Commit | Line | Data |
---|---|---|
e43473b7 VG |
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 "blk-cgroup.h" | |
13 | ||
14 | /* Max dispatch from a group in 1 round */ | |
15 | static int throtl_grp_quantum = 8; | |
16 | ||
17 | /* Total max dispatch from all groups in one round */ | |
18 | static int throtl_quantum = 32; | |
19 | ||
20 | /* Throttling is performed over 100ms slice and after that slice is renewed */ | |
21 | static unsigned long throtl_slice = HZ/10; /* 100 ms */ | |
22 | ||
450adcbe VG |
23 | /* A workqueue to queue throttle related work */ |
24 | static struct workqueue_struct *kthrotld_workqueue; | |
25 | static void throtl_schedule_delayed_work(struct throtl_data *td, | |
26 | unsigned long delay); | |
27 | ||
e43473b7 VG |
28 | struct throtl_rb_root { |
29 | struct rb_root rb; | |
30 | struct rb_node *left; | |
31 | unsigned int count; | |
32 | unsigned long min_disptime; | |
33 | }; | |
34 | ||
35 | #define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \ | |
36 | .count = 0, .min_disptime = 0} | |
37 | ||
38 | #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) | |
39 | ||
40 | struct throtl_grp { | |
41 | /* List of throtl groups on the request queue*/ | |
42 | struct hlist_node tg_node; | |
43 | ||
44 | /* active throtl group service_tree member */ | |
45 | struct rb_node rb_node; | |
46 | ||
47 | /* | |
48 | * Dispatch time in jiffies. This is the estimated time when group | |
49 | * will unthrottle and is ready to dispatch more bio. It is used as | |
50 | * key to sort active groups in service tree. | |
51 | */ | |
52 | unsigned long disptime; | |
53 | ||
54 | struct blkio_group blkg; | |
55 | atomic_t ref; | |
56 | unsigned int flags; | |
57 | ||
58 | /* Two lists for READ and WRITE */ | |
59 | struct bio_list bio_lists[2]; | |
60 | ||
61 | /* Number of queued bios on READ and WRITE lists */ | |
62 | unsigned int nr_queued[2]; | |
63 | ||
64 | /* bytes per second rate limits */ | |
65 | uint64_t bps[2]; | |
66 | ||
8e89d13f VG |
67 | /* IOPS limits */ |
68 | unsigned int iops[2]; | |
69 | ||
e43473b7 VG |
70 | /* Number of bytes disptached in current slice */ |
71 | uint64_t bytes_disp[2]; | |
8e89d13f VG |
72 | /* Number of bio's dispatched in current slice */ |
73 | unsigned int io_disp[2]; | |
e43473b7 VG |
74 | |
75 | /* When did we start a new slice */ | |
76 | unsigned long slice_start[2]; | |
77 | unsigned long slice_end[2]; | |
fe071437 VG |
78 | |
79 | /* Some throttle limits got updated for the group */ | |
80 | bool limits_changed; | |
e43473b7 VG |
81 | }; |
82 | ||
83 | struct throtl_data | |
84 | { | |
85 | /* List of throtl groups */ | |
86 | struct hlist_head tg_list; | |
87 | ||
88 | /* service tree for active throtl groups */ | |
89 | struct throtl_rb_root tg_service_tree; | |
90 | ||
91 | struct throtl_grp root_tg; | |
92 | struct request_queue *queue; | |
93 | ||
94 | /* Total Number of queued bios on READ and WRITE lists */ | |
95 | unsigned int nr_queued[2]; | |
96 | ||
97 | /* | |
02977e4a | 98 | * number of total undestroyed groups |
e43473b7 VG |
99 | */ |
100 | unsigned int nr_undestroyed_grps; | |
101 | ||
102 | /* Work for dispatching throttled bios */ | |
103 | struct delayed_work throtl_work; | |
fe071437 | 104 | |
de701c74 | 105 | bool limits_changed; |
e43473b7 VG |
106 | }; |
107 | ||
108 | enum tg_state_flags { | |
109 | THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */ | |
110 | }; | |
111 | ||
112 | #define THROTL_TG_FNS(name) \ | |
113 | static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \ | |
114 | { \ | |
115 | (tg)->flags |= (1 << THROTL_TG_FLAG_##name); \ | |
116 | } \ | |
117 | static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \ | |
118 | { \ | |
119 | (tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \ | |
120 | } \ | |
121 | static inline int throtl_tg_##name(const struct throtl_grp *tg) \ | |
122 | { \ | |
123 | return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \ | |
124 | } | |
125 | ||
126 | THROTL_TG_FNS(on_rr); | |
127 | ||
128 | #define throtl_log_tg(td, tg, fmt, args...) \ | |
129 | blk_add_trace_msg((td)->queue, "throtl %s " fmt, \ | |
130 | blkg_path(&(tg)->blkg), ##args); \ | |
131 | ||
132 | #define throtl_log(td, fmt, args...) \ | |
133 | blk_add_trace_msg((td)->queue, "throtl " fmt, ##args) | |
134 | ||
135 | static inline struct throtl_grp *tg_of_blkg(struct blkio_group *blkg) | |
136 | { | |
137 | if (blkg) | |
138 | return container_of(blkg, struct throtl_grp, blkg); | |
139 | ||
140 | return NULL; | |
141 | } | |
142 | ||
143 | static inline int total_nr_queued(struct throtl_data *td) | |
144 | { | |
145 | return (td->nr_queued[0] + td->nr_queued[1]); | |
146 | } | |
147 | ||
148 | static inline struct throtl_grp *throtl_ref_get_tg(struct throtl_grp *tg) | |
149 | { | |
150 | atomic_inc(&tg->ref); | |
151 | return tg; | |
152 | } | |
153 | ||
154 | static void throtl_put_tg(struct throtl_grp *tg) | |
155 | { | |
156 | BUG_ON(atomic_read(&tg->ref) <= 0); | |
157 | if (!atomic_dec_and_test(&tg->ref)) | |
158 | return; | |
159 | kfree(tg); | |
160 | } | |
161 | ||
162 | static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, | |
163 | struct cgroup *cgroup) | |
164 | { | |
165 | struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); | |
166 | struct throtl_grp *tg = NULL; | |
167 | void *key = td; | |
168 | struct backing_dev_info *bdi = &td->queue->backing_dev_info; | |
169 | unsigned int major, minor; | |
170 | ||
171 | /* | |
172 | * TODO: Speed up blkiocg_lookup_group() by maintaining a radix | |
173 | * tree of blkg (instead of traversing through hash list all | |
174 | * the time. | |
175 | */ | |
be2c6b19 VG |
176 | |
177 | /* | |
178 | * This is the common case when there are no blkio cgroups. | |
179 | * Avoid lookup in this case | |
180 | */ | |
181 | if (blkcg == &blkio_root_cgroup) | |
182 | tg = &td->root_tg; | |
183 | else | |
184 | tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key)); | |
e43473b7 VG |
185 | |
186 | /* Fill in device details for root group */ | |
187 | if (tg && !tg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { | |
188 | sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); | |
189 | tg->blkg.dev = MKDEV(major, minor); | |
190 | goto done; | |
191 | } | |
192 | ||
193 | if (tg) | |
194 | goto done; | |
195 | ||
196 | tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node); | |
197 | if (!tg) | |
198 | goto done; | |
199 | ||
200 | INIT_HLIST_NODE(&tg->tg_node); | |
201 | RB_CLEAR_NODE(&tg->rb_node); | |
202 | bio_list_init(&tg->bio_lists[0]); | |
203 | bio_list_init(&tg->bio_lists[1]); | |
de701c74 | 204 | td->limits_changed = false; |
e43473b7 VG |
205 | |
206 | /* | |
207 | * Take the initial reference that will be released on destroy | |
208 | * This can be thought of a joint reference by cgroup and | |
209 | * request queue which will be dropped by either request queue | |
210 | * exit or cgroup deletion path depending on who is exiting first. | |
211 | */ | |
212 | atomic_set(&tg->ref, 1); | |
213 | ||
214 | /* Add group onto cgroup list */ | |
215 | sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); | |
216 | blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td, | |
217 | MKDEV(major, minor), BLKIO_POLICY_THROTL); | |
218 | ||
219 | tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev); | |
220 | tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev); | |
8e89d13f VG |
221 | tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev); |
222 | tg->iops[WRITE] = blkcg_get_write_iops(blkcg, tg->blkg.dev); | |
e43473b7 VG |
223 | |
224 | hlist_add_head(&tg->tg_node, &td->tg_list); | |
225 | td->nr_undestroyed_grps++; | |
226 | done: | |
227 | return tg; | |
228 | } | |
229 | ||
230 | static struct throtl_grp * throtl_get_tg(struct throtl_data *td) | |
231 | { | |
232 | struct cgroup *cgroup; | |
233 | struct throtl_grp *tg = NULL; | |
234 | ||
235 | rcu_read_lock(); | |
236 | cgroup = task_cgroup(current, blkio_subsys_id); | |
237 | tg = throtl_find_alloc_tg(td, cgroup); | |
238 | if (!tg) | |
239 | tg = &td->root_tg; | |
240 | rcu_read_unlock(); | |
241 | return tg; | |
242 | } | |
243 | ||
244 | static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root) | |
245 | { | |
246 | /* Service tree is empty */ | |
247 | if (!root->count) | |
248 | return NULL; | |
249 | ||
250 | if (!root->left) | |
251 | root->left = rb_first(&root->rb); | |
252 | ||
253 | if (root->left) | |
254 | return rb_entry_tg(root->left); | |
255 | ||
256 | return NULL; | |
257 | } | |
258 | ||
259 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) | |
260 | { | |
261 | rb_erase(n, root); | |
262 | RB_CLEAR_NODE(n); | |
263 | } | |
264 | ||
265 | static void throtl_rb_erase(struct rb_node *n, struct throtl_rb_root *root) | |
266 | { | |
267 | if (root->left == n) | |
268 | root->left = NULL; | |
269 | rb_erase_init(n, &root->rb); | |
270 | --root->count; | |
271 | } | |
272 | ||
273 | static void update_min_dispatch_time(struct throtl_rb_root *st) | |
274 | { | |
275 | struct throtl_grp *tg; | |
276 | ||
277 | tg = throtl_rb_first(st); | |
278 | if (!tg) | |
279 | return; | |
280 | ||
281 | st->min_disptime = tg->disptime; | |
282 | } | |
283 | ||
284 | static void | |
285 | tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg) | |
286 | { | |
287 | struct rb_node **node = &st->rb.rb_node; | |
288 | struct rb_node *parent = NULL; | |
289 | struct throtl_grp *__tg; | |
290 | unsigned long key = tg->disptime; | |
291 | int left = 1; | |
292 | ||
293 | while (*node != NULL) { | |
294 | parent = *node; | |
295 | __tg = rb_entry_tg(parent); | |
296 | ||
297 | if (time_before(key, __tg->disptime)) | |
298 | node = &parent->rb_left; | |
299 | else { | |
300 | node = &parent->rb_right; | |
301 | left = 0; | |
302 | } | |
303 | } | |
304 | ||
305 | if (left) | |
306 | st->left = &tg->rb_node; | |
307 | ||
308 | rb_link_node(&tg->rb_node, parent, node); | |
309 | rb_insert_color(&tg->rb_node, &st->rb); | |
310 | } | |
311 | ||
312 | static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg) | |
313 | { | |
314 | struct throtl_rb_root *st = &td->tg_service_tree; | |
315 | ||
316 | tg_service_tree_add(st, tg); | |
317 | throtl_mark_tg_on_rr(tg); | |
318 | st->count++; | |
319 | } | |
320 | ||
321 | static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg) | |
322 | { | |
323 | if (!throtl_tg_on_rr(tg)) | |
324 | __throtl_enqueue_tg(td, tg); | |
325 | } | |
326 | ||
327 | static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg) | |
328 | { | |
329 | throtl_rb_erase(&tg->rb_node, &td->tg_service_tree); | |
330 | throtl_clear_tg_on_rr(tg); | |
331 | } | |
332 | ||
333 | static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg) | |
334 | { | |
335 | if (throtl_tg_on_rr(tg)) | |
336 | __throtl_dequeue_tg(td, tg); | |
337 | } | |
338 | ||
339 | static void throtl_schedule_next_dispatch(struct throtl_data *td) | |
340 | { | |
341 | struct throtl_rb_root *st = &td->tg_service_tree; | |
342 | ||
343 | /* | |
344 | * If there are more bios pending, schedule more work. | |
345 | */ | |
346 | if (!total_nr_queued(td)) | |
347 | return; | |
348 | ||
349 | BUG_ON(!st->count); | |
350 | ||
351 | update_min_dispatch_time(st); | |
352 | ||
353 | if (time_before_eq(st->min_disptime, jiffies)) | |
450adcbe | 354 | throtl_schedule_delayed_work(td, 0); |
e43473b7 | 355 | else |
450adcbe | 356 | throtl_schedule_delayed_work(td, (st->min_disptime - jiffies)); |
e43473b7 VG |
357 | } |
358 | ||
359 | static inline void | |
360 | throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) | |
361 | { | |
362 | tg->bytes_disp[rw] = 0; | |
8e89d13f | 363 | tg->io_disp[rw] = 0; |
e43473b7 VG |
364 | tg->slice_start[rw] = jiffies; |
365 | tg->slice_end[rw] = jiffies + throtl_slice; | |
366 | throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu", | |
367 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
368 | tg->slice_end[rw], jiffies); | |
369 | } | |
370 | ||
d1ae8ffd VG |
371 | static inline void throtl_set_slice_end(struct throtl_data *td, |
372 | struct throtl_grp *tg, bool rw, unsigned long jiffy_end) | |
373 | { | |
374 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); | |
375 | } | |
376 | ||
e43473b7 VG |
377 | static inline void throtl_extend_slice(struct throtl_data *td, |
378 | struct throtl_grp *tg, bool rw, unsigned long jiffy_end) | |
379 | { | |
380 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); | |
381 | throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu", | |
382 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
383 | tg->slice_end[rw], jiffies); | |
384 | } | |
385 | ||
386 | /* Determine if previously allocated or extended slice is complete or not */ | |
387 | static bool | |
388 | throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw) | |
389 | { | |
390 | if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) | |
391 | return 0; | |
392 | ||
393 | return 1; | |
394 | } | |
395 | ||
396 | /* Trim the used slices and adjust slice start accordingly */ | |
397 | static inline void | |
398 | throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) | |
399 | { | |
3aad5d3e VG |
400 | unsigned long nr_slices, time_elapsed, io_trim; |
401 | u64 bytes_trim, tmp; | |
e43473b7 VG |
402 | |
403 | BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); | |
404 | ||
405 | /* | |
406 | * If bps are unlimited (-1), then time slice don't get | |
407 | * renewed. Don't try to trim the slice if slice is used. A new | |
408 | * slice will start when appropriate. | |
409 | */ | |
410 | if (throtl_slice_used(td, tg, rw)) | |
411 | return; | |
412 | ||
d1ae8ffd VG |
413 | /* |
414 | * A bio has been dispatched. Also adjust slice_end. It might happen | |
415 | * that initially cgroup limit was very low resulting in high | |
416 | * slice_end, but later limit was bumped up and bio was dispached | |
417 | * sooner, then we need to reduce slice_end. A high bogus slice_end | |
418 | * is bad because it does not allow new slice to start. | |
419 | */ | |
420 | ||
421 | throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice); | |
422 | ||
e43473b7 VG |
423 | time_elapsed = jiffies - tg->slice_start[rw]; |
424 | ||
425 | nr_slices = time_elapsed / throtl_slice; | |
426 | ||
427 | if (!nr_slices) | |
428 | return; | |
3aad5d3e VG |
429 | tmp = tg->bps[rw] * throtl_slice * nr_slices; |
430 | do_div(tmp, HZ); | |
431 | bytes_trim = tmp; | |
e43473b7 | 432 | |
8e89d13f | 433 | io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ; |
e43473b7 | 434 | |
8e89d13f | 435 | if (!bytes_trim && !io_trim) |
e43473b7 VG |
436 | return; |
437 | ||
438 | if (tg->bytes_disp[rw] >= bytes_trim) | |
439 | tg->bytes_disp[rw] -= bytes_trim; | |
440 | else | |
441 | tg->bytes_disp[rw] = 0; | |
442 | ||
8e89d13f VG |
443 | if (tg->io_disp[rw] >= io_trim) |
444 | tg->io_disp[rw] -= io_trim; | |
445 | else | |
446 | tg->io_disp[rw] = 0; | |
447 | ||
e43473b7 VG |
448 | tg->slice_start[rw] += nr_slices * throtl_slice; |
449 | ||
3aad5d3e | 450 | throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu" |
e43473b7 | 451 | " start=%lu end=%lu jiffies=%lu", |
8e89d13f | 452 | rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, |
e43473b7 VG |
453 | tg->slice_start[rw], tg->slice_end[rw], jiffies); |
454 | } | |
455 | ||
8e89d13f VG |
456 | static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg, |
457 | struct bio *bio, unsigned long *wait) | |
e43473b7 VG |
458 | { |
459 | bool rw = bio_data_dir(bio); | |
8e89d13f | 460 | unsigned int io_allowed; |
e43473b7 | 461 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
c49c06e4 | 462 | u64 tmp; |
e43473b7 | 463 | |
8e89d13f | 464 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
e43473b7 | 465 | |
8e89d13f VG |
466 | /* Slice has just started. Consider one slice interval */ |
467 | if (!jiffy_elapsed) | |
468 | jiffy_elapsed_rnd = throtl_slice; | |
469 | ||
470 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); | |
471 | ||
c49c06e4 VG |
472 | /* |
473 | * jiffy_elapsed_rnd should not be a big value as minimum iops can be | |
474 | * 1 then at max jiffy elapsed should be equivalent of 1 second as we | |
475 | * will allow dispatch after 1 second and after that slice should | |
476 | * have been trimmed. | |
477 | */ | |
478 | ||
479 | tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd; | |
480 | do_div(tmp, HZ); | |
481 | ||
482 | if (tmp > UINT_MAX) | |
483 | io_allowed = UINT_MAX; | |
484 | else | |
485 | io_allowed = tmp; | |
8e89d13f VG |
486 | |
487 | if (tg->io_disp[rw] + 1 <= io_allowed) { | |
e43473b7 VG |
488 | if (wait) |
489 | *wait = 0; | |
490 | return 1; | |
491 | } | |
492 | ||
8e89d13f VG |
493 | /* Calc approx time to dispatch */ |
494 | jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1; | |
495 | ||
496 | if (jiffy_wait > jiffy_elapsed) | |
497 | jiffy_wait = jiffy_wait - jiffy_elapsed; | |
498 | else | |
499 | jiffy_wait = 1; | |
500 | ||
501 | if (wait) | |
502 | *wait = jiffy_wait; | |
503 | return 0; | |
504 | } | |
505 | ||
506 | static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg, | |
507 | struct bio *bio, unsigned long *wait) | |
508 | { | |
509 | bool rw = bio_data_dir(bio); | |
3aad5d3e | 510 | u64 bytes_allowed, extra_bytes, tmp; |
8e89d13f | 511 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
e43473b7 VG |
512 | |
513 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; | |
514 | ||
515 | /* Slice has just started. Consider one slice interval */ | |
516 | if (!jiffy_elapsed) | |
517 | jiffy_elapsed_rnd = throtl_slice; | |
518 | ||
519 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); | |
520 | ||
5e901a2b VG |
521 | tmp = tg->bps[rw] * jiffy_elapsed_rnd; |
522 | do_div(tmp, HZ); | |
3aad5d3e | 523 | bytes_allowed = tmp; |
e43473b7 VG |
524 | |
525 | if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) { | |
526 | if (wait) | |
527 | *wait = 0; | |
528 | return 1; | |
529 | } | |
530 | ||
531 | /* Calc approx time to dispatch */ | |
532 | extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed; | |
533 | jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]); | |
534 | ||
535 | if (!jiffy_wait) | |
536 | jiffy_wait = 1; | |
537 | ||
538 | /* | |
539 | * This wait time is without taking into consideration the rounding | |
540 | * up we did. Add that time also. | |
541 | */ | |
542 | jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); | |
e43473b7 VG |
543 | if (wait) |
544 | *wait = jiffy_wait; | |
8e89d13f VG |
545 | return 0; |
546 | } | |
547 | ||
548 | /* | |
549 | * Returns whether one can dispatch a bio or not. Also returns approx number | |
550 | * of jiffies to wait before this bio is with-in IO rate and can be dispatched | |
551 | */ | |
552 | static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg, | |
553 | struct bio *bio, unsigned long *wait) | |
554 | { | |
555 | bool rw = bio_data_dir(bio); | |
556 | unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; | |
557 | ||
558 | /* | |
559 | * Currently whole state machine of group depends on first bio | |
560 | * queued in the group bio list. So one should not be calling | |
561 | * this function with a different bio if there are other bios | |
562 | * queued. | |
563 | */ | |
564 | BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw])); | |
e43473b7 | 565 | |
8e89d13f VG |
566 | /* If tg->bps = -1, then BW is unlimited */ |
567 | if (tg->bps[rw] == -1 && tg->iops[rw] == -1) { | |
568 | if (wait) | |
569 | *wait = 0; | |
570 | return 1; | |
571 | } | |
572 | ||
573 | /* | |
574 | * If previous slice expired, start a new one otherwise renew/extend | |
575 | * existing slice to make sure it is at least throtl_slice interval | |
576 | * long since now. | |
577 | */ | |
578 | if (throtl_slice_used(td, tg, rw)) | |
579 | throtl_start_new_slice(td, tg, rw); | |
580 | else { | |
581 | if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) | |
582 | throtl_extend_slice(td, tg, rw, jiffies + throtl_slice); | |
583 | } | |
584 | ||
585 | if (tg_with_in_bps_limit(td, tg, bio, &bps_wait) | |
586 | && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) { | |
587 | if (wait) | |
588 | *wait = 0; | |
589 | return 1; | |
590 | } | |
591 | ||
592 | max_wait = max(bps_wait, iops_wait); | |
593 | ||
594 | if (wait) | |
595 | *wait = max_wait; | |
596 | ||
597 | if (time_before(tg->slice_end[rw], jiffies + max_wait)) | |
598 | throtl_extend_slice(td, tg, rw, jiffies + max_wait); | |
e43473b7 VG |
599 | |
600 | return 0; | |
601 | } | |
602 | ||
603 | static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) | |
604 | { | |
605 | bool rw = bio_data_dir(bio); | |
606 | bool sync = bio->bi_rw & REQ_SYNC; | |
607 | ||
608 | /* Charge the bio to the group */ | |
609 | tg->bytes_disp[rw] += bio->bi_size; | |
8e89d13f | 610 | tg->io_disp[rw]++; |
e43473b7 VG |
611 | |
612 | /* | |
613 | * TODO: This will take blkg->stats_lock. Figure out a way | |
614 | * to avoid this cost. | |
615 | */ | |
616 | blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, rw, sync); | |
e43473b7 VG |
617 | } |
618 | ||
619 | static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg, | |
620 | struct bio *bio) | |
621 | { | |
622 | bool rw = bio_data_dir(bio); | |
623 | ||
624 | bio_list_add(&tg->bio_lists[rw], bio); | |
625 | /* Take a bio reference on tg */ | |
626 | throtl_ref_get_tg(tg); | |
627 | tg->nr_queued[rw]++; | |
628 | td->nr_queued[rw]++; | |
629 | throtl_enqueue_tg(td, tg); | |
630 | } | |
631 | ||
632 | static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg) | |
633 | { | |
634 | unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; | |
635 | struct bio *bio; | |
636 | ||
637 | if ((bio = bio_list_peek(&tg->bio_lists[READ]))) | |
638 | tg_may_dispatch(td, tg, bio, &read_wait); | |
639 | ||
640 | if ((bio = bio_list_peek(&tg->bio_lists[WRITE]))) | |
641 | tg_may_dispatch(td, tg, bio, &write_wait); | |
642 | ||
643 | min_wait = min(read_wait, write_wait); | |
644 | disptime = jiffies + min_wait; | |
645 | ||
e43473b7 VG |
646 | /* Update dispatch time */ |
647 | throtl_dequeue_tg(td, tg); | |
648 | tg->disptime = disptime; | |
649 | throtl_enqueue_tg(td, tg); | |
650 | } | |
651 | ||
652 | static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg, | |
653 | bool rw, struct bio_list *bl) | |
654 | { | |
655 | struct bio *bio; | |
656 | ||
657 | bio = bio_list_pop(&tg->bio_lists[rw]); | |
658 | tg->nr_queued[rw]--; | |
659 | /* Drop bio reference on tg */ | |
660 | throtl_put_tg(tg); | |
661 | ||
662 | BUG_ON(td->nr_queued[rw] <= 0); | |
663 | td->nr_queued[rw]--; | |
664 | ||
665 | throtl_charge_bio(tg, bio); | |
666 | bio_list_add(bl, bio); | |
667 | bio->bi_rw |= REQ_THROTTLED; | |
668 | ||
669 | throtl_trim_slice(td, tg, rw); | |
670 | } | |
671 | ||
672 | static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg, | |
673 | struct bio_list *bl) | |
674 | { | |
675 | unsigned int nr_reads = 0, nr_writes = 0; | |
676 | unsigned int max_nr_reads = throtl_grp_quantum*3/4; | |
c2f6805d | 677 | unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; |
e43473b7 VG |
678 | struct bio *bio; |
679 | ||
680 | /* Try to dispatch 75% READS and 25% WRITES */ | |
681 | ||
682 | while ((bio = bio_list_peek(&tg->bio_lists[READ])) | |
683 | && tg_may_dispatch(td, tg, bio, NULL)) { | |
684 | ||
685 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl); | |
686 | nr_reads++; | |
687 | ||
688 | if (nr_reads >= max_nr_reads) | |
689 | break; | |
690 | } | |
691 | ||
692 | while ((bio = bio_list_peek(&tg->bio_lists[WRITE])) | |
693 | && tg_may_dispatch(td, tg, bio, NULL)) { | |
694 | ||
695 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl); | |
696 | nr_writes++; | |
697 | ||
698 | if (nr_writes >= max_nr_writes) | |
699 | break; | |
700 | } | |
701 | ||
702 | return nr_reads + nr_writes; | |
703 | } | |
704 | ||
705 | static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl) | |
706 | { | |
707 | unsigned int nr_disp = 0; | |
708 | struct throtl_grp *tg; | |
709 | struct throtl_rb_root *st = &td->tg_service_tree; | |
710 | ||
711 | while (1) { | |
712 | tg = throtl_rb_first(st); | |
713 | ||
714 | if (!tg) | |
715 | break; | |
716 | ||
717 | if (time_before(jiffies, tg->disptime)) | |
718 | break; | |
719 | ||
720 | throtl_dequeue_tg(td, tg); | |
721 | ||
722 | nr_disp += throtl_dispatch_tg(td, tg, bl); | |
723 | ||
724 | if (tg->nr_queued[0] || tg->nr_queued[1]) { | |
725 | tg_update_disptime(td, tg); | |
726 | throtl_enqueue_tg(td, tg); | |
727 | } | |
728 | ||
729 | if (nr_disp >= throtl_quantum) | |
730 | break; | |
731 | } | |
732 | ||
733 | return nr_disp; | |
734 | } | |
735 | ||
fe071437 VG |
736 | static void throtl_process_limit_change(struct throtl_data *td) |
737 | { | |
738 | struct throtl_grp *tg; | |
739 | struct hlist_node *pos, *n; | |
740 | ||
de701c74 | 741 | if (!td->limits_changed) |
fe071437 VG |
742 | return; |
743 | ||
de701c74 | 744 | xchg(&td->limits_changed, false); |
fe071437 | 745 | |
de701c74 | 746 | throtl_log(td, "limits changed"); |
fe071437 | 747 | |
04a6b516 | 748 | hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) { |
de701c74 VG |
749 | if (!tg->limits_changed) |
750 | continue; | |
751 | ||
752 | if (!xchg(&tg->limits_changed, false)) | |
753 | continue; | |
754 | ||
755 | throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu" | |
756 | " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE], | |
757 | tg->iops[READ], tg->iops[WRITE]); | |
758 | ||
04521db0 VG |
759 | /* |
760 | * Restart the slices for both READ and WRITES. It | |
761 | * might happen that a group's limit are dropped | |
762 | * suddenly and we don't want to account recently | |
763 | * dispatched IO with new low rate | |
764 | */ | |
765 | throtl_start_new_slice(td, tg, 0); | |
766 | throtl_start_new_slice(td, tg, 1); | |
767 | ||
de701c74 | 768 | if (throtl_tg_on_rr(tg)) |
fe071437 | 769 | tg_update_disptime(td, tg); |
fe071437 | 770 | } |
fe071437 VG |
771 | } |
772 | ||
e43473b7 VG |
773 | /* Dispatch throttled bios. Should be called without queue lock held. */ |
774 | static int throtl_dispatch(struct request_queue *q) | |
775 | { | |
776 | struct throtl_data *td = q->td; | |
777 | unsigned int nr_disp = 0; | |
778 | struct bio_list bio_list_on_stack; | |
779 | struct bio *bio; | |
69d60eb9 | 780 | struct blk_plug plug; |
e43473b7 VG |
781 | |
782 | spin_lock_irq(q->queue_lock); | |
783 | ||
fe071437 VG |
784 | throtl_process_limit_change(td); |
785 | ||
e43473b7 VG |
786 | if (!total_nr_queued(td)) |
787 | goto out; | |
788 | ||
789 | bio_list_init(&bio_list_on_stack); | |
790 | ||
791 | throtl_log(td, "dispatch nr_queued=%lu read=%u write=%u", | |
792 | total_nr_queued(td), td->nr_queued[READ], | |
793 | td->nr_queued[WRITE]); | |
794 | ||
795 | nr_disp = throtl_select_dispatch(td, &bio_list_on_stack); | |
796 | ||
797 | if (nr_disp) | |
798 | throtl_log(td, "bios disp=%u", nr_disp); | |
799 | ||
800 | throtl_schedule_next_dispatch(td); | |
801 | out: | |
802 | spin_unlock_irq(q->queue_lock); | |
803 | ||
804 | /* | |
805 | * If we dispatched some requests, unplug the queue to make sure | |
806 | * immediate dispatch | |
807 | */ | |
808 | if (nr_disp) { | |
69d60eb9 | 809 | blk_start_plug(&plug); |
e43473b7 VG |
810 | while((bio = bio_list_pop(&bio_list_on_stack))) |
811 | generic_make_request(bio); | |
69d60eb9 | 812 | blk_finish_plug(&plug); |
e43473b7 VG |
813 | } |
814 | return nr_disp; | |
815 | } | |
816 | ||
817 | void blk_throtl_work(struct work_struct *work) | |
818 | { | |
819 | struct throtl_data *td = container_of(work, struct throtl_data, | |
820 | throtl_work.work); | |
821 | struct request_queue *q = td->queue; | |
822 | ||
823 | throtl_dispatch(q); | |
824 | } | |
825 | ||
826 | /* Call with queue lock held */ | |
450adcbe VG |
827 | static void |
828 | throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay) | |
e43473b7 VG |
829 | { |
830 | ||
e43473b7 VG |
831 | struct delayed_work *dwork = &td->throtl_work; |
832 | ||
04521db0 VG |
833 | /* schedule work if limits changed even if no bio is queued */ |
834 | if (total_nr_queued(td) > 0 || td->limits_changed) { | |
e43473b7 VG |
835 | /* |
836 | * We might have a work scheduled to be executed in future. | |
837 | * Cancel that and schedule a new one. | |
838 | */ | |
839 | __cancel_delayed_work(dwork); | |
450adcbe | 840 | queue_delayed_work(kthrotld_workqueue, dwork, delay); |
e43473b7 VG |
841 | throtl_log(td, "schedule work. delay=%lu jiffies=%lu", |
842 | delay, jiffies); | |
843 | } | |
844 | } | |
e43473b7 VG |
845 | |
846 | static void | |
847 | throtl_destroy_tg(struct throtl_data *td, struct throtl_grp *tg) | |
848 | { | |
849 | /* Something wrong if we are trying to remove same group twice */ | |
850 | BUG_ON(hlist_unhashed(&tg->tg_node)); | |
851 | ||
852 | hlist_del_init(&tg->tg_node); | |
853 | ||
854 | /* | |
855 | * Put the reference taken at the time of creation so that when all | |
856 | * queues are gone, group can be destroyed. | |
857 | */ | |
858 | throtl_put_tg(tg); | |
859 | td->nr_undestroyed_grps--; | |
860 | } | |
861 | ||
862 | static void throtl_release_tgs(struct throtl_data *td) | |
863 | { | |
864 | struct hlist_node *pos, *n; | |
865 | struct throtl_grp *tg; | |
866 | ||
867 | hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) { | |
868 | /* | |
869 | * If cgroup removal path got to blk_group first and removed | |
870 | * it from cgroup list, then it will take care of destroying | |
871 | * cfqg also. | |
872 | */ | |
873 | if (!blkiocg_del_blkio_group(&tg->blkg)) | |
874 | throtl_destroy_tg(td, tg); | |
875 | } | |
876 | } | |
877 | ||
878 | static void throtl_td_free(struct throtl_data *td) | |
879 | { | |
880 | kfree(td); | |
881 | } | |
882 | ||
883 | /* | |
884 | * Blk cgroup controller notification saying that blkio_group object is being | |
885 | * delinked as associated cgroup object is going away. That also means that | |
886 | * no new IO will come in this group. So get rid of this group as soon as | |
887 | * any pending IO in the group is finished. | |
888 | * | |
889 | * This function is called under rcu_read_lock(). key is the rcu protected | |
890 | * pointer. That means "key" is a valid throtl_data pointer as long as we are | |
891 | * rcu read lock. | |
892 | * | |
893 | * "key" was fetched from blkio_group under blkio_cgroup->lock. That means | |
894 | * it should not be NULL as even if queue was going away, cgroup deltion | |
895 | * path got to it first. | |
896 | */ | |
897 | void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg) | |
898 | { | |
899 | unsigned long flags; | |
900 | struct throtl_data *td = key; | |
901 | ||
902 | spin_lock_irqsave(td->queue->queue_lock, flags); | |
903 | throtl_destroy_tg(td, tg_of_blkg(blkg)); | |
904 | spin_unlock_irqrestore(td->queue->queue_lock, flags); | |
905 | } | |
906 | ||
de701c74 VG |
907 | static void throtl_update_blkio_group_common(struct throtl_data *td, |
908 | struct throtl_grp *tg) | |
909 | { | |
910 | xchg(&tg->limits_changed, true); | |
911 | xchg(&td->limits_changed, true); | |
912 | /* Schedule a work now to process the limit change */ | |
913 | throtl_schedule_delayed_work(td, 0); | |
914 | } | |
915 | ||
fe071437 VG |
916 | /* |
917 | * For all update functions, key should be a valid pointer because these | |
918 | * update functions are called under blkcg_lock, that means, blkg is | |
919 | * valid and in turn key is valid. queue exit path can not race becuase | |
920 | * of blkcg_lock | |
921 | * | |
922 | * Can not take queue lock in update functions as queue lock under blkcg_lock | |
923 | * is not allowed. Under other paths we take blkcg_lock under queue_lock. | |
924 | */ | |
925 | static void throtl_update_blkio_group_read_bps(void *key, | |
926 | struct blkio_group *blkg, u64 read_bps) | |
e43473b7 | 927 | { |
fe071437 | 928 | struct throtl_data *td = key; |
de701c74 | 929 | struct throtl_grp *tg = tg_of_blkg(blkg); |
fe071437 | 930 | |
de701c74 VG |
931 | tg->bps[READ] = read_bps; |
932 | throtl_update_blkio_group_common(td, tg); | |
e43473b7 VG |
933 | } |
934 | ||
fe071437 VG |
935 | static void throtl_update_blkio_group_write_bps(void *key, |
936 | struct blkio_group *blkg, u64 write_bps) | |
e43473b7 | 937 | { |
fe071437 | 938 | struct throtl_data *td = key; |
de701c74 | 939 | struct throtl_grp *tg = tg_of_blkg(blkg); |
fe071437 | 940 | |
de701c74 VG |
941 | tg->bps[WRITE] = write_bps; |
942 | throtl_update_blkio_group_common(td, tg); | |
e43473b7 VG |
943 | } |
944 | ||
fe071437 VG |
945 | static void throtl_update_blkio_group_read_iops(void *key, |
946 | struct blkio_group *blkg, unsigned int read_iops) | |
8e89d13f | 947 | { |
fe071437 | 948 | struct throtl_data *td = key; |
de701c74 | 949 | struct throtl_grp *tg = tg_of_blkg(blkg); |
fe071437 | 950 | |
de701c74 VG |
951 | tg->iops[READ] = read_iops; |
952 | throtl_update_blkio_group_common(td, tg); | |
8e89d13f VG |
953 | } |
954 | ||
fe071437 VG |
955 | static void throtl_update_blkio_group_write_iops(void *key, |
956 | struct blkio_group *blkg, unsigned int write_iops) | |
8e89d13f | 957 | { |
fe071437 | 958 | struct throtl_data *td = key; |
de701c74 | 959 | struct throtl_grp *tg = tg_of_blkg(blkg); |
fe071437 | 960 | |
de701c74 VG |
961 | tg->iops[WRITE] = write_iops; |
962 | throtl_update_blkio_group_common(td, tg); | |
8e89d13f VG |
963 | } |
964 | ||
da527770 | 965 | static void throtl_shutdown_wq(struct request_queue *q) |
e43473b7 VG |
966 | { |
967 | struct throtl_data *td = q->td; | |
968 | ||
969 | cancel_delayed_work_sync(&td->throtl_work); | |
970 | } | |
971 | ||
972 | static struct blkio_policy_type blkio_policy_throtl = { | |
973 | .ops = { | |
974 | .blkio_unlink_group_fn = throtl_unlink_blkio_group, | |
975 | .blkio_update_group_read_bps_fn = | |
976 | throtl_update_blkio_group_read_bps, | |
977 | .blkio_update_group_write_bps_fn = | |
978 | throtl_update_blkio_group_write_bps, | |
8e89d13f VG |
979 | .blkio_update_group_read_iops_fn = |
980 | throtl_update_blkio_group_read_iops, | |
981 | .blkio_update_group_write_iops_fn = | |
982 | throtl_update_blkio_group_write_iops, | |
e43473b7 | 983 | }, |
8e89d13f | 984 | .plid = BLKIO_POLICY_THROTL, |
e43473b7 VG |
985 | }; |
986 | ||
987 | int blk_throtl_bio(struct request_queue *q, struct bio **biop) | |
988 | { | |
989 | struct throtl_data *td = q->td; | |
990 | struct throtl_grp *tg; | |
991 | struct bio *bio = *biop; | |
992 | bool rw = bio_data_dir(bio), update_disptime = true; | |
993 | ||
994 | if (bio->bi_rw & REQ_THROTTLED) { | |
995 | bio->bi_rw &= ~REQ_THROTTLED; | |
996 | return 0; | |
997 | } | |
998 | ||
999 | spin_lock_irq(q->queue_lock); | |
1000 | tg = throtl_get_tg(td); | |
1001 | ||
1002 | if (tg->nr_queued[rw]) { | |
1003 | /* | |
1004 | * There is already another bio queued in same dir. No | |
1005 | * need to update dispatch time. | |
1006 | */ | |
231d704b | 1007 | update_disptime = false; |
e43473b7 | 1008 | goto queue_bio; |
de701c74 | 1009 | |
e43473b7 VG |
1010 | } |
1011 | ||
1012 | /* Bio is with-in rate limit of group */ | |
1013 | if (tg_may_dispatch(td, tg, bio, NULL)) { | |
1014 | throtl_charge_bio(tg, bio); | |
04521db0 VG |
1015 | |
1016 | /* | |
1017 | * We need to trim slice even when bios are not being queued | |
1018 | * otherwise it might happen that a bio is not queued for | |
1019 | * a long time and slice keeps on extending and trim is not | |
1020 | * called for a long time. Now if limits are reduced suddenly | |
1021 | * we take into account all the IO dispatched so far at new | |
1022 | * low rate and * newly queued IO gets a really long dispatch | |
1023 | * time. | |
1024 | * | |
1025 | * So keep on trimming slice even if bio is not queued. | |
1026 | */ | |
1027 | throtl_trim_slice(td, tg, rw); | |
e43473b7 VG |
1028 | goto out; |
1029 | } | |
1030 | ||
1031 | queue_bio: | |
8e89d13f VG |
1032 | throtl_log_tg(td, tg, "[%c] bio. bdisp=%u sz=%u bps=%llu" |
1033 | " iodisp=%u iops=%u queued=%d/%d", | |
1034 | rw == READ ? 'R' : 'W', | |
e43473b7 | 1035 | tg->bytes_disp[rw], bio->bi_size, tg->bps[rw], |
8e89d13f | 1036 | tg->io_disp[rw], tg->iops[rw], |
e43473b7 VG |
1037 | tg->nr_queued[READ], tg->nr_queued[WRITE]); |
1038 | ||
1039 | throtl_add_bio_tg(q->td, tg, bio); | |
1040 | *biop = NULL; | |
1041 | ||
1042 | if (update_disptime) { | |
1043 | tg_update_disptime(td, tg); | |
1044 | throtl_schedule_next_dispatch(td); | |
1045 | } | |
1046 | ||
1047 | out: | |
1048 | spin_unlock_irq(q->queue_lock); | |
1049 | return 0; | |
1050 | } | |
1051 | ||
1052 | int blk_throtl_init(struct request_queue *q) | |
1053 | { | |
1054 | struct throtl_data *td; | |
1055 | struct throtl_grp *tg; | |
1056 | ||
1057 | td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); | |
1058 | if (!td) | |
1059 | return -ENOMEM; | |
1060 | ||
1061 | INIT_HLIST_HEAD(&td->tg_list); | |
1062 | td->tg_service_tree = THROTL_RB_ROOT; | |
de701c74 | 1063 | td->limits_changed = false; |
e43473b7 VG |
1064 | |
1065 | /* Init root group */ | |
1066 | tg = &td->root_tg; | |
1067 | INIT_HLIST_NODE(&tg->tg_node); | |
1068 | RB_CLEAR_NODE(&tg->rb_node); | |
1069 | bio_list_init(&tg->bio_lists[0]); | |
1070 | bio_list_init(&tg->bio_lists[1]); | |
1071 | ||
1072 | /* Practically unlimited BW */ | |
1073 | tg->bps[0] = tg->bps[1] = -1; | |
8e89d13f | 1074 | tg->iops[0] = tg->iops[1] = -1; |
de701c74 | 1075 | td->limits_changed = false; |
02977e4a VG |
1076 | |
1077 | /* | |
1078 | * Set root group reference to 2. One reference will be dropped when | |
1079 | * all groups on tg_list are being deleted during queue exit. Other | |
1080 | * reference will remain there as we don't want to delete this group | |
1081 | * as it is statically allocated and gets destroyed when throtl_data | |
1082 | * goes away. | |
1083 | */ | |
1084 | atomic_set(&tg->ref, 2); | |
1085 | hlist_add_head(&tg->tg_node, &td->tg_list); | |
1086 | td->nr_undestroyed_grps++; | |
e43473b7 VG |
1087 | |
1088 | INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work); | |
1089 | ||
1090 | rcu_read_lock(); | |
1091 | blkiocg_add_blkio_group(&blkio_root_cgroup, &tg->blkg, (void *)td, | |
1092 | 0, BLKIO_POLICY_THROTL); | |
1093 | rcu_read_unlock(); | |
1094 | ||
1095 | /* Attach throtl data to request queue */ | |
1096 | td->queue = q; | |
1097 | q->td = td; | |
1098 | return 0; | |
1099 | } | |
1100 | ||
1101 | void blk_throtl_exit(struct request_queue *q) | |
1102 | { | |
1103 | struct throtl_data *td = q->td; | |
1104 | bool wait = false; | |
1105 | ||
1106 | BUG_ON(!td); | |
1107 | ||
da527770 | 1108 | throtl_shutdown_wq(q); |
e43473b7 VG |
1109 | |
1110 | spin_lock_irq(q->queue_lock); | |
1111 | throtl_release_tgs(td); | |
e43473b7 VG |
1112 | |
1113 | /* If there are other groups */ | |
02977e4a | 1114 | if (td->nr_undestroyed_grps > 0) |
e43473b7 VG |
1115 | wait = true; |
1116 | ||
1117 | spin_unlock_irq(q->queue_lock); | |
1118 | ||
1119 | /* | |
1120 | * Wait for tg->blkg->key accessors to exit their grace periods. | |
1121 | * Do this wait only if there are other undestroyed groups out | |
1122 | * there (other than root group). This can happen if cgroup deletion | |
1123 | * path claimed the responsibility of cleaning up a group before | |
1124 | * queue cleanup code get to the group. | |
1125 | * | |
1126 | * Do not call synchronize_rcu() unconditionally as there are drivers | |
1127 | * which create/delete request queue hundreds of times during scan/boot | |
1128 | * and synchronize_rcu() can take significant time and slow down boot. | |
1129 | */ | |
1130 | if (wait) | |
1131 | synchronize_rcu(); | |
fe071437 VG |
1132 | |
1133 | /* | |
1134 | * Just being safe to make sure after previous flush if some body did | |
1135 | * update limits through cgroup and another work got queued, cancel | |
1136 | * it. | |
1137 | */ | |
da527770 | 1138 | throtl_shutdown_wq(q); |
e43473b7 VG |
1139 | throtl_td_free(td); |
1140 | } | |
1141 | ||
1142 | static int __init throtl_init(void) | |
1143 | { | |
450adcbe VG |
1144 | kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); |
1145 | if (!kthrotld_workqueue) | |
1146 | panic("Failed to create kthrotld\n"); | |
1147 | ||
e43473b7 VG |
1148 | blkio_policy_register(&blkio_policy_throtl); |
1149 | return 0; | |
1150 | } | |
1151 | ||
1152 | module_init(throtl_init); |