blob: 9273d0969ebd6377a02cf0be189d34ea619afe3e [file] [log] [blame]
Vivek Goyale43473b2010-09-15 17:06:35 -04001/*
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"
Tejun Heobc9fcbf2011-10-19 14:31:18 +020013#include "blk.h"
Vivek Goyale43473b2010-09-15 17:06:35 -040014
15/* Max dispatch from a group in 1 round */
16static int throtl_grp_quantum = 8;
17
18/* Total max dispatch from all groups in one round */
19static int throtl_quantum = 32;
20
21/* Throttling is performed over 100ms slice and after that slice is renewed */
22static unsigned long throtl_slice = HZ/10; /* 100 ms */
23
Tejun Heo3c798392012-04-16 13:57:25 -070024static struct blkcg_policy blkcg_policy_throtl;
Tejun Heo03814112012-03-05 13:15:14 -080025
Vivek Goyal450adcb2011-03-01 13:40:54 -050026/* A workqueue to queue throttle related work */
27static struct workqueue_struct *kthrotld_workqueue;
Vivek Goyal450adcb2011-03-01 13:40:54 -050028
Tejun Heoc5cc2072013-05-14 13:52:38 -070029/*
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 */
52struct 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
Tejun Heoc9e03322013-05-14 13:52:32 -070058struct throtl_service_queue {
Tejun Heo77216b02013-05-14 13:52:36 -070059 struct throtl_service_queue *parent_sq; /* the parent service_queue */
60
Tejun Heo73f0d492013-05-14 13:52:35 -070061 /*
62 * Bios queued directly to this service_queue or dispatched from
63 * children throtl_grp's.
64 */
Tejun Heoc5cc2072013-05-14 13:52:38 -070065 struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */
Tejun Heo73f0d492013-05-14 13:52:35 -070066 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 */
Tejun Heoc9e03322013-05-14 13:52:32 -070072 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 */
Tejun Heo69df0ab2013-05-14 13:52:36 -070076 struct timer_list pending_timer; /* fires on first_pending_disptime */
Vivek Goyale43473b2010-09-15 17:06:35 -040077};
78
Tejun Heo5b2c16a2013-05-14 13:52:32 -070079enum tg_state_flags {
80 THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */
Tejun Heo0e9f4162013-05-14 13:52:35 -070081 THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */
Tejun Heo5b2c16a2013-05-14 13:52:32 -070082};
83
Vivek Goyale43473b2010-09-15 17:06:35 -040084#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
85
Tejun Heo8a3d2612012-04-01 14:38:44 -070086/* Per-cpu group stats */
87struct tg_stats_cpu {
88 /* total bytes transferred */
89 struct blkg_rwstat service_bytes;
90 /* total IOs serviced, post merge */
91 struct blkg_rwstat serviced;
92};
93
Vivek Goyale43473b2010-09-15 17:06:35 -040094struct throtl_grp {
Tejun Heof95a04a2012-04-16 13:57:26 -070095 /* must be the first member */
96 struct blkg_policy_data pd;
97
Tejun Heoc9e03322013-05-14 13:52:32 -070098 /* active throtl group service_queue member */
Vivek Goyale43473b2010-09-15 17:06:35 -040099 struct rb_node rb_node;
100
Tejun Heo0f3457f2013-05-14 13:52:32 -0700101 /* throtl_data this group belongs to */
102 struct throtl_data *td;
103
Tejun Heo49a2f1e2013-05-14 13:52:34 -0700104 /* this group's service queue */
105 struct throtl_service_queue service_queue;
106
Vivek Goyale43473b2010-09-15 17:06:35 -0400107 /*
Tejun Heoc5cc2072013-05-14 13:52:38 -0700108 * qnode_on_self is used when bios are directly queued to this
109 * throtl_grp so that local bios compete fairly with bios
110 * dispatched from children. qnode_on_parent is used when bios are
111 * dispatched from this throtl_grp into its parent and will compete
112 * with the sibling qnode_on_parents and the parent's
113 * qnode_on_self.
114 */
115 struct throtl_qnode qnode_on_self[2];
116 struct throtl_qnode qnode_on_parent[2];
117
118 /*
Vivek Goyale43473b2010-09-15 17:06:35 -0400119 * Dispatch time in jiffies. This is the estimated time when group
120 * will unthrottle and is ready to dispatch more bio. It is used as
121 * key to sort active groups in service tree.
122 */
123 unsigned long disptime;
124
Vivek Goyale43473b2010-09-15 17:06:35 -0400125 unsigned int flags;
126
Tejun Heo693e7512013-05-14 13:52:38 -0700127 /* are there any throtl rules between this group and td? */
128 bool has_rules[2];
129
Vivek Goyale43473b2010-09-15 17:06:35 -0400130 /* bytes per second rate limits */
131 uint64_t bps[2];
132
Vivek Goyal8e89d132010-09-15 17:06:37 -0400133 /* IOPS limits */
134 unsigned int iops[2];
135
Vivek Goyale43473b2010-09-15 17:06:35 -0400136 /* Number of bytes disptached in current slice */
137 uint64_t bytes_disp[2];
Vivek Goyal8e89d132010-09-15 17:06:37 -0400138 /* Number of bio's dispatched in current slice */
139 unsigned int io_disp[2];
Vivek Goyale43473b2010-09-15 17:06:35 -0400140
141 /* When did we start a new slice */
142 unsigned long slice_start[2];
143 unsigned long slice_end[2];
Vivek Goyalfe071432010-10-01 14:49:49 +0200144
Tejun Heo8a3d2612012-04-01 14:38:44 -0700145 /* Per cpu stats pointer */
146 struct tg_stats_cpu __percpu *stats_cpu;
147
148 /* List of tgs waiting for per cpu stats memory to be allocated */
149 struct list_head stats_alloc_node;
Vivek Goyale43473b2010-09-15 17:06:35 -0400150};
151
152struct throtl_data
153{
Vivek Goyale43473b2010-09-15 17:06:35 -0400154 /* service tree for active throtl groups */
Tejun Heoc9e03322013-05-14 13:52:32 -0700155 struct throtl_service_queue service_queue;
Vivek Goyale43473b2010-09-15 17:06:35 -0400156
Vivek Goyale43473b2010-09-15 17:06:35 -0400157 struct request_queue *queue;
158
159 /* Total Number of queued bios on READ and WRITE lists */
160 unsigned int nr_queued[2];
161
162 /*
Vivek Goyal02977e42010-10-01 14:49:48 +0200163 * number of total undestroyed groups
Vivek Goyale43473b2010-09-15 17:06:35 -0400164 */
165 unsigned int nr_undestroyed_grps;
166
167 /* Work for dispatching throttled bios */
Tejun Heo69df0ab2013-05-14 13:52:36 -0700168 struct work_struct dispatch_work;
Vivek Goyale43473b2010-09-15 17:06:35 -0400169};
170
Tejun Heo8a3d2612012-04-01 14:38:44 -0700171/* list and work item to allocate percpu group stats */
172static DEFINE_SPINLOCK(tg_stats_alloc_lock);
173static LIST_HEAD(tg_stats_alloc_list);
174
175static void tg_stats_alloc_fn(struct work_struct *);
176static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn);
177
Tejun Heo69df0ab2013-05-14 13:52:36 -0700178static void throtl_pending_timer_fn(unsigned long arg);
179
Tejun Heof95a04a2012-04-16 13:57:26 -0700180static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
181{
182 return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
183}
184
Tejun Heo3c798392012-04-16 13:57:25 -0700185static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg)
Tejun Heo03814112012-03-05 13:15:14 -0800186{
Tejun Heof95a04a2012-04-16 13:57:26 -0700187 return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
Tejun Heo03814112012-03-05 13:15:14 -0800188}
189
Tejun Heo3c798392012-04-16 13:57:25 -0700190static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)
Tejun Heo03814112012-03-05 13:15:14 -0800191{
Tejun Heof95a04a2012-04-16 13:57:26 -0700192 return pd_to_blkg(&tg->pd);
Tejun Heo03814112012-03-05 13:15:14 -0800193}
194
Tejun Heo03d8e112012-04-13 13:11:32 -0700195static inline struct throtl_grp *td_root_tg(struct throtl_data *td)
196{
197 return blkg_to_tg(td->queue->root_blkg);
198}
199
Tejun Heofda6f272013-05-14 13:52:36 -0700200/**
201 * sq_to_tg - return the throl_grp the specified service queue belongs to
202 * @sq: the throtl_service_queue of interest
203 *
204 * Return the throtl_grp @sq belongs to. If @sq is the top-level one
205 * embedded in throtl_data, %NULL is returned.
206 */
207static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq)
208{
209 if (sq && sq->parent_sq)
210 return container_of(sq, struct throtl_grp, service_queue);
211 else
212 return NULL;
213}
Vivek Goyale43473b2010-09-15 17:06:35 -0400214
Tejun Heofda6f272013-05-14 13:52:36 -0700215/**
216 * sq_to_td - return throtl_data the specified service queue belongs to
217 * @sq: the throtl_service_queue of interest
218 *
219 * A service_queue can be embeded in either a throtl_grp or throtl_data.
220 * Determine the associated throtl_data accordingly and return it.
221 */
222static struct throtl_data *sq_to_td(struct throtl_service_queue *sq)
223{
224 struct throtl_grp *tg = sq_to_tg(sq);
225
226 if (tg)
227 return tg->td;
228 else
229 return container_of(sq, struct throtl_data, service_queue);
230}
231
232/**
233 * throtl_log - log debug message via blktrace
234 * @sq: the service_queue being reported
235 * @fmt: printf format string
236 * @args: printf args
237 *
238 * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a
239 * throtl_grp; otherwise, just "throtl".
240 *
241 * TODO: this should be made a function and name formatting should happen
242 * after testing whether blktrace is enabled.
243 */
244#define throtl_log(sq, fmt, args...) do { \
245 struct throtl_grp *__tg = sq_to_tg((sq)); \
246 struct throtl_data *__td = sq_to_td((sq)); \
247 \
248 (void)__td; \
249 if ((__tg)) { \
250 char __pbuf[128]; \
251 \
252 blkg_path(tg_to_blkg(__tg), __pbuf, sizeof(__pbuf)); \
253 blk_add_trace_msg(__td->queue, "throtl %s " fmt, __pbuf, ##args); \
254 } else { \
255 blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \
256 } \
257} while (0)
Vivek Goyale43473b2010-09-15 17:06:35 -0400258
Peter Zijlstra90d38392013-11-12 19:42:14 -0800259static void tg_stats_init(struct tg_stats_cpu *tg_stats)
260{
261 blkg_rwstat_init(&tg_stats->service_bytes);
262 blkg_rwstat_init(&tg_stats->serviced);
263}
264
Tejun Heo8a3d2612012-04-01 14:38:44 -0700265/*
266 * Worker for allocating per cpu stat for tgs. This is scheduled on the
Tejun Heo3b07e9c2012-08-20 14:51:24 -0700267 * system_wq once there are some groups on the alloc_list waiting for
Tejun Heo8a3d2612012-04-01 14:38:44 -0700268 * allocation.
269 */
270static void tg_stats_alloc_fn(struct work_struct *work)
271{
272 static struct tg_stats_cpu *stats_cpu; /* this fn is non-reentrant */
273 struct delayed_work *dwork = to_delayed_work(work);
274 bool empty = false;
275
276alloc_stats:
277 if (!stats_cpu) {
Peter Zijlstra90d38392013-11-12 19:42:14 -0800278 int cpu;
279
Tejun Heo8a3d2612012-04-01 14:38:44 -0700280 stats_cpu = alloc_percpu(struct tg_stats_cpu);
281 if (!stats_cpu) {
282 /* allocation failed, try again after some time */
Tejun Heo3b07e9c2012-08-20 14:51:24 -0700283 schedule_delayed_work(dwork, msecs_to_jiffies(10));
Tejun Heo8a3d2612012-04-01 14:38:44 -0700284 return;
285 }
Peter Zijlstra90d38392013-11-12 19:42:14 -0800286 for_each_possible_cpu(cpu)
287 tg_stats_init(per_cpu_ptr(stats_cpu, cpu));
Tejun Heo8a3d2612012-04-01 14:38:44 -0700288 }
289
290 spin_lock_irq(&tg_stats_alloc_lock);
291
292 if (!list_empty(&tg_stats_alloc_list)) {
293 struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list,
294 struct throtl_grp,
295 stats_alloc_node);
296 swap(tg->stats_cpu, stats_cpu);
297 list_del_init(&tg->stats_alloc_node);
298 }
299
300 empty = list_empty(&tg_stats_alloc_list);
301 spin_unlock_irq(&tg_stats_alloc_lock);
302 if (!empty)
303 goto alloc_stats;
304}
305
Tejun Heoc5cc2072013-05-14 13:52:38 -0700306static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg)
307{
308 INIT_LIST_HEAD(&qn->node);
309 bio_list_init(&qn->bios);
310 qn->tg = tg;
311}
312
313/**
314 * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it
315 * @bio: bio being added
316 * @qn: qnode to add bio to
317 * @queued: the service_queue->queued[] list @qn belongs to
318 *
319 * Add @bio to @qn and put @qn on @queued if it's not already on.
320 * @qn->tg's reference count is bumped when @qn is activated. See the
321 * comment on top of throtl_qnode definition for details.
322 */
323static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn,
324 struct list_head *queued)
325{
326 bio_list_add(&qn->bios, bio);
327 if (list_empty(&qn->node)) {
328 list_add_tail(&qn->node, queued);
329 blkg_get(tg_to_blkg(qn->tg));
330 }
331}
332
333/**
334 * throtl_peek_queued - peek the first bio on a qnode list
335 * @queued: the qnode list to peek
336 */
337static struct bio *throtl_peek_queued(struct list_head *queued)
338{
339 struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node);
340 struct bio *bio;
341
342 if (list_empty(queued))
343 return NULL;
344
345 bio = bio_list_peek(&qn->bios);
346 WARN_ON_ONCE(!bio);
347 return bio;
348}
349
350/**
351 * throtl_pop_queued - pop the first bio form a qnode list
352 * @queued: the qnode list to pop a bio from
353 * @tg_to_put: optional out argument for throtl_grp to put
354 *
355 * Pop the first bio from the qnode list @queued. After popping, the first
356 * qnode is removed from @queued if empty or moved to the end of @queued so
357 * that the popping order is round-robin.
358 *
359 * When the first qnode is removed, its associated throtl_grp should be put
360 * too. If @tg_to_put is NULL, this function automatically puts it;
361 * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is
362 * responsible for putting it.
363 */
364static struct bio *throtl_pop_queued(struct list_head *queued,
365 struct throtl_grp **tg_to_put)
366{
367 struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node);
368 struct bio *bio;
369
370 if (list_empty(queued))
371 return NULL;
372
373 bio = bio_list_pop(&qn->bios);
374 WARN_ON_ONCE(!bio);
375
376 if (bio_list_empty(&qn->bios)) {
377 list_del_init(&qn->node);
378 if (tg_to_put)
379 *tg_to_put = qn->tg;
380 else
381 blkg_put(tg_to_blkg(qn->tg));
382 } else {
383 list_move_tail(&qn->node, queued);
384 }
385
386 return bio;
387}
388
Tejun Heo49a2f1e2013-05-14 13:52:34 -0700389/* init a service_queue, assumes the caller zeroed it */
Tejun Heo77216b02013-05-14 13:52:36 -0700390static void throtl_service_queue_init(struct throtl_service_queue *sq,
391 struct throtl_service_queue *parent_sq)
Tejun Heo49a2f1e2013-05-14 13:52:34 -0700392{
Tejun Heoc5cc2072013-05-14 13:52:38 -0700393 INIT_LIST_HEAD(&sq->queued[0]);
394 INIT_LIST_HEAD(&sq->queued[1]);
Tejun Heo49a2f1e2013-05-14 13:52:34 -0700395 sq->pending_tree = RB_ROOT;
Tejun Heo77216b02013-05-14 13:52:36 -0700396 sq->parent_sq = parent_sq;
Tejun Heo69df0ab2013-05-14 13:52:36 -0700397 setup_timer(&sq->pending_timer, throtl_pending_timer_fn,
398 (unsigned long)sq);
399}
400
401static void throtl_service_queue_exit(struct throtl_service_queue *sq)
402{
403 del_timer_sync(&sq->pending_timer);
Tejun Heo49a2f1e2013-05-14 13:52:34 -0700404}
405
Tejun Heo3c798392012-04-16 13:57:25 -0700406static void throtl_pd_init(struct blkcg_gq *blkg)
Vivek Goyala29a1712011-05-19 15:38:19 -0400407{
Tejun Heo03814112012-03-05 13:15:14 -0800408 struct throtl_grp *tg = blkg_to_tg(blkg);
Tejun Heo77216b02013-05-14 13:52:36 -0700409 struct throtl_data *td = blkg->q->td;
Tejun Heo91381252013-05-14 13:52:38 -0700410 struct throtl_service_queue *parent_sq;
Tejun Heoff26eaa2012-05-23 12:16:21 +0200411 unsigned long flags;
Tejun Heoc5cc2072013-05-14 13:52:38 -0700412 int rw;
Tejun Heocd1604f2012-03-05 13:15:06 -0800413
Tejun Heo91381252013-05-14 13:52:38 -0700414 /*
Tejun Heoaa6ec292014-07-09 10:08:08 -0400415 * If on the default hierarchy, we switch to properly hierarchical
Tejun Heo91381252013-05-14 13:52:38 -0700416 * behavior where limits on a given throtl_grp are applied to the
417 * whole subtree rather than just the group itself. e.g. If 16M
418 * read_bps limit is set on the root group, the whole system can't
419 * exceed 16M for the device.
420 *
Tejun Heoaa6ec292014-07-09 10:08:08 -0400421 * If not on the default hierarchy, the broken flat hierarchy
Tejun Heo91381252013-05-14 13:52:38 -0700422 * behavior is retained where all throtl_grps are treated as if
423 * they're all separate root groups right below throtl_data.
424 * Limits of a group don't interact with limits of other groups
425 * regardless of the position of the group in the hierarchy.
426 */
427 parent_sq = &td->service_queue;
428
Tejun Heoaa6ec292014-07-09 10:08:08 -0400429 if (cgroup_on_dfl(blkg->blkcg->css.cgroup) && blkg->parent)
Tejun Heo91381252013-05-14 13:52:38 -0700430 parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
431
432 throtl_service_queue_init(&tg->service_queue, parent_sq);
433
Tejun Heoc5cc2072013-05-14 13:52:38 -0700434 for (rw = READ; rw <= WRITE; rw++) {
435 throtl_qnode_init(&tg->qnode_on_self[rw], tg);
436 throtl_qnode_init(&tg->qnode_on_parent[rw], tg);
437 }
438
Vivek Goyala29a1712011-05-19 15:38:19 -0400439 RB_CLEAR_NODE(&tg->rb_node);
Tejun Heo77216b02013-05-14 13:52:36 -0700440 tg->td = td;
Vivek Goyala29a1712011-05-19 15:38:19 -0400441
Tejun Heoe56da7e2012-03-05 13:15:07 -0800442 tg->bps[READ] = -1;
443 tg->bps[WRITE] = -1;
444 tg->iops[READ] = -1;
445 tg->iops[WRITE] = -1;
Tejun Heo8a3d2612012-04-01 14:38:44 -0700446
447 /*
448 * Ugh... We need to perform per-cpu allocation for tg->stats_cpu
449 * but percpu allocator can't be called from IO path. Queue tg on
450 * tg_stats_alloc_list and allocate from work item.
451 */
Tejun Heoff26eaa2012-05-23 12:16:21 +0200452 spin_lock_irqsave(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700453 list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);
Tejun Heo3b07e9c2012-08-20 14:51:24 -0700454 schedule_delayed_work(&tg_stats_alloc_work, 0);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200455 spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700456}
457
Tejun Heo693e7512013-05-14 13:52:38 -0700458/*
459 * Set has_rules[] if @tg or any of its parents have limits configured.
460 * This doesn't require walking up to the top of the hierarchy as the
461 * parent's has_rules[] is guaranteed to be correct.
462 */
463static void tg_update_has_rules(struct throtl_grp *tg)
464{
465 struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq);
466 int rw;
467
468 for (rw = READ; rw <= WRITE; rw++)
469 tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) ||
470 (tg->bps[rw] != -1 || tg->iops[rw] != -1);
471}
472
473static void throtl_pd_online(struct blkcg_gq *blkg)
474{
475 /*
476 * We don't want new groups to escape the limits of its ancestors.
477 * Update has_rules[] after a new group is brought online.
478 */
479 tg_update_has_rules(blkg_to_tg(blkg));
480}
481
Tejun Heo3c798392012-04-16 13:57:25 -0700482static void throtl_pd_exit(struct blkcg_gq *blkg)
Tejun Heo8a3d2612012-04-01 14:38:44 -0700483{
484 struct throtl_grp *tg = blkg_to_tg(blkg);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200485 unsigned long flags;
Tejun Heo8a3d2612012-04-01 14:38:44 -0700486
Tejun Heoff26eaa2012-05-23 12:16:21 +0200487 spin_lock_irqsave(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700488 list_del_init(&tg->stats_alloc_node);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200489 spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700490
491 free_percpu(tg->stats_cpu);
Tejun Heo69df0ab2013-05-14 13:52:36 -0700492
493 throtl_service_queue_exit(&tg->service_queue);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700494}
495
Tejun Heo3c798392012-04-16 13:57:25 -0700496static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
Tejun Heo8a3d2612012-04-01 14:38:44 -0700497{
498 struct throtl_grp *tg = blkg_to_tg(blkg);
499 int cpu;
500
501 if (tg->stats_cpu == NULL)
502 return;
503
504 for_each_possible_cpu(cpu) {
505 struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
506
507 blkg_rwstat_reset(&sc->service_bytes);
508 blkg_rwstat_reset(&sc->serviced);
509 }
Vivek Goyala29a1712011-05-19 15:38:19 -0400510}
511
Tejun Heo3c798392012-04-16 13:57:25 -0700512static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td,
513 struct blkcg *blkcg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400514{
Vivek Goyale43473b2010-09-15 17:06:35 -0400515 /*
Tejun Heo3c798392012-04-16 13:57:25 -0700516 * This is the common case when there are no blkcgs. Avoid lookup
517 * in this case
Tejun Heocd1604f2012-03-05 13:15:06 -0800518 */
Tejun Heo3c798392012-04-16 13:57:25 -0700519 if (blkcg == &blkcg_root)
Tejun Heo03d8e112012-04-13 13:11:32 -0700520 return td_root_tg(td);
Vivek Goyale43473b2010-09-15 17:06:35 -0400521
Tejun Heoe8989fa2012-03-05 13:15:20 -0800522 return blkg_to_tg(blkg_lookup(blkcg, td->queue));
Vivek Goyale43473b2010-09-15 17:06:35 -0400523}
524
Tejun Heocd1604f2012-03-05 13:15:06 -0800525static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
Tejun Heo3c798392012-04-16 13:57:25 -0700526 struct blkcg *blkcg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400527{
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400528 struct request_queue *q = td->queue;
Tejun Heocd1604f2012-03-05 13:15:06 -0800529 struct throtl_grp *tg = NULL;
Tejun Heo0a5a7d02012-03-05 13:15:02 -0800530
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400531 /*
Tejun Heo3c798392012-04-16 13:57:25 -0700532 * This is the common case when there are no blkcgs. Avoid lookup
533 * in this case
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400534 */
Tejun Heo3c798392012-04-16 13:57:25 -0700535 if (blkcg == &blkcg_root) {
Tejun Heo03d8e112012-04-13 13:11:32 -0700536 tg = td_root_tg(td);
Tejun Heocd1604f2012-03-05 13:15:06 -0800537 } else {
Tejun Heo3c798392012-04-16 13:57:25 -0700538 struct blkcg_gq *blkg;
Tejun Heocd1604f2012-03-05 13:15:06 -0800539
Tejun Heo3c96cb32012-04-13 13:11:34 -0700540 blkg = blkg_lookup_create(blkcg, q);
Tejun Heocd1604f2012-03-05 13:15:06 -0800541
542 /* if %NULL and @q is alive, fall back to root_tg */
543 if (!IS_ERR(blkg))
Tejun Heo03814112012-03-05 13:15:14 -0800544 tg = blkg_to_tg(blkg);
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100545 else if (!blk_queue_dying(q))
Tejun Heo03d8e112012-04-13 13:11:32 -0700546 tg = td_root_tg(td);
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400547 }
548
Vivek Goyale43473b2010-09-15 17:06:35 -0400549 return tg;
550}
551
Tejun Heo0049af72013-05-14 13:52:33 -0700552static struct throtl_grp *
553throtl_rb_first(struct throtl_service_queue *parent_sq)
Vivek Goyale43473b2010-09-15 17:06:35 -0400554{
555 /* Service tree is empty */
Tejun Heo0049af72013-05-14 13:52:33 -0700556 if (!parent_sq->nr_pending)
Vivek Goyale43473b2010-09-15 17:06:35 -0400557 return NULL;
558
Tejun Heo0049af72013-05-14 13:52:33 -0700559 if (!parent_sq->first_pending)
560 parent_sq->first_pending = rb_first(&parent_sq->pending_tree);
Vivek Goyale43473b2010-09-15 17:06:35 -0400561
Tejun Heo0049af72013-05-14 13:52:33 -0700562 if (parent_sq->first_pending)
563 return rb_entry_tg(parent_sq->first_pending);
Vivek Goyale43473b2010-09-15 17:06:35 -0400564
565 return NULL;
566}
567
568static void rb_erase_init(struct rb_node *n, struct rb_root *root)
569{
570 rb_erase(n, root);
571 RB_CLEAR_NODE(n);
572}
573
Tejun Heo0049af72013-05-14 13:52:33 -0700574static void throtl_rb_erase(struct rb_node *n,
575 struct throtl_service_queue *parent_sq)
Vivek Goyale43473b2010-09-15 17:06:35 -0400576{
Tejun Heo0049af72013-05-14 13:52:33 -0700577 if (parent_sq->first_pending == n)
578 parent_sq->first_pending = NULL;
579 rb_erase_init(n, &parent_sq->pending_tree);
580 --parent_sq->nr_pending;
Vivek Goyale43473b2010-09-15 17:06:35 -0400581}
582
Tejun Heo0049af72013-05-14 13:52:33 -0700583static void update_min_dispatch_time(struct throtl_service_queue *parent_sq)
Vivek Goyale43473b2010-09-15 17:06:35 -0400584{
585 struct throtl_grp *tg;
586
Tejun Heo0049af72013-05-14 13:52:33 -0700587 tg = throtl_rb_first(parent_sq);
Vivek Goyale43473b2010-09-15 17:06:35 -0400588 if (!tg)
589 return;
590
Tejun Heo0049af72013-05-14 13:52:33 -0700591 parent_sq->first_pending_disptime = tg->disptime;
Vivek Goyale43473b2010-09-15 17:06:35 -0400592}
593
Tejun Heo77216b02013-05-14 13:52:36 -0700594static void tg_service_queue_add(struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400595{
Tejun Heo77216b02013-05-14 13:52:36 -0700596 struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;
Tejun Heo0049af72013-05-14 13:52:33 -0700597 struct rb_node **node = &parent_sq->pending_tree.rb_node;
Vivek Goyale43473b2010-09-15 17:06:35 -0400598 struct rb_node *parent = NULL;
599 struct throtl_grp *__tg;
600 unsigned long key = tg->disptime;
601 int left = 1;
602
603 while (*node != NULL) {
604 parent = *node;
605 __tg = rb_entry_tg(parent);
606
607 if (time_before(key, __tg->disptime))
608 node = &parent->rb_left;
609 else {
610 node = &parent->rb_right;
611 left = 0;
612 }
613 }
614
615 if (left)
Tejun Heo0049af72013-05-14 13:52:33 -0700616 parent_sq->first_pending = &tg->rb_node;
Vivek Goyale43473b2010-09-15 17:06:35 -0400617
618 rb_link_node(&tg->rb_node, parent, node);
Tejun Heo0049af72013-05-14 13:52:33 -0700619 rb_insert_color(&tg->rb_node, &parent_sq->pending_tree);
Vivek Goyale43473b2010-09-15 17:06:35 -0400620}
621
Tejun Heo77216b02013-05-14 13:52:36 -0700622static void __throtl_enqueue_tg(struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400623{
Tejun Heo77216b02013-05-14 13:52:36 -0700624 tg_service_queue_add(tg);
Tejun Heo5b2c16a2013-05-14 13:52:32 -0700625 tg->flags |= THROTL_TG_PENDING;
Tejun Heo77216b02013-05-14 13:52:36 -0700626 tg->service_queue.parent_sq->nr_pending++;
Vivek Goyale43473b2010-09-15 17:06:35 -0400627}
628
Tejun Heo77216b02013-05-14 13:52:36 -0700629static void throtl_enqueue_tg(struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400630{
Tejun Heo5b2c16a2013-05-14 13:52:32 -0700631 if (!(tg->flags & THROTL_TG_PENDING))
Tejun Heo77216b02013-05-14 13:52:36 -0700632 __throtl_enqueue_tg(tg);
Vivek Goyale43473b2010-09-15 17:06:35 -0400633}
634
Tejun Heo77216b02013-05-14 13:52:36 -0700635static void __throtl_dequeue_tg(struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400636{
Tejun Heo77216b02013-05-14 13:52:36 -0700637 throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);
Tejun Heo5b2c16a2013-05-14 13:52:32 -0700638 tg->flags &= ~THROTL_TG_PENDING;
Vivek Goyale43473b2010-09-15 17:06:35 -0400639}
640
Tejun Heo77216b02013-05-14 13:52:36 -0700641static void throtl_dequeue_tg(struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400642{
Tejun Heo5b2c16a2013-05-14 13:52:32 -0700643 if (tg->flags & THROTL_TG_PENDING)
Tejun Heo77216b02013-05-14 13:52:36 -0700644 __throtl_dequeue_tg(tg);
Vivek Goyale43473b2010-09-15 17:06:35 -0400645}
646
Tejun Heoa9131a22013-05-14 13:52:31 -0700647/* Call with queue lock held */
Tejun Heo69df0ab2013-05-14 13:52:36 -0700648static void throtl_schedule_pending_timer(struct throtl_service_queue *sq,
649 unsigned long expires)
Tejun Heoa9131a22013-05-14 13:52:31 -0700650{
Tejun Heo69df0ab2013-05-14 13:52:36 -0700651 mod_timer(&sq->pending_timer, expires);
652 throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu",
653 expires - jiffies, jiffies);
Tejun Heoa9131a22013-05-14 13:52:31 -0700654}
655
Tejun Heo7f52f982013-05-14 13:52:37 -0700656/**
657 * throtl_schedule_next_dispatch - schedule the next dispatch cycle
658 * @sq: the service_queue to schedule dispatch for
659 * @force: force scheduling
660 *
661 * Arm @sq->pending_timer so that the next dispatch cycle starts on the
662 * dispatch time of the first pending child. Returns %true if either timer
663 * is armed or there's no pending child left. %false if the current
664 * dispatch window is still open and the caller should continue
665 * dispatching.
666 *
667 * If @force is %true, the dispatch timer is always scheduled and this
668 * function is guaranteed to return %true. This is to be used when the
669 * caller can't dispatch itself and needs to invoke pending_timer
670 * unconditionally. Note that forced scheduling is likely to induce short
671 * delay before dispatch starts even if @sq->first_pending_disptime is not
672 * in the future and thus shouldn't be used in hot paths.
673 */
674static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq,
675 bool force)
Vivek Goyale43473b2010-09-15 17:06:35 -0400676{
Tejun Heo6a525602013-05-14 13:52:32 -0700677 /* any pending children left? */
Tejun Heoc9e03322013-05-14 13:52:32 -0700678 if (!sq->nr_pending)
Tejun Heo7f52f982013-05-14 13:52:37 -0700679 return true;
Vivek Goyale43473b2010-09-15 17:06:35 -0400680
Tejun Heoc9e03322013-05-14 13:52:32 -0700681 update_min_dispatch_time(sq);
Vivek Goyale43473b2010-09-15 17:06:35 -0400682
Tejun Heo69df0ab2013-05-14 13:52:36 -0700683 /* is the next dispatch time in the future? */
Tejun Heo7f52f982013-05-14 13:52:37 -0700684 if (force || time_after(sq->first_pending_disptime, jiffies)) {
Tejun Heo69df0ab2013-05-14 13:52:36 -0700685 throtl_schedule_pending_timer(sq, sq->first_pending_disptime);
Tejun Heo7f52f982013-05-14 13:52:37 -0700686 return true;
Tejun Heo69df0ab2013-05-14 13:52:36 -0700687 }
688
Tejun Heo7f52f982013-05-14 13:52:37 -0700689 /* tell the caller to continue dispatching */
690 return false;
Vivek Goyale43473b2010-09-15 17:06:35 -0400691}
692
Vivek Goyal32ee5bc2013-05-14 13:52:38 -0700693static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg,
694 bool rw, unsigned long start)
695{
696 tg->bytes_disp[rw] = 0;
697 tg->io_disp[rw] = 0;
698
699 /*
700 * Previous slice has expired. We must have trimmed it after last
701 * bio dispatch. That means since start of last slice, we never used
702 * that bandwidth. Do try to make use of that bandwidth while giving
703 * credit.
704 */
705 if (time_after_eq(start, tg->slice_start[rw]))
706 tg->slice_start[rw] = start;
707
708 tg->slice_end[rw] = jiffies + throtl_slice;
709 throtl_log(&tg->service_queue,
710 "[%c] new slice with credit start=%lu end=%lu jiffies=%lu",
711 rw == READ ? 'R' : 'W', tg->slice_start[rw],
712 tg->slice_end[rw], jiffies);
713}
714
Tejun Heo0f3457f2013-05-14 13:52:32 -0700715static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw)
Vivek Goyale43473b2010-09-15 17:06:35 -0400716{
717 tg->bytes_disp[rw] = 0;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400718 tg->io_disp[rw] = 0;
Vivek Goyale43473b2010-09-15 17:06:35 -0400719 tg->slice_start[rw] = jiffies;
720 tg->slice_end[rw] = jiffies + throtl_slice;
Tejun Heofda6f272013-05-14 13:52:36 -0700721 throtl_log(&tg->service_queue,
722 "[%c] new slice start=%lu end=%lu jiffies=%lu",
723 rw == READ ? 'R' : 'W', tg->slice_start[rw],
724 tg->slice_end[rw], jiffies);
Vivek Goyale43473b2010-09-15 17:06:35 -0400725}
726
Tejun Heo0f3457f2013-05-14 13:52:32 -0700727static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw,
728 unsigned long jiffy_end)
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100729{
730 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
731}
732
Tejun Heo0f3457f2013-05-14 13:52:32 -0700733static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw,
734 unsigned long jiffy_end)
Vivek Goyale43473b2010-09-15 17:06:35 -0400735{
736 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
Tejun Heofda6f272013-05-14 13:52:36 -0700737 throtl_log(&tg->service_queue,
738 "[%c] extend slice start=%lu end=%lu jiffies=%lu",
739 rw == READ ? 'R' : 'W', tg->slice_start[rw],
740 tg->slice_end[rw], jiffies);
Vivek Goyale43473b2010-09-15 17:06:35 -0400741}
742
743/* Determine if previously allocated or extended slice is complete or not */
Tejun Heo0f3457f2013-05-14 13:52:32 -0700744static bool throtl_slice_used(struct throtl_grp *tg, bool rw)
Vivek Goyale43473b2010-09-15 17:06:35 -0400745{
746 if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
Fabian Frederick5cf8c222014-05-02 18:28:17 +0200747 return false;
Vivek Goyale43473b2010-09-15 17:06:35 -0400748
749 return 1;
750}
751
752/* Trim the used slices and adjust slice start accordingly */
Tejun Heo0f3457f2013-05-14 13:52:32 -0700753static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
Vivek Goyale43473b2010-09-15 17:06:35 -0400754{
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200755 unsigned long nr_slices, time_elapsed, io_trim;
756 u64 bytes_trim, tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400757
758 BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
759
760 /*
761 * If bps are unlimited (-1), then time slice don't get
762 * renewed. Don't try to trim the slice if slice is used. A new
763 * slice will start when appropriate.
764 */
Tejun Heo0f3457f2013-05-14 13:52:32 -0700765 if (throtl_slice_used(tg, rw))
Vivek Goyale43473b2010-09-15 17:06:35 -0400766 return;
767
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100768 /*
769 * A bio has been dispatched. Also adjust slice_end. It might happen
770 * that initially cgroup limit was very low resulting in high
771 * slice_end, but later limit was bumped up and bio was dispached
772 * sooner, then we need to reduce slice_end. A high bogus slice_end
773 * is bad because it does not allow new slice to start.
774 */
775
Tejun Heo0f3457f2013-05-14 13:52:32 -0700776 throtl_set_slice_end(tg, rw, jiffies + throtl_slice);
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100777
Vivek Goyale43473b2010-09-15 17:06:35 -0400778 time_elapsed = jiffies - tg->slice_start[rw];
779
780 nr_slices = time_elapsed / throtl_slice;
781
782 if (!nr_slices)
783 return;
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200784 tmp = tg->bps[rw] * throtl_slice * nr_slices;
785 do_div(tmp, HZ);
786 bytes_trim = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400787
Vivek Goyal8e89d132010-09-15 17:06:37 -0400788 io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
Vivek Goyale43473b2010-09-15 17:06:35 -0400789
Vivek Goyal8e89d132010-09-15 17:06:37 -0400790 if (!bytes_trim && !io_trim)
Vivek Goyale43473b2010-09-15 17:06:35 -0400791 return;
792
793 if (tg->bytes_disp[rw] >= bytes_trim)
794 tg->bytes_disp[rw] -= bytes_trim;
795 else
796 tg->bytes_disp[rw] = 0;
797
Vivek Goyal8e89d132010-09-15 17:06:37 -0400798 if (tg->io_disp[rw] >= io_trim)
799 tg->io_disp[rw] -= io_trim;
800 else
801 tg->io_disp[rw] = 0;
802
Vivek Goyale43473b2010-09-15 17:06:35 -0400803 tg->slice_start[rw] += nr_slices * throtl_slice;
804
Tejun Heofda6f272013-05-14 13:52:36 -0700805 throtl_log(&tg->service_queue,
806 "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu",
807 rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
808 tg->slice_start[rw], tg->slice_end[rw], jiffies);
Vivek Goyale43473b2010-09-15 17:06:35 -0400809}
810
Tejun Heo0f3457f2013-05-14 13:52:32 -0700811static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
812 unsigned long *wait)
Vivek Goyale43473b2010-09-15 17:06:35 -0400813{
814 bool rw = bio_data_dir(bio);
Vivek Goyal8e89d132010-09-15 17:06:37 -0400815 unsigned int io_allowed;
Vivek Goyale43473b2010-09-15 17:06:35 -0400816 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200817 u64 tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400818
Vivek Goyal8e89d132010-09-15 17:06:37 -0400819 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
Vivek Goyale43473b2010-09-15 17:06:35 -0400820
Vivek Goyal8e89d132010-09-15 17:06:37 -0400821 /* Slice has just started. Consider one slice interval */
822 if (!jiffy_elapsed)
823 jiffy_elapsed_rnd = throtl_slice;
824
825 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
826
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200827 /*
828 * jiffy_elapsed_rnd should not be a big value as minimum iops can be
829 * 1 then at max jiffy elapsed should be equivalent of 1 second as we
830 * will allow dispatch after 1 second and after that slice should
831 * have been trimmed.
832 */
833
834 tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
835 do_div(tmp, HZ);
836
837 if (tmp > UINT_MAX)
838 io_allowed = UINT_MAX;
839 else
840 io_allowed = tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400841
842 if (tg->io_disp[rw] + 1 <= io_allowed) {
Vivek Goyale43473b2010-09-15 17:06:35 -0400843 if (wait)
844 *wait = 0;
Fabian Frederick5cf8c222014-05-02 18:28:17 +0200845 return true;
Vivek Goyale43473b2010-09-15 17:06:35 -0400846 }
847
Vivek Goyal8e89d132010-09-15 17:06:37 -0400848 /* Calc approx time to dispatch */
849 jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
850
851 if (jiffy_wait > jiffy_elapsed)
852 jiffy_wait = jiffy_wait - jiffy_elapsed;
853 else
854 jiffy_wait = 1;
855
856 if (wait)
857 *wait = jiffy_wait;
858 return 0;
859}
860
Tejun Heo0f3457f2013-05-14 13:52:32 -0700861static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
862 unsigned long *wait)
Vivek Goyal8e89d132010-09-15 17:06:37 -0400863{
864 bool rw = bio_data_dir(bio);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200865 u64 bytes_allowed, extra_bytes, tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400866 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyale43473b2010-09-15 17:06:35 -0400867
868 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
869
870 /* Slice has just started. Consider one slice interval */
871 if (!jiffy_elapsed)
872 jiffy_elapsed_rnd = throtl_slice;
873
874 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
875
Vivek Goyal5e901a22010-10-01 21:16:38 +0200876 tmp = tg->bps[rw] * jiffy_elapsed_rnd;
877 do_div(tmp, HZ);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200878 bytes_allowed = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400879
Kent Overstreet4f024f32013-10-11 15:44:27 -0700880 if (tg->bytes_disp[rw] + bio->bi_iter.bi_size <= bytes_allowed) {
Vivek Goyale43473b2010-09-15 17:06:35 -0400881 if (wait)
882 *wait = 0;
Fabian Frederick5cf8c222014-05-02 18:28:17 +0200883 return true;
Vivek Goyale43473b2010-09-15 17:06:35 -0400884 }
885
886 /* Calc approx time to dispatch */
Kent Overstreet4f024f32013-10-11 15:44:27 -0700887 extra_bytes = tg->bytes_disp[rw] + bio->bi_iter.bi_size - bytes_allowed;
Vivek Goyale43473b2010-09-15 17:06:35 -0400888 jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
889
890 if (!jiffy_wait)
891 jiffy_wait = 1;
892
893 /*
894 * This wait time is without taking into consideration the rounding
895 * up we did. Add that time also.
896 */
897 jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
Vivek Goyale43473b2010-09-15 17:06:35 -0400898 if (wait)
899 *wait = jiffy_wait;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400900 return 0;
901}
Vivek Goyale43473b2010-09-15 17:06:35 -0400902
Vivek Goyal8e89d132010-09-15 17:06:37 -0400903/*
904 * Returns whether one can dispatch a bio or not. Also returns approx number
905 * of jiffies to wait before this bio is with-in IO rate and can be dispatched
906 */
Tejun Heo0f3457f2013-05-14 13:52:32 -0700907static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
908 unsigned long *wait)
Vivek Goyal8e89d132010-09-15 17:06:37 -0400909{
910 bool rw = bio_data_dir(bio);
911 unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
912
913 /*
914 * Currently whole state machine of group depends on first bio
915 * queued in the group bio list. So one should not be calling
916 * this function with a different bio if there are other bios
917 * queued.
918 */
Tejun Heo73f0d492013-05-14 13:52:35 -0700919 BUG_ON(tg->service_queue.nr_queued[rw] &&
Tejun Heoc5cc2072013-05-14 13:52:38 -0700920 bio != throtl_peek_queued(&tg->service_queue.queued[rw]));
Vivek Goyal8e89d132010-09-15 17:06:37 -0400921
922 /* If tg->bps = -1, then BW is unlimited */
923 if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
924 if (wait)
925 *wait = 0;
Fabian Frederick5cf8c222014-05-02 18:28:17 +0200926 return true;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400927 }
928
929 /*
930 * If previous slice expired, start a new one otherwise renew/extend
931 * existing slice to make sure it is at least throtl_slice interval
932 * long since now.
933 */
Tejun Heo0f3457f2013-05-14 13:52:32 -0700934 if (throtl_slice_used(tg, rw))
935 throtl_start_new_slice(tg, rw);
Vivek Goyal8e89d132010-09-15 17:06:37 -0400936 else {
937 if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
Tejun Heo0f3457f2013-05-14 13:52:32 -0700938 throtl_extend_slice(tg, rw, jiffies + throtl_slice);
Vivek Goyal8e89d132010-09-15 17:06:37 -0400939 }
940
Tejun Heo0f3457f2013-05-14 13:52:32 -0700941 if (tg_with_in_bps_limit(tg, bio, &bps_wait) &&
942 tg_with_in_iops_limit(tg, bio, &iops_wait)) {
Vivek Goyal8e89d132010-09-15 17:06:37 -0400943 if (wait)
944 *wait = 0;
945 return 1;
946 }
947
948 max_wait = max(bps_wait, iops_wait);
949
950 if (wait)
951 *wait = max_wait;
952
953 if (time_before(tg->slice_end[rw], jiffies + max_wait))
Tejun Heo0f3457f2013-05-14 13:52:32 -0700954 throtl_extend_slice(tg, rw, jiffies + max_wait);
Vivek Goyale43473b2010-09-15 17:06:35 -0400955
956 return 0;
957}
958
Tejun Heo3c798392012-04-16 13:57:25 -0700959static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes,
Tejun Heo629ed0b2012-04-01 14:38:44 -0700960 int rw)
961{
Tejun Heo8a3d2612012-04-01 14:38:44 -0700962 struct throtl_grp *tg = blkg_to_tg(blkg);
963 struct tg_stats_cpu *stats_cpu;
Tejun Heo629ed0b2012-04-01 14:38:44 -0700964 unsigned long flags;
965
966 /* If per cpu stats are not allocated yet, don't do any accounting. */
Tejun Heo8a3d2612012-04-01 14:38:44 -0700967 if (tg->stats_cpu == NULL)
Tejun Heo629ed0b2012-04-01 14:38:44 -0700968 return;
969
970 /*
971 * Disabling interrupts to provide mutual exclusion between two
972 * writes on same cpu. It probably is not needed for 64bit. Not
973 * optimizing that case yet.
974 */
975 local_irq_save(flags);
976
Tejun Heo8a3d2612012-04-01 14:38:44 -0700977 stats_cpu = this_cpu_ptr(tg->stats_cpu);
Tejun Heo629ed0b2012-04-01 14:38:44 -0700978
Tejun Heo629ed0b2012-04-01 14:38:44 -0700979 blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
980 blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
981
982 local_irq_restore(flags);
983}
984
Vivek Goyale43473b2010-09-15 17:06:35 -0400985static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
986{
987 bool rw = bio_data_dir(bio);
Vivek Goyale43473b2010-09-15 17:06:35 -0400988
989 /* Charge the bio to the group */
Kent Overstreet4f024f32013-10-11 15:44:27 -0700990 tg->bytes_disp[rw] += bio->bi_iter.bi_size;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400991 tg->io_disp[rw]++;
Vivek Goyale43473b2010-09-15 17:06:35 -0400992
Tejun Heo2a0f61e2013-05-14 13:52:36 -0700993 /*
994 * REQ_THROTTLED is used to prevent the same bio to be throttled
995 * more than once as a throttled bio will go through blk-throtl the
996 * second time when it eventually gets issued. Set it when a bio
997 * is being charged to a tg.
998 *
999 * Dispatch stats aren't recursive and each @bio should only be
1000 * accounted by the @tg it was originally associated with. Let's
1001 * update the stats when setting REQ_THROTTLED for the first time
1002 * which is guaranteed to be for the @bio's original tg.
1003 */
1004 if (!(bio->bi_rw & REQ_THROTTLED)) {
1005 bio->bi_rw |= REQ_THROTTLED;
Kent Overstreet4f024f32013-10-11 15:44:27 -07001006 throtl_update_dispatch_stats(tg_to_blkg(tg),
1007 bio->bi_iter.bi_size, bio->bi_rw);
Tejun Heo2a0f61e2013-05-14 13:52:36 -07001008 }
Vivek Goyale43473b2010-09-15 17:06:35 -04001009}
1010
Tejun Heoc5cc2072013-05-14 13:52:38 -07001011/**
1012 * throtl_add_bio_tg - add a bio to the specified throtl_grp
1013 * @bio: bio to add
1014 * @qn: qnode to use
1015 * @tg: the target throtl_grp
1016 *
1017 * Add @bio to @tg's service_queue using @qn. If @qn is not specified,
1018 * tg->qnode_on_self[] is used.
1019 */
1020static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn,
1021 struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -04001022{
Tejun Heo73f0d492013-05-14 13:52:35 -07001023 struct throtl_service_queue *sq = &tg->service_queue;
Vivek Goyale43473b2010-09-15 17:06:35 -04001024 bool rw = bio_data_dir(bio);
1025
Tejun Heoc5cc2072013-05-14 13:52:38 -07001026 if (!qn)
1027 qn = &tg->qnode_on_self[rw];
1028
Tejun Heo0e9f4162013-05-14 13:52:35 -07001029 /*
1030 * If @tg doesn't currently have any bios queued in the same
1031 * direction, queueing @bio can change when @tg should be
1032 * dispatched. Mark that @tg was empty. This is automatically
1033 * cleaered on the next tg_update_disptime().
1034 */
1035 if (!sq->nr_queued[rw])
1036 tg->flags |= THROTL_TG_WAS_EMPTY;
1037
Tejun Heoc5cc2072013-05-14 13:52:38 -07001038 throtl_qnode_add_bio(bio, qn, &sq->queued[rw]);
1039
Tejun Heo73f0d492013-05-14 13:52:35 -07001040 sq->nr_queued[rw]++;
Tejun Heo77216b02013-05-14 13:52:36 -07001041 throtl_enqueue_tg(tg);
Vivek Goyale43473b2010-09-15 17:06:35 -04001042}
1043
Tejun Heo77216b02013-05-14 13:52:36 -07001044static void tg_update_disptime(struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -04001045{
Tejun Heo73f0d492013-05-14 13:52:35 -07001046 struct throtl_service_queue *sq = &tg->service_queue;
Vivek Goyale43473b2010-09-15 17:06:35 -04001047 unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
1048 struct bio *bio;
1049
Tejun Heoc5cc2072013-05-14 13:52:38 -07001050 if ((bio = throtl_peek_queued(&sq->queued[READ])))
Tejun Heo0f3457f2013-05-14 13:52:32 -07001051 tg_may_dispatch(tg, bio, &read_wait);
Vivek Goyale43473b2010-09-15 17:06:35 -04001052
Tejun Heoc5cc2072013-05-14 13:52:38 -07001053 if ((bio = throtl_peek_queued(&sq->queued[WRITE])))
Tejun Heo0f3457f2013-05-14 13:52:32 -07001054 tg_may_dispatch(tg, bio, &write_wait);
Vivek Goyale43473b2010-09-15 17:06:35 -04001055
1056 min_wait = min(read_wait, write_wait);
1057 disptime = jiffies + min_wait;
1058
Vivek Goyale43473b2010-09-15 17:06:35 -04001059 /* Update dispatch time */
Tejun Heo77216b02013-05-14 13:52:36 -07001060 throtl_dequeue_tg(tg);
Vivek Goyale43473b2010-09-15 17:06:35 -04001061 tg->disptime = disptime;
Tejun Heo77216b02013-05-14 13:52:36 -07001062 throtl_enqueue_tg(tg);
Tejun Heo0e9f4162013-05-14 13:52:35 -07001063
1064 /* see throtl_add_bio_tg() */
1065 tg->flags &= ~THROTL_TG_WAS_EMPTY;
Vivek Goyale43473b2010-09-15 17:06:35 -04001066}
1067
Vivek Goyal32ee5bc2013-05-14 13:52:38 -07001068static void start_parent_slice_with_credit(struct throtl_grp *child_tg,
1069 struct throtl_grp *parent_tg, bool rw)
1070{
1071 if (throtl_slice_used(parent_tg, rw)) {
1072 throtl_start_new_slice_with_credit(parent_tg, rw,
1073 child_tg->slice_start[rw]);
1074 }
1075
1076}
1077
Tejun Heo77216b02013-05-14 13:52:36 -07001078static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw)
Vivek Goyale43473b2010-09-15 17:06:35 -04001079{
Tejun Heo73f0d492013-05-14 13:52:35 -07001080 struct throtl_service_queue *sq = &tg->service_queue;
Tejun Heo6bc9c2b2013-05-14 13:52:38 -07001081 struct throtl_service_queue *parent_sq = sq->parent_sq;
1082 struct throtl_grp *parent_tg = sq_to_tg(parent_sq);
Tejun Heoc5cc2072013-05-14 13:52:38 -07001083 struct throtl_grp *tg_to_put = NULL;
Vivek Goyale43473b2010-09-15 17:06:35 -04001084 struct bio *bio;
1085
Tejun Heoc5cc2072013-05-14 13:52:38 -07001086 /*
1087 * @bio is being transferred from @tg to @parent_sq. Popping a bio
1088 * from @tg may put its reference and @parent_sq might end up
1089 * getting released prematurely. Remember the tg to put and put it
1090 * after @bio is transferred to @parent_sq.
1091 */
1092 bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put);
Tejun Heo73f0d492013-05-14 13:52:35 -07001093 sq->nr_queued[rw]--;
Vivek Goyale43473b2010-09-15 17:06:35 -04001094
1095 throtl_charge_bio(tg, bio);
Tejun Heo6bc9c2b2013-05-14 13:52:38 -07001096
1097 /*
1098 * If our parent is another tg, we just need to transfer @bio to
1099 * the parent using throtl_add_bio_tg(). If our parent is
1100 * @td->service_queue, @bio is ready to be issued. Put it on its
1101 * bio_lists[] and decrease total number queued. The caller is
1102 * responsible for issuing these bios.
1103 */
1104 if (parent_tg) {
Tejun Heoc5cc2072013-05-14 13:52:38 -07001105 throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg);
Vivek Goyal32ee5bc2013-05-14 13:52:38 -07001106 start_parent_slice_with_credit(tg, parent_tg, rw);
Tejun Heo6bc9c2b2013-05-14 13:52:38 -07001107 } else {
Tejun Heoc5cc2072013-05-14 13:52:38 -07001108 throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw],
1109 &parent_sq->queued[rw]);
Tejun Heo6bc9c2b2013-05-14 13:52:38 -07001110 BUG_ON(tg->td->nr_queued[rw] <= 0);
1111 tg->td->nr_queued[rw]--;
1112 }
Vivek Goyale43473b2010-09-15 17:06:35 -04001113
Tejun Heo0f3457f2013-05-14 13:52:32 -07001114 throtl_trim_slice(tg, rw);
Tejun Heo6bc9c2b2013-05-14 13:52:38 -07001115
Tejun Heoc5cc2072013-05-14 13:52:38 -07001116 if (tg_to_put)
1117 blkg_put(tg_to_blkg(tg_to_put));
Vivek Goyale43473b2010-09-15 17:06:35 -04001118}
1119
Tejun Heo77216b02013-05-14 13:52:36 -07001120static int throtl_dispatch_tg(struct throtl_grp *tg)
Vivek Goyale43473b2010-09-15 17:06:35 -04001121{
Tejun Heo73f0d492013-05-14 13:52:35 -07001122 struct throtl_service_queue *sq = &tg->service_queue;
Vivek Goyale43473b2010-09-15 17:06:35 -04001123 unsigned int nr_reads = 0, nr_writes = 0;
1124 unsigned int max_nr_reads = throtl_grp_quantum*3/4;
Vivek Goyalc2f68052010-11-15 19:32:42 +01001125 unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
Vivek Goyale43473b2010-09-15 17:06:35 -04001126 struct bio *bio;
1127
1128 /* Try to dispatch 75% READS and 25% WRITES */
1129
Tejun Heoc5cc2072013-05-14 13:52:38 -07001130 while ((bio = throtl_peek_queued(&sq->queued[READ])) &&
Tejun Heo0f3457f2013-05-14 13:52:32 -07001131 tg_may_dispatch(tg, bio, NULL)) {
Vivek Goyale43473b2010-09-15 17:06:35 -04001132
Tejun Heo77216b02013-05-14 13:52:36 -07001133 tg_dispatch_one_bio(tg, bio_data_dir(bio));
Vivek Goyale43473b2010-09-15 17:06:35 -04001134 nr_reads++;
1135
1136 if (nr_reads >= max_nr_reads)
1137 break;
1138 }
1139
Tejun Heoc5cc2072013-05-14 13:52:38 -07001140 while ((bio = throtl_peek_queued(&sq->queued[WRITE])) &&
Tejun Heo0f3457f2013-05-14 13:52:32 -07001141 tg_may_dispatch(tg, bio, NULL)) {
Vivek Goyale43473b2010-09-15 17:06:35 -04001142
Tejun Heo77216b02013-05-14 13:52:36 -07001143 tg_dispatch_one_bio(tg, bio_data_dir(bio));
Vivek Goyale43473b2010-09-15 17:06:35 -04001144 nr_writes++;
1145
1146 if (nr_writes >= max_nr_writes)
1147 break;
1148 }
1149
1150 return nr_reads + nr_writes;
1151}
1152
Tejun Heo651930b2013-05-14 13:52:35 -07001153static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
Vivek Goyale43473b2010-09-15 17:06:35 -04001154{
1155 unsigned int nr_disp = 0;
Vivek Goyale43473b2010-09-15 17:06:35 -04001156
1157 while (1) {
Tejun Heo73f0d492013-05-14 13:52:35 -07001158 struct throtl_grp *tg = throtl_rb_first(parent_sq);
1159 struct throtl_service_queue *sq = &tg->service_queue;
Vivek Goyale43473b2010-09-15 17:06:35 -04001160
1161 if (!tg)
1162 break;
1163
1164 if (time_before(jiffies, tg->disptime))
1165 break;
1166
Tejun Heo77216b02013-05-14 13:52:36 -07001167 throtl_dequeue_tg(tg);
Vivek Goyale43473b2010-09-15 17:06:35 -04001168
Tejun Heo77216b02013-05-14 13:52:36 -07001169 nr_disp += throtl_dispatch_tg(tg);
Vivek Goyale43473b2010-09-15 17:06:35 -04001170
Tejun Heo73f0d492013-05-14 13:52:35 -07001171 if (sq->nr_queued[0] || sq->nr_queued[1])
Tejun Heo77216b02013-05-14 13:52:36 -07001172 tg_update_disptime(tg);
Vivek Goyale43473b2010-09-15 17:06:35 -04001173
1174 if (nr_disp >= throtl_quantum)
1175 break;
1176 }
1177
1178 return nr_disp;
1179}
1180
Tejun Heo6e1a5702013-05-14 13:52:37 -07001181/**
1182 * throtl_pending_timer_fn - timer function for service_queue->pending_timer
1183 * @arg: the throtl_service_queue being serviced
1184 *
1185 * This timer is armed when a child throtl_grp with active bio's become
1186 * pending and queued on the service_queue's pending_tree and expires when
1187 * the first child throtl_grp should be dispatched. This function
Tejun Heo2e48a532013-05-14 13:52:38 -07001188 * dispatches bio's from the children throtl_grps to the parent
1189 * service_queue.
1190 *
1191 * If the parent's parent is another throtl_grp, dispatching is propagated
1192 * by either arming its pending_timer or repeating dispatch directly. If
1193 * the top-level service_tree is reached, throtl_data->dispatch_work is
1194 * kicked so that the ready bio's are issued.
Tejun Heo6e1a5702013-05-14 13:52:37 -07001195 */
Tejun Heo69df0ab2013-05-14 13:52:36 -07001196static void throtl_pending_timer_fn(unsigned long arg)
1197{
1198 struct throtl_service_queue *sq = (void *)arg;
Tejun Heo2e48a532013-05-14 13:52:38 -07001199 struct throtl_grp *tg = sq_to_tg(sq);
Tejun Heo69df0ab2013-05-14 13:52:36 -07001200 struct throtl_data *td = sq_to_td(sq);
Tejun Heocb761992013-05-14 13:52:31 -07001201 struct request_queue *q = td->queue;
Tejun Heo2e48a532013-05-14 13:52:38 -07001202 struct throtl_service_queue *parent_sq;
1203 bool dispatched;
Tejun Heo6e1a5702013-05-14 13:52:37 -07001204 int ret;
Vivek Goyale43473b2010-09-15 17:06:35 -04001205
1206 spin_lock_irq(q->queue_lock);
Tejun Heo2e48a532013-05-14 13:52:38 -07001207again:
1208 parent_sq = sq->parent_sq;
1209 dispatched = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001210
Tejun Heo7f52f982013-05-14 13:52:37 -07001211 while (true) {
1212 throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u",
Tejun Heo2e48a532013-05-14 13:52:38 -07001213 sq->nr_queued[READ] + sq->nr_queued[WRITE],
1214 sq->nr_queued[READ], sq->nr_queued[WRITE]);
Vivek Goyale43473b2010-09-15 17:06:35 -04001215
Tejun Heo7f52f982013-05-14 13:52:37 -07001216 ret = throtl_select_dispatch(sq);
1217 if (ret) {
Tejun Heo7f52f982013-05-14 13:52:37 -07001218 throtl_log(sq, "bios disp=%u", ret);
1219 dispatched = true;
Tejun Heo651930b2013-05-14 13:52:35 -07001220 }
Vivek Goyale43473b2010-09-15 17:06:35 -04001221
Tejun Heo7f52f982013-05-14 13:52:37 -07001222 if (throtl_schedule_next_dispatch(sq, false))
1223 break;
1224
1225 /* this dispatch windows is still open, relax and repeat */
1226 spin_unlock_irq(q->queue_lock);
1227 cpu_relax();
1228 spin_lock_irq(q->queue_lock);
1229 }
Tejun Heo6a525602013-05-14 13:52:32 -07001230
Tejun Heo2e48a532013-05-14 13:52:38 -07001231 if (!dispatched)
1232 goto out_unlock;
Tejun Heo6e1a5702013-05-14 13:52:37 -07001233
Tejun Heo2e48a532013-05-14 13:52:38 -07001234 if (parent_sq) {
1235 /* @parent_sq is another throl_grp, propagate dispatch */
1236 if (tg->flags & THROTL_TG_WAS_EMPTY) {
1237 tg_update_disptime(tg);
1238 if (!throtl_schedule_next_dispatch(parent_sq, false)) {
1239 /* window is already open, repeat dispatching */
1240 sq = parent_sq;
1241 tg = sq_to_tg(sq);
1242 goto again;
1243 }
1244 }
1245 } else {
1246 /* reached the top-level, queue issueing */
1247 queue_work(kthrotld_workqueue, &td->dispatch_work);
1248 }
1249out_unlock:
Tejun Heo6e1a5702013-05-14 13:52:37 -07001250 spin_unlock_irq(q->queue_lock);
1251}
1252
1253/**
1254 * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work
1255 * @work: work item being executed
1256 *
1257 * This function is queued for execution when bio's reach the bio_lists[]
1258 * of throtl_data->service_queue. Those bio's are ready and issued by this
1259 * function.
1260 */
Fabian Frederick8876e1402014-04-17 21:41:16 +02001261static void blk_throtl_dispatch_work_fn(struct work_struct *work)
Tejun Heo6e1a5702013-05-14 13:52:37 -07001262{
1263 struct throtl_data *td = container_of(work, struct throtl_data,
1264 dispatch_work);
1265 struct throtl_service_queue *td_sq = &td->service_queue;
1266 struct request_queue *q = td->queue;
1267 struct bio_list bio_list_on_stack;
1268 struct bio *bio;
1269 struct blk_plug plug;
1270 int rw;
1271
1272 bio_list_init(&bio_list_on_stack);
1273
1274 spin_lock_irq(q->queue_lock);
Tejun Heoc5cc2072013-05-14 13:52:38 -07001275 for (rw = READ; rw <= WRITE; rw++)
1276 while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL)))
1277 bio_list_add(&bio_list_on_stack, bio);
Vivek Goyale43473b2010-09-15 17:06:35 -04001278 spin_unlock_irq(q->queue_lock);
1279
Tejun Heo6e1a5702013-05-14 13:52:37 -07001280 if (!bio_list_empty(&bio_list_on_stack)) {
Vivek Goyal69d60eb2011-03-09 08:27:37 +01001281 blk_start_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -04001282 while((bio = bio_list_pop(&bio_list_on_stack)))
1283 generic_make_request(bio);
Vivek Goyal69d60eb2011-03-09 08:27:37 +01001284 blk_finish_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -04001285 }
Vivek Goyale43473b2010-09-15 17:06:35 -04001286}
1287
Tejun Heof95a04a2012-04-16 13:57:26 -07001288static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
1289 struct blkg_policy_data *pd, int off)
Tejun Heo41b38b62012-04-01 14:38:44 -07001290{
Tejun Heof95a04a2012-04-16 13:57:26 -07001291 struct throtl_grp *tg = pd_to_tg(pd);
Tejun Heo41b38b62012-04-01 14:38:44 -07001292 struct blkg_rwstat rwstat = { }, tmp;
1293 int i, cpu;
1294
1295 for_each_possible_cpu(cpu) {
Tejun Heo8a3d2612012-04-01 14:38:44 -07001296 struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
Tejun Heo41b38b62012-04-01 14:38:44 -07001297
1298 tmp = blkg_rwstat_read((void *)sc + off);
1299 for (i = 0; i < BLKG_RWSTAT_NR; i++)
1300 rwstat.cnt[i] += tmp.cnt[i];
1301 }
1302
Tejun Heof95a04a2012-04-16 13:57:26 -07001303 return __blkg_prfill_rwstat(sf, pd, &rwstat);
Tejun Heo41b38b62012-04-01 14:38:44 -07001304}
1305
Tejun Heo2da8ca82013-12-05 12:28:04 -05001306static int tg_print_cpu_rwstat(struct seq_file *sf, void *v)
Tejun Heo41b38b62012-04-01 14:38:44 -07001307{
Tejun Heo2da8ca82013-12-05 12:28:04 -05001308 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_cpu_rwstat,
1309 &blkcg_policy_throtl, seq_cft(sf)->private, true);
Tejun Heo41b38b62012-04-01 14:38:44 -07001310 return 0;
1311}
1312
Tejun Heof95a04a2012-04-16 13:57:26 -07001313static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
1314 int off)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001315{
Tejun Heof95a04a2012-04-16 13:57:26 -07001316 struct throtl_grp *tg = pd_to_tg(pd);
1317 u64 v = *(u64 *)((void *)tg + off);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001318
Tejun Heoaf133ce2012-04-01 14:38:44 -07001319 if (v == -1)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001320 return 0;
Tejun Heof95a04a2012-04-16 13:57:26 -07001321 return __blkg_prfill_u64(sf, pd, v);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001322}
1323
Tejun Heof95a04a2012-04-16 13:57:26 -07001324static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,
1325 int off)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001326{
Tejun Heof95a04a2012-04-16 13:57:26 -07001327 struct throtl_grp *tg = pd_to_tg(pd);
1328 unsigned int v = *(unsigned int *)((void *)tg + off);
Tejun Heoaf133ce2012-04-01 14:38:44 -07001329
1330 if (v == -1)
1331 return 0;
Tejun Heof95a04a2012-04-16 13:57:26 -07001332 return __blkg_prfill_u64(sf, pd, v);
Tejun Heoaf133ce2012-04-01 14:38:44 -07001333}
1334
Tejun Heo2da8ca82013-12-05 12:28:04 -05001335static int tg_print_conf_u64(struct seq_file *sf, void *v)
Tejun Heoaf133ce2012-04-01 14:38:44 -07001336{
Tejun Heo2da8ca82013-12-05 12:28:04 -05001337 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64,
1338 &blkcg_policy_throtl, seq_cft(sf)->private, false);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001339 return 0;
1340}
1341
Tejun Heo2da8ca82013-12-05 12:28:04 -05001342static int tg_print_conf_uint(struct seq_file *sf, void *v)
Vivek Goyale43473b2010-09-15 17:06:35 -04001343{
Tejun Heo2da8ca82013-12-05 12:28:04 -05001344 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint,
1345 &blkcg_policy_throtl, seq_cft(sf)->private, false);
Tejun Heoaf133ce2012-04-01 14:38:44 -07001346 return 0;
Vivek Goyale43473b2010-09-15 17:06:35 -04001347}
1348
Tejun Heo451af502014-05-13 12:16:21 -04001349static ssize_t tg_set_conf(struct kernfs_open_file *of,
1350 char *buf, size_t nbytes, loff_t off, bool is_u64)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001351{
Tejun Heo451af502014-05-13 12:16:21 -04001352 struct blkcg *blkcg = css_to_blkcg(of_css(of));
Tejun Heo60c2bc22012-04-01 14:38:43 -07001353 struct blkg_conf_ctx ctx;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001354 struct throtl_grp *tg;
Tejun Heo69df0ab2013-05-14 13:52:36 -07001355 struct throtl_service_queue *sq;
Tejun Heo693e7512013-05-14 13:52:38 -07001356 struct blkcg_gq *blkg;
Tejun Heo492eb212013-08-08 20:11:25 -04001357 struct cgroup_subsys_state *pos_css;
Tejun Heo60c2bc22012-04-01 14:38:43 -07001358 int ret;
1359
Tejun Heo3c798392012-04-16 13:57:25 -07001360 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001361 if (ret)
1362 return ret;
1363
Tejun Heoaf133ce2012-04-01 14:38:44 -07001364 tg = blkg_to_tg(ctx.blkg);
Tejun Heo69df0ab2013-05-14 13:52:36 -07001365 sq = &tg->service_queue;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001366
Tejun Heoa2b16932012-04-13 13:11:33 -07001367 if (!ctx.v)
1368 ctx.v = -1;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001369
Tejun Heoa2b16932012-04-13 13:11:33 -07001370 if (is_u64)
Tejun Heo451af502014-05-13 12:16:21 -04001371 *(u64 *)((void *)tg + of_cft(of)->private) = ctx.v;
Tejun Heoa2b16932012-04-13 13:11:33 -07001372 else
Tejun Heo451af502014-05-13 12:16:21 -04001373 *(unsigned int *)((void *)tg + of_cft(of)->private) = ctx.v;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001374
Tejun Heofda6f272013-05-14 13:52:36 -07001375 throtl_log(&tg->service_queue,
1376 "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
1377 tg->bps[READ], tg->bps[WRITE],
1378 tg->iops[READ], tg->iops[WRITE]);
Tejun Heo632b4492013-05-14 13:52:31 -07001379
1380 /*
Tejun Heo693e7512013-05-14 13:52:38 -07001381 * Update has_rules[] flags for the updated tg's subtree. A tg is
1382 * considered to have rules if either the tg itself or any of its
1383 * ancestors has rules. This identifies groups without any
1384 * restrictions in the whole hierarchy and allows them to bypass
1385 * blk-throttle.
1386 */
Tejun Heo492eb212013-08-08 20:11:25 -04001387 blkg_for_each_descendant_pre(blkg, pos_css, ctx.blkg)
Tejun Heo693e7512013-05-14 13:52:38 -07001388 tg_update_has_rules(blkg_to_tg(blkg));
1389
1390 /*
Tejun Heo632b4492013-05-14 13:52:31 -07001391 * We're already holding queue_lock and know @tg is valid. Let's
1392 * apply the new config directly.
1393 *
1394 * Restart the slices for both READ and WRITES. It might happen
1395 * that a group's limit are dropped suddenly and we don't want to
1396 * account recently dispatched IO with new low rate.
1397 */
Tejun Heo0f3457f2013-05-14 13:52:32 -07001398 throtl_start_new_slice(tg, 0);
1399 throtl_start_new_slice(tg, 1);
Tejun Heo632b4492013-05-14 13:52:31 -07001400
Tejun Heo5b2c16a2013-05-14 13:52:32 -07001401 if (tg->flags & THROTL_TG_PENDING) {
Tejun Heo77216b02013-05-14 13:52:36 -07001402 tg_update_disptime(tg);
Tejun Heo7f52f982013-05-14 13:52:37 -07001403 throtl_schedule_next_dispatch(sq->parent_sq, true);
Tejun Heo632b4492013-05-14 13:52:31 -07001404 }
Tejun Heo60c2bc22012-04-01 14:38:43 -07001405
1406 blkg_conf_finish(&ctx);
Tejun Heo451af502014-05-13 12:16:21 -04001407 return nbytes;
Tejun Heo60c2bc22012-04-01 14:38:43 -07001408}
1409
Tejun Heo451af502014-05-13 12:16:21 -04001410static ssize_t tg_set_conf_u64(struct kernfs_open_file *of,
1411 char *buf, size_t nbytes, loff_t off)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001412{
Tejun Heo451af502014-05-13 12:16:21 -04001413 return tg_set_conf(of, buf, nbytes, off, true);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001414}
1415
Tejun Heo451af502014-05-13 12:16:21 -04001416static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,
1417 char *buf, size_t nbytes, loff_t off)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001418{
Tejun Heo451af502014-05-13 12:16:21 -04001419 return tg_set_conf(of, buf, nbytes, off, false);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001420}
1421
1422static struct cftype throtl_files[] = {
1423 {
1424 .name = "throttle.read_bps_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001425 .private = offsetof(struct throtl_grp, bps[READ]),
Tejun Heo2da8ca82013-12-05 12:28:04 -05001426 .seq_show = tg_print_conf_u64,
Tejun Heo451af502014-05-13 12:16:21 -04001427 .write = tg_set_conf_u64,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001428 },
1429 {
1430 .name = "throttle.write_bps_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001431 .private = offsetof(struct throtl_grp, bps[WRITE]),
Tejun Heo2da8ca82013-12-05 12:28:04 -05001432 .seq_show = tg_print_conf_u64,
Tejun Heo451af502014-05-13 12:16:21 -04001433 .write = tg_set_conf_u64,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001434 },
1435 {
1436 .name = "throttle.read_iops_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001437 .private = offsetof(struct throtl_grp, iops[READ]),
Tejun Heo2da8ca82013-12-05 12:28:04 -05001438 .seq_show = tg_print_conf_uint,
Tejun Heo451af502014-05-13 12:16:21 -04001439 .write = tg_set_conf_uint,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001440 },
1441 {
1442 .name = "throttle.write_iops_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001443 .private = offsetof(struct throtl_grp, iops[WRITE]),
Tejun Heo2da8ca82013-12-05 12:28:04 -05001444 .seq_show = tg_print_conf_uint,
Tejun Heo451af502014-05-13 12:16:21 -04001445 .write = tg_set_conf_uint,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001446 },
1447 {
1448 .name = "throttle.io_service_bytes",
Tejun Heo5bc4afb12012-04-01 14:38:45 -07001449 .private = offsetof(struct tg_stats_cpu, service_bytes),
Tejun Heo2da8ca82013-12-05 12:28:04 -05001450 .seq_show = tg_print_cpu_rwstat,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001451 },
1452 {
1453 .name = "throttle.io_serviced",
Tejun Heo5bc4afb12012-04-01 14:38:45 -07001454 .private = offsetof(struct tg_stats_cpu, serviced),
Tejun Heo2da8ca82013-12-05 12:28:04 -05001455 .seq_show = tg_print_cpu_rwstat,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001456 },
1457 { } /* terminate */
1458};
1459
Vivek Goyalda527772011-03-02 19:05:33 -05001460static void throtl_shutdown_wq(struct request_queue *q)
Vivek Goyale43473b2010-09-15 17:06:35 -04001461{
1462 struct throtl_data *td = q->td;
1463
Tejun Heo69df0ab2013-05-14 13:52:36 -07001464 cancel_work_sync(&td->dispatch_work);
Vivek Goyale43473b2010-09-15 17:06:35 -04001465}
1466
Tejun Heo3c798392012-04-16 13:57:25 -07001467static struct blkcg_policy blkcg_policy_throtl = {
Tejun Heof9fcc2d2012-04-16 13:57:27 -07001468 .pd_size = sizeof(struct throtl_grp),
1469 .cftypes = throtl_files,
1470
1471 .pd_init_fn = throtl_pd_init,
Tejun Heo693e7512013-05-14 13:52:38 -07001472 .pd_online_fn = throtl_pd_online,
Tejun Heof9fcc2d2012-04-16 13:57:27 -07001473 .pd_exit_fn = throtl_pd_exit,
1474 .pd_reset_stats_fn = throtl_pd_reset_stats,
Vivek Goyale43473b2010-09-15 17:06:35 -04001475};
1476
Tejun Heobc16a4f2011-10-19 14:33:01 +02001477bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
Vivek Goyale43473b2010-09-15 17:06:35 -04001478{
1479 struct throtl_data *td = q->td;
Tejun Heoc5cc2072013-05-14 13:52:38 -07001480 struct throtl_qnode *qn = NULL;
Vivek Goyale43473b2010-09-15 17:06:35 -04001481 struct throtl_grp *tg;
Tejun Heo73f0d492013-05-14 13:52:35 -07001482 struct throtl_service_queue *sq;
Tejun Heo0e9f4162013-05-14 13:52:35 -07001483 bool rw = bio_data_dir(bio);
Tejun Heo3c798392012-04-16 13:57:25 -07001484 struct blkcg *blkcg;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001485 bool throttled = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001486
Tejun Heo2a0f61e2013-05-14 13:52:36 -07001487 /* see throtl_charge_bio() */
1488 if (bio->bi_rw & REQ_THROTTLED)
Tejun Heobc16a4f2011-10-19 14:33:01 +02001489 goto out;
Vivek Goyale43473b2010-09-15 17:06:35 -04001490
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001491 /*
1492 * A throtl_grp pointer retrieved under rcu can be used to access
1493 * basic fields like stats and io rates. If a group has no rules,
1494 * just update the dispatch stats in lockless manner and return.
1495 */
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001496 rcu_read_lock();
Tejun Heo3c798392012-04-16 13:57:25 -07001497 blkcg = bio_blkcg(bio);
Tejun Heocd1604f2012-03-05 13:15:06 -08001498 tg = throtl_lookup_tg(td, blkcg);
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001499 if (tg) {
Tejun Heo693e7512013-05-14 13:52:38 -07001500 if (!tg->has_rules[rw]) {
Tejun Heo629ed0b2012-04-01 14:38:44 -07001501 throtl_update_dispatch_stats(tg_to_blkg(tg),
Kent Overstreet4f024f32013-10-11 15:44:27 -07001502 bio->bi_iter.bi_size, bio->bi_rw);
Tejun Heo2a7f1242012-03-05 13:15:01 -08001503 goto out_unlock_rcu;
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001504 }
1505 }
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001506
1507 /*
1508 * Either group has not been allocated yet or it is not an unlimited
1509 * IO group
1510 */
Vivek Goyale43473b2010-09-15 17:06:35 -04001511 spin_lock_irq(q->queue_lock);
Tejun Heocd1604f2012-03-05 13:15:06 -08001512 tg = throtl_lookup_create_tg(td, blkcg);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001513 if (unlikely(!tg))
1514 goto out_unlock;
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001515
Tejun Heo73f0d492013-05-14 13:52:35 -07001516 sq = &tg->service_queue;
1517
Tejun Heo9e660ac2013-05-14 13:52:38 -07001518 while (true) {
1519 /* throtl is FIFO - if bios are already queued, should queue */
1520 if (sq->nr_queued[rw])
1521 break;
Vivek Goyalde701c72011-03-07 21:09:32 +01001522
Tejun Heo9e660ac2013-05-14 13:52:38 -07001523 /* if above limits, break to queue */
1524 if (!tg_may_dispatch(tg, bio, NULL))
1525 break;
1526
1527 /* within limits, let's charge and dispatch directly */
Vivek Goyale43473b2010-09-15 17:06:35 -04001528 throtl_charge_bio(tg, bio);
Vivek Goyal04521db2011-03-22 21:54:29 +01001529
1530 /*
1531 * We need to trim slice even when bios are not being queued
1532 * otherwise it might happen that a bio is not queued for
1533 * a long time and slice keeps on extending and trim is not
1534 * called for a long time. Now if limits are reduced suddenly
1535 * we take into account all the IO dispatched so far at new
1536 * low rate and * newly queued IO gets a really long dispatch
1537 * time.
1538 *
1539 * So keep on trimming slice even if bio is not queued.
1540 */
Tejun Heo0f3457f2013-05-14 13:52:32 -07001541 throtl_trim_slice(tg, rw);
Tejun Heo9e660ac2013-05-14 13:52:38 -07001542
1543 /*
1544 * @bio passed through this layer without being throttled.
1545 * Climb up the ladder. If we''re already at the top, it
1546 * can be executed directly.
1547 */
Tejun Heoc5cc2072013-05-14 13:52:38 -07001548 qn = &tg->qnode_on_parent[rw];
Tejun Heo9e660ac2013-05-14 13:52:38 -07001549 sq = sq->parent_sq;
1550 tg = sq_to_tg(sq);
1551 if (!tg)
1552 goto out_unlock;
Vivek Goyale43473b2010-09-15 17:06:35 -04001553 }
1554
Tejun Heo9e660ac2013-05-14 13:52:38 -07001555 /* out-of-limit, queue to @tg */
Tejun Heofda6f272013-05-14 13:52:36 -07001556 throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d",
1557 rw == READ ? 'R' : 'W',
Kent Overstreet4f024f32013-10-11 15:44:27 -07001558 tg->bytes_disp[rw], bio->bi_iter.bi_size, tg->bps[rw],
Tejun Heofda6f272013-05-14 13:52:36 -07001559 tg->io_disp[rw], tg->iops[rw],
1560 sq->nr_queued[READ], sq->nr_queued[WRITE]);
Vivek Goyale43473b2010-09-15 17:06:35 -04001561
Tejun Heo671058f2012-03-05 13:15:29 -08001562 bio_associate_current(bio);
Tejun Heo6bc9c2b2013-05-14 13:52:38 -07001563 tg->td->nr_queued[rw]++;
Tejun Heoc5cc2072013-05-14 13:52:38 -07001564 throtl_add_bio_tg(bio, qn, tg);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001565 throttled = true;
Vivek Goyale43473b2010-09-15 17:06:35 -04001566
Tejun Heo7f52f982013-05-14 13:52:37 -07001567 /*
1568 * Update @tg's dispatch time and force schedule dispatch if @tg
1569 * was empty before @bio. The forced scheduling isn't likely to
1570 * cause undue delay as @bio is likely to be dispatched directly if
1571 * its @tg's disptime is not in the future.
1572 */
Tejun Heo0e9f4162013-05-14 13:52:35 -07001573 if (tg->flags & THROTL_TG_WAS_EMPTY) {
Tejun Heo77216b02013-05-14 13:52:36 -07001574 tg_update_disptime(tg);
Tejun Heo7f52f982013-05-14 13:52:37 -07001575 throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true);
Vivek Goyale43473b2010-09-15 17:06:35 -04001576 }
1577
Tejun Heobc16a4f2011-10-19 14:33:01 +02001578out_unlock:
Vivek Goyale43473b2010-09-15 17:06:35 -04001579 spin_unlock_irq(q->queue_lock);
Tejun Heo2a7f1242012-03-05 13:15:01 -08001580out_unlock_rcu:
1581 rcu_read_unlock();
Tejun Heobc16a4f2011-10-19 14:33:01 +02001582out:
Tejun Heo2a0f61e2013-05-14 13:52:36 -07001583 /*
1584 * As multiple blk-throtls may stack in the same issue path, we
1585 * don't want bios to leave with the flag set. Clear the flag if
1586 * being issued.
1587 */
1588 if (!throttled)
1589 bio->bi_rw &= ~REQ_THROTTLED;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001590 return throttled;
Vivek Goyale43473b2010-09-15 17:06:35 -04001591}
1592
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001593/*
1594 * Dispatch all bios from all children tg's queued on @parent_sq. On
1595 * return, @parent_sq is guaranteed to not have any active children tg's
1596 * and all bios from previously active tg's are on @parent_sq->bio_lists[].
1597 */
1598static void tg_drain_bios(struct throtl_service_queue *parent_sq)
1599{
1600 struct throtl_grp *tg;
1601
1602 while ((tg = throtl_rb_first(parent_sq))) {
1603 struct throtl_service_queue *sq = &tg->service_queue;
1604 struct bio *bio;
1605
1606 throtl_dequeue_tg(tg);
1607
Tejun Heoc5cc2072013-05-14 13:52:38 -07001608 while ((bio = throtl_peek_queued(&sq->queued[READ])))
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001609 tg_dispatch_one_bio(tg, bio_data_dir(bio));
Tejun Heoc5cc2072013-05-14 13:52:38 -07001610 while ((bio = throtl_peek_queued(&sq->queued[WRITE])))
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001611 tg_dispatch_one_bio(tg, bio_data_dir(bio));
1612 }
1613}
1614
Tejun Heoc9a929d2011-10-19 14:42:16 +02001615/**
1616 * blk_throtl_drain - drain throttled bios
1617 * @q: request_queue to drain throttled bios for
1618 *
1619 * Dispatch all currently throttled bios on @q through ->make_request_fn().
1620 */
1621void blk_throtl_drain(struct request_queue *q)
1622 __releases(q->queue_lock) __acquires(q->queue_lock)
1623{
1624 struct throtl_data *td = q->td;
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001625 struct blkcg_gq *blkg;
Tejun Heo492eb212013-08-08 20:11:25 -04001626 struct cgroup_subsys_state *pos_css;
Tejun Heoc9a929d2011-10-19 14:42:16 +02001627 struct bio *bio;
Tejun Heo651930b2013-05-14 13:52:35 -07001628 int rw;
Tejun Heoc9a929d2011-10-19 14:42:16 +02001629
Andi Kleen8bcb6c72012-03-30 12:33:28 +02001630 queue_lockdep_assert_held(q);
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001631 rcu_read_lock();
Tejun Heoc9a929d2011-10-19 14:42:16 +02001632
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001633 /*
1634 * Drain each tg while doing post-order walk on the blkg tree, so
1635 * that all bios are propagated to td->service_queue. It'd be
1636 * better to walk service_queue tree directly but blkg walk is
1637 * easier.
1638 */
Tejun Heo492eb212013-08-08 20:11:25 -04001639 blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg)
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001640 tg_drain_bios(&blkg_to_tg(blkg)->service_queue);
Tejun Heo73f0d492013-05-14 13:52:35 -07001641
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001642 /* finally, transfer bios from top-level tg's into the td */
1643 tg_drain_bios(&td->service_queue);
1644
1645 rcu_read_unlock();
Tejun Heoc9a929d2011-10-19 14:42:16 +02001646 spin_unlock_irq(q->queue_lock);
1647
Tejun Heo2a12f0d2013-05-14 13:52:37 -07001648 /* all bios now should be in td->service_queue, issue them */
Tejun Heo651930b2013-05-14 13:52:35 -07001649 for (rw = READ; rw <= WRITE; rw++)
Tejun Heoc5cc2072013-05-14 13:52:38 -07001650 while ((bio = throtl_pop_queued(&td->service_queue.queued[rw],
1651 NULL)))
Tejun Heo651930b2013-05-14 13:52:35 -07001652 generic_make_request(bio);
Tejun Heoc9a929d2011-10-19 14:42:16 +02001653
1654 spin_lock_irq(q->queue_lock);
1655}
1656
Vivek Goyale43473b2010-09-15 17:06:35 -04001657int blk_throtl_init(struct request_queue *q)
1658{
1659 struct throtl_data *td;
Tejun Heoa2b16932012-04-13 13:11:33 -07001660 int ret;
Vivek Goyale43473b2010-09-15 17:06:35 -04001661
1662 td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
1663 if (!td)
1664 return -ENOMEM;
1665
Tejun Heo69df0ab2013-05-14 13:52:36 -07001666 INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
Tejun Heo77216b02013-05-14 13:52:36 -07001667 throtl_service_queue_init(&td->service_queue, NULL);
Vivek Goyale43473b2010-09-15 17:06:35 -04001668
Tejun Heocd1604f2012-03-05 13:15:06 -08001669 q->td = td;
Vivek Goyal29b12582011-05-19 15:38:24 -04001670 td->queue = q;
Vivek Goyal02977e42010-10-01 14:49:48 +02001671
Tejun Heoa2b16932012-04-13 13:11:33 -07001672 /* activate policy */
Tejun Heo3c798392012-04-16 13:57:25 -07001673 ret = blkcg_activate_policy(q, &blkcg_policy_throtl);
Tejun Heoa2b16932012-04-13 13:11:33 -07001674 if (ret)
Vivek Goyal29b12582011-05-19 15:38:24 -04001675 kfree(td);
Tejun Heoa2b16932012-04-13 13:11:33 -07001676 return ret;
Vivek Goyale43473b2010-09-15 17:06:35 -04001677}
1678
1679void blk_throtl_exit(struct request_queue *q)
1680{
Tejun Heoc875f4d2012-03-05 13:15:22 -08001681 BUG_ON(!q->td);
Vivek Goyalda527772011-03-02 19:05:33 -05001682 throtl_shutdown_wq(q);
Tejun Heo3c798392012-04-16 13:57:25 -07001683 blkcg_deactivate_policy(q, &blkcg_policy_throtl);
Tejun Heoc9a929d2011-10-19 14:42:16 +02001684 kfree(q->td);
Vivek Goyale43473b2010-09-15 17:06:35 -04001685}
1686
1687static int __init throtl_init(void)
1688{
Vivek Goyal450adcb2011-03-01 13:40:54 -05001689 kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
1690 if (!kthrotld_workqueue)
1691 panic("Failed to create kthrotld\n");
1692
Tejun Heo3c798392012-04-16 13:57:25 -07001693 return blkcg_policy_register(&blkcg_policy_throtl);
Vivek Goyale43473b2010-09-15 17:06:35 -04001694}
1695
1696module_init(throtl_init);