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> | |
eea8f41c | 12 | #include <linux/blk-cgroup.h> |
bc9fcbf9 | 13 | #include "blk.h" |
e43473b7 VG |
14 | |
15 | /* Max dispatch from a group in 1 round */ | |
16 | static int throtl_grp_quantum = 8; | |
17 | ||
18 | /* Total max dispatch from all groups in one round */ | |
19 | static int throtl_quantum = 32; | |
20 | ||
21 | /* Throttling is performed over 100ms slice and after that slice is renewed */ | |
22 | static unsigned long throtl_slice = HZ/10; /* 100 ms */ | |
23 | ||
3c798398 | 24 | static struct blkcg_policy blkcg_policy_throtl; |
0381411e | 25 | |
450adcbe VG |
26 | /* A workqueue to queue throttle related work */ |
27 | static struct workqueue_struct *kthrotld_workqueue; | |
450adcbe | 28 | |
c5cc2070 TH |
29 | /* |
30 | * To implement hierarchical throttling, throtl_grps form a tree and bios | |
31 | * are dispatched upwards level by level until they reach the top and get | |
32 | * issued. When dispatching bios from the children and local group at each | |
33 | * level, if the bios are dispatched into a single bio_list, there's a risk | |
34 | * of a local or child group which can queue many bios at once filling up | |
35 | * the list starving others. | |
36 | * | |
37 | * To avoid such starvation, dispatched bios are queued separately | |
38 | * according to where they came from. When they are again dispatched to | |
39 | * the parent, they're popped in round-robin order so that no single source | |
40 | * hogs the dispatch window. | |
41 | * | |
42 | * throtl_qnode is used to keep the queued bios separated by their sources. | |
43 | * Bios are queued to throtl_qnode which in turn is queued to | |
44 | * throtl_service_queue and then dispatched in round-robin order. | |
45 | * | |
46 | * It's also used to track the reference counts on blkg's. A qnode always | |
47 | * belongs to a throtl_grp and gets queued on itself or the parent, so | |
48 | * incrementing the reference of the associated throtl_grp when a qnode is | |
49 | * queued and decrementing when dequeued is enough to keep the whole blkg | |
50 | * tree pinned while bios are in flight. | |
51 | */ | |
52 | struct throtl_qnode { | |
53 | struct list_head node; /* service_queue->queued[] */ | |
54 | struct bio_list bios; /* queued bios */ | |
55 | struct throtl_grp *tg; /* tg this qnode belongs to */ | |
56 | }; | |
57 | ||
c9e0332e | 58 | struct throtl_service_queue { |
77216b04 TH |
59 | struct throtl_service_queue *parent_sq; /* the parent service_queue */ |
60 | ||
73f0d49a TH |
61 | /* |
62 | * Bios queued directly to this service_queue or dispatched from | |
63 | * children throtl_grp's. | |
64 | */ | |
c5cc2070 | 65 | struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ |
73f0d49a TH |
66 | unsigned int nr_queued[2]; /* number of queued bios */ |
67 | ||
68 | /* | |
69 | * RB tree of active children throtl_grp's, which are sorted by | |
70 | * their ->disptime. | |
71 | */ | |
c9e0332e TH |
72 | struct rb_root pending_tree; /* RB tree of active tgs */ |
73 | struct rb_node *first_pending; /* first node in the tree */ | |
74 | unsigned int nr_pending; /* # queued in the tree */ | |
75 | unsigned long first_pending_disptime; /* disptime of the first tg */ | |
69df0ab0 | 76 | struct timer_list pending_timer; /* fires on first_pending_disptime */ |
e43473b7 VG |
77 | }; |
78 | ||
5b2c16aa TH |
79 | enum tg_state_flags { |
80 | THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ | |
0e9f4164 | 81 | THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ |
5b2c16aa TH |
82 | }; |
83 | ||
e43473b7 VG |
84 | #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) |
85 | ||
86 | struct throtl_grp { | |
f95a04af TH |
87 | /* must be the first member */ |
88 | struct blkg_policy_data pd; | |
89 | ||
c9e0332e | 90 | /* active throtl group service_queue member */ |
e43473b7 VG |
91 | struct rb_node rb_node; |
92 | ||
0f3457f6 TH |
93 | /* throtl_data this group belongs to */ |
94 | struct throtl_data *td; | |
95 | ||
49a2f1e3 TH |
96 | /* this group's service queue */ |
97 | struct throtl_service_queue service_queue; | |
98 | ||
c5cc2070 TH |
99 | /* |
100 | * qnode_on_self is used when bios are directly queued to this | |
101 | * throtl_grp so that local bios compete fairly with bios | |
102 | * dispatched from children. qnode_on_parent is used when bios are | |
103 | * dispatched from this throtl_grp into its parent and will compete | |
104 | * with the sibling qnode_on_parents and the parent's | |
105 | * qnode_on_self. | |
106 | */ | |
107 | struct throtl_qnode qnode_on_self[2]; | |
108 | struct throtl_qnode qnode_on_parent[2]; | |
109 | ||
e43473b7 VG |
110 | /* |
111 | * Dispatch time in jiffies. This is the estimated time when group | |
112 | * will unthrottle and is ready to dispatch more bio. It is used as | |
113 | * key to sort active groups in service tree. | |
114 | */ | |
115 | unsigned long disptime; | |
116 | ||
e43473b7 VG |
117 | unsigned int flags; |
118 | ||
693e751e TH |
119 | /* are there any throtl rules between this group and td? */ |
120 | bool has_rules[2]; | |
121 | ||
e43473b7 VG |
122 | /* bytes per second rate limits */ |
123 | uint64_t bps[2]; | |
124 | ||
8e89d13f VG |
125 | /* IOPS limits */ |
126 | unsigned int iops[2]; | |
127 | ||
e43473b7 VG |
128 | /* Number of bytes disptached in current slice */ |
129 | uint64_t bytes_disp[2]; | |
8e89d13f VG |
130 | /* Number of bio's dispatched in current slice */ |
131 | unsigned int io_disp[2]; | |
e43473b7 VG |
132 | |
133 | /* When did we start a new slice */ | |
134 | unsigned long slice_start[2]; | |
135 | unsigned long slice_end[2]; | |
136 | }; | |
137 | ||
138 | struct throtl_data | |
139 | { | |
e43473b7 | 140 | /* service tree for active throtl groups */ |
c9e0332e | 141 | struct throtl_service_queue service_queue; |
e43473b7 | 142 | |
e43473b7 VG |
143 | struct request_queue *queue; |
144 | ||
145 | /* Total Number of queued bios on READ and WRITE lists */ | |
146 | unsigned int nr_queued[2]; | |
147 | ||
148 | /* | |
02977e4a | 149 | * number of total undestroyed groups |
e43473b7 VG |
150 | */ |
151 | unsigned int nr_undestroyed_grps; | |
152 | ||
153 | /* Work for dispatching throttled bios */ | |
69df0ab0 | 154 | struct work_struct dispatch_work; |
e43473b7 VG |
155 | }; |
156 | ||
69df0ab0 TH |
157 | static void throtl_pending_timer_fn(unsigned long arg); |
158 | ||
f95a04af TH |
159 | static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) |
160 | { | |
161 | return pd ? container_of(pd, struct throtl_grp, pd) : NULL; | |
162 | } | |
163 | ||
3c798398 | 164 | static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) |
0381411e | 165 | { |
f95a04af | 166 | return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); |
0381411e TH |
167 | } |
168 | ||
3c798398 | 169 | static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg) |
0381411e | 170 | { |
f95a04af | 171 | return pd_to_blkg(&tg->pd); |
0381411e TH |
172 | } |
173 | ||
fda6f272 TH |
174 | /** |
175 | * sq_to_tg - return the throl_grp the specified service queue belongs to | |
176 | * @sq: the throtl_service_queue of interest | |
177 | * | |
178 | * Return the throtl_grp @sq belongs to. If @sq is the top-level one | |
179 | * embedded in throtl_data, %NULL is returned. | |
180 | */ | |
181 | static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq) | |
182 | { | |
183 | if (sq && sq->parent_sq) | |
184 | return container_of(sq, struct throtl_grp, service_queue); | |
185 | else | |
186 | return NULL; | |
187 | } | |
188 | ||
189 | /** | |
190 | * sq_to_td - return throtl_data the specified service queue belongs to | |
191 | * @sq: the throtl_service_queue of interest | |
192 | * | |
193 | * A service_queue can be embeded in either a throtl_grp or throtl_data. | |
194 | * Determine the associated throtl_data accordingly and return it. | |
195 | */ | |
196 | static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) | |
197 | { | |
198 | struct throtl_grp *tg = sq_to_tg(sq); | |
199 | ||
200 | if (tg) | |
201 | return tg->td; | |
202 | else | |
203 | return container_of(sq, struct throtl_data, service_queue); | |
204 | } | |
205 | ||
206 | /** | |
207 | * throtl_log - log debug message via blktrace | |
208 | * @sq: the service_queue being reported | |
209 | * @fmt: printf format string | |
210 | * @args: printf args | |
211 | * | |
212 | * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a | |
213 | * throtl_grp; otherwise, just "throtl". | |
fda6f272 TH |
214 | */ |
215 | #define throtl_log(sq, fmt, args...) do { \ | |
216 | struct throtl_grp *__tg = sq_to_tg((sq)); \ | |
217 | struct throtl_data *__td = sq_to_td((sq)); \ | |
218 | \ | |
219 | (void)__td; \ | |
59fa0224 SL |
220 | if (likely(!blk_trace_note_message_enabled(__td->queue))) \ |
221 | break; \ | |
fda6f272 TH |
222 | if ((__tg)) { \ |
223 | char __pbuf[128]; \ | |
54e7ed12 | 224 | \ |
fda6f272 TH |
225 | blkg_path(tg_to_blkg(__tg), __pbuf, sizeof(__pbuf)); \ |
226 | blk_add_trace_msg(__td->queue, "throtl %s " fmt, __pbuf, ##args); \ | |
227 | } else { \ | |
228 | blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \ | |
229 | } \ | |
54e7ed12 | 230 | } while (0) |
e43473b7 | 231 | |
c5cc2070 TH |
232 | static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg) |
233 | { | |
234 | INIT_LIST_HEAD(&qn->node); | |
235 | bio_list_init(&qn->bios); | |
236 | qn->tg = tg; | |
237 | } | |
238 | ||
239 | /** | |
240 | * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it | |
241 | * @bio: bio being added | |
242 | * @qn: qnode to add bio to | |
243 | * @queued: the service_queue->queued[] list @qn belongs to | |
244 | * | |
245 | * Add @bio to @qn and put @qn on @queued if it's not already on. | |
246 | * @qn->tg's reference count is bumped when @qn is activated. See the | |
247 | * comment on top of throtl_qnode definition for details. | |
248 | */ | |
249 | static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn, | |
250 | struct list_head *queued) | |
251 | { | |
252 | bio_list_add(&qn->bios, bio); | |
253 | if (list_empty(&qn->node)) { | |
254 | list_add_tail(&qn->node, queued); | |
255 | blkg_get(tg_to_blkg(qn->tg)); | |
256 | } | |
257 | } | |
258 | ||
259 | /** | |
260 | * throtl_peek_queued - peek the first bio on a qnode list | |
261 | * @queued: the qnode list to peek | |
262 | */ | |
263 | static struct bio *throtl_peek_queued(struct list_head *queued) | |
264 | { | |
265 | struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); | |
266 | struct bio *bio; | |
267 | ||
268 | if (list_empty(queued)) | |
269 | return NULL; | |
270 | ||
271 | bio = bio_list_peek(&qn->bios); | |
272 | WARN_ON_ONCE(!bio); | |
273 | return bio; | |
274 | } | |
275 | ||
276 | /** | |
277 | * throtl_pop_queued - pop the first bio form a qnode list | |
278 | * @queued: the qnode list to pop a bio from | |
279 | * @tg_to_put: optional out argument for throtl_grp to put | |
280 | * | |
281 | * Pop the first bio from the qnode list @queued. After popping, the first | |
282 | * qnode is removed from @queued if empty or moved to the end of @queued so | |
283 | * that the popping order is round-robin. | |
284 | * | |
285 | * When the first qnode is removed, its associated throtl_grp should be put | |
286 | * too. If @tg_to_put is NULL, this function automatically puts it; | |
287 | * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is | |
288 | * responsible for putting it. | |
289 | */ | |
290 | static struct bio *throtl_pop_queued(struct list_head *queued, | |
291 | struct throtl_grp **tg_to_put) | |
292 | { | |
293 | struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); | |
294 | struct bio *bio; | |
295 | ||
296 | if (list_empty(queued)) | |
297 | return NULL; | |
298 | ||
299 | bio = bio_list_pop(&qn->bios); | |
300 | WARN_ON_ONCE(!bio); | |
301 | ||
302 | if (bio_list_empty(&qn->bios)) { | |
303 | list_del_init(&qn->node); | |
304 | if (tg_to_put) | |
305 | *tg_to_put = qn->tg; | |
306 | else | |
307 | blkg_put(tg_to_blkg(qn->tg)); | |
308 | } else { | |
309 | list_move_tail(&qn->node, queued); | |
310 | } | |
311 | ||
312 | return bio; | |
313 | } | |
314 | ||
49a2f1e3 | 315 | /* init a service_queue, assumes the caller zeroed it */ |
b2ce2643 | 316 | static void throtl_service_queue_init(struct throtl_service_queue *sq) |
49a2f1e3 | 317 | { |
c5cc2070 TH |
318 | INIT_LIST_HEAD(&sq->queued[0]); |
319 | INIT_LIST_HEAD(&sq->queued[1]); | |
49a2f1e3 | 320 | sq->pending_tree = RB_ROOT; |
69df0ab0 TH |
321 | setup_timer(&sq->pending_timer, throtl_pending_timer_fn, |
322 | (unsigned long)sq); | |
323 | } | |
324 | ||
001bea73 TH |
325 | static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node) |
326 | { | |
4fb72036 | 327 | struct throtl_grp *tg; |
24bdb8ef | 328 | int rw; |
4fb72036 TH |
329 | |
330 | tg = kzalloc_node(sizeof(*tg), gfp, node); | |
331 | if (!tg) | |
77ea7338 | 332 | return NULL; |
4fb72036 | 333 | |
b2ce2643 TH |
334 | throtl_service_queue_init(&tg->service_queue); |
335 | ||
336 | for (rw = READ; rw <= WRITE; rw++) { | |
337 | throtl_qnode_init(&tg->qnode_on_self[rw], tg); | |
338 | throtl_qnode_init(&tg->qnode_on_parent[rw], tg); | |
339 | } | |
340 | ||
341 | RB_CLEAR_NODE(&tg->rb_node); | |
342 | tg->bps[READ] = -1; | |
343 | tg->bps[WRITE] = -1; | |
344 | tg->iops[READ] = -1; | |
345 | tg->iops[WRITE] = -1; | |
346 | ||
4fb72036 | 347 | return &tg->pd; |
001bea73 TH |
348 | } |
349 | ||
a9520cd6 | 350 | static void throtl_pd_init(struct blkg_policy_data *pd) |
a29a171e | 351 | { |
a9520cd6 TH |
352 | struct throtl_grp *tg = pd_to_tg(pd); |
353 | struct blkcg_gq *blkg = tg_to_blkg(tg); | |
77216b04 | 354 | struct throtl_data *td = blkg->q->td; |
b2ce2643 | 355 | struct throtl_service_queue *sq = &tg->service_queue; |
cd1604fa | 356 | |
9138125b | 357 | /* |
aa6ec29b | 358 | * If on the default hierarchy, we switch to properly hierarchical |
9138125b TH |
359 | * behavior where limits on a given throtl_grp are applied to the |
360 | * whole subtree rather than just the group itself. e.g. If 16M | |
361 | * read_bps limit is set on the root group, the whole system can't | |
362 | * exceed 16M for the device. | |
363 | * | |
aa6ec29b | 364 | * If not on the default hierarchy, the broken flat hierarchy |
9138125b TH |
365 | * behavior is retained where all throtl_grps are treated as if |
366 | * they're all separate root groups right below throtl_data. | |
367 | * Limits of a group don't interact with limits of other groups | |
368 | * regardless of the position of the group in the hierarchy. | |
369 | */ | |
b2ce2643 | 370 | sq->parent_sq = &td->service_queue; |
9e10a130 | 371 | if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent) |
b2ce2643 | 372 | sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue; |
77216b04 | 373 | tg->td = td; |
8a3d2615 TH |
374 | } |
375 | ||
693e751e TH |
376 | /* |
377 | * Set has_rules[] if @tg or any of its parents have limits configured. | |
378 | * This doesn't require walking up to the top of the hierarchy as the | |
379 | * parent's has_rules[] is guaranteed to be correct. | |
380 | */ | |
381 | static void tg_update_has_rules(struct throtl_grp *tg) | |
382 | { | |
383 | struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq); | |
384 | int rw; | |
385 | ||
386 | for (rw = READ; rw <= WRITE; rw++) | |
387 | tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) || | |
388 | (tg->bps[rw] != -1 || tg->iops[rw] != -1); | |
389 | } | |
390 | ||
a9520cd6 | 391 | static void throtl_pd_online(struct blkg_policy_data *pd) |
693e751e TH |
392 | { |
393 | /* | |
394 | * We don't want new groups to escape the limits of its ancestors. | |
395 | * Update has_rules[] after a new group is brought online. | |
396 | */ | |
a9520cd6 | 397 | tg_update_has_rules(pd_to_tg(pd)); |
693e751e TH |
398 | } |
399 | ||
001bea73 TH |
400 | static void throtl_pd_free(struct blkg_policy_data *pd) |
401 | { | |
4fb72036 TH |
402 | struct throtl_grp *tg = pd_to_tg(pd); |
403 | ||
b2ce2643 | 404 | del_timer_sync(&tg->service_queue.pending_timer); |
4fb72036 | 405 | kfree(tg); |
001bea73 TH |
406 | } |
407 | ||
0049af73 TH |
408 | static struct throtl_grp * |
409 | throtl_rb_first(struct throtl_service_queue *parent_sq) | |
e43473b7 VG |
410 | { |
411 | /* Service tree is empty */ | |
0049af73 | 412 | if (!parent_sq->nr_pending) |
e43473b7 VG |
413 | return NULL; |
414 | ||
0049af73 TH |
415 | if (!parent_sq->first_pending) |
416 | parent_sq->first_pending = rb_first(&parent_sq->pending_tree); | |
e43473b7 | 417 | |
0049af73 TH |
418 | if (parent_sq->first_pending) |
419 | return rb_entry_tg(parent_sq->first_pending); | |
e43473b7 VG |
420 | |
421 | return NULL; | |
422 | } | |
423 | ||
424 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) | |
425 | { | |
426 | rb_erase(n, root); | |
427 | RB_CLEAR_NODE(n); | |
428 | } | |
429 | ||
0049af73 TH |
430 | static void throtl_rb_erase(struct rb_node *n, |
431 | struct throtl_service_queue *parent_sq) | |
e43473b7 | 432 | { |
0049af73 TH |
433 | if (parent_sq->first_pending == n) |
434 | parent_sq->first_pending = NULL; | |
435 | rb_erase_init(n, &parent_sq->pending_tree); | |
436 | --parent_sq->nr_pending; | |
e43473b7 VG |
437 | } |
438 | ||
0049af73 | 439 | static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) |
e43473b7 VG |
440 | { |
441 | struct throtl_grp *tg; | |
442 | ||
0049af73 | 443 | tg = throtl_rb_first(parent_sq); |
e43473b7 VG |
444 | if (!tg) |
445 | return; | |
446 | ||
0049af73 | 447 | parent_sq->first_pending_disptime = tg->disptime; |
e43473b7 VG |
448 | } |
449 | ||
77216b04 | 450 | static void tg_service_queue_add(struct throtl_grp *tg) |
e43473b7 | 451 | { |
77216b04 | 452 | struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq; |
0049af73 | 453 | struct rb_node **node = &parent_sq->pending_tree.rb_node; |
e43473b7 VG |
454 | struct rb_node *parent = NULL; |
455 | struct throtl_grp *__tg; | |
456 | unsigned long key = tg->disptime; | |
457 | int left = 1; | |
458 | ||
459 | while (*node != NULL) { | |
460 | parent = *node; | |
461 | __tg = rb_entry_tg(parent); | |
462 | ||
463 | if (time_before(key, __tg->disptime)) | |
464 | node = &parent->rb_left; | |
465 | else { | |
466 | node = &parent->rb_right; | |
467 | left = 0; | |
468 | } | |
469 | } | |
470 | ||
471 | if (left) | |
0049af73 | 472 | parent_sq->first_pending = &tg->rb_node; |
e43473b7 VG |
473 | |
474 | rb_link_node(&tg->rb_node, parent, node); | |
0049af73 | 475 | rb_insert_color(&tg->rb_node, &parent_sq->pending_tree); |
e43473b7 VG |
476 | } |
477 | ||
77216b04 | 478 | static void __throtl_enqueue_tg(struct throtl_grp *tg) |
e43473b7 | 479 | { |
77216b04 | 480 | tg_service_queue_add(tg); |
5b2c16aa | 481 | tg->flags |= THROTL_TG_PENDING; |
77216b04 | 482 | tg->service_queue.parent_sq->nr_pending++; |
e43473b7 VG |
483 | } |
484 | ||
77216b04 | 485 | static void throtl_enqueue_tg(struct throtl_grp *tg) |
e43473b7 | 486 | { |
5b2c16aa | 487 | if (!(tg->flags & THROTL_TG_PENDING)) |
77216b04 | 488 | __throtl_enqueue_tg(tg); |
e43473b7 VG |
489 | } |
490 | ||
77216b04 | 491 | static void __throtl_dequeue_tg(struct throtl_grp *tg) |
e43473b7 | 492 | { |
77216b04 | 493 | throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq); |
5b2c16aa | 494 | tg->flags &= ~THROTL_TG_PENDING; |
e43473b7 VG |
495 | } |
496 | ||
77216b04 | 497 | static void throtl_dequeue_tg(struct throtl_grp *tg) |
e43473b7 | 498 | { |
5b2c16aa | 499 | if (tg->flags & THROTL_TG_PENDING) |
77216b04 | 500 | __throtl_dequeue_tg(tg); |
e43473b7 VG |
501 | } |
502 | ||
a9131a27 | 503 | /* Call with queue lock held */ |
69df0ab0 TH |
504 | static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, |
505 | unsigned long expires) | |
a9131a27 | 506 | { |
69df0ab0 TH |
507 | mod_timer(&sq->pending_timer, expires); |
508 | throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu", | |
509 | expires - jiffies, jiffies); | |
a9131a27 TH |
510 | } |
511 | ||
7f52f98c TH |
512 | /** |
513 | * throtl_schedule_next_dispatch - schedule the next dispatch cycle | |
514 | * @sq: the service_queue to schedule dispatch for | |
515 | * @force: force scheduling | |
516 | * | |
517 | * Arm @sq->pending_timer so that the next dispatch cycle starts on the | |
518 | * dispatch time of the first pending child. Returns %true if either timer | |
519 | * is armed or there's no pending child left. %false if the current | |
520 | * dispatch window is still open and the caller should continue | |
521 | * dispatching. | |
522 | * | |
523 | * If @force is %true, the dispatch timer is always scheduled and this | |
524 | * function is guaranteed to return %true. This is to be used when the | |
525 | * caller can't dispatch itself and needs to invoke pending_timer | |
526 | * unconditionally. Note that forced scheduling is likely to induce short | |
527 | * delay before dispatch starts even if @sq->first_pending_disptime is not | |
528 | * in the future and thus shouldn't be used in hot paths. | |
529 | */ | |
530 | static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq, | |
531 | bool force) | |
e43473b7 | 532 | { |
6a525600 | 533 | /* any pending children left? */ |
c9e0332e | 534 | if (!sq->nr_pending) |
7f52f98c | 535 | return true; |
e43473b7 | 536 | |
c9e0332e | 537 | update_min_dispatch_time(sq); |
e43473b7 | 538 | |
69df0ab0 | 539 | /* is the next dispatch time in the future? */ |
7f52f98c | 540 | if (force || time_after(sq->first_pending_disptime, jiffies)) { |
69df0ab0 | 541 | throtl_schedule_pending_timer(sq, sq->first_pending_disptime); |
7f52f98c | 542 | return true; |
69df0ab0 TH |
543 | } |
544 | ||
7f52f98c TH |
545 | /* tell the caller to continue dispatching */ |
546 | return false; | |
e43473b7 VG |
547 | } |
548 | ||
32ee5bc4 VG |
549 | static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg, |
550 | bool rw, unsigned long start) | |
551 | { | |
552 | tg->bytes_disp[rw] = 0; | |
553 | tg->io_disp[rw] = 0; | |
554 | ||
555 | /* | |
556 | * Previous slice has expired. We must have trimmed it after last | |
557 | * bio dispatch. That means since start of last slice, we never used | |
558 | * that bandwidth. Do try to make use of that bandwidth while giving | |
559 | * credit. | |
560 | */ | |
561 | if (time_after_eq(start, tg->slice_start[rw])) | |
562 | tg->slice_start[rw] = start; | |
563 | ||
564 | tg->slice_end[rw] = jiffies + throtl_slice; | |
565 | throtl_log(&tg->service_queue, | |
566 | "[%c] new slice with credit start=%lu end=%lu jiffies=%lu", | |
567 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
568 | tg->slice_end[rw], jiffies); | |
569 | } | |
570 | ||
0f3457f6 | 571 | static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) |
e43473b7 VG |
572 | { |
573 | tg->bytes_disp[rw] = 0; | |
8e89d13f | 574 | tg->io_disp[rw] = 0; |
e43473b7 VG |
575 | tg->slice_start[rw] = jiffies; |
576 | tg->slice_end[rw] = jiffies + throtl_slice; | |
fda6f272 TH |
577 | throtl_log(&tg->service_queue, |
578 | "[%c] new slice start=%lu end=%lu jiffies=%lu", | |
579 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
580 | tg->slice_end[rw], jiffies); | |
e43473b7 VG |
581 | } |
582 | ||
0f3457f6 TH |
583 | static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw, |
584 | unsigned long jiffy_end) | |
d1ae8ffd VG |
585 | { |
586 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); | |
587 | } | |
588 | ||
0f3457f6 TH |
589 | static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw, |
590 | unsigned long jiffy_end) | |
e43473b7 VG |
591 | { |
592 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); | |
fda6f272 TH |
593 | throtl_log(&tg->service_queue, |
594 | "[%c] extend slice start=%lu end=%lu jiffies=%lu", | |
595 | rw == READ ? 'R' : 'W', tg->slice_start[rw], | |
596 | tg->slice_end[rw], jiffies); | |
e43473b7 VG |
597 | } |
598 | ||
599 | /* Determine if previously allocated or extended slice is complete or not */ | |
0f3457f6 | 600 | static bool throtl_slice_used(struct throtl_grp *tg, bool rw) |
e43473b7 VG |
601 | { |
602 | if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) | |
5cf8c227 | 603 | return false; |
e43473b7 VG |
604 | |
605 | return 1; | |
606 | } | |
607 | ||
608 | /* Trim the used slices and adjust slice start accordingly */ | |
0f3457f6 | 609 | static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) |
e43473b7 | 610 | { |
3aad5d3e VG |
611 | unsigned long nr_slices, time_elapsed, io_trim; |
612 | u64 bytes_trim, tmp; | |
e43473b7 VG |
613 | |
614 | BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); | |
615 | ||
616 | /* | |
617 | * If bps are unlimited (-1), then time slice don't get | |
618 | * renewed. Don't try to trim the slice if slice is used. A new | |
619 | * slice will start when appropriate. | |
620 | */ | |
0f3457f6 | 621 | if (throtl_slice_used(tg, rw)) |
e43473b7 VG |
622 | return; |
623 | ||
d1ae8ffd VG |
624 | /* |
625 | * A bio has been dispatched. Also adjust slice_end. It might happen | |
626 | * that initially cgroup limit was very low resulting in high | |
627 | * slice_end, but later limit was bumped up and bio was dispached | |
628 | * sooner, then we need to reduce slice_end. A high bogus slice_end | |
629 | * is bad because it does not allow new slice to start. | |
630 | */ | |
631 | ||
0f3457f6 | 632 | throtl_set_slice_end(tg, rw, jiffies + throtl_slice); |
d1ae8ffd | 633 | |
e43473b7 VG |
634 | time_elapsed = jiffies - tg->slice_start[rw]; |
635 | ||
636 | nr_slices = time_elapsed / throtl_slice; | |
637 | ||
638 | if (!nr_slices) | |
639 | return; | |
3aad5d3e VG |
640 | tmp = tg->bps[rw] * throtl_slice * nr_slices; |
641 | do_div(tmp, HZ); | |
642 | bytes_trim = tmp; | |
e43473b7 | 643 | |
8e89d13f | 644 | io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ; |
e43473b7 | 645 | |
8e89d13f | 646 | if (!bytes_trim && !io_trim) |
e43473b7 VG |
647 | return; |
648 | ||
649 | if (tg->bytes_disp[rw] >= bytes_trim) | |
650 | tg->bytes_disp[rw] -= bytes_trim; | |
651 | else | |
652 | tg->bytes_disp[rw] = 0; | |
653 | ||
8e89d13f VG |
654 | if (tg->io_disp[rw] >= io_trim) |
655 | tg->io_disp[rw] -= io_trim; | |
656 | else | |
657 | tg->io_disp[rw] = 0; | |
658 | ||
e43473b7 VG |
659 | tg->slice_start[rw] += nr_slices * throtl_slice; |
660 | ||
fda6f272 TH |
661 | throtl_log(&tg->service_queue, |
662 | "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", | |
663 | rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, | |
664 | tg->slice_start[rw], tg->slice_end[rw], jiffies); | |
e43473b7 VG |
665 | } |
666 | ||
0f3457f6 TH |
667 | static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, |
668 | unsigned long *wait) | |
e43473b7 VG |
669 | { |
670 | bool rw = bio_data_dir(bio); | |
8e89d13f | 671 | unsigned int io_allowed; |
e43473b7 | 672 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
c49c06e4 | 673 | u64 tmp; |
e43473b7 | 674 | |
8e89d13f | 675 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
e43473b7 | 676 | |
8e89d13f VG |
677 | /* Slice has just started. Consider one slice interval */ |
678 | if (!jiffy_elapsed) | |
679 | jiffy_elapsed_rnd = throtl_slice; | |
680 | ||
681 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); | |
682 | ||
c49c06e4 VG |
683 | /* |
684 | * jiffy_elapsed_rnd should not be a big value as minimum iops can be | |
685 | * 1 then at max jiffy elapsed should be equivalent of 1 second as we | |
686 | * will allow dispatch after 1 second and after that slice should | |
687 | * have been trimmed. | |
688 | */ | |
689 | ||
690 | tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd; | |
691 | do_div(tmp, HZ); | |
692 | ||
693 | if (tmp > UINT_MAX) | |
694 | io_allowed = UINT_MAX; | |
695 | else | |
696 | io_allowed = tmp; | |
8e89d13f VG |
697 | |
698 | if (tg->io_disp[rw] + 1 <= io_allowed) { | |
e43473b7 VG |
699 | if (wait) |
700 | *wait = 0; | |
5cf8c227 | 701 | return true; |
e43473b7 VG |
702 | } |
703 | ||
8e89d13f VG |
704 | /* Calc approx time to dispatch */ |
705 | jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1; | |
706 | ||
707 | if (jiffy_wait > jiffy_elapsed) | |
708 | jiffy_wait = jiffy_wait - jiffy_elapsed; | |
709 | else | |
710 | jiffy_wait = 1; | |
711 | ||
712 | if (wait) | |
713 | *wait = jiffy_wait; | |
714 | return 0; | |
715 | } | |
716 | ||
0f3457f6 TH |
717 | static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, |
718 | unsigned long *wait) | |
8e89d13f VG |
719 | { |
720 | bool rw = bio_data_dir(bio); | |
3aad5d3e | 721 | u64 bytes_allowed, extra_bytes, tmp; |
8e89d13f | 722 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
e43473b7 VG |
723 | |
724 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; | |
725 | ||
726 | /* Slice has just started. Consider one slice interval */ | |
727 | if (!jiffy_elapsed) | |
728 | jiffy_elapsed_rnd = throtl_slice; | |
729 | ||
730 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); | |
731 | ||
5e901a2b VG |
732 | tmp = tg->bps[rw] * jiffy_elapsed_rnd; |
733 | do_div(tmp, HZ); | |
3aad5d3e | 734 | bytes_allowed = tmp; |
e43473b7 | 735 | |
4f024f37 | 736 | if (tg->bytes_disp[rw] + bio->bi_iter.bi_size <= bytes_allowed) { |
e43473b7 VG |
737 | if (wait) |
738 | *wait = 0; | |
5cf8c227 | 739 | return true; |
e43473b7 VG |
740 | } |
741 | ||
742 | /* Calc approx time to dispatch */ | |
4f024f37 | 743 | extra_bytes = tg->bytes_disp[rw] + bio->bi_iter.bi_size - bytes_allowed; |
e43473b7 VG |
744 | jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]); |
745 | ||
746 | if (!jiffy_wait) | |
747 | jiffy_wait = 1; | |
748 | ||
749 | /* | |
750 | * This wait time is without taking into consideration the rounding | |
751 | * up we did. Add that time also. | |
752 | */ | |
753 | jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); | |
e43473b7 VG |
754 | if (wait) |
755 | *wait = jiffy_wait; | |
8e89d13f VG |
756 | return 0; |
757 | } | |
758 | ||
759 | /* | |
760 | * Returns whether one can dispatch a bio or not. Also returns approx number | |
761 | * of jiffies to wait before this bio is with-in IO rate and can be dispatched | |
762 | */ | |
0f3457f6 TH |
763 | static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, |
764 | unsigned long *wait) | |
8e89d13f VG |
765 | { |
766 | bool rw = bio_data_dir(bio); | |
767 | unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; | |
768 | ||
769 | /* | |
770 | * Currently whole state machine of group depends on first bio | |
771 | * queued in the group bio list. So one should not be calling | |
772 | * this function with a different bio if there are other bios | |
773 | * queued. | |
774 | */ | |
73f0d49a | 775 | BUG_ON(tg->service_queue.nr_queued[rw] && |
c5cc2070 | 776 | bio != throtl_peek_queued(&tg->service_queue.queued[rw])); |
e43473b7 | 777 | |
8e89d13f VG |
778 | /* If tg->bps = -1, then BW is unlimited */ |
779 | if (tg->bps[rw] == -1 && tg->iops[rw] == -1) { | |
780 | if (wait) | |
781 | *wait = 0; | |
5cf8c227 | 782 | return true; |
8e89d13f VG |
783 | } |
784 | ||
785 | /* | |
786 | * If previous slice expired, start a new one otherwise renew/extend | |
787 | * existing slice to make sure it is at least throtl_slice interval | |
788 | * long since now. | |
789 | */ | |
0f3457f6 TH |
790 | if (throtl_slice_used(tg, rw)) |
791 | throtl_start_new_slice(tg, rw); | |
8e89d13f VG |
792 | else { |
793 | if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) | |
0f3457f6 | 794 | throtl_extend_slice(tg, rw, jiffies + throtl_slice); |
8e89d13f VG |
795 | } |
796 | ||
0f3457f6 TH |
797 | if (tg_with_in_bps_limit(tg, bio, &bps_wait) && |
798 | tg_with_in_iops_limit(tg, bio, &iops_wait)) { | |
8e89d13f VG |
799 | if (wait) |
800 | *wait = 0; | |
801 | return 1; | |
802 | } | |
803 | ||
804 | max_wait = max(bps_wait, iops_wait); | |
805 | ||
806 | if (wait) | |
807 | *wait = max_wait; | |
808 | ||
809 | if (time_before(tg->slice_end[rw], jiffies + max_wait)) | |
0f3457f6 | 810 | throtl_extend_slice(tg, rw, jiffies + max_wait); |
e43473b7 VG |
811 | |
812 | return 0; | |
813 | } | |
814 | ||
815 | static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) | |
816 | { | |
817 | bool rw = bio_data_dir(bio); | |
e43473b7 VG |
818 | |
819 | /* Charge the bio to the group */ | |
4f024f37 | 820 | tg->bytes_disp[rw] += bio->bi_iter.bi_size; |
8e89d13f | 821 | tg->io_disp[rw]++; |
e43473b7 | 822 | |
2a0f61e6 TH |
823 | /* |
824 | * REQ_THROTTLED is used to prevent the same bio to be throttled | |
825 | * more than once as a throttled bio will go through blk-throtl the | |
826 | * second time when it eventually gets issued. Set it when a bio | |
827 | * is being charged to a tg. | |
2a0f61e6 | 828 | */ |
77ea7338 | 829 | if (!(bio->bi_rw & REQ_THROTTLED)) |
2a0f61e6 | 830 | bio->bi_rw |= REQ_THROTTLED; |
e43473b7 VG |
831 | } |
832 | ||
c5cc2070 TH |
833 | /** |
834 | * throtl_add_bio_tg - add a bio to the specified throtl_grp | |
835 | * @bio: bio to add | |
836 | * @qn: qnode to use | |
837 | * @tg: the target throtl_grp | |
838 | * | |
839 | * Add @bio to @tg's service_queue using @qn. If @qn is not specified, | |
840 | * tg->qnode_on_self[] is used. | |
841 | */ | |
842 | static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn, | |
843 | struct throtl_grp *tg) | |
e43473b7 | 844 | { |
73f0d49a | 845 | struct throtl_service_queue *sq = &tg->service_queue; |
e43473b7 VG |
846 | bool rw = bio_data_dir(bio); |
847 | ||
c5cc2070 TH |
848 | if (!qn) |
849 | qn = &tg->qnode_on_self[rw]; | |
850 | ||
0e9f4164 TH |
851 | /* |
852 | * If @tg doesn't currently have any bios queued in the same | |
853 | * direction, queueing @bio can change when @tg should be | |
854 | * dispatched. Mark that @tg was empty. This is automatically | |
855 | * cleaered on the next tg_update_disptime(). | |
856 | */ | |
857 | if (!sq->nr_queued[rw]) | |
858 | tg->flags |= THROTL_TG_WAS_EMPTY; | |
859 | ||
c5cc2070 TH |
860 | throtl_qnode_add_bio(bio, qn, &sq->queued[rw]); |
861 | ||
73f0d49a | 862 | sq->nr_queued[rw]++; |
77216b04 | 863 | throtl_enqueue_tg(tg); |
e43473b7 VG |
864 | } |
865 | ||
77216b04 | 866 | static void tg_update_disptime(struct throtl_grp *tg) |
e43473b7 | 867 | { |
73f0d49a | 868 | struct throtl_service_queue *sq = &tg->service_queue; |
e43473b7 VG |
869 | unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; |
870 | struct bio *bio; | |
871 | ||
c5cc2070 | 872 | if ((bio = throtl_peek_queued(&sq->queued[READ]))) |
0f3457f6 | 873 | tg_may_dispatch(tg, bio, &read_wait); |
e43473b7 | 874 | |
c5cc2070 | 875 | if ((bio = throtl_peek_queued(&sq->queued[WRITE]))) |
0f3457f6 | 876 | tg_may_dispatch(tg, bio, &write_wait); |
e43473b7 VG |
877 | |
878 | min_wait = min(read_wait, write_wait); | |
879 | disptime = jiffies + min_wait; | |
880 | ||
e43473b7 | 881 | /* Update dispatch time */ |
77216b04 | 882 | throtl_dequeue_tg(tg); |
e43473b7 | 883 | tg->disptime = disptime; |
77216b04 | 884 | throtl_enqueue_tg(tg); |
0e9f4164 TH |
885 | |
886 | /* see throtl_add_bio_tg() */ | |
887 | tg->flags &= ~THROTL_TG_WAS_EMPTY; | |
e43473b7 VG |
888 | } |
889 | ||
32ee5bc4 VG |
890 | static void start_parent_slice_with_credit(struct throtl_grp *child_tg, |
891 | struct throtl_grp *parent_tg, bool rw) | |
892 | { | |
893 | if (throtl_slice_used(parent_tg, rw)) { | |
894 | throtl_start_new_slice_with_credit(parent_tg, rw, | |
895 | child_tg->slice_start[rw]); | |
896 | } | |
897 | ||
898 | } | |
899 | ||
77216b04 | 900 | static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) |
e43473b7 | 901 | { |
73f0d49a | 902 | struct throtl_service_queue *sq = &tg->service_queue; |
6bc9c2b4 TH |
903 | struct throtl_service_queue *parent_sq = sq->parent_sq; |
904 | struct throtl_grp *parent_tg = sq_to_tg(parent_sq); | |
c5cc2070 | 905 | struct throtl_grp *tg_to_put = NULL; |
e43473b7 VG |
906 | struct bio *bio; |
907 | ||
c5cc2070 TH |
908 | /* |
909 | * @bio is being transferred from @tg to @parent_sq. Popping a bio | |
910 | * from @tg may put its reference and @parent_sq might end up | |
911 | * getting released prematurely. Remember the tg to put and put it | |
912 | * after @bio is transferred to @parent_sq. | |
913 | */ | |
914 | bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put); | |
73f0d49a | 915 | sq->nr_queued[rw]--; |
e43473b7 VG |
916 | |
917 | throtl_charge_bio(tg, bio); | |
6bc9c2b4 TH |
918 | |
919 | /* | |
920 | * If our parent is another tg, we just need to transfer @bio to | |
921 | * the parent using throtl_add_bio_tg(). If our parent is | |
922 | * @td->service_queue, @bio is ready to be issued. Put it on its | |
923 | * bio_lists[] and decrease total number queued. The caller is | |
924 | * responsible for issuing these bios. | |
925 | */ | |
926 | if (parent_tg) { | |
c5cc2070 | 927 | throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); |
32ee5bc4 | 928 | start_parent_slice_with_credit(tg, parent_tg, rw); |
6bc9c2b4 | 929 | } else { |
c5cc2070 TH |
930 | throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], |
931 | &parent_sq->queued[rw]); | |
6bc9c2b4 TH |
932 | BUG_ON(tg->td->nr_queued[rw] <= 0); |
933 | tg->td->nr_queued[rw]--; | |
934 | } | |
e43473b7 | 935 | |
0f3457f6 | 936 | throtl_trim_slice(tg, rw); |
6bc9c2b4 | 937 | |
c5cc2070 TH |
938 | if (tg_to_put) |
939 | blkg_put(tg_to_blkg(tg_to_put)); | |
e43473b7 VG |
940 | } |
941 | ||
77216b04 | 942 | static int throtl_dispatch_tg(struct throtl_grp *tg) |
e43473b7 | 943 | { |
73f0d49a | 944 | struct throtl_service_queue *sq = &tg->service_queue; |
e43473b7 VG |
945 | unsigned int nr_reads = 0, nr_writes = 0; |
946 | unsigned int max_nr_reads = throtl_grp_quantum*3/4; | |
c2f6805d | 947 | unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; |
e43473b7 VG |
948 | struct bio *bio; |
949 | ||
950 | /* Try to dispatch 75% READS and 25% WRITES */ | |
951 | ||
c5cc2070 | 952 | while ((bio = throtl_peek_queued(&sq->queued[READ])) && |
0f3457f6 | 953 | tg_may_dispatch(tg, bio, NULL)) { |
e43473b7 | 954 | |
77216b04 | 955 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
e43473b7 VG |
956 | nr_reads++; |
957 | ||
958 | if (nr_reads >= max_nr_reads) | |
959 | break; | |
960 | } | |
961 | ||
c5cc2070 | 962 | while ((bio = throtl_peek_queued(&sq->queued[WRITE])) && |
0f3457f6 | 963 | tg_may_dispatch(tg, bio, NULL)) { |
e43473b7 | 964 | |
77216b04 | 965 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
e43473b7 VG |
966 | nr_writes++; |
967 | ||
968 | if (nr_writes >= max_nr_writes) | |
969 | break; | |
970 | } | |
971 | ||
972 | return nr_reads + nr_writes; | |
973 | } | |
974 | ||
651930bc | 975 | static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) |
e43473b7 VG |
976 | { |
977 | unsigned int nr_disp = 0; | |
e43473b7 VG |
978 | |
979 | while (1) { | |
73f0d49a TH |
980 | struct throtl_grp *tg = throtl_rb_first(parent_sq); |
981 | struct throtl_service_queue *sq = &tg->service_queue; | |
e43473b7 VG |
982 | |
983 | if (!tg) | |
984 | break; | |
985 | ||
986 | if (time_before(jiffies, tg->disptime)) | |
987 | break; | |
988 | ||
77216b04 | 989 | throtl_dequeue_tg(tg); |
e43473b7 | 990 | |
77216b04 | 991 | nr_disp += throtl_dispatch_tg(tg); |
e43473b7 | 992 | |
73f0d49a | 993 | if (sq->nr_queued[0] || sq->nr_queued[1]) |
77216b04 | 994 | tg_update_disptime(tg); |
e43473b7 VG |
995 | |
996 | if (nr_disp >= throtl_quantum) | |
997 | break; | |
998 | } | |
999 | ||
1000 | return nr_disp; | |
1001 | } | |
1002 | ||
6e1a5704 TH |
1003 | /** |
1004 | * throtl_pending_timer_fn - timer function for service_queue->pending_timer | |
1005 | * @arg: the throtl_service_queue being serviced | |
1006 | * | |
1007 | * This timer is armed when a child throtl_grp with active bio's become | |
1008 | * pending and queued on the service_queue's pending_tree and expires when | |
1009 | * the first child throtl_grp should be dispatched. This function | |
2e48a530 TH |
1010 | * dispatches bio's from the children throtl_grps to the parent |
1011 | * service_queue. | |
1012 | * | |
1013 | * If the parent's parent is another throtl_grp, dispatching is propagated | |
1014 | * by either arming its pending_timer or repeating dispatch directly. If | |
1015 | * the top-level service_tree is reached, throtl_data->dispatch_work is | |
1016 | * kicked so that the ready bio's are issued. | |
6e1a5704 | 1017 | */ |
69df0ab0 TH |
1018 | static void throtl_pending_timer_fn(unsigned long arg) |
1019 | { | |
1020 | struct throtl_service_queue *sq = (void *)arg; | |
2e48a530 | 1021 | struct throtl_grp *tg = sq_to_tg(sq); |
69df0ab0 | 1022 | struct throtl_data *td = sq_to_td(sq); |
cb76199c | 1023 | struct request_queue *q = td->queue; |
2e48a530 TH |
1024 | struct throtl_service_queue *parent_sq; |
1025 | bool dispatched; | |
6e1a5704 | 1026 | int ret; |
e43473b7 VG |
1027 | |
1028 | spin_lock_irq(q->queue_lock); | |
2e48a530 TH |
1029 | again: |
1030 | parent_sq = sq->parent_sq; | |
1031 | dispatched = false; | |
e43473b7 | 1032 | |
7f52f98c TH |
1033 | while (true) { |
1034 | throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u", | |
2e48a530 TH |
1035 | sq->nr_queued[READ] + sq->nr_queued[WRITE], |
1036 | sq->nr_queued[READ], sq->nr_queued[WRITE]); | |
7f52f98c TH |
1037 | |
1038 | ret = throtl_select_dispatch(sq); | |
1039 | if (ret) { | |
7f52f98c TH |
1040 | throtl_log(sq, "bios disp=%u", ret); |
1041 | dispatched = true; | |
1042 | } | |
e43473b7 | 1043 | |
7f52f98c TH |
1044 | if (throtl_schedule_next_dispatch(sq, false)) |
1045 | break; | |
e43473b7 | 1046 | |
7f52f98c TH |
1047 | /* this dispatch windows is still open, relax and repeat */ |
1048 | spin_unlock_irq(q->queue_lock); | |
1049 | cpu_relax(); | |
1050 | spin_lock_irq(q->queue_lock); | |
651930bc | 1051 | } |
e43473b7 | 1052 | |
2e48a530 TH |
1053 | if (!dispatched) |
1054 | goto out_unlock; | |
6e1a5704 | 1055 | |
2e48a530 TH |
1056 | if (parent_sq) { |
1057 | /* @parent_sq is another throl_grp, propagate dispatch */ | |
1058 | if (tg->flags & THROTL_TG_WAS_EMPTY) { | |
1059 | tg_update_disptime(tg); | |
1060 | if (!throtl_schedule_next_dispatch(parent_sq, false)) { | |
1061 | /* window is already open, repeat dispatching */ | |
1062 | sq = parent_sq; | |
1063 | tg = sq_to_tg(sq); | |
1064 | goto again; | |
1065 | } | |
1066 | } | |
1067 | } else { | |
1068 | /* reached the top-level, queue issueing */ | |
1069 | queue_work(kthrotld_workqueue, &td->dispatch_work); | |
1070 | } | |
1071 | out_unlock: | |
e43473b7 | 1072 | spin_unlock_irq(q->queue_lock); |
6e1a5704 | 1073 | } |
e43473b7 | 1074 | |
6e1a5704 TH |
1075 | /** |
1076 | * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work | |
1077 | * @work: work item being executed | |
1078 | * | |
1079 | * This function is queued for execution when bio's reach the bio_lists[] | |
1080 | * of throtl_data->service_queue. Those bio's are ready and issued by this | |
1081 | * function. | |
1082 | */ | |
8876e140 | 1083 | static void blk_throtl_dispatch_work_fn(struct work_struct *work) |
6e1a5704 TH |
1084 | { |
1085 | struct throtl_data *td = container_of(work, struct throtl_data, | |
1086 | dispatch_work); | |
1087 | struct throtl_service_queue *td_sq = &td->service_queue; | |
1088 | struct request_queue *q = td->queue; | |
1089 | struct bio_list bio_list_on_stack; | |
1090 | struct bio *bio; | |
1091 | struct blk_plug plug; | |
1092 | int rw; | |
1093 | ||
1094 | bio_list_init(&bio_list_on_stack); | |
1095 | ||
1096 | spin_lock_irq(q->queue_lock); | |
c5cc2070 TH |
1097 | for (rw = READ; rw <= WRITE; rw++) |
1098 | while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) | |
1099 | bio_list_add(&bio_list_on_stack, bio); | |
6e1a5704 TH |
1100 | spin_unlock_irq(q->queue_lock); |
1101 | ||
1102 | if (!bio_list_empty(&bio_list_on_stack)) { | |
69d60eb9 | 1103 | blk_start_plug(&plug); |
e43473b7 VG |
1104 | while((bio = bio_list_pop(&bio_list_on_stack))) |
1105 | generic_make_request(bio); | |
69d60eb9 | 1106 | blk_finish_plug(&plug); |
e43473b7 | 1107 | } |
e43473b7 VG |
1108 | } |
1109 | ||
f95a04af TH |
1110 | static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, |
1111 | int off) | |
60c2bc2d | 1112 | { |
f95a04af TH |
1113 | struct throtl_grp *tg = pd_to_tg(pd); |
1114 | u64 v = *(u64 *)((void *)tg + off); | |
60c2bc2d | 1115 | |
af133ceb | 1116 | if (v == -1) |
60c2bc2d | 1117 | return 0; |
f95a04af | 1118 | return __blkg_prfill_u64(sf, pd, v); |
60c2bc2d TH |
1119 | } |
1120 | ||
f95a04af TH |
1121 | static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, |
1122 | int off) | |
e43473b7 | 1123 | { |
f95a04af TH |
1124 | struct throtl_grp *tg = pd_to_tg(pd); |
1125 | unsigned int v = *(unsigned int *)((void *)tg + off); | |
fe071437 | 1126 | |
af133ceb TH |
1127 | if (v == -1) |
1128 | return 0; | |
f95a04af | 1129 | return __blkg_prfill_u64(sf, pd, v); |
e43473b7 VG |
1130 | } |
1131 | ||
2da8ca82 | 1132 | static int tg_print_conf_u64(struct seq_file *sf, void *v) |
8e89d13f | 1133 | { |
2da8ca82 TH |
1134 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64, |
1135 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
af133ceb | 1136 | return 0; |
8e89d13f VG |
1137 | } |
1138 | ||
2da8ca82 | 1139 | static int tg_print_conf_uint(struct seq_file *sf, void *v) |
8e89d13f | 1140 | { |
2da8ca82 TH |
1141 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint, |
1142 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
af133ceb | 1143 | return 0; |
60c2bc2d TH |
1144 | } |
1145 | ||
69948b07 | 1146 | static void tg_conf_updated(struct throtl_grp *tg) |
60c2bc2d | 1147 | { |
69948b07 | 1148 | struct throtl_service_queue *sq = &tg->service_queue; |
492eb21b | 1149 | struct cgroup_subsys_state *pos_css; |
69948b07 | 1150 | struct blkcg_gq *blkg; |
af133ceb | 1151 | |
fda6f272 TH |
1152 | throtl_log(&tg->service_queue, |
1153 | "limit change rbps=%llu wbps=%llu riops=%u wiops=%u", | |
1154 | tg->bps[READ], tg->bps[WRITE], | |
1155 | tg->iops[READ], tg->iops[WRITE]); | |
632b4493 | 1156 | |
693e751e TH |
1157 | /* |
1158 | * Update has_rules[] flags for the updated tg's subtree. A tg is | |
1159 | * considered to have rules if either the tg itself or any of its | |
1160 | * ancestors has rules. This identifies groups without any | |
1161 | * restrictions in the whole hierarchy and allows them to bypass | |
1162 | * blk-throttle. | |
1163 | */ | |
69948b07 | 1164 | blkg_for_each_descendant_pre(blkg, pos_css, tg_to_blkg(tg)) |
693e751e TH |
1165 | tg_update_has_rules(blkg_to_tg(blkg)); |
1166 | ||
632b4493 TH |
1167 | /* |
1168 | * We're already holding queue_lock and know @tg is valid. Let's | |
1169 | * apply the new config directly. | |
1170 | * | |
1171 | * Restart the slices for both READ and WRITES. It might happen | |
1172 | * that a group's limit are dropped suddenly and we don't want to | |
1173 | * account recently dispatched IO with new low rate. | |
1174 | */ | |
0f3457f6 TH |
1175 | throtl_start_new_slice(tg, 0); |
1176 | throtl_start_new_slice(tg, 1); | |
632b4493 | 1177 | |
5b2c16aa | 1178 | if (tg->flags & THROTL_TG_PENDING) { |
77216b04 | 1179 | tg_update_disptime(tg); |
7f52f98c | 1180 | throtl_schedule_next_dispatch(sq->parent_sq, true); |
632b4493 | 1181 | } |
69948b07 TH |
1182 | } |
1183 | ||
1184 | static ssize_t tg_set_conf(struct kernfs_open_file *of, | |
1185 | char *buf, size_t nbytes, loff_t off, bool is_u64) | |
1186 | { | |
1187 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); | |
1188 | struct blkg_conf_ctx ctx; | |
1189 | struct throtl_grp *tg; | |
1190 | int ret; | |
1191 | u64 v; | |
1192 | ||
1193 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); | |
1194 | if (ret) | |
1195 | return ret; | |
1196 | ||
1197 | ret = -EINVAL; | |
1198 | if (sscanf(ctx.body, "%llu", &v) != 1) | |
1199 | goto out_finish; | |
1200 | if (!v) | |
1201 | v = -1; | |
1202 | ||
1203 | tg = blkg_to_tg(ctx.blkg); | |
1204 | ||
1205 | if (is_u64) | |
1206 | *(u64 *)((void *)tg + of_cft(of)->private) = v; | |
1207 | else | |
1208 | *(unsigned int *)((void *)tg + of_cft(of)->private) = v; | |
60c2bc2d | 1209 | |
69948b07 | 1210 | tg_conf_updated(tg); |
36aa9e5f TH |
1211 | ret = 0; |
1212 | out_finish: | |
60c2bc2d | 1213 | blkg_conf_finish(&ctx); |
36aa9e5f | 1214 | return ret ?: nbytes; |
8e89d13f VG |
1215 | } |
1216 | ||
451af504 TH |
1217 | static ssize_t tg_set_conf_u64(struct kernfs_open_file *of, |
1218 | char *buf, size_t nbytes, loff_t off) | |
60c2bc2d | 1219 | { |
451af504 | 1220 | return tg_set_conf(of, buf, nbytes, off, true); |
60c2bc2d TH |
1221 | } |
1222 | ||
451af504 TH |
1223 | static ssize_t tg_set_conf_uint(struct kernfs_open_file *of, |
1224 | char *buf, size_t nbytes, loff_t off) | |
60c2bc2d | 1225 | { |
451af504 | 1226 | return tg_set_conf(of, buf, nbytes, off, false); |
60c2bc2d TH |
1227 | } |
1228 | ||
880f50e2 | 1229 | static struct cftype throtl_legacy_files[] = { |
60c2bc2d TH |
1230 | { |
1231 | .name = "throttle.read_bps_device", | |
af133ceb | 1232 | .private = offsetof(struct throtl_grp, bps[READ]), |
2da8ca82 | 1233 | .seq_show = tg_print_conf_u64, |
451af504 | 1234 | .write = tg_set_conf_u64, |
60c2bc2d TH |
1235 | }, |
1236 | { | |
1237 | .name = "throttle.write_bps_device", | |
af133ceb | 1238 | .private = offsetof(struct throtl_grp, bps[WRITE]), |
2da8ca82 | 1239 | .seq_show = tg_print_conf_u64, |
451af504 | 1240 | .write = tg_set_conf_u64, |
60c2bc2d TH |
1241 | }, |
1242 | { | |
1243 | .name = "throttle.read_iops_device", | |
af133ceb | 1244 | .private = offsetof(struct throtl_grp, iops[READ]), |
2da8ca82 | 1245 | .seq_show = tg_print_conf_uint, |
451af504 | 1246 | .write = tg_set_conf_uint, |
60c2bc2d TH |
1247 | }, |
1248 | { | |
1249 | .name = "throttle.write_iops_device", | |
af133ceb | 1250 | .private = offsetof(struct throtl_grp, iops[WRITE]), |
2da8ca82 | 1251 | .seq_show = tg_print_conf_uint, |
451af504 | 1252 | .write = tg_set_conf_uint, |
60c2bc2d TH |
1253 | }, |
1254 | { | |
1255 | .name = "throttle.io_service_bytes", | |
77ea7338 TH |
1256 | .private = (unsigned long)&blkcg_policy_throtl, |
1257 | .seq_show = blkg_print_stat_bytes, | |
60c2bc2d TH |
1258 | }, |
1259 | { | |
1260 | .name = "throttle.io_serviced", | |
77ea7338 TH |
1261 | .private = (unsigned long)&blkcg_policy_throtl, |
1262 | .seq_show = blkg_print_stat_ios, | |
60c2bc2d TH |
1263 | }, |
1264 | { } /* terminate */ | |
1265 | }; | |
1266 | ||
2ee867dc TH |
1267 | static u64 tg_prfill_max(struct seq_file *sf, struct blkg_policy_data *pd, |
1268 | int off) | |
1269 | { | |
1270 | struct throtl_grp *tg = pd_to_tg(pd); | |
1271 | const char *dname = blkg_dev_name(pd->blkg); | |
1272 | char bufs[4][21] = { "max", "max", "max", "max" }; | |
1273 | ||
1274 | if (!dname) | |
1275 | return 0; | |
1276 | if (tg->bps[READ] == -1 && tg->bps[WRITE] == -1 && | |
1277 | tg->iops[READ] == -1 && tg->iops[WRITE] == -1) | |
1278 | return 0; | |
1279 | ||
1280 | if (tg->bps[READ] != -1) | |
1281 | snprintf(bufs[0], sizeof(bufs[0]), "%llu", tg->bps[READ]); | |
1282 | if (tg->bps[WRITE] != -1) | |
1283 | snprintf(bufs[1], sizeof(bufs[1]), "%llu", tg->bps[WRITE]); | |
1284 | if (tg->iops[READ] != -1) | |
1285 | snprintf(bufs[2], sizeof(bufs[2]), "%u", tg->iops[READ]); | |
1286 | if (tg->iops[WRITE] != -1) | |
1287 | snprintf(bufs[3], sizeof(bufs[3]), "%u", tg->iops[WRITE]); | |
1288 | ||
1289 | seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s\n", | |
1290 | dname, bufs[0], bufs[1], bufs[2], bufs[3]); | |
1291 | return 0; | |
1292 | } | |
1293 | ||
1294 | static int tg_print_max(struct seq_file *sf, void *v) | |
1295 | { | |
1296 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_max, | |
1297 | &blkcg_policy_throtl, seq_cft(sf)->private, false); | |
1298 | return 0; | |
1299 | } | |
1300 | ||
1301 | static ssize_t tg_set_max(struct kernfs_open_file *of, | |
1302 | char *buf, size_t nbytes, loff_t off) | |
1303 | { | |
1304 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); | |
1305 | struct blkg_conf_ctx ctx; | |
1306 | struct throtl_grp *tg; | |
1307 | u64 v[4]; | |
1308 | int ret; | |
1309 | ||
1310 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); | |
1311 | if (ret) | |
1312 | return ret; | |
1313 | ||
1314 | tg = blkg_to_tg(ctx.blkg); | |
1315 | ||
1316 | v[0] = tg->bps[READ]; | |
1317 | v[1] = tg->bps[WRITE]; | |
1318 | v[2] = tg->iops[READ]; | |
1319 | v[3] = tg->iops[WRITE]; | |
1320 | ||
1321 | while (true) { | |
1322 | char tok[27]; /* wiops=18446744073709551616 */ | |
1323 | char *p; | |
1324 | u64 val = -1; | |
1325 | int len; | |
1326 | ||
1327 | if (sscanf(ctx.body, "%26s%n", tok, &len) != 1) | |
1328 | break; | |
1329 | if (tok[0] == '\0') | |
1330 | break; | |
1331 | ctx.body += len; | |
1332 | ||
1333 | ret = -EINVAL; | |
1334 | p = tok; | |
1335 | strsep(&p, "="); | |
1336 | if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max"))) | |
1337 | goto out_finish; | |
1338 | ||
1339 | ret = -ERANGE; | |
1340 | if (!val) | |
1341 | goto out_finish; | |
1342 | ||
1343 | ret = -EINVAL; | |
1344 | if (!strcmp(tok, "rbps")) | |
1345 | v[0] = val; | |
1346 | else if (!strcmp(tok, "wbps")) | |
1347 | v[1] = val; | |
1348 | else if (!strcmp(tok, "riops")) | |
1349 | v[2] = min_t(u64, val, UINT_MAX); | |
1350 | else if (!strcmp(tok, "wiops")) | |
1351 | v[3] = min_t(u64, val, UINT_MAX); | |
1352 | else | |
1353 | goto out_finish; | |
1354 | } | |
1355 | ||
1356 | tg->bps[READ] = v[0]; | |
1357 | tg->bps[WRITE] = v[1]; | |
1358 | tg->iops[READ] = v[2]; | |
1359 | tg->iops[WRITE] = v[3]; | |
1360 | ||
1361 | tg_conf_updated(tg); | |
1362 | ret = 0; | |
1363 | out_finish: | |
1364 | blkg_conf_finish(&ctx); | |
1365 | return ret ?: nbytes; | |
1366 | } | |
1367 | ||
1368 | static struct cftype throtl_files[] = { | |
1369 | { | |
1370 | .name = "max", | |
1371 | .flags = CFTYPE_NOT_ON_ROOT, | |
1372 | .seq_show = tg_print_max, | |
1373 | .write = tg_set_max, | |
1374 | }, | |
1375 | { } /* terminate */ | |
1376 | }; | |
1377 | ||
da527770 | 1378 | static void throtl_shutdown_wq(struct request_queue *q) |
e43473b7 VG |
1379 | { |
1380 | struct throtl_data *td = q->td; | |
1381 | ||
69df0ab0 | 1382 | cancel_work_sync(&td->dispatch_work); |
e43473b7 VG |
1383 | } |
1384 | ||
3c798398 | 1385 | static struct blkcg_policy blkcg_policy_throtl = { |
2ee867dc | 1386 | .dfl_cftypes = throtl_files, |
880f50e2 | 1387 | .legacy_cftypes = throtl_legacy_files, |
f9fcc2d3 | 1388 | |
001bea73 | 1389 | .pd_alloc_fn = throtl_pd_alloc, |
f9fcc2d3 | 1390 | .pd_init_fn = throtl_pd_init, |
693e751e | 1391 | .pd_online_fn = throtl_pd_online, |
001bea73 | 1392 | .pd_free_fn = throtl_pd_free, |
e43473b7 VG |
1393 | }; |
1394 | ||
ae118896 TH |
1395 | bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, |
1396 | struct bio *bio) | |
e43473b7 | 1397 | { |
c5cc2070 | 1398 | struct throtl_qnode *qn = NULL; |
ae118896 | 1399 | struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg); |
73f0d49a | 1400 | struct throtl_service_queue *sq; |
0e9f4164 | 1401 | bool rw = bio_data_dir(bio); |
bc16a4f9 | 1402 | bool throttled = false; |
e43473b7 | 1403 | |
ae118896 TH |
1404 | WARN_ON_ONCE(!rcu_read_lock_held()); |
1405 | ||
2a0f61e6 | 1406 | /* see throtl_charge_bio() */ |
ae118896 | 1407 | if ((bio->bi_rw & REQ_THROTTLED) || !tg->has_rules[rw]) |
bc16a4f9 | 1408 | goto out; |
e43473b7 VG |
1409 | |
1410 | spin_lock_irq(q->queue_lock); | |
c9589f03 TH |
1411 | |
1412 | if (unlikely(blk_queue_bypass(q))) | |
bc16a4f9 | 1413 | goto out_unlock; |
f469a7b4 | 1414 | |
73f0d49a TH |
1415 | sq = &tg->service_queue; |
1416 | ||
9e660acf TH |
1417 | while (true) { |
1418 | /* throtl is FIFO - if bios are already queued, should queue */ | |
1419 | if (sq->nr_queued[rw]) | |
1420 | break; | |
de701c74 | 1421 | |
9e660acf TH |
1422 | /* if above limits, break to queue */ |
1423 | if (!tg_may_dispatch(tg, bio, NULL)) | |
1424 | break; | |
1425 | ||
1426 | /* within limits, let's charge and dispatch directly */ | |
e43473b7 | 1427 | throtl_charge_bio(tg, bio); |
04521db0 VG |
1428 | |
1429 | /* | |
1430 | * We need to trim slice even when bios are not being queued | |
1431 | * otherwise it might happen that a bio is not queued for | |
1432 | * a long time and slice keeps on extending and trim is not | |
1433 | * called for a long time. Now if limits are reduced suddenly | |
1434 | * we take into account all the IO dispatched so far at new | |
1435 | * low rate and * newly queued IO gets a really long dispatch | |
1436 | * time. | |
1437 | * | |
1438 | * So keep on trimming slice even if bio is not queued. | |
1439 | */ | |
0f3457f6 | 1440 | throtl_trim_slice(tg, rw); |
9e660acf TH |
1441 | |
1442 | /* | |
1443 | * @bio passed through this layer without being throttled. | |
1444 | * Climb up the ladder. If we''re already at the top, it | |
1445 | * can be executed directly. | |
1446 | */ | |
c5cc2070 | 1447 | qn = &tg->qnode_on_parent[rw]; |
9e660acf TH |
1448 | sq = sq->parent_sq; |
1449 | tg = sq_to_tg(sq); | |
1450 | if (!tg) | |
1451 | goto out_unlock; | |
e43473b7 VG |
1452 | } |
1453 | ||
9e660acf | 1454 | /* out-of-limit, queue to @tg */ |
fda6f272 TH |
1455 | throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", |
1456 | rw == READ ? 'R' : 'W', | |
4f024f37 | 1457 | tg->bytes_disp[rw], bio->bi_iter.bi_size, tg->bps[rw], |
fda6f272 TH |
1458 | tg->io_disp[rw], tg->iops[rw], |
1459 | sq->nr_queued[READ], sq->nr_queued[WRITE]); | |
e43473b7 | 1460 | |
671058fb | 1461 | bio_associate_current(bio); |
6bc9c2b4 | 1462 | tg->td->nr_queued[rw]++; |
c5cc2070 | 1463 | throtl_add_bio_tg(bio, qn, tg); |
bc16a4f9 | 1464 | throttled = true; |
e43473b7 | 1465 | |
7f52f98c TH |
1466 | /* |
1467 | * Update @tg's dispatch time and force schedule dispatch if @tg | |
1468 | * was empty before @bio. The forced scheduling isn't likely to | |
1469 | * cause undue delay as @bio is likely to be dispatched directly if | |
1470 | * its @tg's disptime is not in the future. | |
1471 | */ | |
0e9f4164 | 1472 | if (tg->flags & THROTL_TG_WAS_EMPTY) { |
77216b04 | 1473 | tg_update_disptime(tg); |
7f52f98c | 1474 | throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true); |
e43473b7 VG |
1475 | } |
1476 | ||
bc16a4f9 | 1477 | out_unlock: |
e43473b7 | 1478 | spin_unlock_irq(q->queue_lock); |
bc16a4f9 | 1479 | out: |
2a0f61e6 TH |
1480 | /* |
1481 | * As multiple blk-throtls may stack in the same issue path, we | |
1482 | * don't want bios to leave with the flag set. Clear the flag if | |
1483 | * being issued. | |
1484 | */ | |
1485 | if (!throttled) | |
1486 | bio->bi_rw &= ~REQ_THROTTLED; | |
bc16a4f9 | 1487 | return throttled; |
e43473b7 VG |
1488 | } |
1489 | ||
2a12f0dc TH |
1490 | /* |
1491 | * Dispatch all bios from all children tg's queued on @parent_sq. On | |
1492 | * return, @parent_sq is guaranteed to not have any active children tg's | |
1493 | * and all bios from previously active tg's are on @parent_sq->bio_lists[]. | |
1494 | */ | |
1495 | static void tg_drain_bios(struct throtl_service_queue *parent_sq) | |
1496 | { | |
1497 | struct throtl_grp *tg; | |
1498 | ||
1499 | while ((tg = throtl_rb_first(parent_sq))) { | |
1500 | struct throtl_service_queue *sq = &tg->service_queue; | |
1501 | struct bio *bio; | |
1502 | ||
1503 | throtl_dequeue_tg(tg); | |
1504 | ||
c5cc2070 | 1505 | while ((bio = throtl_peek_queued(&sq->queued[READ]))) |
2a12f0dc | 1506 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
c5cc2070 | 1507 | while ((bio = throtl_peek_queued(&sq->queued[WRITE]))) |
2a12f0dc TH |
1508 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
1509 | } | |
1510 | } | |
1511 | ||
c9a929dd TH |
1512 | /** |
1513 | * blk_throtl_drain - drain throttled bios | |
1514 | * @q: request_queue to drain throttled bios for | |
1515 | * | |
1516 | * Dispatch all currently throttled bios on @q through ->make_request_fn(). | |
1517 | */ | |
1518 | void blk_throtl_drain(struct request_queue *q) | |
1519 | __releases(q->queue_lock) __acquires(q->queue_lock) | |
1520 | { | |
1521 | struct throtl_data *td = q->td; | |
2a12f0dc | 1522 | struct blkcg_gq *blkg; |
492eb21b | 1523 | struct cgroup_subsys_state *pos_css; |
c9a929dd | 1524 | struct bio *bio; |
651930bc | 1525 | int rw; |
c9a929dd | 1526 | |
8bcb6c7d | 1527 | queue_lockdep_assert_held(q); |
2a12f0dc | 1528 | rcu_read_lock(); |
c9a929dd | 1529 | |
2a12f0dc TH |
1530 | /* |
1531 | * Drain each tg while doing post-order walk on the blkg tree, so | |
1532 | * that all bios are propagated to td->service_queue. It'd be | |
1533 | * better to walk service_queue tree directly but blkg walk is | |
1534 | * easier. | |
1535 | */ | |
492eb21b | 1536 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) |
2a12f0dc | 1537 | tg_drain_bios(&blkg_to_tg(blkg)->service_queue); |
73f0d49a | 1538 | |
2a12f0dc TH |
1539 | /* finally, transfer bios from top-level tg's into the td */ |
1540 | tg_drain_bios(&td->service_queue); | |
1541 | ||
1542 | rcu_read_unlock(); | |
c9a929dd TH |
1543 | spin_unlock_irq(q->queue_lock); |
1544 | ||
2a12f0dc | 1545 | /* all bios now should be in td->service_queue, issue them */ |
651930bc | 1546 | for (rw = READ; rw <= WRITE; rw++) |
c5cc2070 TH |
1547 | while ((bio = throtl_pop_queued(&td->service_queue.queued[rw], |
1548 | NULL))) | |
651930bc | 1549 | generic_make_request(bio); |
c9a929dd TH |
1550 | |
1551 | spin_lock_irq(q->queue_lock); | |
1552 | } | |
1553 | ||
e43473b7 VG |
1554 | int blk_throtl_init(struct request_queue *q) |
1555 | { | |
1556 | struct throtl_data *td; | |
a2b1693b | 1557 | int ret; |
e43473b7 VG |
1558 | |
1559 | td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); | |
1560 | if (!td) | |
1561 | return -ENOMEM; | |
1562 | ||
69df0ab0 | 1563 | INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn); |
b2ce2643 | 1564 | throtl_service_queue_init(&td->service_queue); |
e43473b7 | 1565 | |
cd1604fa | 1566 | q->td = td; |
29b12589 | 1567 | td->queue = q; |
02977e4a | 1568 | |
a2b1693b | 1569 | /* activate policy */ |
3c798398 | 1570 | ret = blkcg_activate_policy(q, &blkcg_policy_throtl); |
a2b1693b | 1571 | if (ret) |
f51b802c | 1572 | kfree(td); |
a2b1693b | 1573 | return ret; |
e43473b7 VG |
1574 | } |
1575 | ||
1576 | void blk_throtl_exit(struct request_queue *q) | |
1577 | { | |
c875f4d0 | 1578 | BUG_ON(!q->td); |
da527770 | 1579 | throtl_shutdown_wq(q); |
3c798398 | 1580 | blkcg_deactivate_policy(q, &blkcg_policy_throtl); |
c9a929dd | 1581 | kfree(q->td); |
e43473b7 VG |
1582 | } |
1583 | ||
1584 | static int __init throtl_init(void) | |
1585 | { | |
450adcbe VG |
1586 | kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); |
1587 | if (!kthrotld_workqueue) | |
1588 | panic("Failed to create kthrotld\n"); | |
1589 | ||
3c798398 | 1590 | return blkcg_policy_register(&blkcg_policy_throtl); |
e43473b7 VG |
1591 | } |
1592 | ||
1593 | module_init(throtl_init); |