1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Interface for controlling IO bandwidth on a request queue
4 *
5 * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com>
6 */
7
8 #include <linux/module.h>
9 #include <linux/slab.h>
10 #include <linux/blkdev.h>
11 #include <linux/bio.h>
12 #include <linux/blktrace_api.h>
13 #include <linux/blk-cgroup.h>
14 #include "blk.h"
15 #include "blk-cgroup-rwstat.h"
16
17 /* Max dispatch from a group in 1 round */
18 #define THROTL_GRP_QUANTUM 8
19
20 /* Total max dispatch from all groups in one round */
21 #define THROTL_QUANTUM 32
22
23 /* Throttling is performed over a slice and after that slice is renewed */
24 #define DFL_THROTL_SLICE_HD (HZ / 10)
25 #define DFL_THROTL_SLICE_SSD (HZ / 50)
26 #define MAX_THROTL_SLICE (HZ)
27 #define MAX_IDLE_TIME (5L * 1000 * 1000) /* 5 s */
28 #define MIN_THROTL_BPS (320 * 1024)
29 #define MIN_THROTL_IOPS (10)
30 #define DFL_LATENCY_TARGET (-1L)
31 #define DFL_IDLE_THRESHOLD (0)
32 #define DFL_HD_BASELINE_LATENCY (4000L) /* 4ms */
33 #define LATENCY_FILTERED_SSD (0)
34 /*
35 * For HD, very small latency comes from sequential IO. Such IO is helpless to
36 * help determine if its IO is impacted by others, hence we ignore the IO
37 */
38 #define LATENCY_FILTERED_HD (1000L) /* 1ms */
39
40 static struct blkcg_policy blkcg_policy_throtl;
41
42 /* A workqueue to queue throttle related work */
43 static struct workqueue_struct *kthrotld_workqueue;
44
45 /*
46 * To implement hierarchical throttling, throtl_grps form a tree and bios
47 * are dispatched upwards level by level until they reach the top and get
48 * issued. When dispatching bios from the children and local group at each
49 * level, if the bios are dispatched into a single bio_list, there's a risk
50 * of a local or child group which can queue many bios at once filling up
51 * the list starving others.
52 *
53 * To avoid such starvation, dispatched bios are queued separately
54 * according to where they came from. When they are again dispatched to
55 * the parent, they're popped in round-robin order so that no single source
56 * hogs the dispatch window.
57 *
58 * throtl_qnode is used to keep the queued bios separated by their sources.
59 * Bios are queued to throtl_qnode which in turn is queued to
60 * throtl_service_queue and then dispatched in round-robin order.
61 *
62 * It's also used to track the reference counts on blkg's. A qnode always
63 * belongs to a throtl_grp and gets queued on itself or the parent, so
64 * incrementing the reference of the associated throtl_grp when a qnode is
65 * queued and decrementing when dequeued is enough to keep the whole blkg
66 * tree pinned while bios are in flight.
67 */
68 struct throtl_qnode {
69 struct list_head node; /* service_queue->queued[] */
70 struct bio_list bios; /* queued bios */
71 struct throtl_grp *tg; /* tg this qnode belongs to */
72 };
73
74 struct throtl_service_queue {
75 struct throtl_service_queue *parent_sq; /* the parent service_queue */
76
77 /*
78 * Bios queued directly to this service_queue or dispatched from
79 * children throtl_grp's.
80 */
81 struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */
82 unsigned int nr_queued[2]; /* number of queued bios */
83
84 /*
85 * RB tree of active children throtl_grp's, which are sorted by
86 * their ->disptime.
87 */
88 struct rb_root_cached pending_tree; /* RB tree of active tgs */
89 unsigned int nr_pending; /* # queued in the tree */
90 unsigned long first_pending_disptime; /* disptime of the first tg */
91 struct timer_list pending_timer; /* fires on first_pending_disptime */
92 };
93
94 enum tg_state_flags {
95 THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */
96 THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */
97 };
98
99 #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
100
101 enum {
102 LIMIT_LOW,
103 LIMIT_MAX,
104 LIMIT_CNT,
105 };
106
107 struct throtl_grp {
108 /* must be the first member */
109 struct blkg_policy_data pd;
110
111 /* active throtl group service_queue member */
112 struct rb_node rb_node;
113
114 /* throtl_data this group belongs to */
115 struct throtl_data *td;
116
117 /* this group's service queue */
118 struct throtl_service_queue service_queue;
119
120 /*
121 * qnode_on_self is used when bios are directly queued to this
122 * throtl_grp so that local bios compete fairly with bios
123 * dispatched from children. qnode_on_parent is used when bios are
124 * dispatched from this throtl_grp into its parent and will compete
125 * with the sibling qnode_on_parents and the parent's
126 * qnode_on_self.
127 */
128 struct throtl_qnode qnode_on_self[2];
129 struct throtl_qnode qnode_on_parent[2];
130
131 /*
132 * Dispatch time in jiffies. This is the estimated time when group
133 * will unthrottle and is ready to dispatch more bio. It is used as
134 * key to sort active groups in service tree.
135 */
136 unsigned long disptime;
137
138 unsigned int flags;
139
140 /* are there any throtl rules between this group and td? */
141 bool has_rules[2];
142
143 /* internally used bytes per second rate limits */
144 uint64_t bps[2][LIMIT_CNT];
145 /* user configured bps limits */
146 uint64_t bps_conf[2][LIMIT_CNT];
147
148 /* internally used IOPS limits */
149 unsigned int iops[2][LIMIT_CNT];
150 /* user configured IOPS limits */
151 unsigned int iops_conf[2][LIMIT_CNT];
152
153 /* Number of bytes dispatched in current slice */
154 uint64_t bytes_disp[2];
155 /* Number of bio's dispatched in current slice */
156 unsigned int io_disp[2];
157
158 unsigned long last_low_overflow_time[2];
159
160 uint64_t last_bytes_disp[2];
161 unsigned int last_io_disp[2];
162
163 unsigned long last_check_time;
164
165 unsigned long latency_target; /* us */
166 unsigned long latency_target_conf; /* us */
167 /* When did we start a new slice */
168 unsigned long slice_start[2];
169 unsigned long slice_end[2];
170
171 unsigned long last_finish_time; /* ns / 1024 */
172 unsigned long checked_last_finish_time; /* ns / 1024 */
173 unsigned long avg_idletime; /* ns / 1024 */
174 unsigned long idletime_threshold; /* us */
175 unsigned long idletime_threshold_conf; /* us */
176
177 unsigned int bio_cnt; /* total bios */
178 unsigned int bad_bio_cnt; /* bios exceeding latency threshold */
179 unsigned long bio_cnt_reset_time;
180
181 atomic_t io_split_cnt[2];
182 atomic_t last_io_split_cnt[2];
183
184 struct blkg_rwstat stat_bytes;
185 struct blkg_rwstat stat_ios;
186 };
187
188 /* We measure latency for request size from <= 4k to >= 1M */
189 #define LATENCY_BUCKET_SIZE 9
190
191 struct latency_bucket {
192 unsigned long total_latency; /* ns / 1024 */
193 int samples;
194 };
195
196 struct avg_latency_bucket {
197 unsigned long latency; /* ns / 1024 */
198 bool valid;
199 };
200
201 struct throtl_data
202 {
203 /* service tree for active throtl groups */
204 struct throtl_service_queue service_queue;
205
206 struct request_queue *queue;
207
208 /* Total Number of queued bios on READ and WRITE lists */
209 unsigned int nr_queued[2];
210
211 unsigned int throtl_slice;
212
213 /* Work for dispatching throttled bios */
214 struct work_struct dispatch_work;
215 unsigned int limit_index;
216 bool limit_valid[LIMIT_CNT];
217
218 unsigned long low_upgrade_time;
219 unsigned long low_downgrade_time;
220
221 unsigned int scale;
222
223 struct latency_bucket tmp_buckets[2][LATENCY_BUCKET_SIZE];
224 struct avg_latency_bucket avg_buckets[2][LATENCY_BUCKET_SIZE];
225 struct latency_bucket __percpu *latency_buckets[2];
226 unsigned long last_calculate_time;
227 unsigned long filtered_latency;
228
229 bool track_bio_latency;
230 };
231
232 static void throtl_pending_timer_fn(struct timer_list *t);
233
pd_to_tg(struct blkg_policy_data * pd)234 static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
235 {
236 return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
237 }
238
blkg_to_tg(struct blkcg_gq * blkg)239 static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg)
240 {
241 return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
242 }
243
tg_to_blkg(struct throtl_grp * tg)244 static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)
245 {
246 return pd_to_blkg(&tg->pd);
247 }
248
249 /**
250 * sq_to_tg - return the throl_grp the specified service queue belongs to
251 * @sq: the throtl_service_queue of interest
252 *
253 * Return the throtl_grp @sq belongs to. If @sq is the top-level one
254 * embedded in throtl_data, %NULL is returned.
255 */
sq_to_tg(struct throtl_service_queue * sq)256 static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq)
257 {
258 if (sq && sq->parent_sq)
259 return container_of(sq, struct throtl_grp, service_queue);
260 else
261 return NULL;
262 }
263
264 /**
265 * sq_to_td - return throtl_data the specified service queue belongs to
266 * @sq: the throtl_service_queue of interest
267 *
268 * A service_queue can be embedded in either a throtl_grp or throtl_data.
269 * Determine the associated throtl_data accordingly and return it.
270 */
sq_to_td(struct throtl_service_queue * sq)271 static struct throtl_data *sq_to_td(struct throtl_service_queue *sq)
272 {
273 struct throtl_grp *tg = sq_to_tg(sq);
274
275 if (tg)
276 return tg->td;
277 else
278 return container_of(sq, struct throtl_data, service_queue);
279 }
280
281 /*
282 * cgroup's limit in LIMIT_MAX is scaled if low limit is set. This scale is to
283 * make the IO dispatch more smooth.
284 * Scale up: linearly scale up according to lapsed time since upgrade. For
285 * every throtl_slice, the limit scales up 1/2 .low limit till the
286 * limit hits .max limit
287 * Scale down: exponentially scale down if a cgroup doesn't hit its .low limit
288 */
throtl_adjusted_limit(uint64_t low,struct throtl_data * td)289 static uint64_t throtl_adjusted_limit(uint64_t low, struct throtl_data *td)
290 {
291 /* arbitrary value to avoid too big scale */
292 if (td->scale < 4096 && time_after_eq(jiffies,
293 td->low_upgrade_time + td->scale * td->throtl_slice))
294 td->scale = (jiffies - td->low_upgrade_time) / td->throtl_slice;
295
296 return low + (low >> 1) * td->scale;
297 }
298
tg_bps_limit(struct throtl_grp * tg,int rw)299 static uint64_t tg_bps_limit(struct throtl_grp *tg, int rw)
300 {
301 struct blkcg_gq *blkg = tg_to_blkg(tg);
302 struct throtl_data *td;
303 uint64_t ret;
304
305 if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent)
306 return U64_MAX;
307
308 td = tg->td;
309 ret = tg->bps[rw][td->limit_index];
310 if (ret == 0 && td->limit_index == LIMIT_LOW) {
311 /* intermediate node or iops isn't 0 */
312 if (!list_empty(&blkg->blkcg->css.children) ||
313 tg->iops[rw][td->limit_index])
314 return U64_MAX;
315 else
316 return MIN_THROTL_BPS;
317 }
318
319 if (td->limit_index == LIMIT_MAX && tg->bps[rw][LIMIT_LOW] &&
320 tg->bps[rw][LIMIT_LOW] != tg->bps[rw][LIMIT_MAX]) {
321 uint64_t adjusted;
322
323 adjusted = throtl_adjusted_limit(tg->bps[rw][LIMIT_LOW], td);
324 ret = min(tg->bps[rw][LIMIT_MAX], adjusted);
325 }
326 return ret;
327 }
328
tg_iops_limit(struct throtl_grp * tg,int rw)329 static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw)
330 {
331 struct blkcg_gq *blkg = tg_to_blkg(tg);
332 struct throtl_data *td;
333 unsigned int ret;
334
335 if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent)
336 return UINT_MAX;
337
338 td = tg->td;
339 ret = tg->iops[rw][td->limit_index];
340 if (ret == 0 && tg->td->limit_index == LIMIT_LOW) {
341 /* intermediate node or bps isn't 0 */
342 if (!list_empty(&blkg->blkcg->css.children) ||
343 tg->bps[rw][td->limit_index])
344 return UINT_MAX;
345 else
346 return MIN_THROTL_IOPS;
347 }
348
349 if (td->limit_index == LIMIT_MAX && tg->iops[rw][LIMIT_LOW] &&
350 tg->iops[rw][LIMIT_LOW] != tg->iops[rw][LIMIT_MAX]) {
351 uint64_t adjusted;
352
353 adjusted = throtl_adjusted_limit(tg->iops[rw][LIMIT_LOW], td);
354 if (adjusted > UINT_MAX)
355 adjusted = UINT_MAX;
356 ret = min_t(unsigned int, tg->iops[rw][LIMIT_MAX], adjusted);
357 }
358 return ret;
359 }
360
361 #define request_bucket_index(sectors) \
362 clamp_t(int, order_base_2(sectors) - 3, 0, LATENCY_BUCKET_SIZE - 1)
363
364 /**
365 * throtl_log - log debug message via blktrace
366 * @sq: the service_queue being reported
367 * @fmt: printf format string
368 * @args: printf args
369 *
370 * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a
371 * throtl_grp; otherwise, just "throtl".
372 */
373 #define throtl_log(sq, fmt, args...) do { \
374 struct throtl_grp *__tg = sq_to_tg((sq)); \
375 struct throtl_data *__td = sq_to_td((sq)); \
376 \
377 (void)__td; \
378 if (likely(!blk_trace_note_message_enabled(__td->queue))) \
379 break; \
380 if ((__tg)) { \
381 blk_add_cgroup_trace_msg(__td->queue, \
382 tg_to_blkg(__tg)->blkcg, "throtl " fmt, ##args);\
383 } else { \
384 blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \
385 } \
386 } while (0)
387
throtl_bio_data_size(struct bio * bio)388 static inline unsigned int throtl_bio_data_size(struct bio *bio)
389 {
390 /* assume it's one sector */
391 if (unlikely(bio_op(bio) == REQ_OP_DISCARD))
392 return 512;
393 return bio->bi_iter.bi_size;
394 }
395
throtl_qnode_init(struct throtl_qnode * qn,struct throtl_grp * tg)396 static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg)
397 {
398 INIT_LIST_HEAD(&qn->node);
399 bio_list_init(&qn->bios);
400 qn->tg = tg;
401 }
402
403 /**
404 * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it
405 * @bio: bio being added
406 * @qn: qnode to add bio to
407 * @queued: the service_queue->queued[] list @qn belongs to
408 *
409 * Add @bio to @qn and put @qn on @queued if it's not already on.
410 * @qn->tg's reference count is bumped when @qn is activated. See the
411 * comment on top of throtl_qnode definition for details.
412 */
throtl_qnode_add_bio(struct bio * bio,struct throtl_qnode * qn,struct list_head * queued)413 static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn,
414 struct list_head *queued)
415 {
416 bio_list_add(&qn->bios, bio);
417 if (list_empty(&qn->node)) {
418 list_add_tail(&qn->node, queued);
419 blkg_get(tg_to_blkg(qn->tg));
420 }
421 }
422
423 /**
424 * throtl_peek_queued - peek the first bio on a qnode list
425 * @queued: the qnode list to peek
426 */
throtl_peek_queued(struct list_head * queued)427 static struct bio *throtl_peek_queued(struct list_head *queued)
428 {
429 struct throtl_qnode *qn;
430 struct bio *bio;
431
432 if (list_empty(queued))
433 return NULL;
434
435 qn = list_first_entry(queued, struct throtl_qnode, node);
436 bio = bio_list_peek(&qn->bios);
437 WARN_ON_ONCE(!bio);
438 return bio;
439 }
440
441 /**
442 * throtl_pop_queued - pop the first bio form a qnode list
443 * @queued: the qnode list to pop a bio from
444 * @tg_to_put: optional out argument for throtl_grp to put
445 *
446 * Pop the first bio from the qnode list @queued. After popping, the first
447 * qnode is removed from @queued if empty or moved to the end of @queued so
448 * that the popping order is round-robin.
449 *
450 * When the first qnode is removed, its associated throtl_grp should be put
451 * too. If @tg_to_put is NULL, this function automatically puts it;
452 * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is
453 * responsible for putting it.
454 */
throtl_pop_queued(struct list_head * queued,struct throtl_grp ** tg_to_put)455 static struct bio *throtl_pop_queued(struct list_head *queued,
456 struct throtl_grp **tg_to_put)
457 {
458 struct throtl_qnode *qn;
459 struct bio *bio;
460
461 if (list_empty(queued))
462 return NULL;
463
464 qn = list_first_entry(queued, struct throtl_qnode, node);
465 bio = bio_list_pop(&qn->bios);
466 WARN_ON_ONCE(!bio);
467
468 if (bio_list_empty(&qn->bios)) {
469 list_del_init(&qn->node);
470 if (tg_to_put)
471 *tg_to_put = qn->tg;
472 else
473 blkg_put(tg_to_blkg(qn->tg));
474 } else {
475 list_move_tail(&qn->node, queued);
476 }
477
478 return bio;
479 }
480
481 /* init a service_queue, assumes the caller zeroed it */
throtl_service_queue_init(struct throtl_service_queue * sq)482 static void throtl_service_queue_init(struct throtl_service_queue *sq)
483 {
484 INIT_LIST_HEAD(&sq->queued[0]);
485 INIT_LIST_HEAD(&sq->queued[1]);
486 sq->pending_tree = RB_ROOT_CACHED;
487 timer_setup(&sq->pending_timer, throtl_pending_timer_fn, 0);
488 }
489
throtl_pd_alloc(gfp_t gfp,struct request_queue * q,struct blkcg * blkcg)490 static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp,
491 struct request_queue *q,
492 struct blkcg *blkcg)
493 {
494 struct throtl_grp *tg;
495 int rw;
496
497 tg = kzalloc_node(sizeof(*tg), gfp, q->node);
498 if (!tg)
499 return NULL;
500
501 if (blkg_rwstat_init(&tg->stat_bytes, gfp))
502 goto err_free_tg;
503
504 if (blkg_rwstat_init(&tg->stat_ios, gfp))
505 goto err_exit_stat_bytes;
506
507 throtl_service_queue_init(&tg->service_queue);
508
509 for (rw = READ; rw <= WRITE; rw++) {
510 throtl_qnode_init(&tg->qnode_on_self[rw], tg);
511 throtl_qnode_init(&tg->qnode_on_parent[rw], tg);
512 }
513
514 RB_CLEAR_NODE(&tg->rb_node);
515 tg->bps[READ][LIMIT_MAX] = U64_MAX;
516 tg->bps[WRITE][LIMIT_MAX] = U64_MAX;
517 tg->iops[READ][LIMIT_MAX] = UINT_MAX;
518 tg->iops[WRITE][LIMIT_MAX] = UINT_MAX;
519 tg->bps_conf[READ][LIMIT_MAX] = U64_MAX;
520 tg->bps_conf[WRITE][LIMIT_MAX] = U64_MAX;
521 tg->iops_conf[READ][LIMIT_MAX] = UINT_MAX;
522 tg->iops_conf[WRITE][LIMIT_MAX] = UINT_MAX;
523 /* LIMIT_LOW will have default value 0 */
524
525 tg->latency_target = DFL_LATENCY_TARGET;
526 tg->latency_target_conf = DFL_LATENCY_TARGET;
527 tg->idletime_threshold = DFL_IDLE_THRESHOLD;
528 tg->idletime_threshold_conf = DFL_IDLE_THRESHOLD;
529
530 return &tg->pd;
531
532 err_exit_stat_bytes:
533 blkg_rwstat_exit(&tg->stat_bytes);
534 err_free_tg:
535 kfree(tg);
536 return NULL;
537 }
538
throtl_pd_init(struct blkg_policy_data * pd)539 static void throtl_pd_init(struct blkg_policy_data *pd)
540 {
541 struct throtl_grp *tg = pd_to_tg(pd);
542 struct blkcg_gq *blkg = tg_to_blkg(tg);
543 struct throtl_data *td = blkg->q->td;
544 struct throtl_service_queue *sq = &tg->service_queue;
545
546 /*
547 * If on the default hierarchy, we switch to properly hierarchical
548 * behavior where limits on a given throtl_grp are applied to the
549 * whole subtree rather than just the group itself. e.g. If 16M
550 * read_bps limit is set on the root group, the whole system can't
551 * exceed 16M for the device.
552 *
553 * If not on the default hierarchy, the broken flat hierarchy
554 * behavior is retained where all throtl_grps are treated as if
555 * they're all separate root groups right below throtl_data.
556 * Limits of a group don't interact with limits of other groups
557 * regardless of the position of the group in the hierarchy.
558 */
559 sq->parent_sq = &td->service_queue;
560 if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent)
561 sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
562 tg->td = td;
563 }
564
565 /*
566 * Set has_rules[] if @tg or any of its parents have limits configured.
567 * This doesn't require walking up to the top of the hierarchy as the
568 * parent's has_rules[] is guaranteed to be correct.
569 */
tg_update_has_rules(struct throtl_grp * tg)570 static void tg_update_has_rules(struct throtl_grp *tg)
571 {
572 struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq);
573 struct throtl_data *td = tg->td;
574 int rw;
575
576 for (rw = READ; rw <= WRITE; rw++)
577 tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) ||
578 (td->limit_valid[td->limit_index] &&
579 (tg_bps_limit(tg, rw) != U64_MAX ||
580 tg_iops_limit(tg, rw) != UINT_MAX));
581 }
582
throtl_pd_online(struct blkg_policy_data * pd)583 static void throtl_pd_online(struct blkg_policy_data *pd)
584 {
585 struct throtl_grp *tg = pd_to_tg(pd);
586 /*
587 * We don't want new groups to escape the limits of its ancestors.
588 * Update has_rules[] after a new group is brought online.
589 */
590 tg_update_has_rules(tg);
591 }
592
blk_throtl_update_limit_valid(struct throtl_data * td)593 static void blk_throtl_update_limit_valid(struct throtl_data *td)
594 {
595 struct cgroup_subsys_state *pos_css;
596 struct blkcg_gq *blkg;
597 bool low_valid = false;
598
599 rcu_read_lock();
600 blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
601 struct throtl_grp *tg = blkg_to_tg(blkg);
602
603 if (tg->bps[READ][LIMIT_LOW] || tg->bps[WRITE][LIMIT_LOW] ||
604 tg->iops[READ][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) {
605 low_valid = true;
606 break;
607 }
608 }
609 rcu_read_unlock();
610
611 td->limit_valid[LIMIT_LOW] = low_valid;
612 }
613
614 static void throtl_upgrade_state(struct throtl_data *td);
throtl_pd_offline(struct blkg_policy_data * pd)615 static void throtl_pd_offline(struct blkg_policy_data *pd)
616 {
617 struct throtl_grp *tg = pd_to_tg(pd);
618
619 tg->bps[READ][LIMIT_LOW] = 0;
620 tg->bps[WRITE][LIMIT_LOW] = 0;
621 tg->iops[READ][LIMIT_LOW] = 0;
622 tg->iops[WRITE][LIMIT_LOW] = 0;
623
624 blk_throtl_update_limit_valid(tg->td);
625
626 if (!tg->td->limit_valid[tg->td->limit_index])
627 throtl_upgrade_state(tg->td);
628 }
629
throtl_pd_free(struct blkg_policy_data * pd)630 static void throtl_pd_free(struct blkg_policy_data *pd)
631 {
632 struct throtl_grp *tg = pd_to_tg(pd);
633
634 del_timer_sync(&tg->service_queue.pending_timer);
635 blkg_rwstat_exit(&tg->stat_bytes);
636 blkg_rwstat_exit(&tg->stat_ios);
637 kfree(tg);
638 }
639
640 static struct throtl_grp *
throtl_rb_first(struct throtl_service_queue * parent_sq)641 throtl_rb_first(struct throtl_service_queue *parent_sq)
642 {
643 struct rb_node *n;
644
645 n = rb_first_cached(&parent_sq->pending_tree);
646 WARN_ON_ONCE(!n);
647 if (!n)
648 return NULL;
649 return rb_entry_tg(n);
650 }
651
throtl_rb_erase(struct rb_node * n,struct throtl_service_queue * parent_sq)652 static void throtl_rb_erase(struct rb_node *n,
653 struct throtl_service_queue *parent_sq)
654 {
655 rb_erase_cached(n, &parent_sq->pending_tree);
656 RB_CLEAR_NODE(n);
657 --parent_sq->nr_pending;
658 }
659
update_min_dispatch_time(struct throtl_service_queue * parent_sq)660 static void update_min_dispatch_time(struct throtl_service_queue *parent_sq)
661 {
662 struct throtl_grp *tg;
663
664 tg = throtl_rb_first(parent_sq);
665 if (!tg)
666 return;
667
668 parent_sq->first_pending_disptime = tg->disptime;
669 }
670
tg_service_queue_add(struct throtl_grp * tg)671 static void tg_service_queue_add(struct throtl_grp *tg)
672 {
673 struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;
674 struct rb_node **node = &parent_sq->pending_tree.rb_root.rb_node;
675 struct rb_node *parent = NULL;
676 struct throtl_grp *__tg;
677 unsigned long key = tg->disptime;
678 bool leftmost = true;
679
680 while (*node != NULL) {
681 parent = *node;
682 __tg = rb_entry_tg(parent);
683
684 if (time_before(key, __tg->disptime))
685 node = &parent->rb_left;
686 else {
687 node = &parent->rb_right;
688 leftmost = false;
689 }
690 }
691
692 rb_link_node(&tg->rb_node, parent, node);
693 rb_insert_color_cached(&tg->rb_node, &parent_sq->pending_tree,
694 leftmost);
695 }
696
throtl_enqueue_tg(struct throtl_grp * tg)697 static void throtl_enqueue_tg(struct throtl_grp *tg)
698 {
699 if (!(tg->flags & THROTL_TG_PENDING)) {
700 tg_service_queue_add(tg);
701 tg->flags |= THROTL_TG_PENDING;
702 tg->service_queue.parent_sq->nr_pending++;
703 }
704 }
705
throtl_dequeue_tg(struct throtl_grp * tg)706 static void throtl_dequeue_tg(struct throtl_grp *tg)
707 {
708 if (tg->flags & THROTL_TG_PENDING) {
709 throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);
710 tg->flags &= ~THROTL_TG_PENDING;
711 }
712 }
713
714 /* Call with queue lock held */
throtl_schedule_pending_timer(struct throtl_service_queue * sq,unsigned long expires)715 static void throtl_schedule_pending_timer(struct throtl_service_queue *sq,
716 unsigned long expires)
717 {
718 unsigned long max_expire = jiffies + 8 * sq_to_td(sq)->throtl_slice;
719
720 /*
721 * Since we are adjusting the throttle limit dynamically, the sleep
722 * time calculated according to previous limit might be invalid. It's
723 * possible the cgroup sleep time is very long and no other cgroups
724 * have IO running so notify the limit changes. Make sure the cgroup
725 * doesn't sleep too long to avoid the missed notification.
726 */
727 if (time_after(expires, max_expire))
728 expires = max_expire;
729 mod_timer(&sq->pending_timer, expires);
730 throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu",
731 expires - jiffies, jiffies);
732 }
733
734 /**
735 * throtl_schedule_next_dispatch - schedule the next dispatch cycle
736 * @sq: the service_queue to schedule dispatch for
737 * @force: force scheduling
738 *
739 * Arm @sq->pending_timer so that the next dispatch cycle starts on the
740 * dispatch time of the first pending child. Returns %true if either timer
741 * is armed or there's no pending child left. %false if the current
742 * dispatch window is still open and the caller should continue
743 * dispatching.
744 *
745 * If @force is %true, the dispatch timer is always scheduled and this
746 * function is guaranteed to return %true. This is to be used when the
747 * caller can't dispatch itself and needs to invoke pending_timer
748 * unconditionally. Note that forced scheduling is likely to induce short
749 * delay before dispatch starts even if @sq->first_pending_disptime is not
750 * in the future and thus shouldn't be used in hot paths.
751 */
throtl_schedule_next_dispatch(struct throtl_service_queue * sq,bool force)752 static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq,
753 bool force)
754 {
755 /* any pending children left? */
756 if (!sq->nr_pending)
757 return true;
758
759 update_min_dispatch_time(sq);
760
761 /* is the next dispatch time in the future? */
762 if (force || time_after(sq->first_pending_disptime, jiffies)) {
763 throtl_schedule_pending_timer(sq, sq->first_pending_disptime);
764 return true;
765 }
766
767 /* tell the caller to continue dispatching */
768 return false;
769 }
770
throtl_start_new_slice_with_credit(struct throtl_grp * tg,bool rw,unsigned long start)771 static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg,
772 bool rw, unsigned long start)
773 {
774 tg->bytes_disp[rw] = 0;
775 tg->io_disp[rw] = 0;
776
777 atomic_set(&tg->io_split_cnt[rw], 0);
778
779 /*
780 * Previous slice has expired. We must have trimmed it after last
781 * bio dispatch. That means since start of last slice, we never used
782 * that bandwidth. Do try to make use of that bandwidth while giving
783 * credit.
784 */
785 if (time_after_eq(start, tg->slice_start[rw]))
786 tg->slice_start[rw] = start;
787
788 tg->slice_end[rw] = jiffies + tg->td->throtl_slice;
789 throtl_log(&tg->service_queue,
790 "[%c] new slice with credit start=%lu end=%lu jiffies=%lu",
791 rw == READ ? 'R' : 'W', tg->slice_start[rw],
792 tg->slice_end[rw], jiffies);
793 }
794
throtl_start_new_slice(struct throtl_grp * tg,bool rw)795 static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw)
796 {
797 tg->bytes_disp[rw] = 0;
798 tg->io_disp[rw] = 0;
799 tg->slice_start[rw] = jiffies;
800 tg->slice_end[rw] = jiffies + tg->td->throtl_slice;
801
802 atomic_set(&tg->io_split_cnt[rw], 0);
803
804 throtl_log(&tg->service_queue,
805 "[%c] new slice start=%lu end=%lu jiffies=%lu",
806 rw == READ ? 'R' : 'W', tg->slice_start[rw],
807 tg->slice_end[rw], jiffies);
808 }
809
throtl_set_slice_end(struct throtl_grp * tg,bool rw,unsigned long jiffy_end)810 static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw,
811 unsigned long jiffy_end)
812 {
813 tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice);
814 }
815
throtl_extend_slice(struct throtl_grp * tg,bool rw,unsigned long jiffy_end)816 static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw,
817 unsigned long jiffy_end)
818 {
819 throtl_set_slice_end(tg, rw, jiffy_end);
820 throtl_log(&tg->service_queue,
821 "[%c] extend slice start=%lu end=%lu jiffies=%lu",
822 rw == READ ? 'R' : 'W', tg->slice_start[rw],
823 tg->slice_end[rw], jiffies);
824 }
825
826 /* Determine if previously allocated or extended slice is complete or not */
throtl_slice_used(struct throtl_grp * tg,bool rw)827 static bool throtl_slice_used(struct throtl_grp *tg, bool rw)
828 {
829 if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
830 return false;
831
832 return true;
833 }
834
835 /* Trim the used slices and adjust slice start accordingly */
throtl_trim_slice(struct throtl_grp * tg,bool rw)836 static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
837 {
838 unsigned long nr_slices, time_elapsed, io_trim;
839 u64 bytes_trim, tmp;
840
841 BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
842
843 /*
844 * If bps are unlimited (-1), then time slice don't get
845 * renewed. Don't try to trim the slice if slice is used. A new
846 * slice will start when appropriate.
847 */
848 if (throtl_slice_used(tg, rw))
849 return;
850
851 /*
852 * A bio has been dispatched. Also adjust slice_end. It might happen
853 * that initially cgroup limit was very low resulting in high
854 * slice_end, but later limit was bumped up and bio was dispatched
855 * sooner, then we need to reduce slice_end. A high bogus slice_end
856 * is bad because it does not allow new slice to start.
857 */
858
859 throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice);
860
861 time_elapsed = jiffies - tg->slice_start[rw];
862
863 nr_slices = time_elapsed / tg->td->throtl_slice;
864
865 if (!nr_slices)
866 return;
867 tmp = tg_bps_limit(tg, rw) * tg->td->throtl_slice * nr_slices;
868 do_div(tmp, HZ);
869 bytes_trim = tmp;
870
871 io_trim = (tg_iops_limit(tg, rw) * tg->td->throtl_slice * nr_slices) /
872 HZ;
873
874 if (!bytes_trim && !io_trim)
875 return;
876
877 if (tg->bytes_disp[rw] >= bytes_trim)
878 tg->bytes_disp[rw] -= bytes_trim;
879 else
880 tg->bytes_disp[rw] = 0;
881
882 if (tg->io_disp[rw] >= io_trim)
883 tg->io_disp[rw] -= io_trim;
884 else
885 tg->io_disp[rw] = 0;
886
887 tg->slice_start[rw] += nr_slices * tg->td->throtl_slice;
888
889 throtl_log(&tg->service_queue,
890 "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu",
891 rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
892 tg->slice_start[rw], tg->slice_end[rw], jiffies);
893 }
894
tg_with_in_iops_limit(struct throtl_grp * tg,struct bio * bio,u32 iops_limit,unsigned long * wait)895 static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
896 u32 iops_limit, unsigned long *wait)
897 {
898 bool rw = bio_data_dir(bio);
899 unsigned int io_allowed;
900 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
901 u64 tmp;
902
903 if (iops_limit == UINT_MAX) {
904 if (wait)
905 *wait = 0;
906 return true;
907 }
908
909 jiffy_elapsed = jiffies - tg->slice_start[rw];
910
911 /* Round up to the next throttle slice, wait time must be nonzero */
912 jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice);
913
914 /*
915 * jiffy_elapsed_rnd should not be a big value as minimum iops can be
916 * 1 then at max jiffy elapsed should be equivalent of 1 second as we
917 * will allow dispatch after 1 second and after that slice should
918 * have been trimmed.
919 */
920
921 tmp = (u64)iops_limit * jiffy_elapsed_rnd;
922 do_div(tmp, HZ);
923
924 if (tmp > UINT_MAX)
925 io_allowed = UINT_MAX;
926 else
927 io_allowed = tmp;
928
929 if (tg->io_disp[rw] + 1 <= io_allowed) {
930 if (wait)
931 *wait = 0;
932 return true;
933 }
934
935 /* Calc approx time to dispatch */
936 jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed;
937
938 if (wait)
939 *wait = jiffy_wait;
940 return false;
941 }
942
tg_with_in_bps_limit(struct throtl_grp * tg,struct bio * bio,u64 bps_limit,unsigned long * wait)943 static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
944 u64 bps_limit, unsigned long *wait)
945 {
946 bool rw = bio_data_dir(bio);
947 u64 bytes_allowed, extra_bytes;
948 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
949 unsigned int bio_size = throtl_bio_data_size(bio);
950
951 if (bps_limit == U64_MAX) {
952 if (wait)
953 *wait = 0;
954 return true;
955 }
956
957 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
958
959 /* Slice has just started. Consider one slice interval */
960 if (!jiffy_elapsed)
961 jiffy_elapsed_rnd = tg->td->throtl_slice;
962
963 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);
964 bytes_allowed = mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed_rnd,
965 (u64)HZ);
966
967 if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) {
968 if (wait)
969 *wait = 0;
970 return true;
971 }
972
973 /* Calc approx time to dispatch */
974 extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed;
975 jiffy_wait = div64_u64(extra_bytes * HZ, bps_limit);
976
977 if (!jiffy_wait)
978 jiffy_wait = 1;
979
980 /*
981 * This wait time is without taking into consideration the rounding
982 * up we did. Add that time also.
983 */
984 jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
985 if (wait)
986 *wait = jiffy_wait;
987 return false;
988 }
989
990 /*
991 * Returns whether one can dispatch a bio or not. Also returns approx number
992 * of jiffies to wait before this bio is with-in IO rate and can be dispatched
993 */
tg_may_dispatch(struct throtl_grp * tg,struct bio * bio,unsigned long * wait)994 static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
995 unsigned long *wait)
996 {
997 bool rw = bio_data_dir(bio);
998 unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
999 u64 bps_limit = tg_bps_limit(tg, rw);
1000 u32 iops_limit = tg_iops_limit(tg, rw);
1001
1002 /*
1003 * Currently whole state machine of group depends on first bio
1004 * queued in the group bio list. So one should not be calling
1005 * this function with a different bio if there are other bios
1006 * queued.
1007 */
1008 BUG_ON(tg->service_queue.nr_queued[rw] &&
1009 bio != throtl_peek_queued(&tg->service_queue.queued[rw]));
1010
1011 /* If tg->bps = -1, then BW is unlimited */
1012 if (bps_limit == U64_MAX && iops_limit == UINT_MAX) {
1013 if (wait)
1014 *wait = 0;
1015 return true;
1016 }
1017
1018 /*
1019 * If previous slice expired, start a new one otherwise renew/extend
1020 * existing slice to make sure it is at least throtl_slice interval
1021 * long since now. New slice is started only for empty throttle group.
1022 * If there is queued bio, that means there should be an active
1023 * slice and it should be extended instead.
1024 */
1025 if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw]))
1026 throtl_start_new_slice(tg, rw);
1027 else {
1028 if (time_before(tg->slice_end[rw],
1029 jiffies + tg->td->throtl_slice))
1030 throtl_extend_slice(tg, rw,
1031 jiffies + tg->td->throtl_slice);
1032 }
1033
1034 if (iops_limit != UINT_MAX)
1035 tg->io_disp[rw] += atomic_xchg(&tg->io_split_cnt[rw], 0);
1036
1037 if (tg_with_in_bps_limit(tg, bio, bps_limit, &bps_wait) &&
1038 tg_with_in_iops_limit(tg, bio, iops_limit, &iops_wait)) {
1039 if (wait)
1040 *wait = 0;
1041 return true;
1042 }
1043
1044 max_wait = max(bps_wait, iops_wait);
1045
1046 if (wait)
1047 *wait = max_wait;
1048
1049 if (time_before(tg->slice_end[rw], jiffies + max_wait))
1050 throtl_extend_slice(tg, rw, jiffies + max_wait);
1051
1052 return false;
1053 }
1054
throtl_charge_bio(struct throtl_grp * tg,struct bio * bio)1055 static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
1056 {
1057 bool rw = bio_data_dir(bio);
1058 unsigned int bio_size = throtl_bio_data_size(bio);
1059
1060 /* Charge the bio to the group */
1061 tg->bytes_disp[rw] += bio_size;
1062 tg->io_disp[rw]++;
1063 tg->last_bytes_disp[rw] += bio_size;
1064 tg->last_io_disp[rw]++;
1065
1066 /*
1067 * BIO_THROTTLED is used to prevent the same bio to be throttled
1068 * more than once as a throttled bio will go through blk-throtl the
1069 * second time when it eventually gets issued. Set it when a bio
1070 * is being charged to a tg.
1071 */
1072 if (!bio_flagged(bio, BIO_THROTTLED))
1073 bio_set_flag(bio, BIO_THROTTLED);
1074 }
1075
1076 /**
1077 * throtl_add_bio_tg - add a bio to the specified throtl_grp
1078 * @bio: bio to add
1079 * @qn: qnode to use
1080 * @tg: the target throtl_grp
1081 *
1082 * Add @bio to @tg's service_queue using @qn. If @qn is not specified,
1083 * tg->qnode_on_self[] is used.
1084 */
throtl_add_bio_tg(struct bio * bio,struct throtl_qnode * qn,struct throtl_grp * tg)1085 static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn,
1086 struct throtl_grp *tg)
1087 {
1088 struct throtl_service_queue *sq = &tg->service_queue;
1089 bool rw = bio_data_dir(bio);
1090
1091 if (!qn)
1092 qn = &tg->qnode_on_self[rw];
1093
1094 /*
1095 * If @tg doesn't currently have any bios queued in the same
1096 * direction, queueing @bio can change when @tg should be
1097 * dispatched. Mark that @tg was empty. This is automatically
1098 * cleared on the next tg_update_disptime().
1099 */
1100 if (!sq->nr_queued[rw])
1101 tg->flags |= THROTL_TG_WAS_EMPTY;
1102
1103 throtl_qnode_add_bio(bio, qn, &sq->queued[rw]);
1104
1105 sq->nr_queued[rw]++;
1106 throtl_enqueue_tg(tg);
1107 }
1108
tg_update_disptime(struct throtl_grp * tg)1109 static void tg_update_disptime(struct throtl_grp *tg)
1110 {
1111 struct throtl_service_queue *sq = &tg->service_queue;
1112 unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
1113 struct bio *bio;
1114
1115 bio = throtl_peek_queued(&sq->queued[READ]);
1116 if (bio)
1117 tg_may_dispatch(tg, bio, &read_wait);
1118
1119 bio = throtl_peek_queued(&sq->queued[WRITE]);
1120 if (bio)
1121 tg_may_dispatch(tg, bio, &write_wait);
1122
1123 min_wait = min(read_wait, write_wait);
1124 disptime = jiffies + min_wait;
1125
1126 /* Update dispatch time */
1127 throtl_dequeue_tg(tg);
1128 tg->disptime = disptime;
1129 throtl_enqueue_tg(tg);
1130
1131 /* see throtl_add_bio_tg() */
1132 tg->flags &= ~THROTL_TG_WAS_EMPTY;
1133 }
1134
start_parent_slice_with_credit(struct throtl_grp * child_tg,struct throtl_grp * parent_tg,bool rw)1135 static void start_parent_slice_with_credit(struct throtl_grp *child_tg,
1136 struct throtl_grp *parent_tg, bool rw)
1137 {
1138 if (throtl_slice_used(parent_tg, rw)) {
1139 throtl_start_new_slice_with_credit(parent_tg, rw,
1140 child_tg->slice_start[rw]);
1141 }
1142
1143 }
1144
tg_dispatch_one_bio(struct throtl_grp * tg,bool rw)1145 static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw)
1146 {
1147 struct throtl_service_queue *sq = &tg->service_queue;
1148 struct throtl_service_queue *parent_sq = sq->parent_sq;
1149 struct throtl_grp *parent_tg = sq_to_tg(parent_sq);
1150 struct throtl_grp *tg_to_put = NULL;
1151 struct bio *bio;
1152
1153 /*
1154 * @bio is being transferred from @tg to @parent_sq. Popping a bio
1155 * from @tg may put its reference and @parent_sq might end up
1156 * getting released prematurely. Remember the tg to put and put it
1157 * after @bio is transferred to @parent_sq.
1158 */
1159 bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put);
1160 sq->nr_queued[rw]--;
1161
1162 throtl_charge_bio(tg, bio);
1163
1164 /*
1165 * If our parent is another tg, we just need to transfer @bio to
1166 * the parent using throtl_add_bio_tg(). If our parent is
1167 * @td->service_queue, @bio is ready to be issued. Put it on its
1168 * bio_lists[] and decrease total number queued. The caller is
1169 * responsible for issuing these bios.
1170 */
1171 if (parent_tg) {
1172 throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg);
1173 start_parent_slice_with_credit(tg, parent_tg, rw);
1174 } else {
1175 throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw],
1176 &parent_sq->queued[rw]);
1177 BUG_ON(tg->td->nr_queued[rw] <= 0);
1178 tg->td->nr_queued[rw]--;
1179 }
1180
1181 throtl_trim_slice(tg, rw);
1182
1183 if (tg_to_put)
1184 blkg_put(tg_to_blkg(tg_to_put));
1185 }
1186
throtl_dispatch_tg(struct throtl_grp * tg)1187 static int throtl_dispatch_tg(struct throtl_grp *tg)
1188 {
1189 struct throtl_service_queue *sq = &tg->service_queue;
1190 unsigned int nr_reads = 0, nr_writes = 0;
1191 unsigned int max_nr_reads = THROTL_GRP_QUANTUM * 3 / 4;
1192 unsigned int max_nr_writes = THROTL_GRP_QUANTUM - max_nr_reads;
1193 struct bio *bio;
1194
1195 /* Try to dispatch 75% READS and 25% WRITES */
1196
1197 while ((bio = throtl_peek_queued(&sq->queued[READ])) &&
1198 tg_may_dispatch(tg, bio, NULL)) {
1199
1200 tg_dispatch_one_bio(tg, bio_data_dir(bio));
1201 nr_reads++;
1202
1203 if (nr_reads >= max_nr_reads)
1204 break;
1205 }
1206
1207 while ((bio = throtl_peek_queued(&sq->queued[WRITE])) &&
1208 tg_may_dispatch(tg, bio, NULL)) {
1209
1210 tg_dispatch_one_bio(tg, bio_data_dir(bio));
1211 nr_writes++;
1212
1213 if (nr_writes >= max_nr_writes)
1214 break;
1215 }
1216
1217 return nr_reads + nr_writes;
1218 }
1219
throtl_select_dispatch(struct throtl_service_queue * parent_sq)1220 static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
1221 {
1222 unsigned int nr_disp = 0;
1223
1224 while (1) {
1225 struct throtl_grp *tg;
1226 struct throtl_service_queue *sq;
1227
1228 if (!parent_sq->nr_pending)
1229 break;
1230
1231 tg = throtl_rb_first(parent_sq);
1232 if (!tg)
1233 break;
1234
1235 if (time_before(jiffies, tg->disptime))
1236 break;
1237
1238 throtl_dequeue_tg(tg);
1239
1240 nr_disp += throtl_dispatch_tg(tg);
1241
1242 sq = &tg->service_queue;
1243 if (sq->nr_queued[0] || sq->nr_queued[1])
1244 tg_update_disptime(tg);
1245
1246 if (nr_disp >= THROTL_QUANTUM)
1247 break;
1248 }
1249
1250 return nr_disp;
1251 }
1252
1253 static bool throtl_can_upgrade(struct throtl_data *td,
1254 struct throtl_grp *this_tg);
1255 /**
1256 * throtl_pending_timer_fn - timer function for service_queue->pending_timer
1257 * @t: the pending_timer member of the throtl_service_queue being serviced
1258 *
1259 * This timer is armed when a child throtl_grp with active bio's become
1260 * pending and queued on the service_queue's pending_tree and expires when
1261 * the first child throtl_grp should be dispatched. This function
1262 * dispatches bio's from the children throtl_grps to the parent
1263 * service_queue.
1264 *
1265 * If the parent's parent is another throtl_grp, dispatching is propagated
1266 * by either arming its pending_timer or repeating dispatch directly. If
1267 * the top-level service_tree is reached, throtl_data->dispatch_work is
1268 * kicked so that the ready bio's are issued.
1269 */
throtl_pending_timer_fn(struct timer_list * t)1270 static void throtl_pending_timer_fn(struct timer_list *t)
1271 {
1272 struct throtl_service_queue *sq = from_timer(sq, t, pending_timer);
1273 struct throtl_grp *tg = sq_to_tg(sq);
1274 struct throtl_data *td = sq_to_td(sq);
1275 struct request_queue *q = td->queue;
1276 struct throtl_service_queue *parent_sq;
1277 bool dispatched;
1278 int ret;
1279
1280 spin_lock_irq(&q->queue_lock);
1281 if (throtl_can_upgrade(td, NULL))
1282 throtl_upgrade_state(td);
1283
1284 again:
1285 parent_sq = sq->parent_sq;
1286 dispatched = false;
1287
1288 while (true) {
1289 throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u",
1290 sq->nr_queued[READ] + sq->nr_queued[WRITE],
1291 sq->nr_queued[READ], sq->nr_queued[WRITE]);
1292
1293 ret = throtl_select_dispatch(sq);
1294 if (ret) {
1295 throtl_log(sq, "bios disp=%u", ret);
1296 dispatched = true;
1297 }
1298
1299 if (throtl_schedule_next_dispatch(sq, false))
1300 break;
1301
1302 /* this dispatch windows is still open, relax and repeat */
1303 spin_unlock_irq(&q->queue_lock);
1304 cpu_relax();
1305 spin_lock_irq(&q->queue_lock);
1306 }
1307
1308 if (!dispatched)
1309 goto out_unlock;
1310
1311 if (parent_sq) {
1312 /* @parent_sq is another throl_grp, propagate dispatch */
1313 if (tg->flags & THROTL_TG_WAS_EMPTY) {
1314 tg_update_disptime(tg);
1315 if (!throtl_schedule_next_dispatch(parent_sq, false)) {
1316 /* window is already open, repeat dispatching */
1317 sq = parent_sq;
1318 tg = sq_to_tg(sq);
1319 goto again;
1320 }
1321 }
1322 } else {
1323 /* reached the top-level, queue issuing */
1324 queue_work(kthrotld_workqueue, &td->dispatch_work);
1325 }
1326 out_unlock:
1327 spin_unlock_irq(&q->queue_lock);
1328 }
1329
1330 /**
1331 * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work
1332 * @work: work item being executed
1333 *
1334 * This function is queued for execution when bios reach the bio_lists[]
1335 * of throtl_data->service_queue. Those bios are ready and issued by this
1336 * function.
1337 */
blk_throtl_dispatch_work_fn(struct work_struct * work)1338 static void blk_throtl_dispatch_work_fn(struct work_struct *work)
1339 {
1340 struct throtl_data *td = container_of(work, struct throtl_data,
1341 dispatch_work);
1342 struct throtl_service_queue *td_sq = &td->service_queue;
1343 struct request_queue *q = td->queue;
1344 struct bio_list bio_list_on_stack;
1345 struct bio *bio;
1346 struct blk_plug plug;
1347 int rw;
1348
1349 bio_list_init(&bio_list_on_stack);
1350
1351 spin_lock_irq(&q->queue_lock);
1352 for (rw = READ; rw <= WRITE; rw++)
1353 while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL)))
1354 bio_list_add(&bio_list_on_stack, bio);
1355 spin_unlock_irq(&q->queue_lock);
1356
1357 if (!bio_list_empty(&bio_list_on_stack)) {
1358 blk_start_plug(&plug);
1359 while ((bio = bio_list_pop(&bio_list_on_stack)))
1360 submit_bio_noacct(bio);
1361 blk_finish_plug(&plug);
1362 }
1363 }
1364
tg_prfill_conf_u64(struct seq_file * sf,struct blkg_policy_data * pd,int off)1365 static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
1366 int off)
1367 {
1368 struct throtl_grp *tg = pd_to_tg(pd);
1369 u64 v = *(u64 *)((void *)tg + off);
1370
1371 if (v == U64_MAX)
1372 return 0;
1373 return __blkg_prfill_u64(sf, pd, v);
1374 }
1375
tg_prfill_conf_uint(struct seq_file * sf,struct blkg_policy_data * pd,int off)1376 static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,
1377 int off)
1378 {
1379 struct throtl_grp *tg = pd_to_tg(pd);
1380 unsigned int v = *(unsigned int *)((void *)tg + off);
1381
1382 if (v == UINT_MAX)
1383 return 0;
1384 return __blkg_prfill_u64(sf, pd, v);
1385 }
1386
tg_print_conf_u64(struct seq_file * sf,void * v)1387 static int tg_print_conf_u64(struct seq_file *sf, void *v)
1388 {
1389 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64,
1390 &blkcg_policy_throtl, seq_cft(sf)->private, false);
1391 return 0;
1392 }
1393
tg_print_conf_uint(struct seq_file * sf,void * v)1394 static int tg_print_conf_uint(struct seq_file *sf, void *v)
1395 {
1396 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint,
1397 &blkcg_policy_throtl, seq_cft(sf)->private, false);
1398 return 0;
1399 }
1400
tg_conf_updated(struct throtl_grp * tg,bool global)1401 static void tg_conf_updated(struct throtl_grp *tg, bool global)
1402 {
1403 struct throtl_service_queue *sq = &tg->service_queue;
1404 struct cgroup_subsys_state *pos_css;
1405 struct blkcg_gq *blkg;
1406
1407 throtl_log(&tg->service_queue,
1408 "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
1409 tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE),
1410 tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE));
1411
1412 rcu_read_lock();
1413 /*
1414 * Update has_rules[] flags for the updated tg's subtree. A tg is
1415 * considered to have rules if either the tg itself or any of its
1416 * ancestors has rules. This identifies groups without any
1417 * restrictions in the whole hierarchy and allows them to bypass
1418 * blk-throttle.
1419 */
1420 blkg_for_each_descendant_pre(blkg, pos_css,
1421 global ? tg->td->queue->root_blkg : tg_to_blkg(tg)) {
1422 struct throtl_grp *this_tg = blkg_to_tg(blkg);
1423 struct throtl_grp *parent_tg;
1424
1425 tg_update_has_rules(this_tg);
1426 /* ignore root/second level */
1427 if (!cgroup_subsys_on_dfl(io_cgrp_subsys) || !blkg->parent ||
1428 !blkg->parent->parent)
1429 continue;
1430 parent_tg = blkg_to_tg(blkg->parent);
1431 /*
1432 * make sure all children has lower idle time threshold and
1433 * higher latency target
1434 */
1435 this_tg->idletime_threshold = min(this_tg->idletime_threshold,
1436 parent_tg->idletime_threshold);
1437 this_tg->latency_target = max(this_tg->latency_target,
1438 parent_tg->latency_target);
1439 }
1440 rcu_read_unlock();
1441
1442 /*
1443 * We're already holding queue_lock and know @tg is valid. Let's
1444 * apply the new config directly.
1445 *
1446 * Restart the slices for both READ and WRITES. It might happen
1447 * that a group's limit are dropped suddenly and we don't want to
1448 * account recently dispatched IO with new low rate.
1449 */
1450 throtl_start_new_slice(tg, READ);
1451 throtl_start_new_slice(tg, WRITE);
1452
1453 if (tg->flags & THROTL_TG_PENDING) {
1454 tg_update_disptime(tg);
1455 throtl_schedule_next_dispatch(sq->parent_sq, true);
1456 }
1457 }
1458
tg_set_conf(struct kernfs_open_file * of,char * buf,size_t nbytes,loff_t off,bool is_u64)1459 static ssize_t tg_set_conf(struct kernfs_open_file *of,
1460 char *buf, size_t nbytes, loff_t off, bool is_u64)
1461 {
1462 struct blkcg *blkcg = css_to_blkcg(of_css(of));
1463 struct blkg_conf_ctx ctx;
1464 struct throtl_grp *tg;
1465 int ret;
1466 u64 v;
1467
1468 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
1469 if (ret)
1470 return ret;
1471
1472 ret = -EINVAL;
1473 if (sscanf(ctx.body, "%llu", &v) != 1)
1474 goto out_finish;
1475 if (!v)
1476 v = U64_MAX;
1477
1478 tg = blkg_to_tg(ctx.blkg);
1479
1480 if (is_u64)
1481 *(u64 *)((void *)tg + of_cft(of)->private) = v;
1482 else
1483 *(unsigned int *)((void *)tg + of_cft(of)->private) = v;
1484
1485 tg_conf_updated(tg, false);
1486 ret = 0;
1487 out_finish:
1488 blkg_conf_finish(&ctx);
1489 return ret ?: nbytes;
1490 }
1491
tg_set_conf_u64(struct kernfs_open_file * of,char * buf,size_t nbytes,loff_t off)1492 static ssize_t tg_set_conf_u64(struct kernfs_open_file *of,
1493 char *buf, size_t nbytes, loff_t off)
1494 {
1495 return tg_set_conf(of, buf, nbytes, off, true);
1496 }
1497
tg_set_conf_uint(struct kernfs_open_file * of,char * buf,size_t nbytes,loff_t off)1498 static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,
1499 char *buf, size_t nbytes, loff_t off)
1500 {
1501 return tg_set_conf(of, buf, nbytes, off, false);
1502 }
1503
tg_print_rwstat(struct seq_file * sf,void * v)1504 static int tg_print_rwstat(struct seq_file *sf, void *v)
1505 {
1506 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1507 blkg_prfill_rwstat, &blkcg_policy_throtl,
1508 seq_cft(sf)->private, true);
1509 return 0;
1510 }
1511
tg_prfill_rwstat_recursive(struct seq_file * sf,struct blkg_policy_data * pd,int off)1512 static u64 tg_prfill_rwstat_recursive(struct seq_file *sf,
1513 struct blkg_policy_data *pd, int off)
1514 {
1515 struct blkg_rwstat_sample sum;
1516
1517 blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_throtl, off,
1518 &sum);
1519 return __blkg_prfill_rwstat(sf, pd, &sum);
1520 }
1521
tg_print_rwstat_recursive(struct seq_file * sf,void * v)1522 static int tg_print_rwstat_recursive(struct seq_file *sf, void *v)
1523 {
1524 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1525 tg_prfill_rwstat_recursive, &blkcg_policy_throtl,
1526 seq_cft(sf)->private, true);
1527 return 0;
1528 }
1529
1530 static struct cftype throtl_legacy_files[] = {
1531 {
1532 .name = "throttle.read_bps_device",
1533 .private = offsetof(struct throtl_grp, bps[READ][LIMIT_MAX]),
1534 .seq_show = tg_print_conf_u64,
1535 .write = tg_set_conf_u64,
1536 },
1537 {
1538 .name = "throttle.write_bps_device",
1539 .private = offsetof(struct throtl_grp, bps[WRITE][LIMIT_MAX]),
1540 .seq_show = tg_print_conf_u64,
1541 .write = tg_set_conf_u64,
1542 },
1543 {
1544 .name = "throttle.read_iops_device",
1545 .private = offsetof(struct throtl_grp, iops[READ][LIMIT_MAX]),
1546 .seq_show = tg_print_conf_uint,
1547 .write = tg_set_conf_uint,
1548 },
1549 {
1550 .name = "throttle.write_iops_device",
1551 .private = offsetof(struct throtl_grp, iops[WRITE][LIMIT_MAX]),
1552 .seq_show = tg_print_conf_uint,
1553 .write = tg_set_conf_uint,
1554 },
1555 {
1556 .name = "throttle.io_service_bytes",
1557 .private = offsetof(struct throtl_grp, stat_bytes),
1558 .seq_show = tg_print_rwstat,
1559 },
1560 {
1561 .name = "throttle.io_service_bytes_recursive",
1562 .private = offsetof(struct throtl_grp, stat_bytes),
1563 .seq_show = tg_print_rwstat_recursive,
1564 },
1565 {
1566 .name = "throttle.io_serviced",
1567 .private = offsetof(struct throtl_grp, stat_ios),
1568 .seq_show = tg_print_rwstat,
1569 },
1570 {
1571 .name = "throttle.io_serviced_recursive",
1572 .private = offsetof(struct throtl_grp, stat_ios),
1573 .seq_show = tg_print_rwstat_recursive,
1574 },
1575 { } /* terminate */
1576 };
1577
tg_prfill_limit(struct seq_file * sf,struct blkg_policy_data * pd,int off)1578 static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
1579 int off)
1580 {
1581 struct throtl_grp *tg = pd_to_tg(pd);
1582 const char *dname = blkg_dev_name(pd->blkg);
1583 char bufs[4][21] = { "max", "max", "max", "max" };
1584 u64 bps_dft;
1585 unsigned int iops_dft;
1586 char idle_time[26] = "";
1587 char latency_time[26] = "";
1588
1589 if (!dname)
1590 return 0;
1591
1592 if (off == LIMIT_LOW) {
1593 bps_dft = 0;
1594 iops_dft = 0;
1595 } else {
1596 bps_dft = U64_MAX;
1597 iops_dft = UINT_MAX;
1598 }
1599
1600 if (tg->bps_conf[READ][off] == bps_dft &&
1601 tg->bps_conf[WRITE][off] == bps_dft &&
1602 tg->iops_conf[READ][off] == iops_dft &&
1603 tg->iops_conf[WRITE][off] == iops_dft &&
1604 (off != LIMIT_LOW ||
1605 (tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD &&
1606 tg->latency_target_conf == DFL_LATENCY_TARGET)))
1607 return 0;
1608
1609 if (tg->bps_conf[READ][off] != U64_MAX)
1610 snprintf(bufs[0], sizeof(bufs[0]), "%llu",
1611 tg->bps_conf[READ][off]);
1612 if (tg->bps_conf[WRITE][off] != U64_MAX)
1613 snprintf(bufs[1], sizeof(bufs[1]), "%llu",
1614 tg->bps_conf[WRITE][off]);
1615 if (tg->iops_conf[READ][off] != UINT_MAX)
1616 snprintf(bufs[2], sizeof(bufs[2]), "%u",
1617 tg->iops_conf[READ][off]);
1618 if (tg->iops_conf[WRITE][off] != UINT_MAX)
1619 snprintf(bufs[3], sizeof(bufs[3]), "%u",
1620 tg->iops_conf[WRITE][off]);
1621 if (off == LIMIT_LOW) {
1622 if (tg->idletime_threshold_conf == ULONG_MAX)
1623 strcpy(idle_time, " idle=max");
1624 else
1625 snprintf(idle_time, sizeof(idle_time), " idle=%lu",
1626 tg->idletime_threshold_conf);
1627
1628 if (tg->latency_target_conf == ULONG_MAX)
1629 strcpy(latency_time, " latency=max");
1630 else
1631 snprintf(latency_time, sizeof(latency_time),
1632 " latency=%lu", tg->latency_target_conf);
1633 }
1634
1635 seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n",
1636 dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time,
1637 latency_time);
1638 return 0;
1639 }
1640
tg_print_limit(struct seq_file * sf,void * v)1641 static int tg_print_limit(struct seq_file *sf, void *v)
1642 {
1643 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_limit,
1644 &blkcg_policy_throtl, seq_cft(sf)->private, false);
1645 return 0;
1646 }
1647
tg_set_limit(struct kernfs_open_file * of,char * buf,size_t nbytes,loff_t off)1648 static ssize_t tg_set_limit(struct kernfs_open_file *of,
1649 char *buf, size_t nbytes, loff_t off)
1650 {
1651 struct blkcg *blkcg = css_to_blkcg(of_css(of));
1652 struct blkg_conf_ctx ctx;
1653 struct throtl_grp *tg;
1654 u64 v[4];
1655 unsigned long idle_time;
1656 unsigned long latency_time;
1657 int ret;
1658 int index = of_cft(of)->private;
1659
1660 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
1661 if (ret)
1662 return ret;
1663
1664 tg = blkg_to_tg(ctx.blkg);
1665
1666 v[0] = tg->bps_conf[READ][index];
1667 v[1] = tg->bps_conf[WRITE][index];
1668 v[2] = tg->iops_conf[READ][index];
1669 v[3] = tg->iops_conf[WRITE][index];
1670
1671 idle_time = tg->idletime_threshold_conf;
1672 latency_time = tg->latency_target_conf;
1673 while (true) {
1674 char tok[27]; /* wiops=18446744073709551616 */
1675 char *p;
1676 u64 val = U64_MAX;
1677 int len;
1678
1679 if (sscanf(ctx.body, "%26s%n", tok, &len) != 1)
1680 break;
1681 if (tok[0] == '\0')
1682 break;
1683 ctx.body += len;
1684
1685 ret = -EINVAL;
1686 p = tok;
1687 strsep(&p, "=");
1688 if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max")))
1689 goto out_finish;
1690
1691 ret = -ERANGE;
1692 if (!val)
1693 goto out_finish;
1694
1695 ret = -EINVAL;
1696 if (!strcmp(tok, "rbps") && val > 1)
1697 v[0] = val;
1698 else if (!strcmp(tok, "wbps") && val > 1)
1699 v[1] = val;
1700 else if (!strcmp(tok, "riops") && val > 1)
1701 v[2] = min_t(u64, val, UINT_MAX);
1702 else if (!strcmp(tok, "wiops") && val > 1)
1703 v[3] = min_t(u64, val, UINT_MAX);
1704 else if (off == LIMIT_LOW && !strcmp(tok, "idle"))
1705 idle_time = val;
1706 else if (off == LIMIT_LOW && !strcmp(tok, "latency"))
1707 latency_time = val;
1708 else
1709 goto out_finish;
1710 }
1711
1712 tg->bps_conf[READ][index] = v[0];
1713 tg->bps_conf[WRITE][index] = v[1];
1714 tg->iops_conf[READ][index] = v[2];
1715 tg->iops_conf[WRITE][index] = v[3];
1716
1717 if (index == LIMIT_MAX) {
1718 tg->bps[READ][index] = v[0];
1719 tg->bps[WRITE][index] = v[1];
1720 tg->iops[READ][index] = v[2];
1721 tg->iops[WRITE][index] = v[3];
1722 }
1723 tg->bps[READ][LIMIT_LOW] = min(tg->bps_conf[READ][LIMIT_LOW],
1724 tg->bps_conf[READ][LIMIT_MAX]);
1725 tg->bps[WRITE][LIMIT_LOW] = min(tg->bps_conf[WRITE][LIMIT_LOW],
1726 tg->bps_conf[WRITE][LIMIT_MAX]);
1727 tg->iops[READ][LIMIT_LOW] = min(tg->iops_conf[READ][LIMIT_LOW],
1728 tg->iops_conf[READ][LIMIT_MAX]);
1729 tg->iops[WRITE][LIMIT_LOW] = min(tg->iops_conf[WRITE][LIMIT_LOW],
1730 tg->iops_conf[WRITE][LIMIT_MAX]);
1731 tg->idletime_threshold_conf = idle_time;
1732 tg->latency_target_conf = latency_time;
1733
1734 /* force user to configure all settings for low limit */
1735 if (!(tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW] ||
1736 tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) ||
1737 tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD ||
1738 tg->latency_target_conf == DFL_LATENCY_TARGET) {
1739 tg->bps[READ][LIMIT_LOW] = 0;
1740 tg->bps[WRITE][LIMIT_LOW] = 0;
1741 tg->iops[READ][LIMIT_LOW] = 0;
1742 tg->iops[WRITE][LIMIT_LOW] = 0;
1743 tg->idletime_threshold = DFL_IDLE_THRESHOLD;
1744 tg->latency_target = DFL_LATENCY_TARGET;
1745 } else if (index == LIMIT_LOW) {
1746 tg->idletime_threshold = tg->idletime_threshold_conf;
1747 tg->latency_target = tg->latency_target_conf;
1748 }
1749
1750 blk_throtl_update_limit_valid(tg->td);
1751 if (tg->td->limit_valid[LIMIT_LOW]) {
1752 if (index == LIMIT_LOW)
1753 tg->td->limit_index = LIMIT_LOW;
1754 } else
1755 tg->td->limit_index = LIMIT_MAX;
1756 tg_conf_updated(tg, index == LIMIT_LOW &&
1757 tg->td->limit_valid[LIMIT_LOW]);
1758 ret = 0;
1759 out_finish:
1760 blkg_conf_finish(&ctx);
1761 return ret ?: nbytes;
1762 }
1763
1764 static struct cftype throtl_files[] = {
1765 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
1766 {
1767 .name = "low",
1768 .flags = CFTYPE_NOT_ON_ROOT,
1769 .seq_show = tg_print_limit,
1770 .write = tg_set_limit,
1771 .private = LIMIT_LOW,
1772 },
1773 #endif
1774 {
1775 .name = "max",
1776 .flags = CFTYPE_NOT_ON_ROOT,
1777 .seq_show = tg_print_limit,
1778 .write = tg_set_limit,
1779 .private = LIMIT_MAX,
1780 },
1781 { } /* terminate */
1782 };
1783
throtl_shutdown_wq(struct request_queue * q)1784 static void throtl_shutdown_wq(struct request_queue *q)
1785 {
1786 struct throtl_data *td = q->td;
1787
1788 cancel_work_sync(&td->dispatch_work);
1789 }
1790
1791 static struct blkcg_policy blkcg_policy_throtl = {
1792 .dfl_cftypes = throtl_files,
1793 .legacy_cftypes = throtl_legacy_files,
1794
1795 .pd_alloc_fn = throtl_pd_alloc,
1796 .pd_init_fn = throtl_pd_init,
1797 .pd_online_fn = throtl_pd_online,
1798 .pd_offline_fn = throtl_pd_offline,
1799 .pd_free_fn = throtl_pd_free,
1800 };
1801
__tg_last_low_overflow_time(struct throtl_grp * tg)1802 static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg)
1803 {
1804 unsigned long rtime = jiffies, wtime = jiffies;
1805
1806 if (tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW])
1807 rtime = tg->last_low_overflow_time[READ];
1808 if (tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW])
1809 wtime = tg->last_low_overflow_time[WRITE];
1810 return min(rtime, wtime);
1811 }
1812
1813 /* tg should not be an intermediate node */
tg_last_low_overflow_time(struct throtl_grp * tg)1814 static unsigned long tg_last_low_overflow_time(struct throtl_grp *tg)
1815 {
1816 struct throtl_service_queue *parent_sq;
1817 struct throtl_grp *parent = tg;
1818 unsigned long ret = __tg_last_low_overflow_time(tg);
1819
1820 while (true) {
1821 parent_sq = parent->service_queue.parent_sq;
1822 parent = sq_to_tg(parent_sq);
1823 if (!parent)
1824 break;
1825
1826 /*
1827 * The parent doesn't have low limit, it always reaches low
1828 * limit. Its overflow time is useless for children
1829 */
1830 if (!parent->bps[READ][LIMIT_LOW] &&
1831 !parent->iops[READ][LIMIT_LOW] &&
1832 !parent->bps[WRITE][LIMIT_LOW] &&
1833 !parent->iops[WRITE][LIMIT_LOW])
1834 continue;
1835 if (time_after(__tg_last_low_overflow_time(parent), ret))
1836 ret = __tg_last_low_overflow_time(parent);
1837 }
1838 return ret;
1839 }
1840
throtl_tg_is_idle(struct throtl_grp * tg)1841 static bool throtl_tg_is_idle(struct throtl_grp *tg)
1842 {
1843 /*
1844 * cgroup is idle if:
1845 * - single idle is too long, longer than a fixed value (in case user
1846 * configure a too big threshold) or 4 times of idletime threshold
1847 * - average think time is more than threshold
1848 * - IO latency is largely below threshold
1849 */
1850 unsigned long time;
1851 bool ret;
1852
1853 time = min_t(unsigned long, MAX_IDLE_TIME, 4 * tg->idletime_threshold);
1854 ret = tg->latency_target == DFL_LATENCY_TARGET ||
1855 tg->idletime_threshold == DFL_IDLE_THRESHOLD ||
1856 (ktime_get_ns() >> 10) - tg->last_finish_time > time ||
1857 tg->avg_idletime > tg->idletime_threshold ||
1858 (tg->latency_target && tg->bio_cnt &&
1859 tg->bad_bio_cnt * 5 < tg->bio_cnt);
1860 throtl_log(&tg->service_queue,
1861 "avg_idle=%ld, idle_threshold=%ld, bad_bio=%d, total_bio=%d, is_idle=%d, scale=%d",
1862 tg->avg_idletime, tg->idletime_threshold, tg->bad_bio_cnt,
1863 tg->bio_cnt, ret, tg->td->scale);
1864 return ret;
1865 }
1866
throtl_tg_can_upgrade(struct throtl_grp * tg)1867 static bool throtl_tg_can_upgrade(struct throtl_grp *tg)
1868 {
1869 struct throtl_service_queue *sq = &tg->service_queue;
1870 bool read_limit, write_limit;
1871
1872 /*
1873 * if cgroup reaches low limit (if low limit is 0, the cgroup always
1874 * reaches), it's ok to upgrade to next limit
1875 */
1876 read_limit = tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW];
1877 write_limit = tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW];
1878 if (!read_limit && !write_limit)
1879 return true;
1880 if (read_limit && sq->nr_queued[READ] &&
1881 (!write_limit || sq->nr_queued[WRITE]))
1882 return true;
1883 if (write_limit && sq->nr_queued[WRITE] &&
1884 (!read_limit || sq->nr_queued[READ]))
1885 return true;
1886
1887 if (time_after_eq(jiffies,
1888 tg_last_low_overflow_time(tg) + tg->td->throtl_slice) &&
1889 throtl_tg_is_idle(tg))
1890 return true;
1891 return false;
1892 }
1893
throtl_hierarchy_can_upgrade(struct throtl_grp * tg)1894 static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg)
1895 {
1896 while (true) {
1897 if (throtl_tg_can_upgrade(tg))
1898 return true;
1899 tg = sq_to_tg(tg->service_queue.parent_sq);
1900 if (!tg || !tg_to_blkg(tg)->parent)
1901 return false;
1902 }
1903 return false;
1904 }
1905
throtl_can_upgrade(struct throtl_data * td,struct throtl_grp * this_tg)1906 static bool throtl_can_upgrade(struct throtl_data *td,
1907 struct throtl_grp *this_tg)
1908 {
1909 struct cgroup_subsys_state *pos_css;
1910 struct blkcg_gq *blkg;
1911
1912 if (td->limit_index != LIMIT_LOW)
1913 return false;
1914
1915 if (time_before(jiffies, td->low_downgrade_time + td->throtl_slice))
1916 return false;
1917
1918 rcu_read_lock();
1919 blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
1920 struct throtl_grp *tg = blkg_to_tg(blkg);
1921
1922 if (tg == this_tg)
1923 continue;
1924 if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children))
1925 continue;
1926 if (!throtl_hierarchy_can_upgrade(tg)) {
1927 rcu_read_unlock();
1928 return false;
1929 }
1930 }
1931 rcu_read_unlock();
1932 return true;
1933 }
1934
throtl_upgrade_check(struct throtl_grp * tg)1935 static void throtl_upgrade_check(struct throtl_grp *tg)
1936 {
1937 unsigned long now = jiffies;
1938
1939 if (tg->td->limit_index != LIMIT_LOW)
1940 return;
1941
1942 if (time_after(tg->last_check_time + tg->td->throtl_slice, now))
1943 return;
1944
1945 tg->last_check_time = now;
1946
1947 if (!time_after_eq(now,
1948 __tg_last_low_overflow_time(tg) + tg->td->throtl_slice))
1949 return;
1950
1951 if (throtl_can_upgrade(tg->td, NULL))
1952 throtl_upgrade_state(tg->td);
1953 }
1954
throtl_upgrade_state(struct throtl_data * td)1955 static void throtl_upgrade_state(struct throtl_data *td)
1956 {
1957 struct cgroup_subsys_state *pos_css;
1958 struct blkcg_gq *blkg;
1959
1960 throtl_log(&td->service_queue, "upgrade to max");
1961 td->limit_index = LIMIT_MAX;
1962 td->low_upgrade_time = jiffies;
1963 td->scale = 0;
1964 rcu_read_lock();
1965 blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
1966 struct throtl_grp *tg = blkg_to_tg(blkg);
1967 struct throtl_service_queue *sq = &tg->service_queue;
1968
1969 tg->disptime = jiffies - 1;
1970 throtl_select_dispatch(sq);
1971 throtl_schedule_next_dispatch(sq, true);
1972 }
1973 rcu_read_unlock();
1974 throtl_select_dispatch(&td->service_queue);
1975 throtl_schedule_next_dispatch(&td->service_queue, true);
1976 queue_work(kthrotld_workqueue, &td->dispatch_work);
1977 }
1978
throtl_downgrade_state(struct throtl_data * td)1979 static void throtl_downgrade_state(struct throtl_data *td)
1980 {
1981 td->scale /= 2;
1982
1983 throtl_log(&td->service_queue, "downgrade, scale %d", td->scale);
1984 if (td->scale) {
1985 td->low_upgrade_time = jiffies - td->scale * td->throtl_slice;
1986 return;
1987 }
1988
1989 td->limit_index = LIMIT_LOW;
1990 td->low_downgrade_time = jiffies;
1991 }
1992
throtl_tg_can_downgrade(struct throtl_grp * tg)1993 static bool throtl_tg_can_downgrade(struct throtl_grp *tg)
1994 {
1995 struct throtl_data *td = tg->td;
1996 unsigned long now = jiffies;
1997
1998 /*
1999 * If cgroup is below low limit, consider downgrade and throttle other
2000 * cgroups
2001 */
2002 if (time_after_eq(now, td->low_upgrade_time + td->throtl_slice) &&
2003 time_after_eq(now, tg_last_low_overflow_time(tg) +
2004 td->throtl_slice) &&
2005 (!throtl_tg_is_idle(tg) ||
2006 !list_empty(&tg_to_blkg(tg)->blkcg->css.children)))
2007 return true;
2008 return false;
2009 }
2010
throtl_hierarchy_can_downgrade(struct throtl_grp * tg)2011 static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg)
2012 {
2013 while (true) {
2014 if (!throtl_tg_can_downgrade(tg))
2015 return false;
2016 tg = sq_to_tg(tg->service_queue.parent_sq);
2017 if (!tg || !tg_to_blkg(tg)->parent)
2018 break;
2019 }
2020 return true;
2021 }
2022
throtl_downgrade_check(struct throtl_grp * tg)2023 static void throtl_downgrade_check(struct throtl_grp *tg)
2024 {
2025 uint64_t bps;
2026 unsigned int iops;
2027 unsigned long elapsed_time;
2028 unsigned long now = jiffies;
2029
2030 if (tg->td->limit_index != LIMIT_MAX ||
2031 !tg->td->limit_valid[LIMIT_LOW])
2032 return;
2033 if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children))
2034 return;
2035 if (time_after(tg->last_check_time + tg->td->throtl_slice, now))
2036 return;
2037
2038 elapsed_time = now - tg->last_check_time;
2039 tg->last_check_time = now;
2040
2041 if (time_before(now, tg_last_low_overflow_time(tg) +
2042 tg->td->throtl_slice))
2043 return;
2044
2045 if (tg->bps[READ][LIMIT_LOW]) {
2046 bps = tg->last_bytes_disp[READ] * HZ;
2047 do_div(bps, elapsed_time);
2048 if (bps >= tg->bps[READ][LIMIT_LOW])
2049 tg->last_low_overflow_time[READ] = now;
2050 }
2051
2052 if (tg->bps[WRITE][LIMIT_LOW]) {
2053 bps = tg->last_bytes_disp[WRITE] * HZ;
2054 do_div(bps, elapsed_time);
2055 if (bps >= tg->bps[WRITE][LIMIT_LOW])
2056 tg->last_low_overflow_time[WRITE] = now;
2057 }
2058
2059 if (tg->iops[READ][LIMIT_LOW]) {
2060 tg->last_io_disp[READ] += atomic_xchg(&tg->last_io_split_cnt[READ], 0);
2061 iops = tg->last_io_disp[READ] * HZ / elapsed_time;
2062 if (iops >= tg->iops[READ][LIMIT_LOW])
2063 tg->last_low_overflow_time[READ] = now;
2064 }
2065
2066 if (tg->iops[WRITE][LIMIT_LOW]) {
2067 tg->last_io_disp[WRITE] += atomic_xchg(&tg->last_io_split_cnt[WRITE], 0);
2068 iops = tg->last_io_disp[WRITE] * HZ / elapsed_time;
2069 if (iops >= tg->iops[WRITE][LIMIT_LOW])
2070 tg->last_low_overflow_time[WRITE] = now;
2071 }
2072
2073 /*
2074 * If cgroup is below low limit, consider downgrade and throttle other
2075 * cgroups
2076 */
2077 if (throtl_hierarchy_can_downgrade(tg))
2078 throtl_downgrade_state(tg->td);
2079
2080 tg->last_bytes_disp[READ] = 0;
2081 tg->last_bytes_disp[WRITE] = 0;
2082 tg->last_io_disp[READ] = 0;
2083 tg->last_io_disp[WRITE] = 0;
2084 }
2085
blk_throtl_update_idletime(struct throtl_grp * tg)2086 static void blk_throtl_update_idletime(struct throtl_grp *tg)
2087 {
2088 unsigned long now;
2089 unsigned long last_finish_time = tg->last_finish_time;
2090
2091 if (last_finish_time == 0)
2092 return;
2093
2094 now = ktime_get_ns() >> 10;
2095 if (now <= last_finish_time ||
2096 last_finish_time == tg->checked_last_finish_time)
2097 return;
2098
2099 tg->avg_idletime = (tg->avg_idletime * 7 + now - last_finish_time) >> 3;
2100 tg->checked_last_finish_time = last_finish_time;
2101 }
2102
2103 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
throtl_update_latency_buckets(struct throtl_data * td)2104 static void throtl_update_latency_buckets(struct throtl_data *td)
2105 {
2106 struct avg_latency_bucket avg_latency[2][LATENCY_BUCKET_SIZE];
2107 int i, cpu, rw;
2108 unsigned long last_latency[2] = { 0 };
2109 unsigned long latency[2];
2110
2111 if (!blk_queue_nonrot(td->queue) || !td->limit_valid[LIMIT_LOW])
2112 return;
2113 if (time_before(jiffies, td->last_calculate_time + HZ))
2114 return;
2115 td->last_calculate_time = jiffies;
2116
2117 memset(avg_latency, 0, sizeof(avg_latency));
2118 for (rw = READ; rw <= WRITE; rw++) {
2119 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) {
2120 struct latency_bucket *tmp = &td->tmp_buckets[rw][i];
2121
2122 for_each_possible_cpu(cpu) {
2123 struct latency_bucket *bucket;
2124
2125 /* this isn't race free, but ok in practice */
2126 bucket = per_cpu_ptr(td->latency_buckets[rw],
2127 cpu);
2128 tmp->total_latency += bucket[i].total_latency;
2129 tmp->samples += bucket[i].samples;
2130 bucket[i].total_latency = 0;
2131 bucket[i].samples = 0;
2132 }
2133
2134 if (tmp->samples >= 32) {
2135 int samples = tmp->samples;
2136
2137 latency[rw] = tmp->total_latency;
2138
2139 tmp->total_latency = 0;
2140 tmp->samples = 0;
2141 latency[rw] /= samples;
2142 if (latency[rw] == 0)
2143 continue;
2144 avg_latency[rw][i].latency = latency[rw];
2145 }
2146 }
2147 }
2148
2149 for (rw = READ; rw <= WRITE; rw++) {
2150 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) {
2151 if (!avg_latency[rw][i].latency) {
2152 if (td->avg_buckets[rw][i].latency < last_latency[rw])
2153 td->avg_buckets[rw][i].latency =
2154 last_latency[rw];
2155 continue;
2156 }
2157
2158 if (!td->avg_buckets[rw][i].valid)
2159 latency[rw] = avg_latency[rw][i].latency;
2160 else
2161 latency[rw] = (td->avg_buckets[rw][i].latency * 7 +
2162 avg_latency[rw][i].latency) >> 3;
2163
2164 td->avg_buckets[rw][i].latency = max(latency[rw],
2165 last_latency[rw]);
2166 td->avg_buckets[rw][i].valid = true;
2167 last_latency[rw] = td->avg_buckets[rw][i].latency;
2168 }
2169 }
2170
2171 for (i = 0; i < LATENCY_BUCKET_SIZE; i++)
2172 throtl_log(&td->service_queue,
2173 "Latency bucket %d: read latency=%ld, read valid=%d, "
2174 "write latency=%ld, write valid=%d", i,
2175 td->avg_buckets[READ][i].latency,
2176 td->avg_buckets[READ][i].valid,
2177 td->avg_buckets[WRITE][i].latency,
2178 td->avg_buckets[WRITE][i].valid);
2179 }
2180 #else
throtl_update_latency_buckets(struct throtl_data * td)2181 static inline void throtl_update_latency_buckets(struct throtl_data *td)
2182 {
2183 }
2184 #endif
2185
blk_throtl_charge_bio_split(struct bio * bio)2186 void blk_throtl_charge_bio_split(struct bio *bio)
2187 {
2188 struct blkcg_gq *blkg = bio->bi_blkg;
2189 struct throtl_grp *parent = blkg_to_tg(blkg);
2190 struct throtl_service_queue *parent_sq;
2191 bool rw = bio_data_dir(bio);
2192
2193 do {
2194 if (!parent->has_rules[rw])
2195 break;
2196
2197 atomic_inc(&parent->io_split_cnt[rw]);
2198 atomic_inc(&parent->last_io_split_cnt[rw]);
2199
2200 parent_sq = parent->service_queue.parent_sq;
2201 parent = sq_to_tg(parent_sq);
2202 } while (parent);
2203 }
2204
blk_throtl_bio(struct bio * bio)2205 bool blk_throtl_bio(struct bio *bio)
2206 {
2207 struct request_queue *q = bio->bi_disk->queue;
2208 struct blkcg_gq *blkg = bio->bi_blkg;
2209 struct throtl_qnode *qn = NULL;
2210 struct throtl_grp *tg = blkg_to_tg(blkg);
2211 struct throtl_service_queue *sq;
2212 bool rw = bio_data_dir(bio);
2213 bool throttled = false;
2214 struct throtl_data *td = tg->td;
2215
2216 rcu_read_lock();
2217
2218 /* see throtl_charge_bio() */
2219 if (bio_flagged(bio, BIO_THROTTLED))
2220 goto out;
2221
2222 if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) {
2223 blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf,
2224 bio->bi_iter.bi_size);
2225 blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1);
2226 }
2227
2228 if (!tg->has_rules[rw])
2229 goto out;
2230
2231 spin_lock_irq(&q->queue_lock);
2232
2233 throtl_update_latency_buckets(td);
2234
2235 blk_throtl_update_idletime(tg);
2236
2237 sq = &tg->service_queue;
2238
2239 again:
2240 while (true) {
2241 if (tg->last_low_overflow_time[rw] == 0)
2242 tg->last_low_overflow_time[rw] = jiffies;
2243 throtl_downgrade_check(tg);
2244 throtl_upgrade_check(tg);
2245 /* throtl is FIFO - if bios are already queued, should queue */
2246 if (sq->nr_queued[rw])
2247 break;
2248
2249 /* if above limits, break to queue */
2250 if (!tg_may_dispatch(tg, bio, NULL)) {
2251 tg->last_low_overflow_time[rw] = jiffies;
2252 if (throtl_can_upgrade(td, tg)) {
2253 throtl_upgrade_state(td);
2254 goto again;
2255 }
2256 break;
2257 }
2258
2259 /* within limits, let's charge and dispatch directly */
2260 throtl_charge_bio(tg, bio);
2261
2262 /*
2263 * We need to trim slice even when bios are not being queued
2264 * otherwise it might happen that a bio is not queued for
2265 * a long time and slice keeps on extending and trim is not
2266 * called for a long time. Now if limits are reduced suddenly
2267 * we take into account all the IO dispatched so far at new
2268 * low rate and * newly queued IO gets a really long dispatch
2269 * time.
2270 *
2271 * So keep on trimming slice even if bio is not queued.
2272 */
2273 throtl_trim_slice(tg, rw);
2274
2275 /*
2276 * @bio passed through this layer without being throttled.
2277 * Climb up the ladder. If we're already at the top, it
2278 * can be executed directly.
2279 */
2280 qn = &tg->qnode_on_parent[rw];
2281 sq = sq->parent_sq;
2282 tg = sq_to_tg(sq);
2283 if (!tg)
2284 goto out_unlock;
2285 }
2286
2287 /* out-of-limit, queue to @tg */
2288 throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d",
2289 rw == READ ? 'R' : 'W',
2290 tg->bytes_disp[rw], bio->bi_iter.bi_size,
2291 tg_bps_limit(tg, rw),
2292 tg->io_disp[rw], tg_iops_limit(tg, rw),
2293 sq->nr_queued[READ], sq->nr_queued[WRITE]);
2294
2295 tg->last_low_overflow_time[rw] = jiffies;
2296
2297 td->nr_queued[rw]++;
2298 throtl_add_bio_tg(bio, qn, tg);
2299 throttled = true;
2300
2301 /*
2302 * Update @tg's dispatch time and force schedule dispatch if @tg
2303 * was empty before @bio. The forced scheduling isn't likely to
2304 * cause undue delay as @bio is likely to be dispatched directly if
2305 * its @tg's disptime is not in the future.
2306 */
2307 if (tg->flags & THROTL_TG_WAS_EMPTY) {
2308 tg_update_disptime(tg);
2309 throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true);
2310 }
2311
2312 out_unlock:
2313 spin_unlock_irq(&q->queue_lock);
2314 out:
2315 bio_set_flag(bio, BIO_THROTTLED);
2316
2317 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
2318 if (throttled || !td->track_bio_latency)
2319 bio->bi_issue.value |= BIO_ISSUE_THROTL_SKIP_LATENCY;
2320 #endif
2321 rcu_read_unlock();
2322 return throttled;
2323 }
2324
2325 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
throtl_track_latency(struct throtl_data * td,sector_t size,int op,unsigned long time)2326 static void throtl_track_latency(struct throtl_data *td, sector_t size,
2327 int op, unsigned long time)
2328 {
2329 struct latency_bucket *latency;
2330 int index;
2331
2332 if (!td || td->limit_index != LIMIT_LOW ||
2333 !(op == REQ_OP_READ || op == REQ_OP_WRITE) ||
2334 !blk_queue_nonrot(td->queue))
2335 return;
2336
2337 index = request_bucket_index(size);
2338
2339 latency = get_cpu_ptr(td->latency_buckets[op]);
2340 latency[index].total_latency += time;
2341 latency[index].samples++;
2342 put_cpu_ptr(td->latency_buckets[op]);
2343 }
2344
blk_throtl_stat_add(struct request * rq,u64 time_ns)2345 void blk_throtl_stat_add(struct request *rq, u64 time_ns)
2346 {
2347 struct request_queue *q = rq->q;
2348 struct throtl_data *td = q->td;
2349
2350 throtl_track_latency(td, blk_rq_stats_sectors(rq), req_op(rq),
2351 time_ns >> 10);
2352 }
2353
blk_throtl_bio_endio(struct bio * bio)2354 void blk_throtl_bio_endio(struct bio *bio)
2355 {
2356 struct blkcg_gq *blkg;
2357 struct throtl_grp *tg;
2358 u64 finish_time_ns;
2359 unsigned long finish_time;
2360 unsigned long start_time;
2361 unsigned long lat;
2362 int rw = bio_data_dir(bio);
2363
2364 blkg = bio->bi_blkg;
2365 if (!blkg)
2366 return;
2367 tg = blkg_to_tg(blkg);
2368 if (!tg->td->limit_valid[LIMIT_LOW])
2369 return;
2370
2371 finish_time_ns = ktime_get_ns();
2372 tg->last_finish_time = finish_time_ns >> 10;
2373
2374 start_time = bio_issue_time(&bio->bi_issue) >> 10;
2375 finish_time = __bio_issue_time(finish_time_ns) >> 10;
2376 if (!start_time || finish_time <= start_time)
2377 return;
2378
2379 lat = finish_time - start_time;
2380 /* this is only for bio based driver */
2381 if (!(bio->bi_issue.value & BIO_ISSUE_THROTL_SKIP_LATENCY))
2382 throtl_track_latency(tg->td, bio_issue_size(&bio->bi_issue),
2383 bio_op(bio), lat);
2384
2385 if (tg->latency_target && lat >= tg->td->filtered_latency) {
2386 int bucket;
2387 unsigned int threshold;
2388
2389 bucket = request_bucket_index(bio_issue_size(&bio->bi_issue));
2390 threshold = tg->td->avg_buckets[rw][bucket].latency +
2391 tg->latency_target;
2392 if (lat > threshold)
2393 tg->bad_bio_cnt++;
2394 /*
2395 * Not race free, could get wrong count, which means cgroups
2396 * will be throttled
2397 */
2398 tg->bio_cnt++;
2399 }
2400
2401 if (time_after(jiffies, tg->bio_cnt_reset_time) || tg->bio_cnt > 1024) {
2402 tg->bio_cnt_reset_time = tg->td->throtl_slice + jiffies;
2403 tg->bio_cnt /= 2;
2404 tg->bad_bio_cnt /= 2;
2405 }
2406 }
2407 #endif
2408
blk_throtl_init(struct request_queue * q)2409 int blk_throtl_init(struct request_queue *q)
2410 {
2411 struct throtl_data *td;
2412 int ret;
2413
2414 td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
2415 if (!td)
2416 return -ENOMEM;
2417 td->latency_buckets[READ] = __alloc_percpu(sizeof(struct latency_bucket) *
2418 LATENCY_BUCKET_SIZE, __alignof__(u64));
2419 if (!td->latency_buckets[READ]) {
2420 kfree(td);
2421 return -ENOMEM;
2422 }
2423 td->latency_buckets[WRITE] = __alloc_percpu(sizeof(struct latency_bucket) *
2424 LATENCY_BUCKET_SIZE, __alignof__(u64));
2425 if (!td->latency_buckets[WRITE]) {
2426 free_percpu(td->latency_buckets[READ]);
2427 kfree(td);
2428 return -ENOMEM;
2429 }
2430
2431 INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
2432 throtl_service_queue_init(&td->service_queue);
2433
2434 q->td = td;
2435 td->queue = q;
2436
2437 td->limit_valid[LIMIT_MAX] = true;
2438 td->limit_index = LIMIT_MAX;
2439 td->low_upgrade_time = jiffies;
2440 td->low_downgrade_time = jiffies;
2441
2442 /* activate policy */
2443 ret = blkcg_activate_policy(q, &blkcg_policy_throtl);
2444 if (ret) {
2445 free_percpu(td->latency_buckets[READ]);
2446 free_percpu(td->latency_buckets[WRITE]);
2447 kfree(td);
2448 }
2449 return ret;
2450 }
2451
blk_throtl_exit(struct request_queue * q)2452 void blk_throtl_exit(struct request_queue *q)
2453 {
2454 BUG_ON(!q->td);
2455 del_timer_sync(&q->td->service_queue.pending_timer);
2456 throtl_shutdown_wq(q);
2457 blkcg_deactivate_policy(q, &blkcg_policy_throtl);
2458 free_percpu(q->td->latency_buckets[READ]);
2459 free_percpu(q->td->latency_buckets[WRITE]);
2460 kfree(q->td);
2461 }
2462
blk_throtl_register_queue(struct request_queue * q)2463 void blk_throtl_register_queue(struct request_queue *q)
2464 {
2465 struct throtl_data *td;
2466 int i;
2467
2468 td = q->td;
2469 BUG_ON(!td);
2470
2471 if (blk_queue_nonrot(q)) {
2472 td->throtl_slice = DFL_THROTL_SLICE_SSD;
2473 td->filtered_latency = LATENCY_FILTERED_SSD;
2474 } else {
2475 td->throtl_slice = DFL_THROTL_SLICE_HD;
2476 td->filtered_latency = LATENCY_FILTERED_HD;
2477 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) {
2478 td->avg_buckets[READ][i].latency = DFL_HD_BASELINE_LATENCY;
2479 td->avg_buckets[WRITE][i].latency = DFL_HD_BASELINE_LATENCY;
2480 }
2481 }
2482 #ifndef CONFIG_BLK_DEV_THROTTLING_LOW
2483 /* if no low limit, use previous default */
2484 td->throtl_slice = DFL_THROTL_SLICE_HD;
2485 #endif
2486
2487 td->track_bio_latency = !queue_is_mq(q);
2488 if (!td->track_bio_latency)
2489 blk_stat_enable_accounting(q);
2490 }
2491
2492 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
blk_throtl_sample_time_show(struct request_queue * q,char * page)2493 ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page)
2494 {
2495 if (!q->td)
2496 return -EINVAL;
2497 return sprintf(page, "%u\n", jiffies_to_msecs(q->td->throtl_slice));
2498 }
2499
blk_throtl_sample_time_store(struct request_queue * q,const char * page,size_t count)2500 ssize_t blk_throtl_sample_time_store(struct request_queue *q,
2501 const char *page, size_t count)
2502 {
2503 unsigned long v;
2504 unsigned long t;
2505
2506 if (!q->td)
2507 return -EINVAL;
2508 if (kstrtoul(page, 10, &v))
2509 return -EINVAL;
2510 t = msecs_to_jiffies(v);
2511 if (t == 0 || t > MAX_THROTL_SLICE)
2512 return -EINVAL;
2513 q->td->throtl_slice = t;
2514 return count;
2515 }
2516 #endif
2517
throtl_init(void)2518 static int __init throtl_init(void)
2519 {
2520 kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
2521 if (!kthrotld_workqueue)
2522 panic("Failed to create kthrotld\n");
2523
2524 return blkcg_policy_register(&blkcg_policy_throtl);
2525 }
2526
2527 module_init(throtl_init);
2528