3329 | cfq_blkiocg_update_idle_time_stats( | |
3330 | &cfqq->cfqg->blkg); | |
3331 | cfq_mark_cfqq_must_dispatch(cfqq); | |
3332 | } | |
3333 | } | |
3334 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { | |
3335 | /* | |
3336 | * not the active queue - expire current slice if it is | |
3337 | * idle and has expired it's mean thinktime or this new queue | |
3338 | * has some old slice time left and is of higher priority or | |
3339 | * this new queue is RT and the current one is BE | |
3340 | */ | |
3341 | cfq_preempt_queue(cfqd, cfqq); | |
3342 | __blk_run_queue(cfqd->queue); | |
3343 | } | |
3344 | } | |
3345 | ||
3346 | static void cfq_insert_request(struct request_queue *q, struct request *rq) | |
3347 | { | |
3348 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3349 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
3350 | ||
3351 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); | |
3352 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); | |
3353 | ||
3354 | rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); | |
3355 | list_add_tail(&rq->queuelist, &cfqq->fifo); | |
3356 | cfq_add_rq_rb(rq); | |
3357 | cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, | |
3358 | &cfqd->serving_group->blkg, rq_data_dir(rq), | |
3359 | rq_is_sync(rq)); | |
3360 | cfq_rq_enqueued(cfqd, cfqq, rq); | |
3361 | } | |
3362 | ||
3363 | /* | |
3364 | * Update hw_tag based on peak queue depth over 50 samples under | |
3365 | * sufficient load. | |
3366 | */ | |
3367 | static void cfq_update_hw_tag(struct cfq_data *cfqd) | |
3368 | { | |
3369 | struct cfq_queue *cfqq = cfqd->active_queue; | |
3370 | ||
3371 | if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) | |
3372 | cfqd->hw_tag_est_depth = cfqd->rq_in_driver; | |
3373 | ||
3374 | if (cfqd->hw_tag == 1) | |
3375 | return; | |
3376 | ||
3377 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && | |
3378 | cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) | |
3379 | return; | |
3380 | ||
3381 | /* | |
3382 | * If active queue hasn't enough requests and can idle, cfq might not | |
3383 | * dispatch sufficient requests to hardware. Don't zero hw_tag in this | |
3384 | * case | |
3385 | */ | |
3386 | if (cfqq && cfq_cfqq_idle_window(cfqq) && | |
3387 | cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < | |
3388 | CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) | |
3389 | return; | |
3390 | ||
3391 | if (cfqd->hw_tag_samples++ < 50) | |
3392 | return; | |
3393 | ||
3394 | if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) | |
3395 | cfqd->hw_tag = 1; | |
3396 | else | |
3397 | cfqd->hw_tag = 0; | |
3398 | } | |
3399 | ||
3400 | static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
3401 | { | |
3402 | struct cfq_io_context *cic = cfqd->active_cic; | |
3403 | ||
3404 | /* If the queue already has requests, don't wait */ | |
3405 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) | |
3406 | return false; | |
3407 | ||
3408 | /* If there are other queues in the group, don't wait */ | |
3409 | if (cfqq->cfqg->nr_cfqq > 1) | |
3410 | return false; | |
3411 | ||
3412 | if (cfq_slice_used(cfqq)) | |
3413 | return true; | |
3414 | ||
3415 | /* if slice left is less than think time, wait busy */ | |
3416 | if (cic && sample_valid(cic->ttime_samples) | |
3417 | && (cfqq->slice_end - jiffies < cic->ttime_mean)) | |
3418 | return true; | |
3419 | ||
3420 | /* | |
3421 | * If think times is less than a jiffy than ttime_mean=0 and above | |
3422 | * will not be true. It might happen that slice has not expired yet | |
3423 | * but will expire soon (4-5 ns) during select_queue(). To cover the | |
3424 | * case where think time is less than a jiffy, mark the queue wait | |
3425 | * busy if only 1 jiffy is left in the slice. | |
3426 | */ | |
3427 | if (cfqq->slice_end - jiffies == 1) | |
3428 | return true; | |
3429 | ||
3430 | return false; | |
3431 | } | |
3432 | ||
3433 | static void cfq_completed_request(struct request_queue *q, struct request *rq) | |
3434 | { | |
3435 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
3436 | struct cfq_data *cfqd = cfqq->cfqd; | |
3437 | const int sync = rq_is_sync(rq); | |
3438 | unsigned long now; | |
3439 | ||
3440 | now = jiffies; | |
3441 | cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", | |
3442 | !!(rq->cmd_flags & REQ_NOIDLE)); | |
3443 | ||
3444 | cfq_update_hw_tag(cfqd); | |
3445 | ||
3446 | WARN_ON(!cfqd->rq_in_driver); | |
3447 | WARN_ON(!cfqq->dispatched); | |
3448 | cfqd->rq_in_driver--; | |
3449 | cfqq->dispatched--; | |
3450 | (RQ_CFQG(rq))->dispatched--; | |
3451 | cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg, | |
3452 | rq_start_time_ns(rq), rq_io_start_time_ns(rq), | |
3453 | rq_data_dir(rq), rq_is_sync(rq)); | |
3454 | ||
3455 | cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; | |
3456 | ||
3457 | if (sync) { | |
3458 | RQ_CIC(rq)->last_end_request = now; | |
3459 | if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) | |
3460 | cfqd->last_delayed_sync = now; | |
3461 | } | |
3462 | ||
3463 | /* | |
3464 | * If this is the active queue, check if it needs to be expired, | |
3465 | * or if we want to idle in case it has no pending requests. | |
3466 | */ | |
3467 | if (cfqd->active_queue == cfqq) { | |
3468 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); | |
3469 | ||
3470 | if (cfq_cfqq_slice_new(cfqq)) { | |
3471 | cfq_set_prio_slice(cfqd, cfqq); | |
3472 | cfq_clear_cfqq_slice_new(cfqq); | |
3473 | } | |
3474 | ||
3475 | /* | |
3476 | * Should we wait for next request to come in before we expire | |
3477 | * the queue. | |
3478 | */ | |
3479 | if (cfq_should_wait_busy(cfqd, cfqq)) { | |
3480 | unsigned long extend_sl = cfqd->cfq_slice_idle; | |
3481 | if (!cfqd->cfq_slice_idle) | |
3482 | extend_sl = cfqd->cfq_group_idle; | |
3483 | cfqq->slice_end = jiffies + extend_sl; | |
3484 | cfq_mark_cfqq_wait_busy(cfqq); | |
3485 | cfq_log_cfqq(cfqd, cfqq, "will busy wait"); | |
3486 | } | |
3487 | ||
3488 | /* | |
3489 | * Idling is not enabled on: | |
3490 | * - expired queues | |
3491 | * - idle-priority queues | |
3492 | * - async queues | |
3493 | * - queues with still some requests queued | |
3494 | * - when there is a close cooperator | |
3495 | */ | |
3496 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) | |
3497 | cfq_slice_expired(cfqd, 1); | |
3498 | else if (sync && cfqq_empty && | |
3499 | !cfq_close_cooperator(cfqd, cfqq)) { | |
3500 | cfq_arm_slice_timer(cfqd); | |
3501 | } | |
3502 | } | |
3503 | ||
3504 | if (!cfqd->rq_in_driver) | |
3505 | cfq_schedule_dispatch(cfqd); | |
3506 | } | |
3507 | ||
3508 | /* | |
3509 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
3510 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
3511 | */ | |
3512 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
3513 | { | |
3514 | if (has_fs_excl()) { | |
3515 | /* | |
3516 | * boost idle prio on transactions that would lock out other | |
3517 | * users of the filesystem | |
3518 | */ | |
3519 | if (cfq_class_idle(cfqq)) | |
3520 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
3521 | if (cfqq->ioprio > IOPRIO_NORM) | |
3522 | cfqq->ioprio = IOPRIO_NORM; | |
3523 | } else { | |
3524 | /* | |
3525 | * unboost the queue (if needed) | |
3526 | */ | |
3527 | cfqq->ioprio_class = cfqq->org_ioprio_class; | |
3528 | cfqq->ioprio = cfqq->org_ioprio; | |
3529 | } | |
3530 | } | |
3531 | ||
3532 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) | |
3533 | { | |
3534 | if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { | |
3535 | cfq_mark_cfqq_must_alloc_slice(cfqq); | |
3536 | return ELV_MQUEUE_MUST; | |
3537 | } | |
3538 | ||
3539 | return ELV_MQUEUE_MAY; | |
3540 | } | |
3541 | ||
3542 | static int cfq_may_queue(struct request_queue *q, int rw) | |
3543 | { | |
3544 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3545 | struct task_struct *tsk = current; | |
3546 | struct cfq_io_context *cic; | |
3547 | struct cfq_queue *cfqq; | |
3548 | ||
3549 | /* | |
3550 | * don't force setup of a queue from here, as a call to may_queue | |
3551 | * does not necessarily imply that a request actually will be queued. | |
3552 | * so just lookup a possibly existing queue, or return 'may queue' | |
3553 | * if that fails | |
3554 | */ | |
3555 | cic = cfq_cic_lookup(cfqd, tsk->io_context); | |
3556 | if (!cic) | |
3557 | return ELV_MQUEUE_MAY; | |
3558 | ||
3559 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); | |
3560 | if (cfqq) { | |
3561 | cfq_init_prio_data(cfqq, cic->ioc); | |
3562 | cfq_prio_boost(cfqq); | |
3563 | ||
3564 | return __cfq_may_queue(cfqq); | |
3565 | } | |
3566 | ||
3567 | return ELV_MQUEUE_MAY; | |
3568 | } | |
3569 | ||
3570 | /* | |
3571 | * queue lock held here | |
3572 | */ | |
3573 | static void cfq_put_request(struct request *rq) | |
3574 | { | |
3575 | struct cfq_queue *cfqq = RQ_CFQQ(rq); | |
3576 | ||
3577 | if (cfqq) { | |
3578 | const int rw = rq_data_dir(rq); | |
3579 | ||
3580 | BUG_ON(!cfqq->allocated[rw]); | |
3581 | cfqq->allocated[rw]--; | |
3582 | ||
3583 | put_io_context(RQ_CIC(rq)->ioc); | |
3584 | ||
3585 | rq->elevator_private[0] = NULL; | |
3586 | rq->elevator_private[1] = NULL; | |
3587 | ||
3588 | /* Put down rq reference on cfqg */ | |
3589 | cfq_put_cfqg(RQ_CFQG(rq)); | |
3590 | rq->elevator_private[2] = NULL; | |
3591 | ||
3592 | cfq_put_queue(cfqq); | |
3593 | } | |
3594 | } | |
3595 | ||
3596 | static struct cfq_queue * | |
3597 | cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
3598 | struct cfq_queue *cfqq) | |
3599 | { | |
3600 | cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); | |
3601 | cic_set_cfqq(cic, cfqq->new_cfqq, 1); | |
3602 | cfq_mark_cfqq_coop(cfqq->new_cfqq); | |
3603 | cfq_put_queue(cfqq); | |
3604 | return cic_to_cfqq(cic, 1); | |
3605 | } | |
3606 | ||
3607 | /* | |
3608 | * Returns NULL if a new cfqq should be allocated, or the old cfqq if this | |
3609 | * was the last process referring to said cfqq. | |
3610 | */ | |
3611 | static struct cfq_queue * | |
3612 | split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) | |
3613 | { | |
3614 | if (cfqq_process_refs(cfqq) == 1) { | |
3615 | cfqq->pid = current->pid; | |
3616 | cfq_clear_cfqq_coop(cfqq); | |
3617 | cfq_clear_cfqq_split_coop(cfqq); | |
3618 | return cfqq; | |
3619 | } | |
3620 | ||
3621 | cic_set_cfqq(cic, NULL, 1); | |
3622 | ||
3623 | cfq_put_cooperator(cfqq); | |
3624 | ||
3625 | cfq_put_queue(cfqq); | |
3626 | return NULL; | |
3627 | } | |
3628 | /* | |
3629 | * Allocate cfq data structures associated with this request. | |
3630 | */ | |
3631 | static int | |
3632 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) | |
3633 | { | |
3634 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
3635 | struct cfq_io_context *cic; | |
3636 | const int rw = rq_data_dir(rq); | |
3637 | const bool is_sync = rq_is_sync(rq); | |
3638 | struct cfq_queue *cfqq; | |
3639 | unsigned long flags; | |
3640 | ||
3641 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
3642 | ||
3643 | cic = cfq_get_io_context(cfqd, gfp_mask); | |
3644 | ||
3645 | spin_lock_irqsave(q->queue_lock, flags); | |
3646 | ||
3647 | if (!cic) | |
3648 | goto queue_fail; | |
3649 | ||
3650 | new_queue: | |
3651 | cfqq = cic_to_cfqq(cic, is_sync); | |
3652 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { | |
3653 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); | |
3654 | cic_set_cfqq(cic, cfqq, is_sync); | |
3655 | } else { | |
3656 | /* | |
3657 | * If the queue was seeky for too long, break it apart. | |
3658 | */ | |
3659 | if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { | |
3660 | cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); | |
3661 | cfqq = split_cfqq(cic, cfqq); | |
3662 | if (!cfqq) | |
3663 | goto new_queue; | |
3664 | } | |
3665 | ||
3666 | /* | |
3667 | * Check to see if this queue is scheduled to merge with | |
3668 | * another, closely cooperating queue. The merging of | |
3669 | * queues happens here as it must be done in process context. | |
3670 | * The reference on new_cfqq was taken in merge_cfqqs. | |
3671 | */ | |
3672 | if (cfqq->new_cfqq) | |
3673 | cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); | |
3674 | } | |
3675 | ||
3676 | cfqq->allocated[rw]++; | |
3677 | ||
3678 | cfqq->ref++; | |
3679 | rq->elevator_private[0] = cic; | |
3680 | rq->elevator_private[1] = cfqq; | |
3681 | rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg); | |
3682 | spin_unlock_irqrestore(q->queue_lock, flags); | |
3683 | return 0; | |
3684 | ||
3685 | queue_fail: | |
3686 | if (cic) | |
3687 | put_io_context(cic->ioc); | |
3688 | ||
3689 | cfq_schedule_dispatch(cfqd); | |
3690 | spin_unlock_irqrestore(q->queue_lock, flags); | |
3691 | cfq_log(cfqd, "set_request fail"); | |
3692 | return 1; | |
3693 | } | |
3694 | ||
3695 | static void cfq_kick_queue(struct work_struct *work) | |
3696 | { | |
3697 | struct cfq_data *cfqd = | |
3698 | container_of(work, struct cfq_data, unplug_work); | |
3699 | struct request_queue *q = cfqd->queue; | |
3700 | ||
3701 | spin_lock_irq(q->queue_lock); | |
3702 | __blk_run_queue(cfqd->queue); | |
3703 | spin_unlock_irq(q->queue_lock); | |
3704 | } | |
3705 | ||
3706 | /* | |
3707 | * Timer running if the active_queue is currently idling inside its time slice | |
3708 | */ | |
3709 | static void cfq_idle_slice_timer(unsigned long data) | |
3710 | { | |
3711 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
3712 | struct cfq_queue *cfqq; | |
3713 | unsigned long flags; | |
3714 | int timed_out = 1; | |
3715 | ||
3716 | cfq_log(cfqd, "idle timer fired"); | |
3717 | ||
3718 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
3719 | ||
3720 | cfqq = cfqd->active_queue; | |
3721 | if (cfqq) { | |
3722 | timed_out = 0; | |
3723 | ||
3724 | /* | |
3725 | * We saw a request before the queue expired, let it through | |
3726 | */ | |
3727 | if (cfq_cfqq_must_dispatch(cfqq)) | |
3728 | goto out_kick; | |
3729 | ||
3730 | /* | |
3731 | * expired | |
3732 | */ | |
3733 | if (cfq_slice_used(cfqq)) | |
3734 | goto expire; | |
3735 | ||
3736 | /* | |
3737 | * only expire and reinvoke request handler, if there are | |
3738 | * other queues with pending requests | |
3739 | */ | |
3740 | if (!cfqd->busy_queues) | |
3741 | goto out_cont; | |
3742 | ||
3743 | /* | |
3744 | * not expired and it has a request pending, let it dispatch | |
3745 | */ | |
3746 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) | |
3747 | goto out_kick; | |
3748 | ||
3749 | /* | |
3750 | * Queue depth flag is reset only when the idle didn't succeed | |
3751 | */ | |
3752 | cfq_clear_cfqq_deep(cfqq); | |
3753 | } | |
3754 | expire: | |
3755 | cfq_slice_expired(cfqd, timed_out); | |
3756 | out_kick: | |
3757 | cfq_schedule_dispatch(cfqd); | |
3758 | out_cont: | |
3759 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
3760 | } | |
3761 | ||
3762 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) | |
3763 | { | |
3764 | del_timer_sync(&cfqd->idle_slice_timer); | |
3765 | cancel_work_sync(&cfqd->unplug_work); | |
3766 | } | |
3767 | ||
3768 | static void cfq_put_async_queues(struct cfq_data *cfqd) | |
3769 | { | |
3770 | int i; | |
3771 | ||
3772 | for (i = 0; i < IOPRIO_BE_NR; i++) { | |
3773 | if (cfqd->async_cfqq[0][i]) | |
3774 | cfq_put_queue(cfqd->async_cfqq[0][i]); | |
3775 | if (cfqd->async_cfqq[1][i]) | |
3776 | cfq_put_queue(cfqd->async_cfqq[1][i]); | |
3777 | } | |
3778 | ||
3779 | if (cfqd->async_idle_cfqq) | |
3780 | cfq_put_queue(cfqd->async_idle_cfqq); | |
3781 | } | |
3782 | ||
3783 | static void cfq_cfqd_free(struct rcu_head *head) | |
3784 | { | |
3785 | kfree(container_of(head, struct cfq_data, rcu)); | |
3786 | } | |
3787 | ||
3788 | static void cfq_exit_queue(struct elevator_queue *e) | |
3789 | { | |
3790 | struct cfq_data *cfqd = e->elevator_data; | |
3791 | struct request_queue *q = cfqd->queue; | |
3792 | ||
3793 | cfq_shutdown_timer_wq(cfqd); | |
3794 | ||
3795 | spin_lock_irq(q->queue_lock); | |
3796 | ||
3797 | if (cfqd->active_queue) | |
3798 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); | |
3799 | ||
3800 | while (!list_empty(&cfqd->cic_list)) { | |
3801 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, | |
3802 | struct cfq_io_context, | |
3803 | queue_list); | |
3804 | ||
3805 | __cfq_exit_single_io_context(cfqd, cic); | |
3806 | } | |
3807 | ||
3808 | cfq_put_async_queues(cfqd); | |
3809 | cfq_release_cfq_groups(cfqd); | |
3810 | cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg); | |
3811 | ||
3812 | spin_unlock_irq(q->queue_lock); | |
3813 | ||
3814 | cfq_shutdown_timer_wq(cfqd); | |
3815 | ||
3816 | spin_lock(&cic_index_lock); | |
3817 | ida_remove(&cic_index_ida, cfqd->cic_index); | |
3818 | spin_unlock(&cic_index_lock); | |
3819 | ||
3820 | /* Wait for cfqg->blkg->key accessors to exit their grace periods. */ | |
3821 | call_rcu(&cfqd->rcu, cfq_cfqd_free); | |
3822 | } | |
3823 | ||
3824 | static int cfq_alloc_cic_index(void) | |
3825 | { | |
3826 | int index, error; | |
3827 | ||
3828 | do { | |
3829 | if (!ida_pre_get(&cic_index_ida, GFP_KERNEL)) | |
3830 | return -ENOMEM; | |
3831 | ||
3832 | spin_lock(&cic_index_lock); | |
3833 | error = ida_get_new(&cic_index_ida, &index); | |
3834 | spin_unlock(&cic_index_lock); | |
3835 | if (error && error != -EAGAIN) | |
3836 | return error; | |
3837 | } while (error); | |
3838 | ||
3839 | return index; | |
3840 | } | |
3841 | ||
3842 | static void *cfq_init_queue(struct request_queue *q) | |
3843 | { | |
3844 | struct cfq_data *cfqd; | |
3845 | int i, j; | |
3846 | struct cfq_group *cfqg; | |
3847 | struct cfq_rb_root *st; | |
3848 | ||
3849 | i = cfq_alloc_cic_index(); | |
3850 | if (i < 0) | |
3851 | return NULL; | |
3852 | ||
3853 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); | |
3854 | if (!cfqd) | |
3855 | return NULL; | |
3856 | ||
3857 | /* | |
3858 | * Don't need take queue_lock in the routine, since we are | |
3859 | * initializing the ioscheduler, and nobody is using cfqd | |
3860 | */ | |
3861 | cfqd->cic_index = i; | |
3862 | ||
3863 | /* Init root service tree */ | |
3864 | cfqd->grp_service_tree = CFQ_RB_ROOT; | |
3865 | ||
3866 | /* Init root group */ | |
3867 | cfqg = &cfqd->root_group; | |
3868 | for_each_cfqg_st(cfqg, i, j, st) | |
3869 | *st = CFQ_RB_ROOT; | |
3870 | RB_CLEAR_NODE(&cfqg->rb_node); | |
3871 | ||
3872 | /* Give preference to root group over other groups */ | |
3873 | cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; | |
3874 | ||
3875 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
3876 | /* | |
3877 | * Take a reference to root group which we never drop. This is just | |
3878 | * to make sure that cfq_put_cfqg() does not try to kfree root group | |
3879 | */ | |
3880 | cfqg->ref = 1; | |
3881 | rcu_read_lock(); | |
3882 | cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, | |
3883 | (void *)cfqd, 0); | |
3884 | rcu_read_unlock(); | |
3885 | #endif | |
3886 | /* | |
3887 | * Not strictly needed (since RB_ROOT just clears the node and we | |
3888 | * zeroed cfqd on alloc), but better be safe in case someone decides | |
3889 | * to add magic to the rb code | |
3890 | */ | |
3891 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
3892 | cfqd->prio_trees[i] = RB_ROOT; | |
3893 | ||
3894 | /* | |
3895 | * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. | |
3896 | * Grab a permanent reference to it, so that the normal code flow | |
3897 | * will not attempt to free it. | |
3898 | */ | |
3899 | cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); | |
3900 | cfqd->oom_cfqq.ref++; | |
3901 | cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); | |
3902 | ||
3903 | INIT_LIST_HEAD(&cfqd->cic_list); | |
3904 | ||
3905 | cfqd->queue = q; | |
3906 | ||
3907 | init_timer(&cfqd->idle_slice_timer); | |
3908 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
3909 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
3910 | ||
3911 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); | |
3912 | ||
3913 | cfqd->cfq_quantum = cfq_quantum; | |
3914 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; | |
3915 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
3916 | cfqd->cfq_back_max = cfq_back_max; | |
3917 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
3918 | cfqd->cfq_slice[0] = cfq_slice_async; | |
3919 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
3920 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
3921 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
3922 | cfqd->cfq_group_idle = cfq_group_idle; | |
3923 | cfqd->cfq_latency = 1; | |
3924 | cfqd->hw_tag = -1; | |
3925 | /* | |
3926 | * we optimistically start assuming sync ops weren't delayed in last | |
3927 | * second, in order to have larger depth for async operations. | |
3928 | */ | |
3929 | cfqd->last_delayed_sync = jiffies - HZ; | |
3930 | return cfqd; | |
3931 | } | |
3932 | ||
3933 | static void cfq_slab_kill(void) | |
3934 | { | |
3935 | /* | |
3936 | * Caller already ensured that pending RCU callbacks are completed, | |
3937 | * so we should have no busy allocations at this point. | |
3938 | */ | |
3939 | if (cfq_pool) | |
3940 | kmem_cache_destroy(cfq_pool); | |
3941 | if (cfq_ioc_pool) | |
3942 | kmem_cache_destroy(cfq_ioc_pool); | |
3943 | } | |
3944 | ||
3945 | static int __init cfq_slab_setup(void) | |
3946 | { | |
3947 | cfq_pool = KMEM_CACHE(cfq_queue, 0); | |
3948 | if (!cfq_pool) | |
3949 | goto fail; | |
3950 | ||
3951 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); | |
3952 | if (!cfq_ioc_pool) | |
3953 | goto fail; | |
3954 | ||
3955 | return 0; | |
3956 | fail: | |
3957 | cfq_slab_kill(); | |
3958 | return -ENOMEM; | |
3959 | } | |
3960 | ||
3961 | /* | |
3962 | * sysfs parts below --> | |
3963 | */ | |
3964 | static ssize_t | |
3965 | cfq_var_show(unsigned int var, char *page) | |
3966 | { | |
3967 | return sprintf(page, "%d\n", var); | |
3968 | } | |
3969 | ||
3970 | static ssize_t | |
3971 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
3972 | { | |
3973 | char *p = (char *) page; | |
3974 | ||
3975 | *var = simple_strtoul(p, &p, 10); | |
3976 | return count; | |
3977 | } | |
3978 | ||
3979 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ | |
3980 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ | |
3981 | { \ | |
3982 | struct cfq_data *cfqd = e->elevator_data; \ | |
3983 | unsigned int __data = __VAR; \ | |
3984 | if (__CONV) \ | |
3985 | __data = jiffies_to_msecs(__data); \ | |
3986 | return cfq_var_show(__data, (page)); \ | |
3987 | } | |
3988 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
3989 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); | |
3990 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
3991 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); | |
3992 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
3993 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); | |
3994 | SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); | |
3995 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
3996 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
3997 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
3998 | SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); | |
3999 | #undef SHOW_FUNCTION | |
4000 | ||
4001 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
4002 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ | |
4003 | { \ | |
4004 | struct cfq_data *cfqd = e->elevator_data; \ | |
4005 | unsigned int __data; \ | |
4006 | int ret = cfq_var_store(&__data, (page), count); \ | |
4007 | if (__data < (MIN)) \ | |
4008 | __data = (MIN); \ | |
4009 | else if (__data > (MAX)) \ | |
4010 | __data = (MAX); \ | |
4011 | if (__CONV) \ | |
4012 | *(__PTR) = msecs_to_jiffies(__data); \ | |
4013 | else \ | |
4014 | *(__PTR) = __data; \ | |
4015 | return ret; \ | |
4016 | } | |
4017 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
4018 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, | |
4019 | UINT_MAX, 1); | |
4020 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, | |
4021 | UINT_MAX, 1); | |
4022 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); | |
4023 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, | |
4024 | UINT_MAX, 0); | |
4025 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); | |
4026 | STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); | |
4027 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
4028 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
4029 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, | |
4030 | UINT_MAX, 0); | |
4031 | STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); | |
4032 | #undef STORE_FUNCTION | |
4033 | ||
4034 | #define CFQ_ATTR(name) \ | |
4035 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
4036 | ||
4037 | static struct elv_fs_entry cfq_attrs[] = { | |
4038 | CFQ_ATTR(quantum), | |
4039 | CFQ_ATTR(fifo_expire_sync), | |
4040 | CFQ_ATTR(fifo_expire_async), | |
4041 | CFQ_ATTR(back_seek_max), | |
4042 | CFQ_ATTR(back_seek_penalty), | |
4043 | CFQ_ATTR(slice_sync), | |
4044 | CFQ_ATTR(slice_async), | |
4045 | CFQ_ATTR(slice_async_rq), | |
4046 | CFQ_ATTR(slice_idle), | |
4047 | CFQ_ATTR(group_idle), | |
4048 | CFQ_ATTR(low_latency), | |
4049 | __ATTR_NULL | |
4050 | }; | |
4051 | ||
4052 | static struct elevator_type iosched_cfq = { | |
4053 | .ops = { | |
4054 | .elevator_merge_fn = cfq_merge, | |
4055 | .elevator_merged_fn = cfq_merged_request, | |
4056 | .elevator_merge_req_fn = cfq_merged_requests, | |
4057 | .elevator_allow_merge_fn = cfq_allow_merge, | |
4058 | .elevator_bio_merged_fn = cfq_bio_merged, | |
4059 | .elevator_dispatch_fn = cfq_dispatch_requests, | |
4060 | .elevator_add_req_fn = cfq_insert_request, | |
4061 | .elevator_activate_req_fn = cfq_activate_request, | |
4062 | .elevator_deactivate_req_fn = cfq_deactivate_request, | |
4063 | .elevator_queue_empty_fn = cfq_queue_empty, | |
4064 | .elevator_completed_req_fn = cfq_completed_request, | |
4065 | .elevator_former_req_fn = elv_rb_former_request, | |
4066 | .elevator_latter_req_fn = elv_rb_latter_request, | |
4067 | .elevator_set_req_fn = cfq_set_request, | |
4068 | .elevator_put_req_fn = cfq_put_request, | |
4069 | .elevator_may_queue_fn = cfq_may_queue, | |
4070 | .elevator_init_fn = cfq_init_queue, | |
4071 | .elevator_exit_fn = cfq_exit_queue, | |
4072 | .trim = cfq_free_io_context, | |
4073 | }, | |
4074 | .elevator_attrs = cfq_attrs, | |
4075 | .elevator_name = "cfq", | |
4076 | .elevator_owner = THIS_MODULE, | |
4077 | }; | |
4078 | ||
4079 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
4080 | static struct blkio_policy_type blkio_policy_cfq = { | |
4081 | .ops = { | |
4082 | .blkio_unlink_group_fn = cfq_unlink_blkio_group, | |
4083 | .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, | |
4084 | }, | |
4085 | .plid = BLKIO_POLICY_PROP, | |
4086 | }; | |
4087 | #else | |
4088 | static struct blkio_policy_type blkio_policy_cfq; | |
4089 | #endif | |
4090 | ||
4091 | static int __init cfq_init(void) | |
4092 | { | |
4093 | /* | |
4094 | * could be 0 on HZ < 1000 setups | |
4095 | */ | |
4096 | if (!cfq_slice_async) | |
4097 | cfq_slice_async = 1; | |
4098 | if (!cfq_slice_idle) | |
4099 | cfq_slice_idle = 1; | |
4100 | ||
4101 | #ifdef CONFIG_CFQ_GROUP_IOSCHED | |
4102 | if (!cfq_group_idle) | |
4103 | cfq_group_idle = 1; | |
4104 | #else | |
4105 | cfq_group_idle = 0; | |
4106 | #endif | |
4107 | if (cfq_slab_setup()) | |
4108 | return -ENOMEM; | |
4109 | ||
4110 | elv_register(&iosched_cfq); | |
4111 | blkio_policy_register(&blkio_policy_cfq); | |
4112 | ||
4113 | return 0; | |
4114 | } | |
4115 | ||
4116 | static void __exit cfq_exit(void) | |
4117 | { | |
4118 | DECLARE_COMPLETION_ONSTACK(all_gone); | |
4119 | blkio_policy_unregister(&blkio_policy_cfq); | |
4120 | elv_unregister(&iosched_cfq); | |
4121 | ioc_gone = &all_gone; | |
4122 | /* ioc_gone's update must be visible before reading ioc_count */ | |
4123 | smp_wmb(); | |
4124 | ||
4125 | /* | |
4126 | * this also protects us from entering cfq_slab_kill() with | |
4127 | * pending RCU callbacks | |
4128 | */ | |
4129 | if (elv_ioc_count_read(cfq_ioc_count)) | |
4130 | wait_for_completion(&all_gone); | |
4131 | ida_destroy(&cic_index_ida); | |
4132 | cfq_slab_kill(); | |
4133 | } | |
4134 | ||
4135 | module_init(cfq_init); | |
4136 | module_exit(cfq_exit); | |
4137 | ||
4138 | MODULE_AUTHOR("Jens Axboe"); | |
4139 | MODULE_LICENSE("GPL"); | |
4140 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |