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1 | /* | |
2 | * Interface for controlling IO bandwidth on a request queue | |
3 | * | |
4 | * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com> | |
5 | */ | |
6 | ||
7 | #include <linux/module.h> | |
8 | #include <linux/slab.h> | |
9 | #include <linux/blkdev.h> | |
10 | #include <linux/bio.h> | |
11 | #include <linux/blktrace_api.h> | |
12 | #include <linux/blk-cgroup.h> | |
13 | #include "blk.h" | |
14 | ||
15 | /* Max dispatch from a group in 1 round */ | |
16 | static int throtl_grp_quantum = 8; | |
17 | ||
18 | /* Total max dispatch from all groups in one round */ | |
19 | static int throtl_quantum = 32; | |
20 | ||
21 | /* Throttling is performed over a slice and after that slice is renewed */ | |
22 | #define DFL_THROTL_SLICE_HD (HZ / 10) | |
23 | #define DFL_THROTL_SLICE_SSD (HZ / 50) | |
24 | #define MAX_THROTL_SLICE (HZ) | |
25 | #define MAX_IDLE_TIME (5L * 1000 * 1000) /* 5 s */ | |
26 | #define MIN_THROTL_BPS (320 * 1024) | |
27 | #define MIN_THROTL_IOPS (10) | |
28 | #define DFL_LATENCY_TARGET (-1L) | |
29 | #define DFL_IDLE_THRESHOLD (0) | |
30 | ||
31 | #define SKIP_LATENCY (((u64)1) << BLK_STAT_RES_SHIFT) | |
32 | ||
33 | static struct blkcg_policy blkcg_policy_throtl; | |
34 | ||
35 | /* A workqueue to queue throttle related work */ | |
36 | static struct workqueue_struct *kthrotld_workqueue; | |
37 | ||
38 | /* | |
39 | * To implement hierarchical throttling, throtl_grps form a tree and bios | |
40 | * are dispatched upwards level by level until they reach the top and get | |
41 | * issued. When dispatching bios from the children and local group at each | |
42 | * level, if the bios are dispatched into a single bio_list, there's a risk | |
43 | * of a local or child group which can queue many bios at once filling up | |
44 | * the list starving others. | |
45 | * | |
46 | * To avoid such starvation, dispatched bios are queued separately | |
47 | * according to where they came from. When they are again dispatched to | |
48 | * the parent, they're popped in round-robin order so that no single source | |
49 | * hogs the dispatch window. | |
50 | * | |
51 | * throtl_qnode is used to keep the queued bios separated by their sources. | |
52 | * Bios are queued to throtl_qnode which in turn is queued to | |
53 | * throtl_service_queue and then dispatched in round-robin order. | |
54 | * | |
55 | * It's also used to track the reference counts on blkg's. A qnode always | |
56 | * belongs to a throtl_grp and gets queued on itself or the parent, so | |
57 | * incrementing the reference of the associated throtl_grp when a qnode is | |
58 | * queued and decrementing when dequeued is enough to keep the whole blkg | |
59 | * tree pinned while bios are in flight. | |
60 | */ | |
61 | struct throtl_qnode { | |
62 | struct list_head node; /* service_queue->queued[] */ | |
63 | struct bio_list bios; /* queued bios */ | |
64 | struct throtl_grp *tg; /* tg this qnode belongs to */ | |
65 | }; | |
66 | ||
67 | struct throtl_service_queue { | |
68 | struct throtl_service_queue *parent_sq; /* the parent service_queue */ | |
69 | ||
70 | /* | |
71 | * Bios queued directly to this service_queue or dispatched from | |
72 | * children throtl_grp's. | |
73 | */ | |
74 | struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ | |
75 | unsigned int nr_queued[2]; /* number of queued bios */ | |
76 | ||
77 | /* | |
78 | * RB tree of active children throtl_grp's, which are sorted by | |
79 | * their ->disptime. | |
80 | */ | |
81 | struct rb_root pending_tree; /* RB tree of active tgs */ | |
82 | struct rb_node *first_pending; /* first node in the tree */ | |
83 | unsigned int nr_pending; /* # queued in the tree */ | |
84 | unsigned long first_pending_disptime; /* disptime of the first tg */ | |
85 | struct timer_list pending_timer; /* fires on first_pending_disptime */ | |
86 | }; | |
87 | ||
88 | enum tg_state_flags { | |
89 | THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ | |
90 | THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ | |
91 | }; | |
92 | ||
93 | #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) | |
94 | ||
95 | enum { | |
96 | LIMIT_LOW, | |
97 | LIMIT_MAX, | |
98 | LIMIT_CNT, | |
99 | }; | |
100 | ||
101 | struct throtl_grp { | |
102 | /* must be the first member */ | |
103 | struct blkg_policy_data pd; | |
104 | ||
105 | /* active throtl group service_queue member */ | |
106 | struct rb_node rb_node; | |
107 | ||
108 | /* throtl_data this group belongs to */ | |
109 | struct throtl_data *td; | |
110 | ||
111 | /* this group's service queue */ | |
112 | struct throtl_service_queue service_queue; | |
113 | ||
114 | /* | |
115 | * qnode_on_self is used when bios are directly queued to this | |
116 | * throtl_grp so that local bios compete fairly with bios | |
117 | * dispatched from children. qnode_on_parent is used when bios are | |
118 | * dispatched from this throtl_grp into its parent and will compete | |
119 | * with the sibling qnode_on_parents and the parent's | |
120 | * qnode_on_self. | |
121 | */ | |
122 | struct throtl_qnode qnode_on_self[2]; | |
123 | struct throtl_qnode qnode_on_parent[2]; | |
124 | ||
125 | /* | |
126 | * Dispatch time in jiffies. This is the estimated time when group | |
127 | * will unthrottle and is ready to dispatch more bio. It is used as | |
128 | * key to sort active groups in service tree. | |
129 | */ | |
130 | unsigned long disptime; | |
131 | ||
132 | unsigned int flags; | |
133 | ||
134 | /* are there any throtl rules between this group and td? */ | |
135 | bool has_rules[2]; | |
136 | ||
137 | /* internally used bytes per second rate limits */ | |
138 | uint64_t bps[2][LIMIT_CNT]; | |
139 | /* user configured bps limits */ | |
140 | uint64_t bps_conf[2][LIMIT_CNT]; | |
141 | ||
142 | /* internally used IOPS limits */ | |
143 | unsigned int iops[2][LIMIT_CNT]; | |
144 | /* user configured IOPS limits */ | |
145 | unsigned int iops_conf[2][LIMIT_CNT]; | |
146 | ||
147 | /* Number of bytes disptached in current slice */ | |
148 | uint64_t bytes_disp[2]; | |
149 | /* Number of bio's dispatched in current slice */ | |
150 | unsigned int io_disp[2]; | |
151 | ||
152 | unsigned long last_low_overflow_time[2]; | |
153 | ||
154 | uint64_t last_bytes_disp[2]; | |
155 | unsigned int last_io_disp[2]; | |
156 | ||
157 | unsigned long last_check_time; | |
158 | ||
159 | unsigned long latency_target; /* us */ | |
160 | unsigned long latency_target_conf; /* us */ | |
161 | /* When did we start a new slice */ | |
162 | unsigned long slice_start[2]; | |
163 | unsigned long slice_end[2]; | |
164 | ||
165 | unsigned long last_finish_time; /* ns / 1024 */ | |
166 | unsigned long checked_last_finish_time; /* ns / 1024 */ | |
167 | unsigned long avg_idletime; /* ns / 1024 */ | |
168 | unsigned long idletime_threshold; /* us */ | |
169 | unsigned long idletime_threshold_conf; /* us */ | |
170 | ||
171 | unsigned int bio_cnt; /* total bios */ | |
172 | unsigned int bad_bio_cnt; /* bios exceeding latency threshold */ | |
173 | unsigned long bio_cnt_reset_time; | |
174 | }; | |
175 | ||
176 | /* We measure latency for request size from <= 4k to >= 1M */ | |
177 | #define LATENCY_BUCKET_SIZE 9 | |
178 | ||
179 | struct latency_bucket { | |
180 | unsigned long total_latency; /* ns / 1024 */ | |
181 | int samples; | |
182 | }; | |
183 | ||
184 | struct avg_latency_bucket { | |
185 | unsigned long latency; /* ns / 1024 */ | |
186 | bool valid; | |
187 | }; | |
188 | ||
189 | struct throtl_data | |
190 | { | |
191 | /* service tree for active throtl groups */ | |
192 | struct throtl_service_queue service_queue; | |
193 | ||
194 | struct request_queue *queue; | |
195 | ||
196 | /* Total Number of queued bios on READ and WRITE lists */ | |
197 | unsigned int nr_queued[2]; | |
198 | ||
199 | unsigned int throtl_slice; | |
200 | ||
201 | /* Work for dispatching throttled bios */ | |
202 | struct work_struct dispatch_work; | |
203 | unsigned int limit_index; | |
204 | bool limit_valid[LIMIT_CNT]; | |
205 | ||
206 | unsigned long low_upgrade_time; | |
207 | unsigned long low_downgrade_time; | |
208 | ||
209 | unsigned int scale; | |
210 | ||
211 | struct latency_bucket tmp_buckets[LATENCY_BUCKET_SIZE]; | |
212 | struct avg_latency_bucket avg_buckets[LATENCY_BUCKET_SIZE]; | |
213 | struct latency_bucket __percpu *latency_buckets; | |
214 | unsigned long last_calculate_time; | |
215 | ||
216 | bool track_bio_latency; | |
217 | }; | |
218 | ||
219 | static void throtl_pending_timer_fn(unsigned long arg); | |
220 | ||
221 | static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) | |
222 | { | |
223 | return pd ? container_of(pd, struct throtl_grp, pd) : NULL; | |
224 | } | |
225 | ||
226 | static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) | |
227 | { | |
228 | return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); | |
229 | } | |
230 | ||
231 | static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg) | |
232 | { | |
233 | return pd_to_blkg(&tg->pd); | |
234 | } | |
235 | ||
236 | /** | |
237 | * sq_to_tg - return the throl_grp the specified service queue belongs to | |
238 | * @sq: the throtl_service_queue of interest | |
239 | * | |
240 | * Return the throtl_grp @sq belongs to. If @sq is the top-level one | |
241 | * embedded in throtl_data, %NULL is returned. | |
242 | */ | |
243 | static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq) | |
244 | { | |
245 | if (sq && sq->parent_sq) | |
246 | return container_of(sq, struct throtl_grp, service_queue); | |
247 | else | |
248 | return NULL; | |
249 | } | |
250 | ||
251 | /** | |
252 | * sq_to_td - return throtl_data the specified service queue belongs to | |
253 | * @sq: the throtl_service_queue of interest | |
254 | * | |
255 | * A service_queue can be embedded in either a throtl_grp or throtl_data. | |
256 | * Determine the associated throtl_data accordingly and return it. | |
257 | */ | |
258 | static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) | |
259 | { | |
260 | struct throtl_grp *tg = sq_to_tg(sq); | |
261 | ||
262 | if (tg) | |
263 | return tg->td; | |
264 | else | |
265 | return container_of(sq, struct throtl_data, service_queue); | |
266 | } | |
267 | ||
268 | /* | |
269 | * cgroup's limit in LIMIT_MAX is scaled if low limit is set. This scale is to | |
270 | * make the IO dispatch more smooth. | |
271 | * Scale up: linearly scale up according to lapsed time since upgrade. For | |
272 | * every throtl_slice, the limit scales up 1/2 .low limit till the | |
273 | * limit hits .max limit | |
274 | * Scale down: exponentially scale down if a cgroup doesn't hit its .low limit | |
275 | */ | |
276 | static uint64_t throtl_adjusted_limit(uint64_t low, struct throtl_data *td) | |
277 | { | |
278 | /* arbitrary value to avoid too big scale */ | |
279 | if (td->scale < 4096 && time_after_eq(jiffies, | |
280 | td->low_upgrade_time + td->scale * td->throtl_slice)) | |
281 | td->scale = (jiffies - td->low_upgrade_time) / td->throtl_slice; | |
282 | ||
283 | return low + (low >> 1) * td->scale; | |
284 | } | |
285 | ||
286 | static uint64_t tg_bps_limit(struct throtl_grp *tg, int rw) | |
287 | { | |
288 | struct blkcg_gq *blkg = tg_to_blkg(tg); | |
289 | struct throtl_data *td; | |
290 | uint64_t ret; | |
291 | ||
292 | if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent) | |
293 | return U64_MAX; | |
294 | ||
295 | td = tg->td; | |
296 | ret = tg->bps[rw][td->limit_index]; | |
297 | if (ret == 0 && td->limit_index == LIMIT_LOW) { | |
298 | /* intermediate node or iops isn't 0 */ | |
299 | if (!list_empty(&blkg->blkcg->css.children) || | |
300 | tg->iops[rw][td->limit_index]) | |
301 | return U64_MAX; | |
302 | else | |
303 | return MIN_THROTL_BPS; | |
304 | } | |
305 | ||
306 | if (td->limit_index == LIMIT_MAX && tg->bps[rw][LIMIT_LOW] && | |
307 | tg->bps[rw][LIMIT_LOW] != tg->bps[rw][LIMIT_MAX]) { | |
308 | uint64_t adjusted; | |
309 | ||
310 | adjusted = throtl_adjusted_limit(tg->bps[rw][LIMIT_LOW], td); | |
311 | ret = min(tg->bps[rw][LIMIT_MAX], adjusted); | |
312 | } | |
313 | return ret; | |
314 | } | |
315 | ||
316 | static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw) | |
317 | { | |
318 | struct blkcg_gq *blkg = tg_to_blkg(tg); | |
319 | struct throtl_data *td; | |
320 | unsigned int ret; | |
321 | ||
322 | if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent) | |
323 | return UINT_MAX; | |
324 | ||
325 | td = tg->td; | |
326 | ret = tg->iops[rw][td->limit_index]; | |
327 | if (ret == 0 && tg->td->limit_index == LIMIT_LOW) { | |
328 | /* intermediate node or bps isn't 0 */ | |
329 | if (!list_empty(&blkg->blkcg->css.children) || | |
330 | tg->bps[rw][td->limit_index]) | |
331 | return UINT_MAX; | |
332 | else | |
333 | return MIN_THROTL_IOPS; | |
334 | } | |
335 | ||
336 | if (td->limit_index == LIMIT_MAX && tg->iops[rw][LIMIT_LOW] && | |
337 | tg->iops[rw][LIMIT_LOW] != tg->iops[rw][LIMIT_MAX]) { | |
338 | uint64_t adjusted; | |
339 | ||
340 | adjusted = throtl_adjusted_limit(tg->iops[rw][LIMIT_LOW], td); | |
341 | if (adjusted > UINT_MAX) | |
342 | adjusted = UINT_MAX; | |
343 | ret = min_t(unsigned int, tg->iops[rw][LIMIT_MAX], adjusted); | |
344 | } | |
345 | return ret; | |
346 | } | |
347 | ||
348 | #define request_bucket_index(sectors) \ | |
349 | clamp_t(int, order_base_2(sectors) - 3, 0, LATENCY_BUCKET_SIZE - 1) | |
350 | ||
351 | /** | |
352 | * throtl_log - log debug message via blktrace | |
353 | * @sq: the service_queue being reported | |
354 | * @fmt: printf format string | |
355 | * @args: printf args | |
356 | * | |
357 | * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a | |
358 | * throtl_grp; otherwise, just "throtl". | |
359 | */ | |
360 | #define throtl_log(sq, fmt, args...) do { \ | |
361 | struct throtl_grp *__tg = sq_to_tg((sq)); \ | |
362 | struct throtl_data *__td = sq_to_td((sq)); \ | |
363 | \ | |
364 | (void)__td; \ | |
365 | if (likely(!blk_trace_note_message_enabled(__td->queue))) \ | |
366 | break; \ | |
367 | if ((__tg)) { \ | |
368 | char __pbuf[128]; \ | |
369 | \ | |
370 | blkg_path(tg_to_blkg(__tg), __pbuf, sizeof(__pbuf)); \ | |
371 | blk_add_trace_msg(__td->queue, "throtl %s " fmt, __pbuf, ##args); \ | |
372 | } else { \ | |
373 | blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \ | |
374 | } \ | |
375 | } while (0) | |
376 | ||
377 | static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg) | |
378 | { | |
379 | INIT_LIST_HEAD(&qn->node); | |
380 | bio_list_init(&qn->bios); | |
381 | qn->tg = tg; | |
382 | } | |
383 | ||
384 | /** | |
385 | * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it | |
386 | * @bio: bio being added | |
387 | * @qn: qnode to add bio to | |
388 | * @queued: the service_queue->queued[] list @qn belongs to | |
389 | * | |
390 | * Add @bio to @qn and put @qn on @queued if it's not already on. | |
391 | * @qn->tg's reference count is bumped when @qn is activated. See the | |
392 | * comment on top of throtl_qnode definition for details. | |
393 | */ | |
394 | static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn, | |
395 | struct list_head *queued) | |
396 | { | |
397 | bio_list_add(&qn->bios, bio); | |
398 | if (list_empty(&qn->node)) { | |
399 | list_add_tail(&qn->node, queued); | |
400 | blkg_get(tg_to_blkg(qn->tg)); | |
401 | } | |
402 | } | |
403 | ||
404 | /** | |
405 | * throtl_peek_queued - peek the first bio on a qnode list | |
406 | * @queued: the qnode list to peek | |
407 | */ | |
408 | static struct bio *throtl_peek_queued(struct list_head *queued) | |
409 | { | |
410 | struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); | |
411 | struct bio *bio; | |
412 | ||
413 | if (list_empty(queued)) | |
414 | return NULL; | |
415 | ||
416 | bio = bio_list_peek(&qn->bios); | |
417 | WARN_ON_ONCE(!bio); | |
418 | return bio; | |
419 | } | |
420 | ||
421 | /** | |
422 | * throtl_pop_queued - pop the first bio form a qnode list | |
423 | * @queued: the qnode list to pop a bio from | |
424 | * @tg_to_put: optional out argument for throtl_grp to put | |
425 | * | |
426 | * Pop the first bio from the qnode list @queued. After popping, the first | |
427 | * qnode is removed from @queued if empty or moved to the end of @queued so | |
428 | * that the popping order is round-robin. | |
429 | * | |
430 | * When the first qnode is removed, its associated throtl_grp should be put | |
431 | * too. If @tg_to_put is NULL, this function automatically puts it; | |
432 | * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is | |
433 | * responsible for putting it. | |
434 | */ | |
435 | static struct bio *throtl_pop_queued(struct list_head *queued, | |
436 | struct throtl_grp **tg_to_put) | |
437 | { | |
438 | struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); | |
439 | struct bio *bio; | |
440 | ||
441 | if (list_empty(queued)) | |
442 | return NULL; | |
443 | ||
444 | bio = bio_list_pop(&qn->bios); | |
445 | WARN_ON_ONCE(!bio); | |
446 | ||
447 | if (bio_list_empty(&qn->bios)) { | |
448 | list_del_init(&qn->node); | |
449 | if (tg_to_put) | |
450 | *tg_to_put = qn->tg; | |
451 | else | |
452 | blkg_put(tg_to_blkg(qn->tg)); | |
453 | } else { | |
454 | list_move_tail(&qn->node, queued); | |
455 | } | |
456 | ||
457 | return bio; | |
458 | } | |
459 | ||
460 | /* init a service_queue, assumes the caller zeroed it */ | |
461 | static void throtl_service_queue_init(struct throtl_service_queue *sq) | |
462 | { | |
463 | INIT_LIST_HEAD(&sq->queued[0]); | |
464 | INIT_LIST_HEAD(&sq->queued[1]); | |
465 | sq->pending_tree = RB_ROOT; | |
466 | setup_timer(&sq->pending_timer, throtl_pending_timer_fn, | |
467 | (unsigned long)sq); | |
468 | } | |
469 | ||
470 | static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node) | |
471 | { | |
472 | struct throtl_grp *tg; | |
473 | int rw; | |
474 | ||
475 | tg = kzalloc_node(sizeof(*tg), gfp, node); | |
476 | if (!tg) | |
477 | return NULL; | |
478 | ||
479 | throtl_service_queue_init(&tg->service_queue); | |
480 | ||
481 | for (rw = READ; rw <= WRITE; rw++) { | |
482 | throtl_qnode_init(&tg->qnode_on_self[rw], tg); | |
483 | throtl_qnode_init(&tg->qnode_on_parent[rw], tg); | |
484 | } | |
485 | ||
486 | RB_CLEAR_NODE(&tg->rb_node); | |
487 | tg->bps[READ][LIMIT_MAX] = U64_MAX; | |
488 | tg->bps[WRITE][LIMIT_MAX] = U64_MAX; | |
489 | tg->iops[READ][LIMIT_MAX] = UINT_MAX; | |
490 | tg->iops[WRITE][LIMIT_MAX] = UINT_MAX; | |
491 | tg->bps_conf[READ][LIMIT_MAX] = U64_MAX; | |
492 | tg->bps_conf[WRITE][LIMIT_MAX] = U64_MAX; | |
493 | tg->iops_conf[READ][LIMIT_MAX] = UINT_MAX; | |
494 | tg->iops_conf[WRITE][LIMIT_MAX] = UINT_MAX; | |
495 | /* LIMIT_LOW will have default value 0 */ | |
496 | ||
497 | tg->latency_target = DFL_LATENCY_TARGET; | |
498 | tg->latency_target_conf = DFL_LATENCY_TARGET; | |
499 | tg->idletime_threshold = DFL_IDLE_THRESHOLD; | |
500 | tg->idletime_threshold_conf = DFL_IDLE_THRESHOLD; | |
501 | ||
502 | return &tg->pd; | |
503 | } | |
504 | ||
505 | static void throtl_pd_init(struct blkg_policy_data *pd) | |
506 | { | |
507 | struct throtl_grp *tg = pd_to_tg(pd); | |
508 | struct blkcg_gq *blkg = tg_to_blkg(tg); | |
509 | struct throtl_data *td = blkg->q->td; | |
510 | struct throtl_service_queue *sq = &tg->service_queue; | |
511 | ||
512 | /* | |
513 | * If on the default hierarchy, we switch to properly hierarchical | |
514 | * behavior where limits on a given throtl_grp are applied to the | |
515 | * whole subtree rather than just the group itself. e.g. If 16M | |
516 | * read_bps limit is set on the root group, the whole system can't | |
517 | * exceed 16M for the device. | |
518 | * | |
519 | * If not on the default hierarchy, the broken flat hierarchy | |
520 | * behavior is retained where all throtl_grps are treated as if | |
521 | * they're all separate root groups right below throtl_data. | |
522 | * Limits of a group don't interact with limits of other groups | |
523 | * regardless of the position of the group in the hierarchy. | |
524 | */ | |
525 | sq->parent_sq = &td->service_queue; | |
526 | if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent) | |
527 | sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue; | |
528 | tg->td = td; | |
529 | } | |
530 | ||
531 | /* | |
532 | * Set has_rules[] if @tg or any of its parents have limits configured. | |
533 | * This doesn't require walking up to the top of the hierarchy as the | |
534 | * parent's has_rules[] is guaranteed to be correct. | |
535 | */ | |
536 | static void tg_update_has_rules(struct throtl_grp *tg) | |
537 | { | |
538 | struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq); | |
539 | struct throtl_data *td = tg->td; | |
540 | int rw; | |
541 | ||
542 | for (rw = READ; rw <= WRITE; rw++) | |
543 | tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) || | |
544 | (td->limit_valid[td->limit_index] && | |
545 | (tg_bps_limit(tg, rw) != U64_MAX || | |
546 | tg_iops_limit(tg, rw) != UINT_MAX)); | |
547 | } | |
548 | ||
549 | static void throtl_pd_online(struct blkg_policy_data *pd) | |
550 | { | |
551 | struct throtl_grp *tg = pd_to_tg(pd); | |
552 | /* | |
553 | * We don't want new groups to escape the limits of its ancestors. | |
554 | * Update has_rules[] after a new group is brought online. | |
555 | */ | |
556 | tg_update_has_rules(tg); | |
557 | } | |
558 | ||
559 | static void blk_throtl_update_limit_valid(struct throtl_data *td) | |
560 | { | |
561 | struct cgroup_subsys_state *pos_css; | |
562 | struct blkcg_gq *blkg; | |
563 | bool low_valid = false; | |
564 | ||
565 | rcu_read_lock(); | |
566 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { | |
567 | struct throtl_grp *tg = blkg_to_tg(blkg); | |
568 | ||
569 | if (tg->bps[READ][LIMIT_LOW] || tg->bps[WRITE][LIMIT_LOW] || | |
570 | tg->iops[READ][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) | |
571 | low_valid = true; | |
572 | } | |
573 | rcu_read_unlock(); | |
574 | ||
575 | td->limit_valid[LIMIT_LOW] = low_valid; | |
576 | } | |
577 | ||
578 | static void throtl_upgrade_state(struct throtl_data *td); | |
579 | static void throtl_pd_offline(struct blkg_policy_data *pd) | |
580 | { | |
581 | struct throtl_grp *tg = pd_to_tg(pd); | |
582 | ||
583 | tg->bps[READ][LIMIT_LOW] = 0; | |
584 | tg->bps[WRITE][LIMIT_LOW] = 0; | |
585 | tg->iops[READ][LIMIT_LOW] = 0; | |
586 | tg->iops[WRITE][LIMIT_LOW] = 0; | |
587 | ||
588 | blk_throtl_update_limit_valid(tg->td); | |
589 | ||
590 | if (!tg->td->limit_valid[tg->td->limit_index]) | |
591 | throtl_upgrade_state(tg->td); | |
592 | } | |
593 | ||
594 | static void throtl_pd_free(struct blkg_policy_data *pd) | |
595 | { | |
596 | struct throtl_grp *tg = pd_to_tg(pd); | |
597 | ||
598 | del_timer_sync(&tg->service_queue.pending_timer); | |
599 | kfree(tg); | |
600 | } | |
601 | ||
602 | static struct throtl_grp * | |
603 | throtl_rb_first(struct throtl_service_queue *parent_sq) | |
604 | { | |
605 | /* Service tree is empty */ | |
606 | if (!parent_sq->nr_pending) | |
607 | return NULL; | |
608 | ||
609 | if (!parent_sq->first_pending) | |
610 | parent_sq->first_pending = rb_first(&parent_sq->pending_tree); | |
611 | ||
612 | if (parent_sq->first_pending) | |
613 | return rb_entry_tg(parent_sq->first_pending); | |
614 | ||
615 | return NULL; | |
616 | } | |
617 | ||
618 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) | |
619 | { | |
620 | rb_erase(n, root); | |
621 | RB_CLEAR_NODE(n); | |
622 | } | |
623 | ||
624 | static void throtl_rb_erase(struct rb_node *n, | |
625 | struct throtl_service_queue *parent_sq) | |
626 | { | |
627 | if (parent_sq->first_pending == n) | |
628 | parent_sq->first_pending = NULL; | |
629 | rb_erase_init(n, &parent_sq->pending_tree); | |
630 | --parent_sq->nr_pending; | |
631 | } | |
632 | ||
633 | static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) | |
634 | { | |
635 | struct throtl_grp *tg; | |
636 | ||
637 | tg = throtl_rb_first(parent_sq); | |
638 | if (!tg) | |
639 | return; | |
640 | ||
641 | parent_sq->first_pending_disptime = tg->disptime; | |
642 | } | |
643 | ||
644 | static void tg_service_queue_add(struct throtl_grp *tg) | |
645 | { | |
646 | struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq; | |
647 | struct rb_node **node = &parent_sq->pending_tree.rb_node; | |
648 | struct rb_node *parent = NULL; | |
649 | struct throtl_grp *__tg; | |
650 | unsigned long key = tg->disptime; | |
651 | int left = 1; | |
652 | ||
653 | while (*node != NULL) { | |
654 | parent = *node; | |
655 | __tg = rb_entry_tg(parent); | |
656 | ||
657 | if (time_before(key, __tg->disptime)) | |
658 | node = &parent->rb_left; | |
659 | else { | |
660 | node = &parent->rb_right; | |
661 | left = 0; | |
662 | } | |
663 | } | |
664 | ||
665 | if (left) | |
666 | parent_sq->first_pending = &tg->rb_node; | |
667 | ||
668 | rb_link_node(&tg->rb_node, parent, node); | |
669 | rb_insert_color(&tg->rb_node, &parent_sq->pending_tree); | |
670 | } | |
671 | ||
672 | static void __throtl_enqueue_tg(struct throtl_grp *tg) | |
673 | { | |
674 | tg_service_queue_add(tg); | |
675 | tg->flags |= THROTL_TG_PENDING; | |
676 | tg->service_queue.parent_sq->nr_pending++; | |
677 | } | |
678 | ||
679 | static void throtl_enqueue_tg(struct throtl_grp *tg) | |
680 | { | |
681 | if (!(tg->flags & THROTL_TG_PENDING)) | |
682 | __throtl_enqueue_tg(tg); | |
683 | } | |
684 | ||
685 | static void __throtl_dequeue_tg(struct throtl_grp *tg) | |
686 | { | |
687 | throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq); | |
688 | tg->flags &= ~THROTL_TG_PENDING; | |
689 | } | |
690 | ||
691 | static void throtl_dequeue_tg(struct throtl_grp *tg) | |
692 | { | |
693 | if (tg->flags & THROTL_TG_PENDING) | |
694 | __throtl_dequeue_tg(tg); | |
695 | } | |
696 | ||
697 | /* Call with queue lock held */ | |
698 | static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, | |
699 | unsigned long expires) | |
700 | { | |
701 | unsigned long max_expire = jiffies + 8 * sq_to_tg(sq)->td->throtl_slice; | |
702 | ||
703 | /* | |
704 | * Since we are adjusting the throttle limit dynamically, the sleep | |
705 | * time calculated according to previous limit might be invalid. It's | |
706 | * possible the cgroup sleep time is very long and no other cgroups | |
707 | * have IO running so notify the limit changes. Make sure the cgroup | |
708 | * doesn't sleep too long to avoid the missed notification. | |
709 | */ | |
710 | if (time_after(expires, max_expire)) | |
711 | expires = max_expire; | |
712 | mod_timer(&sq->pending_timer, expires); | |
713 | throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu", | |
714 | expires - jiffies, jiffies); | |
715 | } | |
716 | ||
717 | /** | |
718 | * throtl_schedule_next_dispatch - schedule the next dispatch cycle | |
719 | * @sq: the service_queue to schedule dispatch for | |
720 | * @force: force scheduling | |
721 | * | |
722 | * Arm @sq->pending_timer so that the next dispatch cycle starts on the | |
723 | * dispatch time of the first pending child. Returns %true if either timer | |
724 | * is armed or there's no pending child left. %false if the current | |
725 | * dispatch window is still open and the caller should continue | |
726 | * dispatching. | |
727 | * | |
728 | * If @force is %true, the dispatch timer is always scheduled and this | |
729 | * function is guaranteed to return %true. This is to be used when the | |
730 | * caller can't dispatch itself and needs to invoke pending_timer | |
731 | * unconditionally. Note that forced scheduling is likely to induce short | |
732 | * delay before dispatch starts even if @sq->first_pending_disptime is not | |
733 | * in the future and thus shouldn't be used in hot paths. | |
734 | */ | |
735 | static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq, | |
736 | bool force) | |
737 | { | |
738 | /* any pending children left? */ | |
739 | if (!sq->nr_pending) | |
740 | return true; | |
741 | ||
742 | update_min_dispatch_time(sq); | |
743 | ||
744 | /* is the next dispatch time in the future? */ | |
745 | if (force || time_after(sq->first_pending_disptime, jiffies)) { | |
746 | throtl_schedule_pending_timer(sq, sq->first_pending_disptime); | |
747 | return true; | |
748 | } | |
749 | ||
750 | /* tell the caller to continue dispatching */ | |
751 | return false; | |
752 | } | |
753 | ||
754 | static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg, | |
755 | bool rw, unsigned long start) | |
756 | { | |
757 | tg->bytes_disp[rw] = 0; | |
758 | tg->io_disp[rw] = 0; | |
759 | ||
760 | /* | |
761 | * Previous slice has expired. We must have trimmed it after last | |
762 | * bio dispatch. That means since start of last slice, we never used | |
763 | * that bandwidth. Do try to make use of that bandwidth while giving | |
764 | * credit. | |
765 | */ | |
766 | if (time_after_eq(start, tg->slice_start[rw])) | |
767 | tg->slice_start[rw] = start; | |
768 | ||
769 | tg->slice_end[rw] = jiffies + tg->td->throtl_slice; | |
770 | throtl_log(&tg->service_queue, | |
771 | "[%c] new slice with credit start=%lu end=%lu jiffies=%lu", | |
772 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
773 | tg->slice_end[rw], jiffies); | |
774 | } | |
775 | ||
776 | static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) | |
777 | { | |
778 | tg->bytes_disp[rw] = 0; | |
779 | tg->io_disp[rw] = 0; | |
780 | tg->slice_start[rw] = jiffies; | |
781 | tg->slice_end[rw] = jiffies + tg->td->throtl_slice; | |
782 | throtl_log(&tg->service_queue, | |
783 | "[%c] new slice start=%lu end=%lu jiffies=%lu", | |
784 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
785 | tg->slice_end[rw], jiffies); | |
786 | } | |
787 | ||
788 | static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw, | |
789 | unsigned long jiffy_end) | |
790 | { | |
791 | tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice); | |
792 | } | |
793 | ||
794 | static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw, | |
795 | unsigned long jiffy_end) | |
796 | { | |
797 | tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice); | |
798 | throtl_log(&tg->service_queue, | |
799 | "[%c] extend slice start=%lu end=%lu jiffies=%lu", | |
800 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
801 | tg->slice_end[rw], jiffies); | |
802 | } | |
803 | ||
804 | /* Determine if previously allocated or extended slice is complete or not */ | |
805 | static bool throtl_slice_used(struct throtl_grp *tg, bool rw) | |
806 | { | |
807 | if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) | |
808 | return false; | |
809 | ||
810 | return 1; | |
811 | } | |
812 | ||
813 | /* Trim the used slices and adjust slice start accordingly */ | |
814 | static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) | |
815 | { | |
816 | unsigned long nr_slices, time_elapsed, io_trim; | |
817 | u64 bytes_trim, tmp; | |
818 | ||
819 | BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); | |
820 | ||
821 | /* | |
822 | * If bps are unlimited (-1), then time slice don't get | |
823 | * renewed. Don't try to trim the slice if slice is used. A new | |
824 | * slice will start when appropriate. | |
825 | */ | |
826 | if (throtl_slice_used(tg, rw)) | |
827 | return; | |
828 | ||
829 | /* | |
830 | * A bio has been dispatched. Also adjust slice_end. It might happen | |
831 | * that initially cgroup limit was very low resulting in high | |
832 | * slice_end, but later limit was bumped up and bio was dispached | |
833 | * sooner, then we need to reduce slice_end. A high bogus slice_end | |
834 | * is bad because it does not allow new slice to start. | |
835 | */ | |
836 | ||
837 | throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice); | |
838 | ||
839 | time_elapsed = jiffies - tg->slice_start[rw]; | |
840 | ||
841 | nr_slices = time_elapsed / tg->td->throtl_slice; | |
842 | ||
843 | if (!nr_slices) | |
844 | return; | |
845 | tmp = tg_bps_limit(tg, rw) * tg->td->throtl_slice * nr_slices; | |
846 | do_div(tmp, HZ); | |
847 | bytes_trim = tmp; | |
848 | ||
849 | io_trim = (tg_iops_limit(tg, rw) * tg->td->throtl_slice * nr_slices) / | |
850 | HZ; | |
851 | ||
852 | if (!bytes_trim && !io_trim) | |
853 | return; | |
854 | ||
855 | if (tg->bytes_disp[rw] >= bytes_trim) | |
856 | tg->bytes_disp[rw] -= bytes_trim; | |
857 | else | |
858 | tg->bytes_disp[rw] = 0; | |
859 | ||
860 | if (tg->io_disp[rw] >= io_trim) | |
861 | tg->io_disp[rw] -= io_trim; | |
862 | else | |
863 | tg->io_disp[rw] = 0; | |
864 | ||
865 | tg->slice_start[rw] += nr_slices * tg->td->throtl_slice; | |
866 | ||
867 | throtl_log(&tg->service_queue, | |
868 | "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", | |
869 | rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, | |
870 | tg->slice_start[rw], tg->slice_end[rw], jiffies); | |
871 | } | |
872 | ||
873 | static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, | |
874 | unsigned long *wait) | |
875 | { | |
876 | bool rw = bio_data_dir(bio); | |
877 | unsigned int io_allowed; | |
878 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; | |
879 | u64 tmp; | |
880 | ||
881 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; | |
882 | ||
883 | /* Slice has just started. Consider one slice interval */ | |
884 | if (!jiffy_elapsed) | |
885 | jiffy_elapsed_rnd = tg->td->throtl_slice; | |
886 | ||
887 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); | |
888 | ||
889 | /* | |
890 | * jiffy_elapsed_rnd should not be a big value as minimum iops can be | |
891 | * 1 then at max jiffy elapsed should be equivalent of 1 second as we | |
892 | * will allow dispatch after 1 second and after that slice should | |
893 | * have been trimmed. | |
894 | */ | |
895 | ||
896 | tmp = (u64)tg_iops_limit(tg, rw) * jiffy_elapsed_rnd; | |
897 | do_div(tmp, HZ); | |
898 | ||
899 | if (tmp > UINT_MAX) | |
900 | io_allowed = UINT_MAX; | |
901 | else | |
902 | io_allowed = tmp; | |
903 | ||
904 | if (tg->io_disp[rw] + 1 <= io_allowed) { | |
905 | if (wait) | |
906 | *wait = 0; | |
907 | return true; | |
908 | } | |
909 | ||
910 | /* Calc approx time to dispatch */ | |
911 | jiffy_wait = ((tg->io_disp[rw] + 1) * HZ) / tg_iops_limit(tg, rw) + 1; | |
912 | ||
913 | if (jiffy_wait > jiffy_elapsed) | |
914 | jiffy_wait = jiffy_wait - jiffy_elapsed; | |
915 | else | |
916 | jiffy_wait = 1; | |
917 | ||
918 | if (wait) | |
919 | *wait = jiffy_wait; | |
920 | return 0; | |
921 | } | |
922 | ||
923 | static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, | |
924 | unsigned long *wait) | |
925 | { | |
926 | bool rw = bio_data_dir(bio); | |
927 | u64 bytes_allowed, extra_bytes, tmp; | |
928 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; | |
929 | ||
930 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; | |
931 | ||
932 | /* Slice has just started. Consider one slice interval */ | |
933 | if (!jiffy_elapsed) | |
934 | jiffy_elapsed_rnd = tg->td->throtl_slice; | |
935 | ||
936 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); | |
937 | ||
938 | tmp = tg_bps_limit(tg, rw) * jiffy_elapsed_rnd; | |
939 | do_div(tmp, HZ); | |
940 | bytes_allowed = tmp; | |
941 | ||
942 | if (tg->bytes_disp[rw] + bio->bi_iter.bi_size <= bytes_allowed) { | |
943 | if (wait) | |
944 | *wait = 0; | |
945 | return true; | |
946 | } | |
947 | ||
948 | /* Calc approx time to dispatch */ | |
949 | extra_bytes = tg->bytes_disp[rw] + bio->bi_iter.bi_size - bytes_allowed; | |
950 | jiffy_wait = div64_u64(extra_bytes * HZ, tg_bps_limit(tg, rw)); | |
951 | ||
952 | if (!jiffy_wait) | |
953 | jiffy_wait = 1; | |
954 | ||
955 | /* | |
956 | * This wait time is without taking into consideration the rounding | |
957 | * up we did. Add that time also. | |
958 | */ | |
959 | jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); | |
960 | if (wait) | |
961 | *wait = jiffy_wait; | |
962 | return 0; | |
963 | } | |
964 | ||
965 | /* | |
966 | * Returns whether one can dispatch a bio or not. Also returns approx number | |
967 | * of jiffies to wait before this bio is with-in IO rate and can be dispatched | |
968 | */ | |
969 | static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, | |
970 | unsigned long *wait) | |
971 | { | |
972 | bool rw = bio_data_dir(bio); | |
973 | unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; | |
974 | ||
975 | /* | |
976 | * Currently whole state machine of group depends on first bio | |
977 | * queued in the group bio list. So one should not be calling | |
978 | * this function with a different bio if there are other bios | |
979 | * queued. | |
980 | */ | |
981 | BUG_ON(tg->service_queue.nr_queued[rw] && | |
982 | bio != throtl_peek_queued(&tg->service_queue.queued[rw])); | |
983 | ||
984 | /* If tg->bps = -1, then BW is unlimited */ | |
985 | if (tg_bps_limit(tg, rw) == U64_MAX && | |
986 | tg_iops_limit(tg, rw) == UINT_MAX) { | |
987 | if (wait) | |
988 | *wait = 0; | |
989 | return true; | |
990 | } | |
991 | ||
992 | /* | |
993 | * If previous slice expired, start a new one otherwise renew/extend | |
994 | * existing slice to make sure it is at least throtl_slice interval | |
995 | * long since now. New slice is started only for empty throttle group. | |
996 | * If there is queued bio, that means there should be an active | |
997 | * slice and it should be extended instead. | |
998 | */ | |
999 | if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw])) | |
1000 | throtl_start_new_slice(tg, rw); | |
1001 | else { | |
1002 | if (time_before(tg->slice_end[rw], | |
1003 | jiffies + tg->td->throtl_slice)) | |
1004 | throtl_extend_slice(tg, rw, | |
1005 | jiffies + tg->td->throtl_slice); | |
1006 | } | |
1007 | ||
1008 | if (tg_with_in_bps_limit(tg, bio, &bps_wait) && | |
1009 | tg_with_in_iops_limit(tg, bio, &iops_wait)) { | |
1010 | if (wait) | |
1011 | *wait = 0; | |
1012 | return 1; | |
1013 | } | |
1014 | ||
1015 | max_wait = max(bps_wait, iops_wait); | |
1016 | ||
1017 | if (wait) | |
1018 | *wait = max_wait; | |
1019 | ||
1020 | if (time_before(tg->slice_end[rw], jiffies + max_wait)) | |
1021 | throtl_extend_slice(tg, rw, jiffies + max_wait); | |
1022 | ||
1023 | return 0; | |
1024 | } | |
1025 | ||
1026 | static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) | |
1027 | { | |
1028 | bool rw = bio_data_dir(bio); | |
1029 | ||
1030 | /* Charge the bio to the group */ | |
1031 | tg->bytes_disp[rw] += bio->bi_iter.bi_size; | |
1032 | tg->io_disp[rw]++; | |
1033 | tg->last_bytes_disp[rw] += bio->bi_iter.bi_size; | |
1034 | tg->last_io_disp[rw]++; | |
1035 | ||
1036 | /* | |
1037 | * BIO_THROTTLED is used to prevent the same bio to be throttled | |
1038 | * more than once as a throttled bio will go through blk-throtl the | |
1039 | * second time when it eventually gets issued. Set it when a bio | |
1040 | * is being charged to a tg. | |
1041 | */ | |
1042 | if (!bio_flagged(bio, BIO_THROTTLED)) | |
1043 | bio_set_flag(bio, BIO_THROTTLED); | |
1044 | } | |
1045 | ||
1046 | /** | |
1047 | * throtl_add_bio_tg - add a bio to the specified throtl_grp | |
1048 | * @bio: bio to add | |
1049 | * @qn: qnode to use | |
1050 | * @tg: the target throtl_grp | |
1051 | * | |
1052 | * Add @bio to @tg's service_queue using @qn. If @qn is not specified, | |
1053 | * tg->qnode_on_self[] is used. | |
1054 | */ | |
1055 | static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn, | |
1056 | struct throtl_grp *tg) | |
1057 | { | |
1058 | struct throtl_service_queue *sq = &tg->service_queue; | |
1059 | bool rw = bio_data_dir(bio); | |
1060 | ||
1061 | if (!qn) | |
1062 | qn = &tg->qnode_on_self[rw]; | |
1063 | ||
1064 | /* | |
1065 | * If @tg doesn't currently have any bios queued in the same | |
1066 | * direction, queueing @bio can change when @tg should be | |
1067 | * dispatched. Mark that @tg was empty. This is automatically | |
1068 | * cleaered on the next tg_update_disptime(). | |
1069 | */ | |
1070 | if (!sq->nr_queued[rw]) | |
1071 | tg->flags |= THROTL_TG_WAS_EMPTY; | |
1072 | ||
1073 | throtl_qnode_add_bio(bio, qn, &sq->queued[rw]); | |
1074 | ||
1075 | sq->nr_queued[rw]++; | |
1076 | throtl_enqueue_tg(tg); | |
1077 | } | |
1078 | ||
1079 | static void tg_update_disptime(struct throtl_grp *tg) | |
1080 | { | |
1081 | struct throtl_service_queue *sq = &tg->service_queue; | |
1082 | unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; | |
1083 | struct bio *bio; | |
1084 | ||
1085 | bio = throtl_peek_queued(&sq->queued[READ]); | |
1086 | if (bio) | |
1087 | tg_may_dispatch(tg, bio, &read_wait); | |
1088 | ||
1089 | bio = throtl_peek_queued(&sq->queued[WRITE]); | |
1090 | if (bio) | |
1091 | tg_may_dispatch(tg, bio, &write_wait); | |
1092 | ||
1093 | min_wait = min(read_wait, write_wait); | |
1094 | disptime = jiffies + min_wait; | |
1095 | ||
1096 | /* Update dispatch time */ | |
1097 | throtl_dequeue_tg(tg); | |
1098 | tg->disptime = disptime; | |
1099 | throtl_enqueue_tg(tg); | |
1100 | ||
1101 | /* see throtl_add_bio_tg() */ | |
1102 | tg->flags &= ~THROTL_TG_WAS_EMPTY; | |
1103 | } | |
1104 | ||
1105 | static void start_parent_slice_with_credit(struct throtl_grp *child_tg, | |
1106 | struct throtl_grp *parent_tg, bool rw) | |
1107 | { | |
1108 | if (throtl_slice_used(parent_tg, rw)) { | |
1109 | throtl_start_new_slice_with_credit(parent_tg, rw, | |
1110 | child_tg->slice_start[rw]); | |
1111 | } | |
1112 | ||
1113 | } | |
1114 | ||
1115 | static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) | |
1116 | { | |
1117 | struct throtl_service_queue *sq = &tg->service_queue; | |
1118 | struct throtl_service_queue *parent_sq = sq->parent_sq; | |
1119 | struct throtl_grp *parent_tg = sq_to_tg(parent_sq); | |
1120 | struct throtl_grp *tg_to_put = NULL; | |
1121 | struct bio *bio; | |
1122 | ||
1123 | /* | |
1124 | * @bio is being transferred from @tg to @parent_sq. Popping a bio | |
1125 | * from @tg may put its reference and @parent_sq might end up | |
1126 | * getting released prematurely. Remember the tg to put and put it | |
1127 | * after @bio is transferred to @parent_sq. | |
1128 | */ | |
1129 | bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put); | |
1130 | sq->nr_queued[rw]--; | |
1131 | ||
1132 | throtl_charge_bio(tg, bio); | |
1133 | ||
1134 | /* | |
1135 | * If our parent is another tg, we just need to transfer @bio to | |
1136 | * the parent using throtl_add_bio_tg(). If our parent is | |
1137 | * @td->service_queue, @bio is ready to be issued. Put it on its | |
1138 | * bio_lists[] and decrease total number queued. The caller is | |
1139 | * responsible for issuing these bios. | |
1140 | */ | |
1141 | if (parent_tg) { | |
1142 | throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); | |
1143 | start_parent_slice_with_credit(tg, parent_tg, rw); | |
1144 | } else { | |
1145 | throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], | |
1146 | &parent_sq->queued[rw]); | |
1147 | BUG_ON(tg->td->nr_queued[rw] <= 0); | |
1148 | tg->td->nr_queued[rw]--; | |
1149 | } | |
1150 | ||
1151 | throtl_trim_slice(tg, rw); | |
1152 | ||
1153 | if (tg_to_put) | |
1154 | blkg_put(tg_to_blkg(tg_to_put)); | |
1155 | } | |
1156 | ||
1157 | static int throtl_dispatch_tg(struct throtl_grp *tg) | |
1158 | { | |
1159 | struct throtl_service_queue *sq = &tg->service_queue; | |
1160 | unsigned int nr_reads = 0, nr_writes = 0; | |
1161 | unsigned int max_nr_reads = throtl_grp_quantum*3/4; | |
1162 | unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; | |
1163 | struct bio *bio; | |
1164 | ||
1165 | /* Try to dispatch 75% READS and 25% WRITES */ | |
1166 | ||
1167 | while ((bio = throtl_peek_queued(&sq->queued[READ])) && | |
1168 | tg_may_dispatch(tg, bio, NULL)) { | |
1169 | ||
1170 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
1171 | nr_reads++; | |
1172 | ||
1173 | if (nr_reads >= max_nr_reads) | |
1174 | break; | |
1175 | } | |
1176 | ||
1177 | while ((bio = throtl_peek_queued(&sq->queued[WRITE])) && | |
1178 | tg_may_dispatch(tg, bio, NULL)) { | |
1179 | ||
1180 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
1181 | nr_writes++; | |
1182 | ||
1183 | if (nr_writes >= max_nr_writes) | |
1184 | break; | |
1185 | } | |
1186 | ||
1187 | return nr_reads + nr_writes; | |
1188 | } | |
1189 | ||
1190 | static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) | |
1191 | { | |
1192 | unsigned int nr_disp = 0; | |
1193 | ||
1194 | while (1) { | |
1195 | struct throtl_grp *tg = throtl_rb_first(parent_sq); | |
1196 | struct throtl_service_queue *sq = &tg->service_queue; | |
1197 | ||
1198 | if (!tg) | |
1199 | break; | |
1200 | ||
1201 | if (time_before(jiffies, tg->disptime)) | |
1202 | break; | |
1203 | ||
1204 | throtl_dequeue_tg(tg); | |
1205 | ||
1206 | nr_disp += throtl_dispatch_tg(tg); | |
1207 | ||
1208 | if (sq->nr_queued[0] || sq->nr_queued[1]) | |
1209 | tg_update_disptime(tg); | |
1210 | ||
1211 | if (nr_disp >= throtl_quantum) | |
1212 | break; | |
1213 | } | |
1214 | ||
1215 | return nr_disp; | |
1216 | } | |
1217 | ||
1218 | static bool throtl_can_upgrade(struct throtl_data *td, | |
1219 | struct throtl_grp *this_tg); | |
1220 | /** | |
1221 | * throtl_pending_timer_fn - timer function for service_queue->pending_timer | |
1222 | * @arg: the throtl_service_queue being serviced | |
1223 | * | |
1224 | * This timer is armed when a child throtl_grp with active bio's become | |
1225 | * pending and queued on the service_queue's pending_tree and expires when | |
1226 | * the first child throtl_grp should be dispatched. This function | |
1227 | * dispatches bio's from the children throtl_grps to the parent | |
1228 | * service_queue. | |
1229 | * | |
1230 | * If the parent's parent is another throtl_grp, dispatching is propagated | |
1231 | * by either arming its pending_timer or repeating dispatch directly. If | |
1232 | * the top-level service_tree is reached, throtl_data->dispatch_work is | |
1233 | * kicked so that the ready bio's are issued. | |
1234 | */ | |
1235 | static void throtl_pending_timer_fn(unsigned long arg) | |
1236 | { | |
1237 | struct throtl_service_queue *sq = (void *)arg; | |
1238 | struct throtl_grp *tg = sq_to_tg(sq); | |
1239 | struct throtl_data *td = sq_to_td(sq); | |
1240 | struct request_queue *q = td->queue; | |
1241 | struct throtl_service_queue *parent_sq; | |
1242 | bool dispatched; | |
1243 | int ret; | |
1244 | ||
1245 | spin_lock_irq(q->queue_lock); | |
1246 | if (throtl_can_upgrade(td, NULL)) | |
1247 | throtl_upgrade_state(td); | |
1248 | ||
1249 | again: | |
1250 | parent_sq = sq->parent_sq; | |
1251 | dispatched = false; | |
1252 | ||
1253 | while (true) { | |
1254 | throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u", | |
1255 | sq->nr_queued[READ] + sq->nr_queued[WRITE], | |
1256 | sq->nr_queued[READ], sq->nr_queued[WRITE]); | |
1257 | ||
1258 | ret = throtl_select_dispatch(sq); | |
1259 | if (ret) { | |
1260 | throtl_log(sq, "bios disp=%u", ret); | |
1261 | dispatched = true; | |
1262 | } | |
1263 | ||
1264 | if (throtl_schedule_next_dispatch(sq, false)) | |
1265 | break; | |
1266 | ||
1267 | /* this dispatch windows is still open, relax and repeat */ | |
1268 | spin_unlock_irq(q->queue_lock); | |
1269 | cpu_relax(); | |
1270 | spin_lock_irq(q->queue_lock); | |
1271 | } | |
1272 | ||
1273 | if (!dispatched) | |
1274 | goto out_unlock; | |
1275 | ||
1276 | if (parent_sq) { | |
1277 | /* @parent_sq is another throl_grp, propagate dispatch */ | |
1278 | if (tg->flags & THROTL_TG_WAS_EMPTY) { | |
1279 | tg_update_disptime(tg); | |
1280 | if (!throtl_schedule_next_dispatch(parent_sq, false)) { | |
1281 | /* window is already open, repeat dispatching */ | |
1282 | sq = parent_sq; | |
1283 | tg = sq_to_tg(sq); | |
1284 | goto again; | |
1285 | } | |
1286 | } | |
1287 | } else { | |
1288 | /* reached the top-level, queue issueing */ | |
1289 | queue_work(kthrotld_workqueue, &td->dispatch_work); | |
1290 | } | |
1291 | out_unlock: | |
1292 | spin_unlock_irq(q->queue_lock); | |
1293 | } | |
1294 | ||
1295 | /** | |
1296 | * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work | |
1297 | * @work: work item being executed | |
1298 | * | |
1299 | * This function is queued for execution when bio's reach the bio_lists[] | |
1300 | * of throtl_data->service_queue. Those bio's are ready and issued by this | |
1301 | * function. | |
1302 | */ | |
1303 | static void blk_throtl_dispatch_work_fn(struct work_struct *work) | |
1304 | { | |
1305 | struct throtl_data *td = container_of(work, struct throtl_data, | |
1306 | dispatch_work); | |
1307 | struct throtl_service_queue *td_sq = &td->service_queue; | |
1308 | struct request_queue *q = td->queue; | |
1309 | struct bio_list bio_list_on_stack; | |
1310 | struct bio *bio; | |
1311 | struct blk_plug plug; | |
1312 | int rw; | |
1313 | ||
1314 | bio_list_init(&bio_list_on_stack); | |
1315 | ||
1316 | spin_lock_irq(q->queue_lock); | |
1317 | for (rw = READ; rw <= WRITE; rw++) | |
1318 | while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) | |
1319 | bio_list_add(&bio_list_on_stack, bio); | |
1320 | spin_unlock_irq(q->queue_lock); | |
1321 | ||
1322 | if (!bio_list_empty(&bio_list_on_stack)) { | |
1323 | blk_start_plug(&plug); | |
1324 | while((bio = bio_list_pop(&bio_list_on_stack))) | |
1325 | generic_make_request(bio); | |
1326 | blk_finish_plug(&plug); | |
1327 | } | |
1328 | } | |
1329 | ||
1330 | static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, | |
1331 | int off) | |
1332 | { | |
1333 | struct throtl_grp *tg = pd_to_tg(pd); | |
1334 | u64 v = *(u64 *)((void *)tg + off); | |
1335 | ||
1336 | if (v == U64_MAX) | |
1337 | return 0; | |
1338 | return __blkg_prfill_u64(sf, pd, v); | |
1339 | } | |
1340 | ||
1341 | static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, | |
1342 | int off) | |
1343 | { | |
1344 | struct throtl_grp *tg = pd_to_tg(pd); | |
1345 | unsigned int v = *(unsigned int *)((void *)tg + off); | |
1346 | ||
1347 | if (v == UINT_MAX) | |
1348 | return 0; | |
1349 | return __blkg_prfill_u64(sf, pd, v); | |
1350 | } | |
1351 | ||
1352 | static int tg_print_conf_u64(struct seq_file *sf, void *v) | |
1353 | { | |
1354 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64, | |
1355 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
1356 | return 0; | |
1357 | } | |
1358 | ||
1359 | static int tg_print_conf_uint(struct seq_file *sf, void *v) | |
1360 | { | |
1361 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint, | |
1362 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
1363 | return 0; | |
1364 | } | |
1365 | ||
1366 | static void tg_conf_updated(struct throtl_grp *tg, bool global) | |
1367 | { | |
1368 | struct throtl_service_queue *sq = &tg->service_queue; | |
1369 | struct cgroup_subsys_state *pos_css; | |
1370 | struct blkcg_gq *blkg; | |
1371 | ||
1372 | throtl_log(&tg->service_queue, | |
1373 | "limit change rbps=%llu wbps=%llu riops=%u wiops=%u", | |
1374 | tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE), | |
1375 | tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE)); | |
1376 | ||
1377 | /* | |
1378 | * Update has_rules[] flags for the updated tg's subtree. A tg is | |
1379 | * considered to have rules if either the tg itself or any of its | |
1380 | * ancestors has rules. This identifies groups without any | |
1381 | * restrictions in the whole hierarchy and allows them to bypass | |
1382 | * blk-throttle. | |
1383 | */ | |
1384 | blkg_for_each_descendant_pre(blkg, pos_css, | |
1385 | global ? tg->td->queue->root_blkg : tg_to_blkg(tg)) { | |
1386 | struct throtl_grp *this_tg = blkg_to_tg(blkg); | |
1387 | struct throtl_grp *parent_tg; | |
1388 | ||
1389 | tg_update_has_rules(this_tg); | |
1390 | /* ignore root/second level */ | |
1391 | if (!cgroup_subsys_on_dfl(io_cgrp_subsys) || !blkg->parent || | |
1392 | !blkg->parent->parent) | |
1393 | continue; | |
1394 | parent_tg = blkg_to_tg(blkg->parent); | |
1395 | /* | |
1396 | * make sure all children has lower idle time threshold and | |
1397 | * higher latency target | |
1398 | */ | |
1399 | this_tg->idletime_threshold = min(this_tg->idletime_threshold, | |
1400 | parent_tg->idletime_threshold); | |
1401 | this_tg->latency_target = max(this_tg->latency_target, | |
1402 | parent_tg->latency_target); | |
1403 | } | |
1404 | ||
1405 | /* | |
1406 | * We're already holding queue_lock and know @tg is valid. Let's | |
1407 | * apply the new config directly. | |
1408 | * | |
1409 | * Restart the slices for both READ and WRITES. It might happen | |
1410 | * that a group's limit are dropped suddenly and we don't want to | |
1411 | * account recently dispatched IO with new low rate. | |
1412 | */ | |
1413 | throtl_start_new_slice(tg, 0); | |
1414 | throtl_start_new_slice(tg, 1); | |
1415 | ||
1416 | if (tg->flags & THROTL_TG_PENDING) { | |
1417 | tg_update_disptime(tg); | |
1418 | throtl_schedule_next_dispatch(sq->parent_sq, true); | |
1419 | } | |
1420 | } | |
1421 | ||
1422 | static ssize_t tg_set_conf(struct kernfs_open_file *of, | |
1423 | char *buf, size_t nbytes, loff_t off, bool is_u64) | |
1424 | { | |
1425 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); | |
1426 | struct blkg_conf_ctx ctx; | |
1427 | struct throtl_grp *tg; | |
1428 | int ret; | |
1429 | u64 v; | |
1430 | ||
1431 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); | |
1432 | if (ret) | |
1433 | return ret; | |
1434 | ||
1435 | ret = -EINVAL; | |
1436 | if (sscanf(ctx.body, "%llu", &v) != 1) | |
1437 | goto out_finish; | |
1438 | if (!v) | |
1439 | v = U64_MAX; | |
1440 | ||
1441 | tg = blkg_to_tg(ctx.blkg); | |
1442 | ||
1443 | if (is_u64) | |
1444 | *(u64 *)((void *)tg + of_cft(of)->private) = v; | |
1445 | else | |
1446 | *(unsigned int *)((void *)tg + of_cft(of)->private) = v; | |
1447 | ||
1448 | tg_conf_updated(tg, false); | |
1449 | ret = 0; | |
1450 | out_finish: | |
1451 | blkg_conf_finish(&ctx); | |
1452 | return ret ?: nbytes; | |
1453 | } | |
1454 | ||
1455 | static ssize_t tg_set_conf_u64(struct kernfs_open_file *of, | |
1456 | char *buf, size_t nbytes, loff_t off) | |
1457 | { | |
1458 | return tg_set_conf(of, buf, nbytes, off, true); | |
1459 | } | |
1460 | ||
1461 | static ssize_t tg_set_conf_uint(struct kernfs_open_file *of, | |
1462 | char *buf, size_t nbytes, loff_t off) | |
1463 | { | |
1464 | return tg_set_conf(of, buf, nbytes, off, false); | |
1465 | } | |
1466 | ||
1467 | static struct cftype throtl_legacy_files[] = { | |
1468 | { | |
1469 | .name = "throttle.read_bps_device", | |
1470 | .private = offsetof(struct throtl_grp, bps[READ][LIMIT_MAX]), | |
1471 | .seq_show = tg_print_conf_u64, | |
1472 | .write = tg_set_conf_u64, | |
1473 | }, | |
1474 | { | |
1475 | .name = "throttle.write_bps_device", | |
1476 | .private = offsetof(struct throtl_grp, bps[WRITE][LIMIT_MAX]), | |
1477 | .seq_show = tg_print_conf_u64, | |
1478 | .write = tg_set_conf_u64, | |
1479 | }, | |
1480 | { | |
1481 | .name = "throttle.read_iops_device", | |
1482 | .private = offsetof(struct throtl_grp, iops[READ][LIMIT_MAX]), | |
1483 | .seq_show = tg_print_conf_uint, | |
1484 | .write = tg_set_conf_uint, | |
1485 | }, | |
1486 | { | |
1487 | .name = "throttle.write_iops_device", | |
1488 | .private = offsetof(struct throtl_grp, iops[WRITE][LIMIT_MAX]), | |
1489 | .seq_show = tg_print_conf_uint, | |
1490 | .write = tg_set_conf_uint, | |
1491 | }, | |
1492 | { | |
1493 | .name = "throttle.io_service_bytes", | |
1494 | .private = (unsigned long)&blkcg_policy_throtl, | |
1495 | .seq_show = blkg_print_stat_bytes, | |
1496 | }, | |
1497 | { | |
1498 | .name = "throttle.io_serviced", | |
1499 | .private = (unsigned long)&blkcg_policy_throtl, | |
1500 | .seq_show = blkg_print_stat_ios, | |
1501 | }, | |
1502 | { } /* terminate */ | |
1503 | }; | |
1504 | ||
1505 | static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd, | |
1506 | int off) | |
1507 | { | |
1508 | struct throtl_grp *tg = pd_to_tg(pd); | |
1509 | const char *dname = blkg_dev_name(pd->blkg); | |
1510 | char bufs[4][21] = { "max", "max", "max", "max" }; | |
1511 | u64 bps_dft; | |
1512 | unsigned int iops_dft; | |
1513 | char idle_time[26] = ""; | |
1514 | char latency_time[26] = ""; | |
1515 | ||
1516 | if (!dname) | |
1517 | return 0; | |
1518 | ||
1519 | if (off == LIMIT_LOW) { | |
1520 | bps_dft = 0; | |
1521 | iops_dft = 0; | |
1522 | } else { | |
1523 | bps_dft = U64_MAX; | |
1524 | iops_dft = UINT_MAX; | |
1525 | } | |
1526 | ||
1527 | if (tg->bps_conf[READ][off] == bps_dft && | |
1528 | tg->bps_conf[WRITE][off] == bps_dft && | |
1529 | tg->iops_conf[READ][off] == iops_dft && | |
1530 | tg->iops_conf[WRITE][off] == iops_dft && | |
1531 | (off != LIMIT_LOW || | |
1532 | (tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD && | |
1533 | tg->latency_target_conf == DFL_LATENCY_TARGET))) | |
1534 | return 0; | |
1535 | ||
1536 | if (tg->bps_conf[READ][off] != U64_MAX) | |
1537 | snprintf(bufs[0], sizeof(bufs[0]), "%llu", | |
1538 | tg->bps_conf[READ][off]); | |
1539 | if (tg->bps_conf[WRITE][off] != U64_MAX) | |
1540 | snprintf(bufs[1], sizeof(bufs[1]), "%llu", | |
1541 | tg->bps_conf[WRITE][off]); | |
1542 | if (tg->iops_conf[READ][off] != UINT_MAX) | |
1543 | snprintf(bufs[2], sizeof(bufs[2]), "%u", | |
1544 | tg->iops_conf[READ][off]); | |
1545 | if (tg->iops_conf[WRITE][off] != UINT_MAX) | |
1546 | snprintf(bufs[3], sizeof(bufs[3]), "%u", | |
1547 | tg->iops_conf[WRITE][off]); | |
1548 | if (off == LIMIT_LOW) { | |
1549 | if (tg->idletime_threshold_conf == ULONG_MAX) | |
1550 | strcpy(idle_time, " idle=max"); | |
1551 | else | |
1552 | snprintf(idle_time, sizeof(idle_time), " idle=%lu", | |
1553 | tg->idletime_threshold_conf); | |
1554 | ||
1555 | if (tg->latency_target_conf == ULONG_MAX) | |
1556 | strcpy(latency_time, " latency=max"); | |
1557 | else | |
1558 | snprintf(latency_time, sizeof(latency_time), | |
1559 | " latency=%lu", tg->latency_target_conf); | |
1560 | } | |
1561 | ||
1562 | seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n", | |
1563 | dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time, | |
1564 | latency_time); | |
1565 | return 0; | |
1566 | } | |
1567 | ||
1568 | static int tg_print_limit(struct seq_file *sf, void *v) | |
1569 | { | |
1570 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_limit, | |
1571 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
1572 | return 0; | |
1573 | } | |
1574 | ||
1575 | static ssize_t tg_set_limit(struct kernfs_open_file *of, | |
1576 | char *buf, size_t nbytes, loff_t off) | |
1577 | { | |
1578 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); | |
1579 | struct blkg_conf_ctx ctx; | |
1580 | struct throtl_grp *tg; | |
1581 | u64 v[4]; | |
1582 | unsigned long idle_time; | |
1583 | unsigned long latency_time; | |
1584 | int ret; | |
1585 | int index = of_cft(of)->private; | |
1586 | ||
1587 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); | |
1588 | if (ret) | |
1589 | return ret; | |
1590 | ||
1591 | tg = blkg_to_tg(ctx.blkg); | |
1592 | ||
1593 | v[0] = tg->bps_conf[READ][index]; | |
1594 | v[1] = tg->bps_conf[WRITE][index]; | |
1595 | v[2] = tg->iops_conf[READ][index]; | |
1596 | v[3] = tg->iops_conf[WRITE][index]; | |
1597 | ||
1598 | idle_time = tg->idletime_threshold_conf; | |
1599 | latency_time = tg->latency_target_conf; | |
1600 | while (true) { | |
1601 | char tok[27]; /* wiops=18446744073709551616 */ | |
1602 | char *p; | |
1603 | u64 val = U64_MAX; | |
1604 | int len; | |
1605 | ||
1606 | if (sscanf(ctx.body, "%26s%n", tok, &len) != 1) | |
1607 | break; | |
1608 | if (tok[0] == '\0') | |
1609 | break; | |
1610 | ctx.body += len; | |
1611 | ||
1612 | ret = -EINVAL; | |
1613 | p = tok; | |
1614 | strsep(&p, "="); | |
1615 | if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max"))) | |
1616 | goto out_finish; | |
1617 | ||
1618 | ret = -ERANGE; | |
1619 | if (!val) | |
1620 | goto out_finish; | |
1621 | ||
1622 | ret = -EINVAL; | |
1623 | if (!strcmp(tok, "rbps")) | |
1624 | v[0] = val; | |
1625 | else if (!strcmp(tok, "wbps")) | |
1626 | v[1] = val; | |
1627 | else if (!strcmp(tok, "riops")) | |
1628 | v[2] = min_t(u64, val, UINT_MAX); | |
1629 | else if (!strcmp(tok, "wiops")) | |
1630 | v[3] = min_t(u64, val, UINT_MAX); | |
1631 | else if (off == LIMIT_LOW && !strcmp(tok, "idle")) | |
1632 | idle_time = val; | |
1633 | else if (off == LIMIT_LOW && !strcmp(tok, "latency")) | |
1634 | latency_time = val; | |
1635 | else | |
1636 | goto out_finish; | |
1637 | } | |
1638 | ||
1639 | tg->bps_conf[READ][index] = v[0]; | |
1640 | tg->bps_conf[WRITE][index] = v[1]; | |
1641 | tg->iops_conf[READ][index] = v[2]; | |
1642 | tg->iops_conf[WRITE][index] = v[3]; | |
1643 | ||
1644 | if (index == LIMIT_MAX) { | |
1645 | tg->bps[READ][index] = v[0]; | |
1646 | tg->bps[WRITE][index] = v[1]; | |
1647 | tg->iops[READ][index] = v[2]; | |
1648 | tg->iops[WRITE][index] = v[3]; | |
1649 | } | |
1650 | tg->bps[READ][LIMIT_LOW] = min(tg->bps_conf[READ][LIMIT_LOW], | |
1651 | tg->bps_conf[READ][LIMIT_MAX]); | |
1652 | tg->bps[WRITE][LIMIT_LOW] = min(tg->bps_conf[WRITE][LIMIT_LOW], | |
1653 | tg->bps_conf[WRITE][LIMIT_MAX]); | |
1654 | tg->iops[READ][LIMIT_LOW] = min(tg->iops_conf[READ][LIMIT_LOW], | |
1655 | tg->iops_conf[READ][LIMIT_MAX]); | |
1656 | tg->iops[WRITE][LIMIT_LOW] = min(tg->iops_conf[WRITE][LIMIT_LOW], | |
1657 | tg->iops_conf[WRITE][LIMIT_MAX]); | |
1658 | tg->idletime_threshold_conf = idle_time; | |
1659 | tg->latency_target_conf = latency_time; | |
1660 | ||
1661 | /* force user to configure all settings for low limit */ | |
1662 | if (!(tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW] || | |
1663 | tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) || | |
1664 | tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD || | |
1665 | tg->latency_target_conf == DFL_LATENCY_TARGET) { | |
1666 | tg->bps[READ][LIMIT_LOW] = 0; | |
1667 | tg->bps[WRITE][LIMIT_LOW] = 0; | |
1668 | tg->iops[READ][LIMIT_LOW] = 0; | |
1669 | tg->iops[WRITE][LIMIT_LOW] = 0; | |
1670 | tg->idletime_threshold = DFL_IDLE_THRESHOLD; | |
1671 | tg->latency_target = DFL_LATENCY_TARGET; | |
1672 | } else if (index == LIMIT_LOW) { | |
1673 | tg->idletime_threshold = tg->idletime_threshold_conf; | |
1674 | tg->latency_target = tg->latency_target_conf; | |
1675 | } | |
1676 | ||
1677 | blk_throtl_update_limit_valid(tg->td); | |
1678 | if (tg->td->limit_valid[LIMIT_LOW]) { | |
1679 | if (index == LIMIT_LOW) | |
1680 | tg->td->limit_index = LIMIT_LOW; | |
1681 | } else | |
1682 | tg->td->limit_index = LIMIT_MAX; | |
1683 | tg_conf_updated(tg, index == LIMIT_LOW && | |
1684 | tg->td->limit_valid[LIMIT_LOW]); | |
1685 | ret = 0; | |
1686 | out_finish: | |
1687 | blkg_conf_finish(&ctx); | |
1688 | return ret ?: nbytes; | |
1689 | } | |
1690 | ||
1691 | static struct cftype throtl_files[] = { | |
1692 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW | |
1693 | { | |
1694 | .name = "low", | |
1695 | .flags = CFTYPE_NOT_ON_ROOT, | |
1696 | .seq_show = tg_print_limit, | |
1697 | .write = tg_set_limit, | |
1698 | .private = LIMIT_LOW, | |
1699 | }, | |
1700 | #endif | |
1701 | { | |
1702 | .name = "max", | |
1703 | .flags = CFTYPE_NOT_ON_ROOT, | |
1704 | .seq_show = tg_print_limit, | |
1705 | .write = tg_set_limit, | |
1706 | .private = LIMIT_MAX, | |
1707 | }, | |
1708 | { } /* terminate */ | |
1709 | }; | |
1710 | ||
1711 | static void throtl_shutdown_wq(struct request_queue *q) | |
1712 | { | |
1713 | struct throtl_data *td = q->td; | |
1714 | ||
1715 | cancel_work_sync(&td->dispatch_work); | |
1716 | } | |
1717 | ||
1718 | static struct blkcg_policy blkcg_policy_throtl = { | |
1719 | .dfl_cftypes = throtl_files, | |
1720 | .legacy_cftypes = throtl_legacy_files, | |
1721 | ||
1722 | .pd_alloc_fn = throtl_pd_alloc, | |
1723 | .pd_init_fn = throtl_pd_init, | |
1724 | .pd_online_fn = throtl_pd_online, | |
1725 | .pd_offline_fn = throtl_pd_offline, | |
1726 | .pd_free_fn = throtl_pd_free, | |
1727 | }; | |
1728 | ||
1729 | static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg) | |
1730 | { | |
1731 | unsigned long rtime = jiffies, wtime = jiffies; | |
1732 | ||
1733 | if (tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW]) | |
1734 | rtime = tg->last_low_overflow_time[READ]; | |
1735 | if (tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) | |
1736 | wtime = tg->last_low_overflow_time[WRITE]; | |
1737 | return min(rtime, wtime); | |
1738 | } | |
1739 | ||
1740 | /* tg should not be an intermediate node */ | |
1741 | static unsigned long tg_last_low_overflow_time(struct throtl_grp *tg) | |
1742 | { | |
1743 | struct throtl_service_queue *parent_sq; | |
1744 | struct throtl_grp *parent = tg; | |
1745 | unsigned long ret = __tg_last_low_overflow_time(tg); | |
1746 | ||
1747 | while (true) { | |
1748 | parent_sq = parent->service_queue.parent_sq; | |
1749 | parent = sq_to_tg(parent_sq); | |
1750 | if (!parent) | |
1751 | break; | |
1752 | ||
1753 | /* | |
1754 | * The parent doesn't have low limit, it always reaches low | |
1755 | * limit. Its overflow time is useless for children | |
1756 | */ | |
1757 | if (!parent->bps[READ][LIMIT_LOW] && | |
1758 | !parent->iops[READ][LIMIT_LOW] && | |
1759 | !parent->bps[WRITE][LIMIT_LOW] && | |
1760 | !parent->iops[WRITE][LIMIT_LOW]) | |
1761 | continue; | |
1762 | if (time_after(__tg_last_low_overflow_time(parent), ret)) | |
1763 | ret = __tg_last_low_overflow_time(parent); | |
1764 | } | |
1765 | return ret; | |
1766 | } | |
1767 | ||
1768 | static bool throtl_tg_is_idle(struct throtl_grp *tg) | |
1769 | { | |
1770 | /* | |
1771 | * cgroup is idle if: | |
1772 | * - single idle is too long, longer than a fixed value (in case user | |
1773 | * configure a too big threshold) or 4 times of idletime threshold | |
1774 | * - average think time is more than threshold | |
1775 | * - IO latency is largely below threshold | |
1776 | */ | |
1777 | unsigned long time; | |
1778 | bool ret; | |
1779 | ||
1780 | time = min_t(unsigned long, MAX_IDLE_TIME, 4 * tg->idletime_threshold); | |
1781 | ret = tg->latency_target == DFL_LATENCY_TARGET || | |
1782 | tg->idletime_threshold == DFL_IDLE_THRESHOLD || | |
1783 | (ktime_get_ns() >> 10) - tg->last_finish_time > time || | |
1784 | tg->avg_idletime > tg->idletime_threshold || | |
1785 | (tg->latency_target && tg->bio_cnt && | |
1786 | tg->bad_bio_cnt * 5 < tg->bio_cnt); | |
1787 | throtl_log(&tg->service_queue, | |
1788 | "avg_idle=%ld, idle_threshold=%ld, bad_bio=%d, total_bio=%d, is_idle=%d, scale=%d", | |
1789 | tg->avg_idletime, tg->idletime_threshold, tg->bad_bio_cnt, | |
1790 | tg->bio_cnt, ret, tg->td->scale); | |
1791 | return ret; | |
1792 | } | |
1793 | ||
1794 | static bool throtl_tg_can_upgrade(struct throtl_grp *tg) | |
1795 | { | |
1796 | struct throtl_service_queue *sq = &tg->service_queue; | |
1797 | bool read_limit, write_limit; | |
1798 | ||
1799 | /* | |
1800 | * if cgroup reaches low limit (if low limit is 0, the cgroup always | |
1801 | * reaches), it's ok to upgrade to next limit | |
1802 | */ | |
1803 | read_limit = tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW]; | |
1804 | write_limit = tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]; | |
1805 | if (!read_limit && !write_limit) | |
1806 | return true; | |
1807 | if (read_limit && sq->nr_queued[READ] && | |
1808 | (!write_limit || sq->nr_queued[WRITE])) | |
1809 | return true; | |
1810 | if (write_limit && sq->nr_queued[WRITE] && | |
1811 | (!read_limit || sq->nr_queued[READ])) | |
1812 | return true; | |
1813 | ||
1814 | if (time_after_eq(jiffies, | |
1815 | tg_last_low_overflow_time(tg) + tg->td->throtl_slice) && | |
1816 | throtl_tg_is_idle(tg)) | |
1817 | return true; | |
1818 | return false; | |
1819 | } | |
1820 | ||
1821 | static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg) | |
1822 | { | |
1823 | while (true) { | |
1824 | if (throtl_tg_can_upgrade(tg)) | |
1825 | return true; | |
1826 | tg = sq_to_tg(tg->service_queue.parent_sq); | |
1827 | if (!tg || !tg_to_blkg(tg)->parent) | |
1828 | return false; | |
1829 | } | |
1830 | return false; | |
1831 | } | |
1832 | ||
1833 | static bool throtl_can_upgrade(struct throtl_data *td, | |
1834 | struct throtl_grp *this_tg) | |
1835 | { | |
1836 | struct cgroup_subsys_state *pos_css; | |
1837 | struct blkcg_gq *blkg; | |
1838 | ||
1839 | if (td->limit_index != LIMIT_LOW) | |
1840 | return false; | |
1841 | ||
1842 | if (time_before(jiffies, td->low_downgrade_time + td->throtl_slice)) | |
1843 | return false; | |
1844 | ||
1845 | rcu_read_lock(); | |
1846 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { | |
1847 | struct throtl_grp *tg = blkg_to_tg(blkg); | |
1848 | ||
1849 | if (tg == this_tg) | |
1850 | continue; | |
1851 | if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) | |
1852 | continue; | |
1853 | if (!throtl_hierarchy_can_upgrade(tg)) { | |
1854 | rcu_read_unlock(); | |
1855 | return false; | |
1856 | } | |
1857 | } | |
1858 | rcu_read_unlock(); | |
1859 | return true; | |
1860 | } | |
1861 | ||
1862 | static void throtl_upgrade_check(struct throtl_grp *tg) | |
1863 | { | |
1864 | unsigned long now = jiffies; | |
1865 | ||
1866 | if (tg->td->limit_index != LIMIT_LOW) | |
1867 | return; | |
1868 | ||
1869 | if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) | |
1870 | return; | |
1871 | ||
1872 | tg->last_check_time = now; | |
1873 | ||
1874 | if (!time_after_eq(now, | |
1875 | __tg_last_low_overflow_time(tg) + tg->td->throtl_slice)) | |
1876 | return; | |
1877 | ||
1878 | if (throtl_can_upgrade(tg->td, NULL)) | |
1879 | throtl_upgrade_state(tg->td); | |
1880 | } | |
1881 | ||
1882 | static void throtl_upgrade_state(struct throtl_data *td) | |
1883 | { | |
1884 | struct cgroup_subsys_state *pos_css; | |
1885 | struct blkcg_gq *blkg; | |
1886 | ||
1887 | throtl_log(&td->service_queue, "upgrade to max"); | |
1888 | td->limit_index = LIMIT_MAX; | |
1889 | td->low_upgrade_time = jiffies; | |
1890 | td->scale = 0; | |
1891 | rcu_read_lock(); | |
1892 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { | |
1893 | struct throtl_grp *tg = blkg_to_tg(blkg); | |
1894 | struct throtl_service_queue *sq = &tg->service_queue; | |
1895 | ||
1896 | tg->disptime = jiffies - 1; | |
1897 | throtl_select_dispatch(sq); | |
1898 | throtl_schedule_next_dispatch(sq, false); | |
1899 | } | |
1900 | rcu_read_unlock(); | |
1901 | throtl_select_dispatch(&td->service_queue); | |
1902 | throtl_schedule_next_dispatch(&td->service_queue, false); | |
1903 | queue_work(kthrotld_workqueue, &td->dispatch_work); | |
1904 | } | |
1905 | ||
1906 | static void throtl_downgrade_state(struct throtl_data *td, int new) | |
1907 | { | |
1908 | td->scale /= 2; | |
1909 | ||
1910 | throtl_log(&td->service_queue, "downgrade, scale %d", td->scale); | |
1911 | if (td->scale) { | |
1912 | td->low_upgrade_time = jiffies - td->scale * td->throtl_slice; | |
1913 | return; | |
1914 | } | |
1915 | ||
1916 | td->limit_index = new; | |
1917 | td->low_downgrade_time = jiffies; | |
1918 | } | |
1919 | ||
1920 | static bool throtl_tg_can_downgrade(struct throtl_grp *tg) | |
1921 | { | |
1922 | struct throtl_data *td = tg->td; | |
1923 | unsigned long now = jiffies; | |
1924 | ||
1925 | /* | |
1926 | * If cgroup is below low limit, consider downgrade and throttle other | |
1927 | * cgroups | |
1928 | */ | |
1929 | if (time_after_eq(now, td->low_upgrade_time + td->throtl_slice) && | |
1930 | time_after_eq(now, tg_last_low_overflow_time(tg) + | |
1931 | td->throtl_slice) && | |
1932 | (!throtl_tg_is_idle(tg) || | |
1933 | !list_empty(&tg_to_blkg(tg)->blkcg->css.children))) | |
1934 | return true; | |
1935 | return false; | |
1936 | } | |
1937 | ||
1938 | static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg) | |
1939 | { | |
1940 | while (true) { | |
1941 | if (!throtl_tg_can_downgrade(tg)) | |
1942 | return false; | |
1943 | tg = sq_to_tg(tg->service_queue.parent_sq); | |
1944 | if (!tg || !tg_to_blkg(tg)->parent) | |
1945 | break; | |
1946 | } | |
1947 | return true; | |
1948 | } | |
1949 | ||
1950 | static void throtl_downgrade_check(struct throtl_grp *tg) | |
1951 | { | |
1952 | uint64_t bps; | |
1953 | unsigned int iops; | |
1954 | unsigned long elapsed_time; | |
1955 | unsigned long now = jiffies; | |
1956 | ||
1957 | if (tg->td->limit_index != LIMIT_MAX || | |
1958 | !tg->td->limit_valid[LIMIT_LOW]) | |
1959 | return; | |
1960 | if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) | |
1961 | return; | |
1962 | if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) | |
1963 | return; | |
1964 | ||
1965 | elapsed_time = now - tg->last_check_time; | |
1966 | tg->last_check_time = now; | |
1967 | ||
1968 | if (time_before(now, tg_last_low_overflow_time(tg) + | |
1969 | tg->td->throtl_slice)) | |
1970 | return; | |
1971 | ||
1972 | if (tg->bps[READ][LIMIT_LOW]) { | |
1973 | bps = tg->last_bytes_disp[READ] * HZ; | |
1974 | do_div(bps, elapsed_time); | |
1975 | if (bps >= tg->bps[READ][LIMIT_LOW]) | |
1976 | tg->last_low_overflow_time[READ] = now; | |
1977 | } | |
1978 | ||
1979 | if (tg->bps[WRITE][LIMIT_LOW]) { | |
1980 | bps = tg->last_bytes_disp[WRITE] * HZ; | |
1981 | do_div(bps, elapsed_time); | |
1982 | if (bps >= tg->bps[WRITE][LIMIT_LOW]) | |
1983 | tg->last_low_overflow_time[WRITE] = now; | |
1984 | } | |
1985 | ||
1986 | if (tg->iops[READ][LIMIT_LOW]) { | |
1987 | iops = tg->last_io_disp[READ] * HZ / elapsed_time; | |
1988 | if (iops >= tg->iops[READ][LIMIT_LOW]) | |
1989 | tg->last_low_overflow_time[READ] = now; | |
1990 | } | |
1991 | ||
1992 | if (tg->iops[WRITE][LIMIT_LOW]) { | |
1993 | iops = tg->last_io_disp[WRITE] * HZ / elapsed_time; | |
1994 | if (iops >= tg->iops[WRITE][LIMIT_LOW]) | |
1995 | tg->last_low_overflow_time[WRITE] = now; | |
1996 | } | |
1997 | ||
1998 | /* | |
1999 | * If cgroup is below low limit, consider downgrade and throttle other | |
2000 | * cgroups | |
2001 | */ | |
2002 | if (throtl_hierarchy_can_downgrade(tg)) | |
2003 | throtl_downgrade_state(tg->td, LIMIT_LOW); | |
2004 | ||
2005 | tg->last_bytes_disp[READ] = 0; | |
2006 | tg->last_bytes_disp[WRITE] = 0; | |
2007 | tg->last_io_disp[READ] = 0; | |
2008 | tg->last_io_disp[WRITE] = 0; | |
2009 | } | |
2010 | ||
2011 | static void blk_throtl_update_idletime(struct throtl_grp *tg) | |
2012 | { | |
2013 | unsigned long now = ktime_get_ns() >> 10; | |
2014 | unsigned long last_finish_time = tg->last_finish_time; | |
2015 | ||
2016 | if (now <= last_finish_time || last_finish_time == 0 || | |
2017 | last_finish_time == tg->checked_last_finish_time) | |
2018 | return; | |
2019 | ||
2020 | tg->avg_idletime = (tg->avg_idletime * 7 + now - last_finish_time) >> 3; | |
2021 | tg->checked_last_finish_time = last_finish_time; | |
2022 | } | |
2023 | ||
2024 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW | |
2025 | static void throtl_update_latency_buckets(struct throtl_data *td) | |
2026 | { | |
2027 | struct avg_latency_bucket avg_latency[LATENCY_BUCKET_SIZE]; | |
2028 | int i, cpu; | |
2029 | unsigned long last_latency = 0; | |
2030 | unsigned long latency; | |
2031 | ||
2032 | if (!blk_queue_nonrot(td->queue)) | |
2033 | return; | |
2034 | if (time_before(jiffies, td->last_calculate_time + HZ)) | |
2035 | return; | |
2036 | td->last_calculate_time = jiffies; | |
2037 | ||
2038 | memset(avg_latency, 0, sizeof(avg_latency)); | |
2039 | for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { | |
2040 | struct latency_bucket *tmp = &td->tmp_buckets[i]; | |
2041 | ||
2042 | for_each_possible_cpu(cpu) { | |
2043 | struct latency_bucket *bucket; | |
2044 | ||
2045 | /* this isn't race free, but ok in practice */ | |
2046 | bucket = per_cpu_ptr(td->latency_buckets, cpu); | |
2047 | tmp->total_latency += bucket[i].total_latency; | |
2048 | tmp->samples += bucket[i].samples; | |
2049 | bucket[i].total_latency = 0; | |
2050 | bucket[i].samples = 0; | |
2051 | } | |
2052 | ||
2053 | if (tmp->samples >= 32) { | |
2054 | int samples = tmp->samples; | |
2055 | ||
2056 | latency = tmp->total_latency; | |
2057 | ||
2058 | tmp->total_latency = 0; | |
2059 | tmp->samples = 0; | |
2060 | latency /= samples; | |
2061 | if (latency == 0) | |
2062 | continue; | |
2063 | avg_latency[i].latency = latency; | |
2064 | } | |
2065 | } | |
2066 | ||
2067 | for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { | |
2068 | if (!avg_latency[i].latency) { | |
2069 | if (td->avg_buckets[i].latency < last_latency) | |
2070 | td->avg_buckets[i].latency = last_latency; | |
2071 | continue; | |
2072 | } | |
2073 | ||
2074 | if (!td->avg_buckets[i].valid) | |
2075 | latency = avg_latency[i].latency; | |
2076 | else | |
2077 | latency = (td->avg_buckets[i].latency * 7 + | |
2078 | avg_latency[i].latency) >> 3; | |
2079 | ||
2080 | td->avg_buckets[i].latency = max(latency, last_latency); | |
2081 | td->avg_buckets[i].valid = true; | |
2082 | last_latency = td->avg_buckets[i].latency; | |
2083 | } | |
2084 | ||
2085 | for (i = 0; i < LATENCY_BUCKET_SIZE; i++) | |
2086 | throtl_log(&td->service_queue, | |
2087 | "Latency bucket %d: latency=%ld, valid=%d", i, | |
2088 | td->avg_buckets[i].latency, td->avg_buckets[i].valid); | |
2089 | } | |
2090 | #else | |
2091 | static inline void throtl_update_latency_buckets(struct throtl_data *td) | |
2092 | { | |
2093 | } | |
2094 | #endif | |
2095 | ||
2096 | static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio) | |
2097 | { | |
2098 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW | |
2099 | int ret; | |
2100 | ||
2101 | ret = bio_associate_current(bio); | |
2102 | if (ret == 0 || ret == -EBUSY) | |
2103 | bio->bi_cg_private = tg; | |
2104 | blk_stat_set_issue(&bio->bi_issue_stat, bio_sectors(bio)); | |
2105 | #else | |
2106 | bio_associate_current(bio); | |
2107 | #endif | |
2108 | } | |
2109 | ||
2110 | bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, | |
2111 | struct bio *bio) | |
2112 | { | |
2113 | struct throtl_qnode *qn = NULL; | |
2114 | struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg); | |
2115 | struct throtl_service_queue *sq; | |
2116 | bool rw = bio_data_dir(bio); | |
2117 | bool throttled = false; | |
2118 | struct throtl_data *td = tg->td; | |
2119 | ||
2120 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
2121 | ||
2122 | /* see throtl_charge_bio() */ | |
2123 | if (bio_flagged(bio, BIO_THROTTLED) || !tg->has_rules[rw]) | |
2124 | goto out; | |
2125 | ||
2126 | spin_lock_irq(q->queue_lock); | |
2127 | ||
2128 | throtl_update_latency_buckets(td); | |
2129 | ||
2130 | if (unlikely(blk_queue_bypass(q))) | |
2131 | goto out_unlock; | |
2132 | ||
2133 | blk_throtl_assoc_bio(tg, bio); | |
2134 | blk_throtl_update_idletime(tg); | |
2135 | ||
2136 | sq = &tg->service_queue; | |
2137 | ||
2138 | again: | |
2139 | while (true) { | |
2140 | if (tg->last_low_overflow_time[rw] == 0) | |
2141 | tg->last_low_overflow_time[rw] = jiffies; | |
2142 | throtl_downgrade_check(tg); | |
2143 | throtl_upgrade_check(tg); | |
2144 | /* throtl is FIFO - if bios are already queued, should queue */ | |
2145 | if (sq->nr_queued[rw]) | |
2146 | break; | |
2147 | ||
2148 | /* if above limits, break to queue */ | |
2149 | if (!tg_may_dispatch(tg, bio, NULL)) { | |
2150 | tg->last_low_overflow_time[rw] = jiffies; | |
2151 | if (throtl_can_upgrade(td, tg)) { | |
2152 | throtl_upgrade_state(td); | |
2153 | goto again; | |
2154 | } | |
2155 | break; | |
2156 | } | |
2157 | ||
2158 | /* within limits, let's charge and dispatch directly */ | |
2159 | throtl_charge_bio(tg, bio); | |
2160 | ||
2161 | /* | |
2162 | * We need to trim slice even when bios are not being queued | |
2163 | * otherwise it might happen that a bio is not queued for | |
2164 | * a long time and slice keeps on extending and trim is not | |
2165 | * called for a long time. Now if limits are reduced suddenly | |
2166 | * we take into account all the IO dispatched so far at new | |
2167 | * low rate and * newly queued IO gets a really long dispatch | |
2168 | * time. | |
2169 | * | |
2170 | * So keep on trimming slice even if bio is not queued. | |
2171 | */ | |
2172 | throtl_trim_slice(tg, rw); | |
2173 | ||
2174 | /* | |
2175 | * @bio passed through this layer without being throttled. | |
2176 | * Climb up the ladder. If we''re already at the top, it | |
2177 | * can be executed directly. | |
2178 | */ | |
2179 | qn = &tg->qnode_on_parent[rw]; | |
2180 | sq = sq->parent_sq; | |
2181 | tg = sq_to_tg(sq); | |
2182 | if (!tg) | |
2183 | goto out_unlock; | |
2184 | } | |
2185 | ||
2186 | /* out-of-limit, queue to @tg */ | |
2187 | throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", | |
2188 | rw == READ ? 'R' : 'W', | |
2189 | tg->bytes_disp[rw], bio->bi_iter.bi_size, | |
2190 | tg_bps_limit(tg, rw), | |
2191 | tg->io_disp[rw], tg_iops_limit(tg, rw), | |
2192 | sq->nr_queued[READ], sq->nr_queued[WRITE]); | |
2193 | ||
2194 | tg->last_low_overflow_time[rw] = jiffies; | |
2195 | ||
2196 | td->nr_queued[rw]++; | |
2197 | throtl_add_bio_tg(bio, qn, tg); | |
2198 | throttled = true; | |
2199 | ||
2200 | /* | |
2201 | * Update @tg's dispatch time and force schedule dispatch if @tg | |
2202 | * was empty before @bio. The forced scheduling isn't likely to | |
2203 | * cause undue delay as @bio is likely to be dispatched directly if | |
2204 | * its @tg's disptime is not in the future. | |
2205 | */ | |
2206 | if (tg->flags & THROTL_TG_WAS_EMPTY) { | |
2207 | tg_update_disptime(tg); | |
2208 | throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true); | |
2209 | } | |
2210 | ||
2211 | out_unlock: | |
2212 | spin_unlock_irq(q->queue_lock); | |
2213 | out: | |
2214 | /* | |
2215 | * As multiple blk-throtls may stack in the same issue path, we | |
2216 | * don't want bios to leave with the flag set. Clear the flag if | |
2217 | * being issued. | |
2218 | */ | |
2219 | if (!throttled) | |
2220 | bio_clear_flag(bio, BIO_THROTTLED); | |
2221 | ||
2222 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW | |
2223 | if (throttled || !td->track_bio_latency) | |
2224 | bio->bi_issue_stat.stat |= SKIP_LATENCY; | |
2225 | #endif | |
2226 | return throttled; | |
2227 | } | |
2228 | ||
2229 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW | |
2230 | static void throtl_track_latency(struct throtl_data *td, sector_t size, | |
2231 | int op, unsigned long time) | |
2232 | { | |
2233 | struct latency_bucket *latency; | |
2234 | int index; | |
2235 | ||
2236 | if (!td || td->limit_index != LIMIT_LOW || op != REQ_OP_READ || | |
2237 | !blk_queue_nonrot(td->queue)) | |
2238 | return; | |
2239 | ||
2240 | index = request_bucket_index(size); | |
2241 | ||
2242 | latency = get_cpu_ptr(td->latency_buckets); | |
2243 | latency[index].total_latency += time; | |
2244 | latency[index].samples++; | |
2245 | put_cpu_ptr(td->latency_buckets); | |
2246 | } | |
2247 | ||
2248 | void blk_throtl_stat_add(struct request *rq, u64 time_ns) | |
2249 | { | |
2250 | struct request_queue *q = rq->q; | |
2251 | struct throtl_data *td = q->td; | |
2252 | ||
2253 | throtl_track_latency(td, blk_stat_size(&rq->issue_stat), | |
2254 | req_op(rq), time_ns >> 10); | |
2255 | } | |
2256 | ||
2257 | void blk_throtl_bio_endio(struct bio *bio) | |
2258 | { | |
2259 | struct throtl_grp *tg; | |
2260 | u64 finish_time_ns; | |
2261 | unsigned long finish_time; | |
2262 | unsigned long start_time; | |
2263 | unsigned long lat; | |
2264 | ||
2265 | tg = bio->bi_cg_private; | |
2266 | if (!tg) | |
2267 | return; | |
2268 | bio->bi_cg_private = NULL; | |
2269 | ||
2270 | finish_time_ns = ktime_get_ns(); | |
2271 | tg->last_finish_time = finish_time_ns >> 10; | |
2272 | ||
2273 | start_time = blk_stat_time(&bio->bi_issue_stat) >> 10; | |
2274 | finish_time = __blk_stat_time(finish_time_ns) >> 10; | |
2275 | if (!start_time || finish_time <= start_time) | |
2276 | return; | |
2277 | ||
2278 | lat = finish_time - start_time; | |
2279 | /* this is only for bio based driver */ | |
2280 | if (!(bio->bi_issue_stat.stat & SKIP_LATENCY)) | |
2281 | throtl_track_latency(tg->td, blk_stat_size(&bio->bi_issue_stat), | |
2282 | bio_op(bio), lat); | |
2283 | ||
2284 | if (tg->latency_target) { | |
2285 | int bucket; | |
2286 | unsigned int threshold; | |
2287 | ||
2288 | bucket = request_bucket_index( | |
2289 | blk_stat_size(&bio->bi_issue_stat)); | |
2290 | threshold = tg->td->avg_buckets[bucket].latency + | |
2291 | tg->latency_target; | |
2292 | if (lat > threshold) | |
2293 | tg->bad_bio_cnt++; | |
2294 | /* | |
2295 | * Not race free, could get wrong count, which means cgroups | |
2296 | * will be throttled | |
2297 | */ | |
2298 | tg->bio_cnt++; | |
2299 | } | |
2300 | ||
2301 | if (time_after(jiffies, tg->bio_cnt_reset_time) || tg->bio_cnt > 1024) { | |
2302 | tg->bio_cnt_reset_time = tg->td->throtl_slice + jiffies; | |
2303 | tg->bio_cnt /= 2; | |
2304 | tg->bad_bio_cnt /= 2; | |
2305 | } | |
2306 | } | |
2307 | #endif | |
2308 | ||
2309 | /* | |
2310 | * Dispatch all bios from all children tg's queued on @parent_sq. On | |
2311 | * return, @parent_sq is guaranteed to not have any active children tg's | |
2312 | * and all bios from previously active tg's are on @parent_sq->bio_lists[]. | |
2313 | */ | |
2314 | static void tg_drain_bios(struct throtl_service_queue *parent_sq) | |
2315 | { | |
2316 | struct throtl_grp *tg; | |
2317 | ||
2318 | while ((tg = throtl_rb_first(parent_sq))) { | |
2319 | struct throtl_service_queue *sq = &tg->service_queue; | |
2320 | struct bio *bio; | |
2321 | ||
2322 | throtl_dequeue_tg(tg); | |
2323 | ||
2324 | while ((bio = throtl_peek_queued(&sq->queued[READ]))) | |
2325 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
2326 | while ((bio = throtl_peek_queued(&sq->queued[WRITE]))) | |
2327 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
2328 | } | |
2329 | } | |
2330 | ||
2331 | /** | |
2332 | * blk_throtl_drain - drain throttled bios | |
2333 | * @q: request_queue to drain throttled bios for | |
2334 | * | |
2335 | * Dispatch all currently throttled bios on @q through ->make_request_fn(). | |
2336 | */ | |
2337 | void blk_throtl_drain(struct request_queue *q) | |
2338 | __releases(q->queue_lock) __acquires(q->queue_lock) | |
2339 | { | |
2340 | struct throtl_data *td = q->td; | |
2341 | struct blkcg_gq *blkg; | |
2342 | struct cgroup_subsys_state *pos_css; | |
2343 | struct bio *bio; | |
2344 | int rw; | |
2345 | ||
2346 | queue_lockdep_assert_held(q); | |
2347 | rcu_read_lock(); | |
2348 | ||
2349 | /* | |
2350 | * Drain each tg while doing post-order walk on the blkg tree, so | |
2351 | * that all bios are propagated to td->service_queue. It'd be | |
2352 | * better to walk service_queue tree directly but blkg walk is | |
2353 | * easier. | |
2354 | */ | |
2355 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) | |
2356 | tg_drain_bios(&blkg_to_tg(blkg)->service_queue); | |
2357 | ||
2358 | /* finally, transfer bios from top-level tg's into the td */ | |
2359 | tg_drain_bios(&td->service_queue); | |
2360 | ||
2361 | rcu_read_unlock(); | |
2362 | spin_unlock_irq(q->queue_lock); | |
2363 | ||
2364 | /* all bios now should be in td->service_queue, issue them */ | |
2365 | for (rw = READ; rw <= WRITE; rw++) | |
2366 | while ((bio = throtl_pop_queued(&td->service_queue.queued[rw], | |
2367 | NULL))) | |
2368 | generic_make_request(bio); | |
2369 | ||
2370 | spin_lock_irq(q->queue_lock); | |
2371 | } | |
2372 | ||
2373 | int blk_throtl_init(struct request_queue *q) | |
2374 | { | |
2375 | struct throtl_data *td; | |
2376 | int ret; | |
2377 | ||
2378 | td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); | |
2379 | if (!td) | |
2380 | return -ENOMEM; | |
2381 | td->latency_buckets = __alloc_percpu(sizeof(struct latency_bucket) * | |
2382 | LATENCY_BUCKET_SIZE, __alignof__(u64)); | |
2383 | if (!td->latency_buckets) { | |
2384 | kfree(td); | |
2385 | return -ENOMEM; | |
2386 | } | |
2387 | ||
2388 | INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn); | |
2389 | throtl_service_queue_init(&td->service_queue); | |
2390 | ||
2391 | q->td = td; | |
2392 | td->queue = q; | |
2393 | ||
2394 | td->limit_valid[LIMIT_MAX] = true; | |
2395 | td->limit_index = LIMIT_MAX; | |
2396 | td->low_upgrade_time = jiffies; | |
2397 | td->low_downgrade_time = jiffies; | |
2398 | ||
2399 | /* activate policy */ | |
2400 | ret = blkcg_activate_policy(q, &blkcg_policy_throtl); | |
2401 | if (ret) { | |
2402 | free_percpu(td->latency_buckets); | |
2403 | kfree(td); | |
2404 | } | |
2405 | return ret; | |
2406 | } | |
2407 | ||
2408 | void blk_throtl_exit(struct request_queue *q) | |
2409 | { | |
2410 | BUG_ON(!q->td); | |
2411 | throtl_shutdown_wq(q); | |
2412 | blkcg_deactivate_policy(q, &blkcg_policy_throtl); | |
2413 | free_percpu(q->td->latency_buckets); | |
2414 | kfree(q->td); | |
2415 | } | |
2416 | ||
2417 | void blk_throtl_register_queue(struct request_queue *q) | |
2418 | { | |
2419 | struct throtl_data *td; | |
2420 | ||
2421 | td = q->td; | |
2422 | BUG_ON(!td); | |
2423 | ||
2424 | if (blk_queue_nonrot(q)) | |
2425 | td->throtl_slice = DFL_THROTL_SLICE_SSD; | |
2426 | else | |
2427 | td->throtl_slice = DFL_THROTL_SLICE_HD; | |
2428 | #ifndef CONFIG_BLK_DEV_THROTTLING_LOW | |
2429 | /* if no low limit, use previous default */ | |
2430 | td->throtl_slice = DFL_THROTL_SLICE_HD; | |
2431 | #endif | |
2432 | ||
2433 | td->track_bio_latency = !q->mq_ops && !q->request_fn; | |
2434 | if (!td->track_bio_latency) | |
2435 | blk_stat_enable_accounting(q); | |
2436 | } | |
2437 | ||
2438 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW | |
2439 | ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page) | |
2440 | { | |
2441 | if (!q->td) | |
2442 | return -EINVAL; | |
2443 | return sprintf(page, "%u\n", jiffies_to_msecs(q->td->throtl_slice)); | |
2444 | } | |
2445 | ||
2446 | ssize_t blk_throtl_sample_time_store(struct request_queue *q, | |
2447 | const char *page, size_t count) | |
2448 | { | |
2449 | unsigned long v; | |
2450 | unsigned long t; | |
2451 | ||
2452 | if (!q->td) | |
2453 | return -EINVAL; | |
2454 | if (kstrtoul(page, 10, &v)) | |
2455 | return -EINVAL; | |
2456 | t = msecs_to_jiffies(v); | |
2457 | if (t == 0 || t > MAX_THROTL_SLICE) | |
2458 | return -EINVAL; | |
2459 | q->td->throtl_slice = t; | |
2460 | return count; | |
2461 | } | |
2462 | #endif | |
2463 | ||
2464 | static int __init throtl_init(void) | |
2465 | { | |
2466 | kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); | |
2467 | if (!kthrotld_workqueue) | |
2468 | panic("Failed to create kthrotld\n"); | |
2469 | ||
2470 | return blkcg_policy_register(&blkcg_policy_throtl); | |
2471 | } | |
2472 | ||
2473 | module_init(throtl_init); |