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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 100ms slice and after that slice is renewed */ | |
22 | static unsigned long throtl_slice = HZ/10; /* 100 ms */ | |
23 | ||
24 | static struct blkcg_policy blkcg_policy_throtl; | |
25 | ||
26 | /* A workqueue to queue throttle related work */ | |
27 | static struct workqueue_struct *kthrotld_workqueue; | |
28 | ||
29 | /* | |
30 | * To implement hierarchical throttling, throtl_grps form a tree and bios | |
31 | * are dispatched upwards level by level until they reach the top and get | |
32 | * issued. When dispatching bios from the children and local group at each | |
33 | * level, if the bios are dispatched into a single bio_list, there's a risk | |
34 | * of a local or child group which can queue many bios at once filling up | |
35 | * the list starving others. | |
36 | * | |
37 | * To avoid such starvation, dispatched bios are queued separately | |
38 | * according to where they came from. When they are again dispatched to | |
39 | * the parent, they're popped in round-robin order so that no single source | |
40 | * hogs the dispatch window. | |
41 | * | |
42 | * throtl_qnode is used to keep the queued bios separated by their sources. | |
43 | * Bios are queued to throtl_qnode which in turn is queued to | |
44 | * throtl_service_queue and then dispatched in round-robin order. | |
45 | * | |
46 | * It's also used to track the reference counts on blkg's. A qnode always | |
47 | * belongs to a throtl_grp and gets queued on itself or the parent, so | |
48 | * incrementing the reference of the associated throtl_grp when a qnode is | |
49 | * queued and decrementing when dequeued is enough to keep the whole blkg | |
50 | * tree pinned while bios are in flight. | |
51 | */ | |
52 | struct throtl_qnode { | |
53 | struct list_head node; /* service_queue->queued[] */ | |
54 | struct bio_list bios; /* queued bios */ | |
55 | struct throtl_grp *tg; /* tg this qnode belongs to */ | |
56 | }; | |
57 | ||
58 | struct throtl_service_queue { | |
59 | struct throtl_service_queue *parent_sq; /* the parent service_queue */ | |
60 | ||
61 | /* | |
62 | * Bios queued directly to this service_queue or dispatched from | |
63 | * children throtl_grp's. | |
64 | */ | |
65 | struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ | |
66 | unsigned int nr_queued[2]; /* number of queued bios */ | |
67 | ||
68 | /* | |
69 | * RB tree of active children throtl_grp's, which are sorted by | |
70 | * their ->disptime. | |
71 | */ | |
72 | struct rb_root pending_tree; /* RB tree of active tgs */ | |
73 | struct rb_node *first_pending; /* first node in the tree */ | |
74 | unsigned int nr_pending; /* # queued in the tree */ | |
75 | unsigned long first_pending_disptime; /* disptime of the first tg */ | |
76 | struct timer_list pending_timer; /* fires on first_pending_disptime */ | |
77 | }; | |
78 | ||
79 | enum tg_state_flags { | |
80 | THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ | |
81 | THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ | |
82 | }; | |
83 | ||
84 | #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) | |
85 | ||
86 | struct throtl_grp { | |
87 | /* must be the first member */ | |
88 | struct blkg_policy_data pd; | |
89 | ||
90 | /* active throtl group service_queue member */ | |
91 | struct rb_node rb_node; | |
92 | ||
93 | /* throtl_data this group belongs to */ | |
94 | struct throtl_data *td; | |
95 | ||
96 | /* this group's service queue */ | |
97 | struct throtl_service_queue service_queue; | |
98 | ||
99 | /* | |
100 | * qnode_on_self is used when bios are directly queued to this | |
101 | * throtl_grp so that local bios compete fairly with bios | |
102 | * dispatched from children. qnode_on_parent is used when bios are | |
103 | * dispatched from this throtl_grp into its parent and will compete | |
104 | * with the sibling qnode_on_parents and the parent's | |
105 | * qnode_on_self. | |
106 | */ | |
107 | struct throtl_qnode qnode_on_self[2]; | |
108 | struct throtl_qnode qnode_on_parent[2]; | |
109 | ||
110 | /* | |
111 | * Dispatch time in jiffies. This is the estimated time when group | |
112 | * will unthrottle and is ready to dispatch more bio. It is used as | |
113 | * key to sort active groups in service tree. | |
114 | */ | |
115 | unsigned long disptime; | |
116 | ||
117 | unsigned int flags; | |
118 | ||
119 | /* are there any throtl rules between this group and td? */ | |
120 | bool has_rules[2]; | |
121 | ||
122 | /* bytes per second rate limits */ | |
123 | uint64_t bps[2]; | |
124 | ||
125 | /* IOPS limits */ | |
126 | unsigned int iops[2]; | |
127 | ||
128 | /* Number of bytes disptached in current slice */ | |
129 | uint64_t bytes_disp[2]; | |
130 | /* Number of bio's dispatched in current slice */ | |
131 | unsigned int io_disp[2]; | |
132 | ||
133 | /* When did we start a new slice */ | |
134 | unsigned long slice_start[2]; | |
135 | unsigned long slice_end[2]; | |
136 | }; | |
137 | ||
138 | struct throtl_data | |
139 | { | |
140 | /* service tree for active throtl groups */ | |
141 | struct throtl_service_queue service_queue; | |
142 | ||
143 | struct request_queue *queue; | |
144 | ||
145 | /* Total Number of queued bios on READ and WRITE lists */ | |
146 | unsigned int nr_queued[2]; | |
147 | ||
148 | /* | |
149 | * number of total undestroyed groups | |
150 | */ | |
151 | unsigned int nr_undestroyed_grps; | |
152 | ||
153 | /* Work for dispatching throttled bios */ | |
154 | struct work_struct dispatch_work; | |
155 | }; | |
156 | ||
157 | static void throtl_pending_timer_fn(unsigned long arg); | |
158 | ||
159 | static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) | |
160 | { | |
161 | return pd ? container_of(pd, struct throtl_grp, pd) : NULL; | |
162 | } | |
163 | ||
164 | static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) | |
165 | { | |
166 | return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); | |
167 | } | |
168 | ||
169 | static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg) | |
170 | { | |
171 | return pd_to_blkg(&tg->pd); | |
172 | } | |
173 | ||
174 | /** | |
175 | * sq_to_tg - return the throl_grp the specified service queue belongs to | |
176 | * @sq: the throtl_service_queue of interest | |
177 | * | |
178 | * Return the throtl_grp @sq belongs to. If @sq is the top-level one | |
179 | * embedded in throtl_data, %NULL is returned. | |
180 | */ | |
181 | static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq) | |
182 | { | |
183 | if (sq && sq->parent_sq) | |
184 | return container_of(sq, struct throtl_grp, service_queue); | |
185 | else | |
186 | return NULL; | |
187 | } | |
188 | ||
189 | /** | |
190 | * sq_to_td - return throtl_data the specified service queue belongs to | |
191 | * @sq: the throtl_service_queue of interest | |
192 | * | |
193 | * A service_queue can be embeded in either a throtl_grp or throtl_data. | |
194 | * Determine the associated throtl_data accordingly and return it. | |
195 | */ | |
196 | static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) | |
197 | { | |
198 | struct throtl_grp *tg = sq_to_tg(sq); | |
199 | ||
200 | if (tg) | |
201 | return tg->td; | |
202 | else | |
203 | return container_of(sq, struct throtl_data, service_queue); | |
204 | } | |
205 | ||
206 | /** | |
207 | * throtl_log - log debug message via blktrace | |
208 | * @sq: the service_queue being reported | |
209 | * @fmt: printf format string | |
210 | * @args: printf args | |
211 | * | |
212 | * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a | |
213 | * throtl_grp; otherwise, just "throtl". | |
214 | * | |
215 | * TODO: this should be made a function and name formatting should happen | |
216 | * after testing whether blktrace is enabled. | |
217 | */ | |
218 | #define throtl_log(sq, fmt, args...) do { \ | |
219 | struct throtl_grp *__tg = sq_to_tg((sq)); \ | |
220 | struct throtl_data *__td = sq_to_td((sq)); \ | |
221 | \ | |
222 | (void)__td; \ | |
223 | if ((__tg)) { \ | |
224 | char __pbuf[128]; \ | |
225 | \ | |
226 | blkg_path(tg_to_blkg(__tg), __pbuf, sizeof(__pbuf)); \ | |
227 | blk_add_trace_msg(__td->queue, "throtl %s " fmt, __pbuf, ##args); \ | |
228 | } else { \ | |
229 | blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \ | |
230 | } \ | |
231 | } while (0) | |
232 | ||
233 | static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg) | |
234 | { | |
235 | INIT_LIST_HEAD(&qn->node); | |
236 | bio_list_init(&qn->bios); | |
237 | qn->tg = tg; | |
238 | } | |
239 | ||
240 | /** | |
241 | * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it | |
242 | * @bio: bio being added | |
243 | * @qn: qnode to add bio to | |
244 | * @queued: the service_queue->queued[] list @qn belongs to | |
245 | * | |
246 | * Add @bio to @qn and put @qn on @queued if it's not already on. | |
247 | * @qn->tg's reference count is bumped when @qn is activated. See the | |
248 | * comment on top of throtl_qnode definition for details. | |
249 | */ | |
250 | static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn, | |
251 | struct list_head *queued) | |
252 | { | |
253 | bio_list_add(&qn->bios, bio); | |
254 | if (list_empty(&qn->node)) { | |
255 | list_add_tail(&qn->node, queued); | |
256 | blkg_get(tg_to_blkg(qn->tg)); | |
257 | } | |
258 | } | |
259 | ||
260 | /** | |
261 | * throtl_peek_queued - peek the first bio on a qnode list | |
262 | * @queued: the qnode list to peek | |
263 | */ | |
264 | static struct bio *throtl_peek_queued(struct list_head *queued) | |
265 | { | |
266 | struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); | |
267 | struct bio *bio; | |
268 | ||
269 | if (list_empty(queued)) | |
270 | return NULL; | |
271 | ||
272 | bio = bio_list_peek(&qn->bios); | |
273 | WARN_ON_ONCE(!bio); | |
274 | return bio; | |
275 | } | |
276 | ||
277 | /** | |
278 | * throtl_pop_queued - pop the first bio form a qnode list | |
279 | * @queued: the qnode list to pop a bio from | |
280 | * @tg_to_put: optional out argument for throtl_grp to put | |
281 | * | |
282 | * Pop the first bio from the qnode list @queued. After popping, the first | |
283 | * qnode is removed from @queued if empty or moved to the end of @queued so | |
284 | * that the popping order is round-robin. | |
285 | * | |
286 | * When the first qnode is removed, its associated throtl_grp should be put | |
287 | * too. If @tg_to_put is NULL, this function automatically puts it; | |
288 | * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is | |
289 | * responsible for putting it. | |
290 | */ | |
291 | static struct bio *throtl_pop_queued(struct list_head *queued, | |
292 | struct throtl_grp **tg_to_put) | |
293 | { | |
294 | struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); | |
295 | struct bio *bio; | |
296 | ||
297 | if (list_empty(queued)) | |
298 | return NULL; | |
299 | ||
300 | bio = bio_list_pop(&qn->bios); | |
301 | WARN_ON_ONCE(!bio); | |
302 | ||
303 | if (bio_list_empty(&qn->bios)) { | |
304 | list_del_init(&qn->node); | |
305 | if (tg_to_put) | |
306 | *tg_to_put = qn->tg; | |
307 | else | |
308 | blkg_put(tg_to_blkg(qn->tg)); | |
309 | } else { | |
310 | list_move_tail(&qn->node, queued); | |
311 | } | |
312 | ||
313 | return bio; | |
314 | } | |
315 | ||
316 | /* init a service_queue, assumes the caller zeroed it */ | |
317 | static void throtl_service_queue_init(struct throtl_service_queue *sq) | |
318 | { | |
319 | INIT_LIST_HEAD(&sq->queued[0]); | |
320 | INIT_LIST_HEAD(&sq->queued[1]); | |
321 | sq->pending_tree = RB_ROOT; | |
322 | setup_timer(&sq->pending_timer, throtl_pending_timer_fn, | |
323 | (unsigned long)sq); | |
324 | } | |
325 | ||
326 | static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node) | |
327 | { | |
328 | struct throtl_grp *tg; | |
329 | int rw; | |
330 | ||
331 | tg = kzalloc_node(sizeof(*tg), gfp, node); | |
332 | if (!tg) | |
333 | return NULL; | |
334 | ||
335 | throtl_service_queue_init(&tg->service_queue); | |
336 | ||
337 | for (rw = READ; rw <= WRITE; rw++) { | |
338 | throtl_qnode_init(&tg->qnode_on_self[rw], tg); | |
339 | throtl_qnode_init(&tg->qnode_on_parent[rw], tg); | |
340 | } | |
341 | ||
342 | RB_CLEAR_NODE(&tg->rb_node); | |
343 | tg->bps[READ] = -1; | |
344 | tg->bps[WRITE] = -1; | |
345 | tg->iops[READ] = -1; | |
346 | tg->iops[WRITE] = -1; | |
347 | ||
348 | return &tg->pd; | |
349 | } | |
350 | ||
351 | static void throtl_pd_init(struct blkg_policy_data *pd) | |
352 | { | |
353 | struct throtl_grp *tg = pd_to_tg(pd); | |
354 | struct blkcg_gq *blkg = tg_to_blkg(tg); | |
355 | struct throtl_data *td = blkg->q->td; | |
356 | struct throtl_service_queue *sq = &tg->service_queue; | |
357 | ||
358 | /* | |
359 | * If on the default hierarchy, we switch to properly hierarchical | |
360 | * behavior where limits on a given throtl_grp are applied to the | |
361 | * whole subtree rather than just the group itself. e.g. If 16M | |
362 | * read_bps limit is set on the root group, the whole system can't | |
363 | * exceed 16M for the device. | |
364 | * | |
365 | * If not on the default hierarchy, the broken flat hierarchy | |
366 | * behavior is retained where all throtl_grps are treated as if | |
367 | * they're all separate root groups right below throtl_data. | |
368 | * Limits of a group don't interact with limits of other groups | |
369 | * regardless of the position of the group in the hierarchy. | |
370 | */ | |
371 | sq->parent_sq = &td->service_queue; | |
372 | if (cgroup_on_dfl(blkg->blkcg->css.cgroup) && blkg->parent) | |
373 | sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue; | |
374 | tg->td = td; | |
375 | } | |
376 | ||
377 | /* | |
378 | * Set has_rules[] if @tg or any of its parents have limits configured. | |
379 | * This doesn't require walking up to the top of the hierarchy as the | |
380 | * parent's has_rules[] is guaranteed to be correct. | |
381 | */ | |
382 | static void tg_update_has_rules(struct throtl_grp *tg) | |
383 | { | |
384 | struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq); | |
385 | int rw; | |
386 | ||
387 | for (rw = READ; rw <= WRITE; rw++) | |
388 | tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) || | |
389 | (tg->bps[rw] != -1 || tg->iops[rw] != -1); | |
390 | } | |
391 | ||
392 | static void throtl_pd_online(struct blkg_policy_data *pd) | |
393 | { | |
394 | /* | |
395 | * We don't want new groups to escape the limits of its ancestors. | |
396 | * Update has_rules[] after a new group is brought online. | |
397 | */ | |
398 | tg_update_has_rules(pd_to_tg(pd)); | |
399 | } | |
400 | ||
401 | static void throtl_pd_free(struct blkg_policy_data *pd) | |
402 | { | |
403 | struct throtl_grp *tg = pd_to_tg(pd); | |
404 | ||
405 | del_timer_sync(&tg->service_queue.pending_timer); | |
406 | kfree(tg); | |
407 | } | |
408 | ||
409 | static struct throtl_grp * | |
410 | throtl_rb_first(struct throtl_service_queue *parent_sq) | |
411 | { | |
412 | /* Service tree is empty */ | |
413 | if (!parent_sq->nr_pending) | |
414 | return NULL; | |
415 | ||
416 | if (!parent_sq->first_pending) | |
417 | parent_sq->first_pending = rb_first(&parent_sq->pending_tree); | |
418 | ||
419 | if (parent_sq->first_pending) | |
420 | return rb_entry_tg(parent_sq->first_pending); | |
421 | ||
422 | return NULL; | |
423 | } | |
424 | ||
425 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) | |
426 | { | |
427 | rb_erase(n, root); | |
428 | RB_CLEAR_NODE(n); | |
429 | } | |
430 | ||
431 | static void throtl_rb_erase(struct rb_node *n, | |
432 | struct throtl_service_queue *parent_sq) | |
433 | { | |
434 | if (parent_sq->first_pending == n) | |
435 | parent_sq->first_pending = NULL; | |
436 | rb_erase_init(n, &parent_sq->pending_tree); | |
437 | --parent_sq->nr_pending; | |
438 | } | |
439 | ||
440 | static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) | |
441 | { | |
442 | struct throtl_grp *tg; | |
443 | ||
444 | tg = throtl_rb_first(parent_sq); | |
445 | if (!tg) | |
446 | return; | |
447 | ||
448 | parent_sq->first_pending_disptime = tg->disptime; | |
449 | } | |
450 | ||
451 | static void tg_service_queue_add(struct throtl_grp *tg) | |
452 | { | |
453 | struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq; | |
454 | struct rb_node **node = &parent_sq->pending_tree.rb_node; | |
455 | struct rb_node *parent = NULL; | |
456 | struct throtl_grp *__tg; | |
457 | unsigned long key = tg->disptime; | |
458 | int left = 1; | |
459 | ||
460 | while (*node != NULL) { | |
461 | parent = *node; | |
462 | __tg = rb_entry_tg(parent); | |
463 | ||
464 | if (time_before(key, __tg->disptime)) | |
465 | node = &parent->rb_left; | |
466 | else { | |
467 | node = &parent->rb_right; | |
468 | left = 0; | |
469 | } | |
470 | } | |
471 | ||
472 | if (left) | |
473 | parent_sq->first_pending = &tg->rb_node; | |
474 | ||
475 | rb_link_node(&tg->rb_node, parent, node); | |
476 | rb_insert_color(&tg->rb_node, &parent_sq->pending_tree); | |
477 | } | |
478 | ||
479 | static void __throtl_enqueue_tg(struct throtl_grp *tg) | |
480 | { | |
481 | tg_service_queue_add(tg); | |
482 | tg->flags |= THROTL_TG_PENDING; | |
483 | tg->service_queue.parent_sq->nr_pending++; | |
484 | } | |
485 | ||
486 | static void throtl_enqueue_tg(struct throtl_grp *tg) | |
487 | { | |
488 | if (!(tg->flags & THROTL_TG_PENDING)) | |
489 | __throtl_enqueue_tg(tg); | |
490 | } | |
491 | ||
492 | static void __throtl_dequeue_tg(struct throtl_grp *tg) | |
493 | { | |
494 | throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq); | |
495 | tg->flags &= ~THROTL_TG_PENDING; | |
496 | } | |
497 | ||
498 | static void throtl_dequeue_tg(struct throtl_grp *tg) | |
499 | { | |
500 | if (tg->flags & THROTL_TG_PENDING) | |
501 | __throtl_dequeue_tg(tg); | |
502 | } | |
503 | ||
504 | /* Call with queue lock held */ | |
505 | static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, | |
506 | unsigned long expires) | |
507 | { | |
508 | mod_timer(&sq->pending_timer, expires); | |
509 | throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu", | |
510 | expires - jiffies, jiffies); | |
511 | } | |
512 | ||
513 | /** | |
514 | * throtl_schedule_next_dispatch - schedule the next dispatch cycle | |
515 | * @sq: the service_queue to schedule dispatch for | |
516 | * @force: force scheduling | |
517 | * | |
518 | * Arm @sq->pending_timer so that the next dispatch cycle starts on the | |
519 | * dispatch time of the first pending child. Returns %true if either timer | |
520 | * is armed or there's no pending child left. %false if the current | |
521 | * dispatch window is still open and the caller should continue | |
522 | * dispatching. | |
523 | * | |
524 | * If @force is %true, the dispatch timer is always scheduled and this | |
525 | * function is guaranteed to return %true. This is to be used when the | |
526 | * caller can't dispatch itself and needs to invoke pending_timer | |
527 | * unconditionally. Note that forced scheduling is likely to induce short | |
528 | * delay before dispatch starts even if @sq->first_pending_disptime is not | |
529 | * in the future and thus shouldn't be used in hot paths. | |
530 | */ | |
531 | static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq, | |
532 | bool force) | |
533 | { | |
534 | /* any pending children left? */ | |
535 | if (!sq->nr_pending) | |
536 | return true; | |
537 | ||
538 | update_min_dispatch_time(sq); | |
539 | ||
540 | /* is the next dispatch time in the future? */ | |
541 | if (force || time_after(sq->first_pending_disptime, jiffies)) { | |
542 | throtl_schedule_pending_timer(sq, sq->first_pending_disptime); | |
543 | return true; | |
544 | } | |
545 | ||
546 | /* tell the caller to continue dispatching */ | |
547 | return false; | |
548 | } | |
549 | ||
550 | static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg, | |
551 | bool rw, unsigned long start) | |
552 | { | |
553 | tg->bytes_disp[rw] = 0; | |
554 | tg->io_disp[rw] = 0; | |
555 | ||
556 | /* | |
557 | * Previous slice has expired. We must have trimmed it after last | |
558 | * bio dispatch. That means since start of last slice, we never used | |
559 | * that bandwidth. Do try to make use of that bandwidth while giving | |
560 | * credit. | |
561 | */ | |
562 | if (time_after_eq(start, tg->slice_start[rw])) | |
563 | tg->slice_start[rw] = start; | |
564 | ||
565 | tg->slice_end[rw] = jiffies + throtl_slice; | |
566 | throtl_log(&tg->service_queue, | |
567 | "[%c] new slice with credit start=%lu end=%lu jiffies=%lu", | |
568 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
569 | tg->slice_end[rw], jiffies); | |
570 | } | |
571 | ||
572 | static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) | |
573 | { | |
574 | tg->bytes_disp[rw] = 0; | |
575 | tg->io_disp[rw] = 0; | |
576 | tg->slice_start[rw] = jiffies; | |
577 | tg->slice_end[rw] = jiffies + throtl_slice; | |
578 | throtl_log(&tg->service_queue, | |
579 | "[%c] new slice start=%lu end=%lu jiffies=%lu", | |
580 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
581 | tg->slice_end[rw], jiffies); | |
582 | } | |
583 | ||
584 | static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw, | |
585 | unsigned long jiffy_end) | |
586 | { | |
587 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); | |
588 | } | |
589 | ||
590 | static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw, | |
591 | unsigned long jiffy_end) | |
592 | { | |
593 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); | |
594 | throtl_log(&tg->service_queue, | |
595 | "[%c] extend slice start=%lu end=%lu jiffies=%lu", | |
596 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
597 | tg->slice_end[rw], jiffies); | |
598 | } | |
599 | ||
600 | /* Determine if previously allocated or extended slice is complete or not */ | |
601 | static bool throtl_slice_used(struct throtl_grp *tg, bool rw) | |
602 | { | |
603 | if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) | |
604 | return false; | |
605 | ||
606 | return 1; | |
607 | } | |
608 | ||
609 | /* Trim the used slices and adjust slice start accordingly */ | |
610 | static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) | |
611 | { | |
612 | unsigned long nr_slices, time_elapsed, io_trim; | |
613 | u64 bytes_trim, tmp; | |
614 | ||
615 | BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); | |
616 | ||
617 | /* | |
618 | * If bps are unlimited (-1), then time slice don't get | |
619 | * renewed. Don't try to trim the slice if slice is used. A new | |
620 | * slice will start when appropriate. | |
621 | */ | |
622 | if (throtl_slice_used(tg, rw)) | |
623 | return; | |
624 | ||
625 | /* | |
626 | * A bio has been dispatched. Also adjust slice_end. It might happen | |
627 | * that initially cgroup limit was very low resulting in high | |
628 | * slice_end, but later limit was bumped up and bio was dispached | |
629 | * sooner, then we need to reduce slice_end. A high bogus slice_end | |
630 | * is bad because it does not allow new slice to start. | |
631 | */ | |
632 | ||
633 | throtl_set_slice_end(tg, rw, jiffies + throtl_slice); | |
634 | ||
635 | time_elapsed = jiffies - tg->slice_start[rw]; | |
636 | ||
637 | nr_slices = time_elapsed / throtl_slice; | |
638 | ||
639 | if (!nr_slices) | |
640 | return; | |
641 | tmp = tg->bps[rw] * throtl_slice * nr_slices; | |
642 | do_div(tmp, HZ); | |
643 | bytes_trim = tmp; | |
644 | ||
645 | io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ; | |
646 | ||
647 | if (!bytes_trim && !io_trim) | |
648 | return; | |
649 | ||
650 | if (tg->bytes_disp[rw] >= bytes_trim) | |
651 | tg->bytes_disp[rw] -= bytes_trim; | |
652 | else | |
653 | tg->bytes_disp[rw] = 0; | |
654 | ||
655 | if (tg->io_disp[rw] >= io_trim) | |
656 | tg->io_disp[rw] -= io_trim; | |
657 | else | |
658 | tg->io_disp[rw] = 0; | |
659 | ||
660 | tg->slice_start[rw] += nr_slices * throtl_slice; | |
661 | ||
662 | throtl_log(&tg->service_queue, | |
663 | "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", | |
664 | rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, | |
665 | tg->slice_start[rw], tg->slice_end[rw], jiffies); | |
666 | } | |
667 | ||
668 | static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, | |
669 | unsigned long *wait) | |
670 | { | |
671 | bool rw = bio_data_dir(bio); | |
672 | unsigned int io_allowed; | |
673 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; | |
674 | u64 tmp; | |
675 | ||
676 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; | |
677 | ||
678 | /* Slice has just started. Consider one slice interval */ | |
679 | if (!jiffy_elapsed) | |
680 | jiffy_elapsed_rnd = throtl_slice; | |
681 | ||
682 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); | |
683 | ||
684 | /* | |
685 | * jiffy_elapsed_rnd should not be a big value as minimum iops can be | |
686 | * 1 then at max jiffy elapsed should be equivalent of 1 second as we | |
687 | * will allow dispatch after 1 second and after that slice should | |
688 | * have been trimmed. | |
689 | */ | |
690 | ||
691 | tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd; | |
692 | do_div(tmp, HZ); | |
693 | ||
694 | if (tmp > UINT_MAX) | |
695 | io_allowed = UINT_MAX; | |
696 | else | |
697 | io_allowed = tmp; | |
698 | ||
699 | if (tg->io_disp[rw] + 1 <= io_allowed) { | |
700 | if (wait) | |
701 | *wait = 0; | |
702 | return true; | |
703 | } | |
704 | ||
705 | /* Calc approx time to dispatch */ | |
706 | jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1; | |
707 | ||
708 | if (jiffy_wait > jiffy_elapsed) | |
709 | jiffy_wait = jiffy_wait - jiffy_elapsed; | |
710 | else | |
711 | jiffy_wait = 1; | |
712 | ||
713 | if (wait) | |
714 | *wait = jiffy_wait; | |
715 | return 0; | |
716 | } | |
717 | ||
718 | static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, | |
719 | unsigned long *wait) | |
720 | { | |
721 | bool rw = bio_data_dir(bio); | |
722 | u64 bytes_allowed, extra_bytes, tmp; | |
723 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; | |
724 | ||
725 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; | |
726 | ||
727 | /* Slice has just started. Consider one slice interval */ | |
728 | if (!jiffy_elapsed) | |
729 | jiffy_elapsed_rnd = throtl_slice; | |
730 | ||
731 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); | |
732 | ||
733 | tmp = tg->bps[rw] * jiffy_elapsed_rnd; | |
734 | do_div(tmp, HZ); | |
735 | bytes_allowed = tmp; | |
736 | ||
737 | if (tg->bytes_disp[rw] + bio->bi_iter.bi_size <= bytes_allowed) { | |
738 | if (wait) | |
739 | *wait = 0; | |
740 | return true; | |
741 | } | |
742 | ||
743 | /* Calc approx time to dispatch */ | |
744 | extra_bytes = tg->bytes_disp[rw] + bio->bi_iter.bi_size - bytes_allowed; | |
745 | jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]); | |
746 | ||
747 | if (!jiffy_wait) | |
748 | jiffy_wait = 1; | |
749 | ||
750 | /* | |
751 | * This wait time is without taking into consideration the rounding | |
752 | * up we did. Add that time also. | |
753 | */ | |
754 | jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); | |
755 | if (wait) | |
756 | *wait = jiffy_wait; | |
757 | return 0; | |
758 | } | |
759 | ||
760 | /* | |
761 | * Returns whether one can dispatch a bio or not. Also returns approx number | |
762 | * of jiffies to wait before this bio is with-in IO rate and can be dispatched | |
763 | */ | |
764 | static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, | |
765 | unsigned long *wait) | |
766 | { | |
767 | bool rw = bio_data_dir(bio); | |
768 | unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; | |
769 | ||
770 | /* | |
771 | * Currently whole state machine of group depends on first bio | |
772 | * queued in the group bio list. So one should not be calling | |
773 | * this function with a different bio if there are other bios | |
774 | * queued. | |
775 | */ | |
776 | BUG_ON(tg->service_queue.nr_queued[rw] && | |
777 | bio != throtl_peek_queued(&tg->service_queue.queued[rw])); | |
778 | ||
779 | /* If tg->bps = -1, then BW is unlimited */ | |
780 | if (tg->bps[rw] == -1 && tg->iops[rw] == -1) { | |
781 | if (wait) | |
782 | *wait = 0; | |
783 | return true; | |
784 | } | |
785 | ||
786 | /* | |
787 | * If previous slice expired, start a new one otherwise renew/extend | |
788 | * existing slice to make sure it is at least throtl_slice interval | |
789 | * long since now. | |
790 | */ | |
791 | if (throtl_slice_used(tg, rw)) | |
792 | throtl_start_new_slice(tg, rw); | |
793 | else { | |
794 | if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) | |
795 | throtl_extend_slice(tg, rw, jiffies + throtl_slice); | |
796 | } | |
797 | ||
798 | if (tg_with_in_bps_limit(tg, bio, &bps_wait) && | |
799 | tg_with_in_iops_limit(tg, bio, &iops_wait)) { | |
800 | if (wait) | |
801 | *wait = 0; | |
802 | return 1; | |
803 | } | |
804 | ||
805 | max_wait = max(bps_wait, iops_wait); | |
806 | ||
807 | if (wait) | |
808 | *wait = max_wait; | |
809 | ||
810 | if (time_before(tg->slice_end[rw], jiffies + max_wait)) | |
811 | throtl_extend_slice(tg, rw, jiffies + max_wait); | |
812 | ||
813 | return 0; | |
814 | } | |
815 | ||
816 | static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) | |
817 | { | |
818 | bool rw = bio_data_dir(bio); | |
819 | ||
820 | /* Charge the bio to the group */ | |
821 | tg->bytes_disp[rw] += bio->bi_iter.bi_size; | |
822 | tg->io_disp[rw]++; | |
823 | ||
824 | /* | |
825 | * REQ_THROTTLED is used to prevent the same bio to be throttled | |
826 | * more than once as a throttled bio will go through blk-throtl the | |
827 | * second time when it eventually gets issued. Set it when a bio | |
828 | * is being charged to a tg. | |
829 | */ | |
830 | if (!(bio->bi_rw & REQ_THROTTLED)) | |
831 | bio->bi_rw |= REQ_THROTTLED; | |
832 | } | |
833 | ||
834 | /** | |
835 | * throtl_add_bio_tg - add a bio to the specified throtl_grp | |
836 | * @bio: bio to add | |
837 | * @qn: qnode to use | |
838 | * @tg: the target throtl_grp | |
839 | * | |
840 | * Add @bio to @tg's service_queue using @qn. If @qn is not specified, | |
841 | * tg->qnode_on_self[] is used. | |
842 | */ | |
843 | static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn, | |
844 | struct throtl_grp *tg) | |
845 | { | |
846 | struct throtl_service_queue *sq = &tg->service_queue; | |
847 | bool rw = bio_data_dir(bio); | |
848 | ||
849 | if (!qn) | |
850 | qn = &tg->qnode_on_self[rw]; | |
851 | ||
852 | /* | |
853 | * If @tg doesn't currently have any bios queued in the same | |
854 | * direction, queueing @bio can change when @tg should be | |
855 | * dispatched. Mark that @tg was empty. This is automatically | |
856 | * cleaered on the next tg_update_disptime(). | |
857 | */ | |
858 | if (!sq->nr_queued[rw]) | |
859 | tg->flags |= THROTL_TG_WAS_EMPTY; | |
860 | ||
861 | throtl_qnode_add_bio(bio, qn, &sq->queued[rw]); | |
862 | ||
863 | sq->nr_queued[rw]++; | |
864 | throtl_enqueue_tg(tg); | |
865 | } | |
866 | ||
867 | static void tg_update_disptime(struct throtl_grp *tg) | |
868 | { | |
869 | struct throtl_service_queue *sq = &tg->service_queue; | |
870 | unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; | |
871 | struct bio *bio; | |
872 | ||
873 | if ((bio = throtl_peek_queued(&sq->queued[READ]))) | |
874 | tg_may_dispatch(tg, bio, &read_wait); | |
875 | ||
876 | if ((bio = throtl_peek_queued(&sq->queued[WRITE]))) | |
877 | tg_may_dispatch(tg, bio, &write_wait); | |
878 | ||
879 | min_wait = min(read_wait, write_wait); | |
880 | disptime = jiffies + min_wait; | |
881 | ||
882 | /* Update dispatch time */ | |
883 | throtl_dequeue_tg(tg); | |
884 | tg->disptime = disptime; | |
885 | throtl_enqueue_tg(tg); | |
886 | ||
887 | /* see throtl_add_bio_tg() */ | |
888 | tg->flags &= ~THROTL_TG_WAS_EMPTY; | |
889 | } | |
890 | ||
891 | static void start_parent_slice_with_credit(struct throtl_grp *child_tg, | |
892 | struct throtl_grp *parent_tg, bool rw) | |
893 | { | |
894 | if (throtl_slice_used(parent_tg, rw)) { | |
895 | throtl_start_new_slice_with_credit(parent_tg, rw, | |
896 | child_tg->slice_start[rw]); | |
897 | } | |
898 | ||
899 | } | |
900 | ||
901 | static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) | |
902 | { | |
903 | struct throtl_service_queue *sq = &tg->service_queue; | |
904 | struct throtl_service_queue *parent_sq = sq->parent_sq; | |
905 | struct throtl_grp *parent_tg = sq_to_tg(parent_sq); | |
906 | struct throtl_grp *tg_to_put = NULL; | |
907 | struct bio *bio; | |
908 | ||
909 | /* | |
910 | * @bio is being transferred from @tg to @parent_sq. Popping a bio | |
911 | * from @tg may put its reference and @parent_sq might end up | |
912 | * getting released prematurely. Remember the tg to put and put it | |
913 | * after @bio is transferred to @parent_sq. | |
914 | */ | |
915 | bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put); | |
916 | sq->nr_queued[rw]--; | |
917 | ||
918 | throtl_charge_bio(tg, bio); | |
919 | ||
920 | /* | |
921 | * If our parent is another tg, we just need to transfer @bio to | |
922 | * the parent using throtl_add_bio_tg(). If our parent is | |
923 | * @td->service_queue, @bio is ready to be issued. Put it on its | |
924 | * bio_lists[] and decrease total number queued. The caller is | |
925 | * responsible for issuing these bios. | |
926 | */ | |
927 | if (parent_tg) { | |
928 | throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); | |
929 | start_parent_slice_with_credit(tg, parent_tg, rw); | |
930 | } else { | |
931 | throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], | |
932 | &parent_sq->queued[rw]); | |
933 | BUG_ON(tg->td->nr_queued[rw] <= 0); | |
934 | tg->td->nr_queued[rw]--; | |
935 | } | |
936 | ||
937 | throtl_trim_slice(tg, rw); | |
938 | ||
939 | if (tg_to_put) | |
940 | blkg_put(tg_to_blkg(tg_to_put)); | |
941 | } | |
942 | ||
943 | static int throtl_dispatch_tg(struct throtl_grp *tg) | |
944 | { | |
945 | struct throtl_service_queue *sq = &tg->service_queue; | |
946 | unsigned int nr_reads = 0, nr_writes = 0; | |
947 | unsigned int max_nr_reads = throtl_grp_quantum*3/4; | |
948 | unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; | |
949 | struct bio *bio; | |
950 | ||
951 | /* Try to dispatch 75% READS and 25% WRITES */ | |
952 | ||
953 | while ((bio = throtl_peek_queued(&sq->queued[READ])) && | |
954 | tg_may_dispatch(tg, bio, NULL)) { | |
955 | ||
956 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
957 | nr_reads++; | |
958 | ||
959 | if (nr_reads >= max_nr_reads) | |
960 | break; | |
961 | } | |
962 | ||
963 | while ((bio = throtl_peek_queued(&sq->queued[WRITE])) && | |
964 | tg_may_dispatch(tg, bio, NULL)) { | |
965 | ||
966 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
967 | nr_writes++; | |
968 | ||
969 | if (nr_writes >= max_nr_writes) | |
970 | break; | |
971 | } | |
972 | ||
973 | return nr_reads + nr_writes; | |
974 | } | |
975 | ||
976 | static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) | |
977 | { | |
978 | unsigned int nr_disp = 0; | |
979 | ||
980 | while (1) { | |
981 | struct throtl_grp *tg = throtl_rb_first(parent_sq); | |
982 | struct throtl_service_queue *sq = &tg->service_queue; | |
983 | ||
984 | if (!tg) | |
985 | break; | |
986 | ||
987 | if (time_before(jiffies, tg->disptime)) | |
988 | break; | |
989 | ||
990 | throtl_dequeue_tg(tg); | |
991 | ||
992 | nr_disp += throtl_dispatch_tg(tg); | |
993 | ||
994 | if (sq->nr_queued[0] || sq->nr_queued[1]) | |
995 | tg_update_disptime(tg); | |
996 | ||
997 | if (nr_disp >= throtl_quantum) | |
998 | break; | |
999 | } | |
1000 | ||
1001 | return nr_disp; | |
1002 | } | |
1003 | ||
1004 | /** | |
1005 | * throtl_pending_timer_fn - timer function for service_queue->pending_timer | |
1006 | * @arg: the throtl_service_queue being serviced | |
1007 | * | |
1008 | * This timer is armed when a child throtl_grp with active bio's become | |
1009 | * pending and queued on the service_queue's pending_tree and expires when | |
1010 | * the first child throtl_grp should be dispatched. This function | |
1011 | * dispatches bio's from the children throtl_grps to the parent | |
1012 | * service_queue. | |
1013 | * | |
1014 | * If the parent's parent is another throtl_grp, dispatching is propagated | |
1015 | * by either arming its pending_timer or repeating dispatch directly. If | |
1016 | * the top-level service_tree is reached, throtl_data->dispatch_work is | |
1017 | * kicked so that the ready bio's are issued. | |
1018 | */ | |
1019 | static void throtl_pending_timer_fn(unsigned long arg) | |
1020 | { | |
1021 | struct throtl_service_queue *sq = (void *)arg; | |
1022 | struct throtl_grp *tg = sq_to_tg(sq); | |
1023 | struct throtl_data *td = sq_to_td(sq); | |
1024 | struct request_queue *q = td->queue; | |
1025 | struct throtl_service_queue *parent_sq; | |
1026 | bool dispatched; | |
1027 | int ret; | |
1028 | ||
1029 | spin_lock_irq(q->queue_lock); | |
1030 | again: | |
1031 | parent_sq = sq->parent_sq; | |
1032 | dispatched = false; | |
1033 | ||
1034 | while (true) { | |
1035 | throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u", | |
1036 | sq->nr_queued[READ] + sq->nr_queued[WRITE], | |
1037 | sq->nr_queued[READ], sq->nr_queued[WRITE]); | |
1038 | ||
1039 | ret = throtl_select_dispatch(sq); | |
1040 | if (ret) { | |
1041 | throtl_log(sq, "bios disp=%u", ret); | |
1042 | dispatched = true; | |
1043 | } | |
1044 | ||
1045 | if (throtl_schedule_next_dispatch(sq, false)) | |
1046 | break; | |
1047 | ||
1048 | /* this dispatch windows is still open, relax and repeat */ | |
1049 | spin_unlock_irq(q->queue_lock); | |
1050 | cpu_relax(); | |
1051 | spin_lock_irq(q->queue_lock); | |
1052 | } | |
1053 | ||
1054 | if (!dispatched) | |
1055 | goto out_unlock; | |
1056 | ||
1057 | if (parent_sq) { | |
1058 | /* @parent_sq is another throl_grp, propagate dispatch */ | |
1059 | if (tg->flags & THROTL_TG_WAS_EMPTY) { | |
1060 | tg_update_disptime(tg); | |
1061 | if (!throtl_schedule_next_dispatch(parent_sq, false)) { | |
1062 | /* window is already open, repeat dispatching */ | |
1063 | sq = parent_sq; | |
1064 | tg = sq_to_tg(sq); | |
1065 | goto again; | |
1066 | } | |
1067 | } | |
1068 | } else { | |
1069 | /* reached the top-level, queue issueing */ | |
1070 | queue_work(kthrotld_workqueue, &td->dispatch_work); | |
1071 | } | |
1072 | out_unlock: | |
1073 | spin_unlock_irq(q->queue_lock); | |
1074 | } | |
1075 | ||
1076 | /** | |
1077 | * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work | |
1078 | * @work: work item being executed | |
1079 | * | |
1080 | * This function is queued for execution when bio's reach the bio_lists[] | |
1081 | * of throtl_data->service_queue. Those bio's are ready and issued by this | |
1082 | * function. | |
1083 | */ | |
1084 | static void blk_throtl_dispatch_work_fn(struct work_struct *work) | |
1085 | { | |
1086 | struct throtl_data *td = container_of(work, struct throtl_data, | |
1087 | dispatch_work); | |
1088 | struct throtl_service_queue *td_sq = &td->service_queue; | |
1089 | struct request_queue *q = td->queue; | |
1090 | struct bio_list bio_list_on_stack; | |
1091 | struct bio *bio; | |
1092 | struct blk_plug plug; | |
1093 | int rw; | |
1094 | ||
1095 | bio_list_init(&bio_list_on_stack); | |
1096 | ||
1097 | spin_lock_irq(q->queue_lock); | |
1098 | for (rw = READ; rw <= WRITE; rw++) | |
1099 | while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) | |
1100 | bio_list_add(&bio_list_on_stack, bio); | |
1101 | spin_unlock_irq(q->queue_lock); | |
1102 | ||
1103 | if (!bio_list_empty(&bio_list_on_stack)) { | |
1104 | blk_start_plug(&plug); | |
1105 | while((bio = bio_list_pop(&bio_list_on_stack))) | |
1106 | generic_make_request(bio); | |
1107 | blk_finish_plug(&plug); | |
1108 | } | |
1109 | } | |
1110 | ||
1111 | static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, | |
1112 | int off) | |
1113 | { | |
1114 | struct throtl_grp *tg = pd_to_tg(pd); | |
1115 | u64 v = *(u64 *)((void *)tg + off); | |
1116 | ||
1117 | if (v == -1) | |
1118 | return 0; | |
1119 | return __blkg_prfill_u64(sf, pd, v); | |
1120 | } | |
1121 | ||
1122 | static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, | |
1123 | int off) | |
1124 | { | |
1125 | struct throtl_grp *tg = pd_to_tg(pd); | |
1126 | unsigned int v = *(unsigned int *)((void *)tg + off); | |
1127 | ||
1128 | if (v == -1) | |
1129 | return 0; | |
1130 | return __blkg_prfill_u64(sf, pd, v); | |
1131 | } | |
1132 | ||
1133 | static int tg_print_conf_u64(struct seq_file *sf, void *v) | |
1134 | { | |
1135 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64, | |
1136 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
1137 | return 0; | |
1138 | } | |
1139 | ||
1140 | static int tg_print_conf_uint(struct seq_file *sf, void *v) | |
1141 | { | |
1142 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint, | |
1143 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
1144 | return 0; | |
1145 | } | |
1146 | ||
1147 | static ssize_t tg_set_conf(struct kernfs_open_file *of, | |
1148 | char *buf, size_t nbytes, loff_t off, bool is_u64) | |
1149 | { | |
1150 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); | |
1151 | struct blkg_conf_ctx ctx; | |
1152 | struct throtl_grp *tg; | |
1153 | struct throtl_service_queue *sq; | |
1154 | struct blkcg_gq *blkg; | |
1155 | struct cgroup_subsys_state *pos_css; | |
1156 | int ret; | |
1157 | ||
1158 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); | |
1159 | if (ret) | |
1160 | return ret; | |
1161 | ||
1162 | tg = blkg_to_tg(ctx.blkg); | |
1163 | sq = &tg->service_queue; | |
1164 | ||
1165 | if (!ctx.v) | |
1166 | ctx.v = -1; | |
1167 | ||
1168 | if (is_u64) | |
1169 | *(u64 *)((void *)tg + of_cft(of)->private) = ctx.v; | |
1170 | else | |
1171 | *(unsigned int *)((void *)tg + of_cft(of)->private) = ctx.v; | |
1172 | ||
1173 | throtl_log(&tg->service_queue, | |
1174 | "limit change rbps=%llu wbps=%llu riops=%u wiops=%u", | |
1175 | tg->bps[READ], tg->bps[WRITE], | |
1176 | tg->iops[READ], tg->iops[WRITE]); | |
1177 | ||
1178 | /* | |
1179 | * Update has_rules[] flags for the updated tg's subtree. A tg is | |
1180 | * considered to have rules if either the tg itself or any of its | |
1181 | * ancestors has rules. This identifies groups without any | |
1182 | * restrictions in the whole hierarchy and allows them to bypass | |
1183 | * blk-throttle. | |
1184 | */ | |
1185 | blkg_for_each_descendant_pre(blkg, pos_css, ctx.blkg) | |
1186 | tg_update_has_rules(blkg_to_tg(blkg)); | |
1187 | ||
1188 | /* | |
1189 | * We're already holding queue_lock and know @tg is valid. Let's | |
1190 | * apply the new config directly. | |
1191 | * | |
1192 | * Restart the slices for both READ and WRITES. It might happen | |
1193 | * that a group's limit are dropped suddenly and we don't want to | |
1194 | * account recently dispatched IO with new low rate. | |
1195 | */ | |
1196 | throtl_start_new_slice(tg, 0); | |
1197 | throtl_start_new_slice(tg, 1); | |
1198 | ||
1199 | if (tg->flags & THROTL_TG_PENDING) { | |
1200 | tg_update_disptime(tg); | |
1201 | throtl_schedule_next_dispatch(sq->parent_sq, true); | |
1202 | } | |
1203 | ||
1204 | blkg_conf_finish(&ctx); | |
1205 | return nbytes; | |
1206 | } | |
1207 | ||
1208 | static ssize_t tg_set_conf_u64(struct kernfs_open_file *of, | |
1209 | char *buf, size_t nbytes, loff_t off) | |
1210 | { | |
1211 | return tg_set_conf(of, buf, nbytes, off, true); | |
1212 | } | |
1213 | ||
1214 | static ssize_t tg_set_conf_uint(struct kernfs_open_file *of, | |
1215 | char *buf, size_t nbytes, loff_t off) | |
1216 | { | |
1217 | return tg_set_conf(of, buf, nbytes, off, false); | |
1218 | } | |
1219 | ||
1220 | static struct cftype throtl_files[] = { | |
1221 | { | |
1222 | .name = "throttle.read_bps_device", | |
1223 | .private = offsetof(struct throtl_grp, bps[READ]), | |
1224 | .seq_show = tg_print_conf_u64, | |
1225 | .write = tg_set_conf_u64, | |
1226 | }, | |
1227 | { | |
1228 | .name = "throttle.write_bps_device", | |
1229 | .private = offsetof(struct throtl_grp, bps[WRITE]), | |
1230 | .seq_show = tg_print_conf_u64, | |
1231 | .write = tg_set_conf_u64, | |
1232 | }, | |
1233 | { | |
1234 | .name = "throttle.read_iops_device", | |
1235 | .private = offsetof(struct throtl_grp, iops[READ]), | |
1236 | .seq_show = tg_print_conf_uint, | |
1237 | .write = tg_set_conf_uint, | |
1238 | }, | |
1239 | { | |
1240 | .name = "throttle.write_iops_device", | |
1241 | .private = offsetof(struct throtl_grp, iops[WRITE]), | |
1242 | .seq_show = tg_print_conf_uint, | |
1243 | .write = tg_set_conf_uint, | |
1244 | }, | |
1245 | { | |
1246 | .name = "throttle.io_service_bytes", | |
1247 | .private = (unsigned long)&blkcg_policy_throtl, | |
1248 | .seq_show = blkg_print_stat_bytes, | |
1249 | }, | |
1250 | { | |
1251 | .name = "throttle.io_serviced", | |
1252 | .private = (unsigned long)&blkcg_policy_throtl, | |
1253 | .seq_show = blkg_print_stat_ios, | |
1254 | }, | |
1255 | { } /* terminate */ | |
1256 | }; | |
1257 | ||
1258 | static void throtl_shutdown_wq(struct request_queue *q) | |
1259 | { | |
1260 | struct throtl_data *td = q->td; | |
1261 | ||
1262 | cancel_work_sync(&td->dispatch_work); | |
1263 | } | |
1264 | ||
1265 | static struct blkcg_policy blkcg_policy_throtl = { | |
1266 | .cftypes = throtl_files, | |
1267 | ||
1268 | .pd_alloc_fn = throtl_pd_alloc, | |
1269 | .pd_init_fn = throtl_pd_init, | |
1270 | .pd_online_fn = throtl_pd_online, | |
1271 | .pd_free_fn = throtl_pd_free, | |
1272 | }; | |
1273 | ||
1274 | bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, | |
1275 | struct bio *bio) | |
1276 | { | |
1277 | struct throtl_qnode *qn = NULL; | |
1278 | struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg); | |
1279 | struct throtl_service_queue *sq; | |
1280 | bool rw = bio_data_dir(bio); | |
1281 | bool throttled = false; | |
1282 | ||
1283 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
1284 | ||
1285 | /* see throtl_charge_bio() */ | |
1286 | if ((bio->bi_rw & REQ_THROTTLED) || !tg->has_rules[rw]) | |
1287 | goto out; | |
1288 | ||
1289 | spin_lock_irq(q->queue_lock); | |
1290 | ||
1291 | if (unlikely(blk_queue_bypass(q))) | |
1292 | goto out_unlock; | |
1293 | ||
1294 | sq = &tg->service_queue; | |
1295 | ||
1296 | while (true) { | |
1297 | /* throtl is FIFO - if bios are already queued, should queue */ | |
1298 | if (sq->nr_queued[rw]) | |
1299 | break; | |
1300 | ||
1301 | /* if above limits, break to queue */ | |
1302 | if (!tg_may_dispatch(tg, bio, NULL)) | |
1303 | break; | |
1304 | ||
1305 | /* within limits, let's charge and dispatch directly */ | |
1306 | throtl_charge_bio(tg, bio); | |
1307 | ||
1308 | /* | |
1309 | * We need to trim slice even when bios are not being queued | |
1310 | * otherwise it might happen that a bio is not queued for | |
1311 | * a long time and slice keeps on extending and trim is not | |
1312 | * called for a long time. Now if limits are reduced suddenly | |
1313 | * we take into account all the IO dispatched so far at new | |
1314 | * low rate and * newly queued IO gets a really long dispatch | |
1315 | * time. | |
1316 | * | |
1317 | * So keep on trimming slice even if bio is not queued. | |
1318 | */ | |
1319 | throtl_trim_slice(tg, rw); | |
1320 | ||
1321 | /* | |
1322 | * @bio passed through this layer without being throttled. | |
1323 | * Climb up the ladder. If we''re already at the top, it | |
1324 | * can be executed directly. | |
1325 | */ | |
1326 | qn = &tg->qnode_on_parent[rw]; | |
1327 | sq = sq->parent_sq; | |
1328 | tg = sq_to_tg(sq); | |
1329 | if (!tg) | |
1330 | goto out_unlock; | |
1331 | } | |
1332 | ||
1333 | /* out-of-limit, queue to @tg */ | |
1334 | throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", | |
1335 | rw == READ ? 'R' : 'W', | |
1336 | tg->bytes_disp[rw], bio->bi_iter.bi_size, tg->bps[rw], | |
1337 | tg->io_disp[rw], tg->iops[rw], | |
1338 | sq->nr_queued[READ], sq->nr_queued[WRITE]); | |
1339 | ||
1340 | bio_associate_current(bio); | |
1341 | tg->td->nr_queued[rw]++; | |
1342 | throtl_add_bio_tg(bio, qn, tg); | |
1343 | throttled = true; | |
1344 | ||
1345 | /* | |
1346 | * Update @tg's dispatch time and force schedule dispatch if @tg | |
1347 | * was empty before @bio. The forced scheduling isn't likely to | |
1348 | * cause undue delay as @bio is likely to be dispatched directly if | |
1349 | * its @tg's disptime is not in the future. | |
1350 | */ | |
1351 | if (tg->flags & THROTL_TG_WAS_EMPTY) { | |
1352 | tg_update_disptime(tg); | |
1353 | throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true); | |
1354 | } | |
1355 | ||
1356 | out_unlock: | |
1357 | spin_unlock_irq(q->queue_lock); | |
1358 | out: | |
1359 | /* | |
1360 | * As multiple blk-throtls may stack in the same issue path, we | |
1361 | * don't want bios to leave with the flag set. Clear the flag if | |
1362 | * being issued. | |
1363 | */ | |
1364 | if (!throttled) | |
1365 | bio->bi_rw &= ~REQ_THROTTLED; | |
1366 | return throttled; | |
1367 | } | |
1368 | ||
1369 | /* | |
1370 | * Dispatch all bios from all children tg's queued on @parent_sq. On | |
1371 | * return, @parent_sq is guaranteed to not have any active children tg's | |
1372 | * and all bios from previously active tg's are on @parent_sq->bio_lists[]. | |
1373 | */ | |
1374 | static void tg_drain_bios(struct throtl_service_queue *parent_sq) | |
1375 | { | |
1376 | struct throtl_grp *tg; | |
1377 | ||
1378 | while ((tg = throtl_rb_first(parent_sq))) { | |
1379 | struct throtl_service_queue *sq = &tg->service_queue; | |
1380 | struct bio *bio; | |
1381 | ||
1382 | throtl_dequeue_tg(tg); | |
1383 | ||
1384 | while ((bio = throtl_peek_queued(&sq->queued[READ]))) | |
1385 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
1386 | while ((bio = throtl_peek_queued(&sq->queued[WRITE]))) | |
1387 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); | |
1388 | } | |
1389 | } | |
1390 | ||
1391 | /** | |
1392 | * blk_throtl_drain - drain throttled bios | |
1393 | * @q: request_queue to drain throttled bios for | |
1394 | * | |
1395 | * Dispatch all currently throttled bios on @q through ->make_request_fn(). | |
1396 | */ | |
1397 | void blk_throtl_drain(struct request_queue *q) | |
1398 | __releases(q->queue_lock) __acquires(q->queue_lock) | |
1399 | { | |
1400 | struct throtl_data *td = q->td; | |
1401 | struct blkcg_gq *blkg; | |
1402 | struct cgroup_subsys_state *pos_css; | |
1403 | struct bio *bio; | |
1404 | int rw; | |
1405 | ||
1406 | queue_lockdep_assert_held(q); | |
1407 | rcu_read_lock(); | |
1408 | ||
1409 | /* | |
1410 | * Drain each tg while doing post-order walk on the blkg tree, so | |
1411 | * that all bios are propagated to td->service_queue. It'd be | |
1412 | * better to walk service_queue tree directly but blkg walk is | |
1413 | * easier. | |
1414 | */ | |
1415 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) | |
1416 | tg_drain_bios(&blkg_to_tg(blkg)->service_queue); | |
1417 | ||
1418 | /* finally, transfer bios from top-level tg's into the td */ | |
1419 | tg_drain_bios(&td->service_queue); | |
1420 | ||
1421 | rcu_read_unlock(); | |
1422 | spin_unlock_irq(q->queue_lock); | |
1423 | ||
1424 | /* all bios now should be in td->service_queue, issue them */ | |
1425 | for (rw = READ; rw <= WRITE; rw++) | |
1426 | while ((bio = throtl_pop_queued(&td->service_queue.queued[rw], | |
1427 | NULL))) | |
1428 | generic_make_request(bio); | |
1429 | ||
1430 | spin_lock_irq(q->queue_lock); | |
1431 | } | |
1432 | ||
1433 | int blk_throtl_init(struct request_queue *q) | |
1434 | { | |
1435 | struct throtl_data *td; | |
1436 | int ret; | |
1437 | ||
1438 | td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); | |
1439 | if (!td) | |
1440 | return -ENOMEM; | |
1441 | ||
1442 | INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn); | |
1443 | throtl_service_queue_init(&td->service_queue); | |
1444 | ||
1445 | q->td = td; | |
1446 | td->queue = q; | |
1447 | ||
1448 | /* activate policy */ | |
1449 | ret = blkcg_activate_policy(q, &blkcg_policy_throtl); | |
1450 | if (ret) | |
1451 | kfree(td); | |
1452 | return ret; | |
1453 | } | |
1454 | ||
1455 | void blk_throtl_exit(struct request_queue *q) | |
1456 | { | |
1457 | BUG_ON(!q->td); | |
1458 | throtl_shutdown_wq(q); | |
1459 | blkcg_deactivate_policy(q, &blkcg_policy_throtl); | |
1460 | kfree(q->td); | |
1461 | } | |
1462 | ||
1463 | static int __init throtl_init(void) | |
1464 | { | |
1465 | kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); | |
1466 | if (!kthrotld_workqueue) | |
1467 | panic("Failed to create kthrotld\n"); | |
1468 | ||
1469 | return blkcg_policy_register(&blkcg_policy_throtl); | |
1470 | } | |
1471 | ||
1472 | module_init(throtl_init); |