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