Merge branch 'firewire-kernel-streaming' of git://git.alsa-project.org/alsa-kprivate
[firewire-audio.git] / block / cfq-iosched.c
blobea83a4f0c27dfda658ee41d87979a2d57c58450d
1 /*
2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8 */
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
17 #include "cfq.h"
20 * tunables
22 /* max queue in one round of service */
23 static const int cfq_quantum = 8;
24 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
25 /* maximum backwards seek, in KiB */
26 static const int cfq_back_max = 16 * 1024;
27 /* penalty of a backwards seek */
28 static const int cfq_back_penalty = 2;
29 static const int cfq_slice_sync = HZ / 10;
30 static int cfq_slice_async = HZ / 25;
31 static const int cfq_slice_async_rq = 2;
32 static int cfq_slice_idle = HZ / 125;
33 static int cfq_group_idle = HZ / 125;
34 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
35 static const int cfq_hist_divisor = 4;
38 * offset from end of service tree
40 #define CFQ_IDLE_DELAY (HZ / 5)
43 * below this threshold, we consider thinktime immediate
45 #define CFQ_MIN_TT (2)
47 #define CFQ_SLICE_SCALE (5)
48 #define CFQ_HW_QUEUE_MIN (5)
49 #define CFQ_SERVICE_SHIFT 12
51 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
52 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
53 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
54 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
56 #define RQ_CIC(rq) \
57 ((struct cfq_io_context *) (rq)->elevator_private)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
61 static struct kmem_cache *cfq_pool;
62 static struct kmem_cache *cfq_ioc_pool;
64 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
65 static struct completion *ioc_gone;
66 static DEFINE_SPINLOCK(ioc_gone_lock);
68 static DEFINE_SPINLOCK(cic_index_lock);
69 static DEFINE_IDA(cic_index_ida);
71 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
72 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
73 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
75 #define sample_valid(samples) ((samples) > 80)
76 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
84 struct cfq_rb_root {
85 struct rb_root rb;
86 struct rb_node *left;
87 unsigned count;
88 unsigned total_weight;
89 u64 min_vdisktime;
91 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
92 .count = 0, .min_vdisktime = 0, }
95 * Per process-grouping structure
97 struct cfq_queue {
98 /* reference count */
99 int ref;
100 /* various state flags, see below */
101 unsigned int flags;
102 /* parent cfq_data */
103 struct cfq_data *cfqd;
104 /* service_tree member */
105 struct rb_node rb_node;
106 /* service_tree key */
107 unsigned long rb_key;
108 /* prio tree member */
109 struct rb_node p_node;
110 /* prio tree root we belong to, if any */
111 struct rb_root *p_root;
112 /* sorted list of pending requests */
113 struct rb_root sort_list;
114 /* if fifo isn't expired, next request to serve */
115 struct request *next_rq;
116 /* requests queued in sort_list */
117 int queued[2];
118 /* currently allocated requests */
119 int allocated[2];
120 /* fifo list of requests in sort_list */
121 struct list_head fifo;
123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start;
125 unsigned int allocated_slice;
126 unsigned int slice_dispatch;
127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start;
129 unsigned long slice_end;
130 long slice_resid;
132 /* pending metadata requests */
133 int meta_pending;
134 /* number of requests that are on the dispatch list or inside driver */
135 int dispatched;
137 /* io prio of this group */
138 unsigned short ioprio, org_ioprio;
139 unsigned short ioprio_class, org_ioprio_class;
141 pid_t pid;
143 u32 seek_history;
144 sector_t last_request_pos;
146 struct cfq_rb_root *service_tree;
147 struct cfq_queue *new_cfqq;
148 struct cfq_group *cfqg;
149 struct cfq_group *orig_cfqg;
150 /* Number of sectors dispatched from queue in single dispatch round */
151 unsigned long nr_sectors;
155 * First index in the service_trees.
156 * IDLE is handled separately, so it has negative index
158 enum wl_prio_t {
159 BE_WORKLOAD = 0,
160 RT_WORKLOAD = 1,
161 IDLE_WORKLOAD = 2,
162 CFQ_PRIO_NR,
166 * Second index in the service_trees.
168 enum wl_type_t {
169 ASYNC_WORKLOAD = 0,
170 SYNC_NOIDLE_WORKLOAD = 1,
171 SYNC_WORKLOAD = 2
174 /* This is per cgroup per device grouping structure */
175 struct cfq_group {
176 /* group service_tree member */
177 struct rb_node rb_node;
179 /* group service_tree key */
180 u64 vdisktime;
181 unsigned int weight;
183 /* number of cfqq currently on this group */
184 int nr_cfqq;
187 * Per group busy queus average. Useful for workload slice calc. We
188 * create the array for each prio class but at run time it is used
189 * only for RT and BE class and slot for IDLE class remains unused.
190 * This is primarily done to avoid confusion and a gcc warning.
192 unsigned int busy_queues_avg[CFQ_PRIO_NR];
194 * rr lists of queues with requests. We maintain service trees for
195 * RT and BE classes. These trees are subdivided in subclasses
196 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
197 * class there is no subclassification and all the cfq queues go on
198 * a single tree service_tree_idle.
199 * Counts are embedded in the cfq_rb_root
201 struct cfq_rb_root service_trees[2][3];
202 struct cfq_rb_root service_tree_idle;
204 unsigned long saved_workload_slice;
205 enum wl_type_t saved_workload;
206 enum wl_prio_t saved_serving_prio;
207 struct blkio_group blkg;
208 #ifdef CONFIG_CFQ_GROUP_IOSCHED
209 struct hlist_node cfqd_node;
210 int ref;
211 #endif
212 /* number of requests that are on the dispatch list or inside driver */
213 int dispatched;
217 * Per block device queue structure
219 struct cfq_data {
220 struct request_queue *queue;
221 /* Root service tree for cfq_groups */
222 struct cfq_rb_root grp_service_tree;
223 struct cfq_group root_group;
226 * The priority currently being served
228 enum wl_prio_t serving_prio;
229 enum wl_type_t serving_type;
230 unsigned long workload_expires;
231 struct cfq_group *serving_group;
234 * Each priority tree is sorted by next_request position. These
235 * trees are used when determining if two or more queues are
236 * interleaving requests (see cfq_close_cooperator).
238 struct rb_root prio_trees[CFQ_PRIO_LISTS];
240 unsigned int busy_queues;
242 int rq_in_driver;
243 int rq_in_flight[2];
246 * queue-depth detection
248 int rq_queued;
249 int hw_tag;
251 * hw_tag can be
252 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
253 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
254 * 0 => no NCQ
256 int hw_tag_est_depth;
257 unsigned int hw_tag_samples;
260 * idle window management
262 struct timer_list idle_slice_timer;
263 struct work_struct unplug_work;
265 struct cfq_queue *active_queue;
266 struct cfq_io_context *active_cic;
269 * async queue for each priority case
271 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
272 struct cfq_queue *async_idle_cfqq;
274 sector_t last_position;
277 * tunables, see top of file
279 unsigned int cfq_quantum;
280 unsigned int cfq_fifo_expire[2];
281 unsigned int cfq_back_penalty;
282 unsigned int cfq_back_max;
283 unsigned int cfq_slice[2];
284 unsigned int cfq_slice_async_rq;
285 unsigned int cfq_slice_idle;
286 unsigned int cfq_group_idle;
287 unsigned int cfq_latency;
288 unsigned int cfq_group_isolation;
290 unsigned int cic_index;
291 struct list_head cic_list;
294 * Fallback dummy cfqq for extreme OOM conditions
296 struct cfq_queue oom_cfqq;
298 unsigned long last_delayed_sync;
300 /* List of cfq groups being managed on this device*/
301 struct hlist_head cfqg_list;
302 struct rcu_head rcu;
305 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
307 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
308 enum wl_prio_t prio,
309 enum wl_type_t type)
311 if (!cfqg)
312 return NULL;
314 if (prio == IDLE_WORKLOAD)
315 return &cfqg->service_tree_idle;
317 return &cfqg->service_trees[prio][type];
320 enum cfqq_state_flags {
321 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
322 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
323 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
324 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
325 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
326 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
327 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
328 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
329 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
330 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
331 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
332 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
333 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
336 #define CFQ_CFQQ_FNS(name) \
337 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
339 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
341 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
343 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
345 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
347 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
350 CFQ_CFQQ_FNS(on_rr);
351 CFQ_CFQQ_FNS(wait_request);
352 CFQ_CFQQ_FNS(must_dispatch);
353 CFQ_CFQQ_FNS(must_alloc_slice);
354 CFQ_CFQQ_FNS(fifo_expire);
355 CFQ_CFQQ_FNS(idle_window);
356 CFQ_CFQQ_FNS(prio_changed);
357 CFQ_CFQQ_FNS(slice_new);
358 CFQ_CFQQ_FNS(sync);
359 CFQ_CFQQ_FNS(coop);
360 CFQ_CFQQ_FNS(split_coop);
361 CFQ_CFQQ_FNS(deep);
362 CFQ_CFQQ_FNS(wait_busy);
363 #undef CFQ_CFQQ_FNS
365 #ifdef CONFIG_CFQ_GROUP_IOSCHED
366 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
367 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
368 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
369 blkg_path(&(cfqq)->cfqg->blkg), ##args);
371 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
372 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
373 blkg_path(&(cfqg)->blkg), ##args); \
375 #else
376 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
377 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
378 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
379 #endif
380 #define cfq_log(cfqd, fmt, args...) \
381 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
383 /* Traverses through cfq group service trees */
384 #define for_each_cfqg_st(cfqg, i, j, st) \
385 for (i = 0; i <= IDLE_WORKLOAD; i++) \
386 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
387 : &cfqg->service_tree_idle; \
388 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
389 (i == IDLE_WORKLOAD && j == 0); \
390 j++, st = i < IDLE_WORKLOAD ? \
391 &cfqg->service_trees[i][j]: NULL) \
394 static inline bool iops_mode(struct cfq_data *cfqd)
397 * If we are not idling on queues and it is a NCQ drive, parallel
398 * execution of requests is on and measuring time is not possible
399 * in most of the cases until and unless we drive shallower queue
400 * depths and that becomes a performance bottleneck. In such cases
401 * switch to start providing fairness in terms of number of IOs.
403 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
404 return true;
405 else
406 return false;
409 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
411 if (cfq_class_idle(cfqq))
412 return IDLE_WORKLOAD;
413 if (cfq_class_rt(cfqq))
414 return RT_WORKLOAD;
415 return BE_WORKLOAD;
419 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
421 if (!cfq_cfqq_sync(cfqq))
422 return ASYNC_WORKLOAD;
423 if (!cfq_cfqq_idle_window(cfqq))
424 return SYNC_NOIDLE_WORKLOAD;
425 return SYNC_WORKLOAD;
428 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
429 struct cfq_data *cfqd,
430 struct cfq_group *cfqg)
432 if (wl == IDLE_WORKLOAD)
433 return cfqg->service_tree_idle.count;
435 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
436 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
437 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
440 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
441 struct cfq_group *cfqg)
443 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
444 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
447 static void cfq_dispatch_insert(struct request_queue *, struct request *);
448 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
449 struct io_context *, gfp_t);
450 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
451 struct io_context *);
453 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
454 bool is_sync)
456 return cic->cfqq[is_sync];
459 static inline void cic_set_cfqq(struct cfq_io_context *cic,
460 struct cfq_queue *cfqq, bool is_sync)
462 cic->cfqq[is_sync] = cfqq;
465 #define CIC_DEAD_KEY 1ul
466 #define CIC_DEAD_INDEX_SHIFT 1
468 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
470 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
473 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
475 struct cfq_data *cfqd = cic->key;
477 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
478 return NULL;
480 return cfqd;
484 * We regard a request as SYNC, if it's either a read or has the SYNC bit
485 * set (in which case it could also be direct WRITE).
487 static inline bool cfq_bio_sync(struct bio *bio)
489 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
493 * scheduler run of queue, if there are requests pending and no one in the
494 * driver that will restart queueing
496 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
498 if (cfqd->busy_queues) {
499 cfq_log(cfqd, "schedule dispatch");
500 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
504 static int cfq_queue_empty(struct request_queue *q)
506 struct cfq_data *cfqd = q->elevator->elevator_data;
508 return !cfqd->rq_queued;
512 * Scale schedule slice based on io priority. Use the sync time slice only
513 * if a queue is marked sync and has sync io queued. A sync queue with async
514 * io only, should not get full sync slice length.
516 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
517 unsigned short prio)
519 const int base_slice = cfqd->cfq_slice[sync];
521 WARN_ON(prio >= IOPRIO_BE_NR);
523 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
526 static inline int
527 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
529 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
532 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
534 u64 d = delta << CFQ_SERVICE_SHIFT;
536 d = d * BLKIO_WEIGHT_DEFAULT;
537 do_div(d, cfqg->weight);
538 return d;
541 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
543 s64 delta = (s64)(vdisktime - min_vdisktime);
544 if (delta > 0)
545 min_vdisktime = vdisktime;
547 return min_vdisktime;
550 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
552 s64 delta = (s64)(vdisktime - min_vdisktime);
553 if (delta < 0)
554 min_vdisktime = vdisktime;
556 return min_vdisktime;
559 static void update_min_vdisktime(struct cfq_rb_root *st)
561 u64 vdisktime = st->min_vdisktime;
562 struct cfq_group *cfqg;
564 if (st->left) {
565 cfqg = rb_entry_cfqg(st->left);
566 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
569 st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
573 * get averaged number of queues of RT/BE priority.
574 * average is updated, with a formula that gives more weight to higher numbers,
575 * to quickly follows sudden increases and decrease slowly
578 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
579 struct cfq_group *cfqg, bool rt)
581 unsigned min_q, max_q;
582 unsigned mult = cfq_hist_divisor - 1;
583 unsigned round = cfq_hist_divisor / 2;
584 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
586 min_q = min(cfqg->busy_queues_avg[rt], busy);
587 max_q = max(cfqg->busy_queues_avg[rt], busy);
588 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
589 cfq_hist_divisor;
590 return cfqg->busy_queues_avg[rt];
593 static inline unsigned
594 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
596 struct cfq_rb_root *st = &cfqd->grp_service_tree;
598 return cfq_target_latency * cfqg->weight / st->total_weight;
601 static inline unsigned
602 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
604 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
605 if (cfqd->cfq_latency) {
607 * interested queues (we consider only the ones with the same
608 * priority class in the cfq group)
610 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
611 cfq_class_rt(cfqq));
612 unsigned sync_slice = cfqd->cfq_slice[1];
613 unsigned expect_latency = sync_slice * iq;
614 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
616 if (expect_latency > group_slice) {
617 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
618 /* scale low_slice according to IO priority
619 * and sync vs async */
620 unsigned low_slice =
621 min(slice, base_low_slice * slice / sync_slice);
622 /* the adapted slice value is scaled to fit all iqs
623 * into the target latency */
624 slice = max(slice * group_slice / expect_latency,
625 low_slice);
628 return slice;
631 static inline void
632 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
634 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
636 cfqq->slice_start = jiffies;
637 cfqq->slice_end = jiffies + slice;
638 cfqq->allocated_slice = slice;
639 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
643 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
644 * isn't valid until the first request from the dispatch is activated
645 * and the slice time set.
647 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
649 if (cfq_cfqq_slice_new(cfqq))
650 return false;
651 if (time_before(jiffies, cfqq->slice_end))
652 return false;
654 return true;
658 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
659 * We choose the request that is closest to the head right now. Distance
660 * behind the head is penalized and only allowed to a certain extent.
662 static struct request *
663 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
665 sector_t s1, s2, d1 = 0, d2 = 0;
666 unsigned long back_max;
667 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
668 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
669 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
671 if (rq1 == NULL || rq1 == rq2)
672 return rq2;
673 if (rq2 == NULL)
674 return rq1;
676 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
677 return rq1;
678 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
679 return rq2;
680 if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
681 return rq1;
682 else if ((rq2->cmd_flags & REQ_META) &&
683 !(rq1->cmd_flags & REQ_META))
684 return rq2;
686 s1 = blk_rq_pos(rq1);
687 s2 = blk_rq_pos(rq2);
690 * by definition, 1KiB is 2 sectors
692 back_max = cfqd->cfq_back_max * 2;
695 * Strict one way elevator _except_ in the case where we allow
696 * short backward seeks which are biased as twice the cost of a
697 * similar forward seek.
699 if (s1 >= last)
700 d1 = s1 - last;
701 else if (s1 + back_max >= last)
702 d1 = (last - s1) * cfqd->cfq_back_penalty;
703 else
704 wrap |= CFQ_RQ1_WRAP;
706 if (s2 >= last)
707 d2 = s2 - last;
708 else if (s2 + back_max >= last)
709 d2 = (last - s2) * cfqd->cfq_back_penalty;
710 else
711 wrap |= CFQ_RQ2_WRAP;
713 /* Found required data */
716 * By doing switch() on the bit mask "wrap" we avoid having to
717 * check two variables for all permutations: --> faster!
719 switch (wrap) {
720 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
721 if (d1 < d2)
722 return rq1;
723 else if (d2 < d1)
724 return rq2;
725 else {
726 if (s1 >= s2)
727 return rq1;
728 else
729 return rq2;
732 case CFQ_RQ2_WRAP:
733 return rq1;
734 case CFQ_RQ1_WRAP:
735 return rq2;
736 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
737 default:
739 * Since both rqs are wrapped,
740 * start with the one that's further behind head
741 * (--> only *one* back seek required),
742 * since back seek takes more time than forward.
744 if (s1 <= s2)
745 return rq1;
746 else
747 return rq2;
752 * The below is leftmost cache rbtree addon
754 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
756 /* Service tree is empty */
757 if (!root->count)
758 return NULL;
760 if (!root->left)
761 root->left = rb_first(&root->rb);
763 if (root->left)
764 return rb_entry(root->left, struct cfq_queue, rb_node);
766 return NULL;
769 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
771 if (!root->left)
772 root->left = rb_first(&root->rb);
774 if (root->left)
775 return rb_entry_cfqg(root->left);
777 return NULL;
780 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
782 rb_erase(n, root);
783 RB_CLEAR_NODE(n);
786 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
788 if (root->left == n)
789 root->left = NULL;
790 rb_erase_init(n, &root->rb);
791 --root->count;
795 * would be nice to take fifo expire time into account as well
797 static struct request *
798 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
799 struct request *last)
801 struct rb_node *rbnext = rb_next(&last->rb_node);
802 struct rb_node *rbprev = rb_prev(&last->rb_node);
803 struct request *next = NULL, *prev = NULL;
805 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
807 if (rbprev)
808 prev = rb_entry_rq(rbprev);
810 if (rbnext)
811 next = rb_entry_rq(rbnext);
812 else {
813 rbnext = rb_first(&cfqq->sort_list);
814 if (rbnext && rbnext != &last->rb_node)
815 next = rb_entry_rq(rbnext);
818 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
821 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
822 struct cfq_queue *cfqq)
825 * just an approximation, should be ok.
827 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
828 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
831 static inline s64
832 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
834 return cfqg->vdisktime - st->min_vdisktime;
837 static void
838 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
840 struct rb_node **node = &st->rb.rb_node;
841 struct rb_node *parent = NULL;
842 struct cfq_group *__cfqg;
843 s64 key = cfqg_key(st, cfqg);
844 int left = 1;
846 while (*node != NULL) {
847 parent = *node;
848 __cfqg = rb_entry_cfqg(parent);
850 if (key < cfqg_key(st, __cfqg))
851 node = &parent->rb_left;
852 else {
853 node = &parent->rb_right;
854 left = 0;
858 if (left)
859 st->left = &cfqg->rb_node;
861 rb_link_node(&cfqg->rb_node, parent, node);
862 rb_insert_color(&cfqg->rb_node, &st->rb);
865 static void
866 cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
868 struct cfq_rb_root *st = &cfqd->grp_service_tree;
869 struct cfq_group *__cfqg;
870 struct rb_node *n;
872 cfqg->nr_cfqq++;
873 if (!RB_EMPTY_NODE(&cfqg->rb_node))
874 return;
877 * Currently put the group at the end. Later implement something
878 * so that groups get lesser vtime based on their weights, so that
879 * if group does not loose all if it was not continously backlogged.
881 n = rb_last(&st->rb);
882 if (n) {
883 __cfqg = rb_entry_cfqg(n);
884 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
885 } else
886 cfqg->vdisktime = st->min_vdisktime;
888 __cfq_group_service_tree_add(st, cfqg);
889 st->total_weight += cfqg->weight;
892 static void
893 cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
895 struct cfq_rb_root *st = &cfqd->grp_service_tree;
897 BUG_ON(cfqg->nr_cfqq < 1);
898 cfqg->nr_cfqq--;
900 /* If there are other cfq queues under this group, don't delete it */
901 if (cfqg->nr_cfqq)
902 return;
904 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
905 st->total_weight -= cfqg->weight;
906 if (!RB_EMPTY_NODE(&cfqg->rb_node))
907 cfq_rb_erase(&cfqg->rb_node, st);
908 cfqg->saved_workload_slice = 0;
909 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
912 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
914 unsigned int slice_used;
917 * Queue got expired before even a single request completed or
918 * got expired immediately after first request completion.
920 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
922 * Also charge the seek time incurred to the group, otherwise
923 * if there are mutiple queues in the group, each can dispatch
924 * a single request on seeky media and cause lots of seek time
925 * and group will never know it.
927 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
929 } else {
930 slice_used = jiffies - cfqq->slice_start;
931 if (slice_used > cfqq->allocated_slice)
932 slice_used = cfqq->allocated_slice;
935 return slice_used;
938 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
939 struct cfq_queue *cfqq)
941 struct cfq_rb_root *st = &cfqd->grp_service_tree;
942 unsigned int used_sl, charge;
943 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
944 - cfqg->service_tree_idle.count;
946 BUG_ON(nr_sync < 0);
947 used_sl = charge = cfq_cfqq_slice_usage(cfqq);
949 if (iops_mode(cfqd))
950 charge = cfqq->slice_dispatch;
951 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
952 charge = cfqq->allocated_slice;
954 /* Can't update vdisktime while group is on service tree */
955 cfq_rb_erase(&cfqg->rb_node, st);
956 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
957 __cfq_group_service_tree_add(st, cfqg);
959 /* This group is being expired. Save the context */
960 if (time_after(cfqd->workload_expires, jiffies)) {
961 cfqg->saved_workload_slice = cfqd->workload_expires
962 - jiffies;
963 cfqg->saved_workload = cfqd->serving_type;
964 cfqg->saved_serving_prio = cfqd->serving_prio;
965 } else
966 cfqg->saved_workload_slice = 0;
968 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
969 st->min_vdisktime);
970 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u"
971 " sect=%u", used_sl, cfqq->slice_dispatch, charge,
972 iops_mode(cfqd), cfqq->nr_sectors);
973 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
974 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
977 #ifdef CONFIG_CFQ_GROUP_IOSCHED
978 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
980 if (blkg)
981 return container_of(blkg, struct cfq_group, blkg);
982 return NULL;
985 void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
986 unsigned int weight)
988 cfqg_of_blkg(blkg)->weight = weight;
991 static struct cfq_group *
992 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
994 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
995 struct cfq_group *cfqg = NULL;
996 void *key = cfqd;
997 int i, j;
998 struct cfq_rb_root *st;
999 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1000 unsigned int major, minor;
1002 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1003 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1004 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1005 cfqg->blkg.dev = MKDEV(major, minor);
1006 goto done;
1008 if (cfqg || !create)
1009 goto done;
1011 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1012 if (!cfqg)
1013 goto done;
1015 for_each_cfqg_st(cfqg, i, j, st)
1016 *st = CFQ_RB_ROOT;
1017 RB_CLEAR_NODE(&cfqg->rb_node);
1020 * Take the initial reference that will be released on destroy
1021 * This can be thought of a joint reference by cgroup and
1022 * elevator which will be dropped by either elevator exit
1023 * or cgroup deletion path depending on who is exiting first.
1025 cfqg->ref = 1;
1028 * Add group onto cgroup list. It might happen that bdi->dev is
1029 * not initialized yet. Initialize this new group without major
1030 * and minor info and this info will be filled in once a new thread
1031 * comes for IO. See code above.
1033 if (bdi->dev) {
1034 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1035 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1036 MKDEV(major, minor));
1037 } else
1038 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1041 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1043 /* Add group on cfqd list */
1044 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1046 done:
1047 return cfqg;
1051 * Search for the cfq group current task belongs to. If create = 1, then also
1052 * create the cfq group if it does not exist. request_queue lock must be held.
1054 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1056 struct cgroup *cgroup;
1057 struct cfq_group *cfqg = NULL;
1059 rcu_read_lock();
1060 cgroup = task_cgroup(current, blkio_subsys_id);
1061 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1062 if (!cfqg && create)
1063 cfqg = &cfqd->root_group;
1064 rcu_read_unlock();
1065 return cfqg;
1068 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1070 cfqg->ref++;
1071 return cfqg;
1074 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1076 /* Currently, all async queues are mapped to root group */
1077 if (!cfq_cfqq_sync(cfqq))
1078 cfqg = &cfqq->cfqd->root_group;
1080 cfqq->cfqg = cfqg;
1081 /* cfqq reference on cfqg */
1082 cfqq->cfqg->ref++;
1085 static void cfq_put_cfqg(struct cfq_group *cfqg)
1087 struct cfq_rb_root *st;
1088 int i, j;
1090 BUG_ON(cfqg->ref <= 0);
1091 cfqg->ref--;
1092 if (cfqg->ref)
1093 return;
1094 for_each_cfqg_st(cfqg, i, j, st)
1095 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1096 kfree(cfqg);
1099 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1101 /* Something wrong if we are trying to remove same group twice */
1102 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1104 hlist_del_init(&cfqg->cfqd_node);
1107 * Put the reference taken at the time of creation so that when all
1108 * queues are gone, group can be destroyed.
1110 cfq_put_cfqg(cfqg);
1113 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1115 struct hlist_node *pos, *n;
1116 struct cfq_group *cfqg;
1118 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1120 * If cgroup removal path got to blk_group first and removed
1121 * it from cgroup list, then it will take care of destroying
1122 * cfqg also.
1124 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1125 cfq_destroy_cfqg(cfqd, cfqg);
1130 * Blk cgroup controller notification saying that blkio_group object is being
1131 * delinked as associated cgroup object is going away. That also means that
1132 * no new IO will come in this group. So get rid of this group as soon as
1133 * any pending IO in the group is finished.
1135 * This function is called under rcu_read_lock(). key is the rcu protected
1136 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1137 * read lock.
1139 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1140 * it should not be NULL as even if elevator was exiting, cgroup deltion
1141 * path got to it first.
1143 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1145 unsigned long flags;
1146 struct cfq_data *cfqd = key;
1148 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1149 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1150 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1153 #else /* GROUP_IOSCHED */
1154 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1156 return &cfqd->root_group;
1159 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1161 return cfqg;
1164 static inline void
1165 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1166 cfqq->cfqg = cfqg;
1169 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1170 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1172 #endif /* GROUP_IOSCHED */
1175 * The cfqd->service_trees holds all pending cfq_queue's that have
1176 * requests waiting to be processed. It is sorted in the order that
1177 * we will service the queues.
1179 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1180 bool add_front)
1182 struct rb_node **p, *parent;
1183 struct cfq_queue *__cfqq;
1184 unsigned long rb_key;
1185 struct cfq_rb_root *service_tree;
1186 int left;
1187 int new_cfqq = 1;
1188 int group_changed = 0;
1190 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1191 if (!cfqd->cfq_group_isolation
1192 && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
1193 && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
1194 /* Move this cfq to root group */
1195 cfq_log_cfqq(cfqd, cfqq, "moving to root group");
1196 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1197 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1198 cfqq->orig_cfqg = cfqq->cfqg;
1199 cfqq->cfqg = &cfqd->root_group;
1200 cfqd->root_group.ref++;
1201 group_changed = 1;
1202 } else if (!cfqd->cfq_group_isolation
1203 && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
1204 /* cfqq is sequential now needs to go to its original group */
1205 BUG_ON(cfqq->cfqg != &cfqd->root_group);
1206 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1207 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1208 cfq_put_cfqg(cfqq->cfqg);
1209 cfqq->cfqg = cfqq->orig_cfqg;
1210 cfqq->orig_cfqg = NULL;
1211 group_changed = 1;
1212 cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
1214 #endif
1216 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1217 cfqq_type(cfqq));
1218 if (cfq_class_idle(cfqq)) {
1219 rb_key = CFQ_IDLE_DELAY;
1220 parent = rb_last(&service_tree->rb);
1221 if (parent && parent != &cfqq->rb_node) {
1222 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1223 rb_key += __cfqq->rb_key;
1224 } else
1225 rb_key += jiffies;
1226 } else if (!add_front) {
1228 * Get our rb key offset. Subtract any residual slice
1229 * value carried from last service. A negative resid
1230 * count indicates slice overrun, and this should position
1231 * the next service time further away in the tree.
1233 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1234 rb_key -= cfqq->slice_resid;
1235 cfqq->slice_resid = 0;
1236 } else {
1237 rb_key = -HZ;
1238 __cfqq = cfq_rb_first(service_tree);
1239 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1242 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1243 new_cfqq = 0;
1245 * same position, nothing more to do
1247 if (rb_key == cfqq->rb_key &&
1248 cfqq->service_tree == service_tree)
1249 return;
1251 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1252 cfqq->service_tree = NULL;
1255 left = 1;
1256 parent = NULL;
1257 cfqq->service_tree = service_tree;
1258 p = &service_tree->rb.rb_node;
1259 while (*p) {
1260 struct rb_node **n;
1262 parent = *p;
1263 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1266 * sort by key, that represents service time.
1268 if (time_before(rb_key, __cfqq->rb_key))
1269 n = &(*p)->rb_left;
1270 else {
1271 n = &(*p)->rb_right;
1272 left = 0;
1275 p = n;
1278 if (left)
1279 service_tree->left = &cfqq->rb_node;
1281 cfqq->rb_key = rb_key;
1282 rb_link_node(&cfqq->rb_node, parent, p);
1283 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1284 service_tree->count++;
1285 if ((add_front || !new_cfqq) && !group_changed)
1286 return;
1287 cfq_group_service_tree_add(cfqd, cfqq->cfqg);
1290 static struct cfq_queue *
1291 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1292 sector_t sector, struct rb_node **ret_parent,
1293 struct rb_node ***rb_link)
1295 struct rb_node **p, *parent;
1296 struct cfq_queue *cfqq = NULL;
1298 parent = NULL;
1299 p = &root->rb_node;
1300 while (*p) {
1301 struct rb_node **n;
1303 parent = *p;
1304 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1307 * Sort strictly based on sector. Smallest to the left,
1308 * largest to the right.
1310 if (sector > blk_rq_pos(cfqq->next_rq))
1311 n = &(*p)->rb_right;
1312 else if (sector < blk_rq_pos(cfqq->next_rq))
1313 n = &(*p)->rb_left;
1314 else
1315 break;
1316 p = n;
1317 cfqq = NULL;
1320 *ret_parent = parent;
1321 if (rb_link)
1322 *rb_link = p;
1323 return cfqq;
1326 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1328 struct rb_node **p, *parent;
1329 struct cfq_queue *__cfqq;
1331 if (cfqq->p_root) {
1332 rb_erase(&cfqq->p_node, cfqq->p_root);
1333 cfqq->p_root = NULL;
1336 if (cfq_class_idle(cfqq))
1337 return;
1338 if (!cfqq->next_rq)
1339 return;
1341 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1342 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1343 blk_rq_pos(cfqq->next_rq), &parent, &p);
1344 if (!__cfqq) {
1345 rb_link_node(&cfqq->p_node, parent, p);
1346 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1347 } else
1348 cfqq->p_root = NULL;
1352 * Update cfqq's position in the service tree.
1354 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1357 * Resorting requires the cfqq to be on the RR list already.
1359 if (cfq_cfqq_on_rr(cfqq)) {
1360 cfq_service_tree_add(cfqd, cfqq, 0);
1361 cfq_prio_tree_add(cfqd, cfqq);
1366 * add to busy list of queues for service, trying to be fair in ordering
1367 * the pending list according to last request service
1369 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1371 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1372 BUG_ON(cfq_cfqq_on_rr(cfqq));
1373 cfq_mark_cfqq_on_rr(cfqq);
1374 cfqd->busy_queues++;
1376 cfq_resort_rr_list(cfqd, cfqq);
1380 * Called when the cfqq no longer has requests pending, remove it from
1381 * the service tree.
1383 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1385 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1386 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1387 cfq_clear_cfqq_on_rr(cfqq);
1389 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1390 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1391 cfqq->service_tree = NULL;
1393 if (cfqq->p_root) {
1394 rb_erase(&cfqq->p_node, cfqq->p_root);
1395 cfqq->p_root = NULL;
1398 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1399 BUG_ON(!cfqd->busy_queues);
1400 cfqd->busy_queues--;
1404 * rb tree support functions
1406 static void cfq_del_rq_rb(struct request *rq)
1408 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1409 const int sync = rq_is_sync(rq);
1411 BUG_ON(!cfqq->queued[sync]);
1412 cfqq->queued[sync]--;
1414 elv_rb_del(&cfqq->sort_list, rq);
1416 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1418 * Queue will be deleted from service tree when we actually
1419 * expire it later. Right now just remove it from prio tree
1420 * as it is empty.
1422 if (cfqq->p_root) {
1423 rb_erase(&cfqq->p_node, cfqq->p_root);
1424 cfqq->p_root = NULL;
1429 static void cfq_add_rq_rb(struct request *rq)
1431 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1432 struct cfq_data *cfqd = cfqq->cfqd;
1433 struct request *__alias, *prev;
1435 cfqq->queued[rq_is_sync(rq)]++;
1438 * looks a little odd, but the first insert might return an alias.
1439 * if that happens, put the alias on the dispatch list
1441 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1442 cfq_dispatch_insert(cfqd->queue, __alias);
1444 if (!cfq_cfqq_on_rr(cfqq))
1445 cfq_add_cfqq_rr(cfqd, cfqq);
1448 * check if this request is a better next-serve candidate
1450 prev = cfqq->next_rq;
1451 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1454 * adjust priority tree position, if ->next_rq changes
1456 if (prev != cfqq->next_rq)
1457 cfq_prio_tree_add(cfqd, cfqq);
1459 BUG_ON(!cfqq->next_rq);
1462 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1464 elv_rb_del(&cfqq->sort_list, rq);
1465 cfqq->queued[rq_is_sync(rq)]--;
1466 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1467 rq_data_dir(rq), rq_is_sync(rq));
1468 cfq_add_rq_rb(rq);
1469 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1470 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1471 rq_is_sync(rq));
1474 static struct request *
1475 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1477 struct task_struct *tsk = current;
1478 struct cfq_io_context *cic;
1479 struct cfq_queue *cfqq;
1481 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1482 if (!cic)
1483 return NULL;
1485 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1486 if (cfqq) {
1487 sector_t sector = bio->bi_sector + bio_sectors(bio);
1489 return elv_rb_find(&cfqq->sort_list, sector);
1492 return NULL;
1495 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1497 struct cfq_data *cfqd = q->elevator->elevator_data;
1499 cfqd->rq_in_driver++;
1500 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1501 cfqd->rq_in_driver);
1503 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1506 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1508 struct cfq_data *cfqd = q->elevator->elevator_data;
1510 WARN_ON(!cfqd->rq_in_driver);
1511 cfqd->rq_in_driver--;
1512 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1513 cfqd->rq_in_driver);
1516 static void cfq_remove_request(struct request *rq)
1518 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1520 if (cfqq->next_rq == rq)
1521 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1523 list_del_init(&rq->queuelist);
1524 cfq_del_rq_rb(rq);
1526 cfqq->cfqd->rq_queued--;
1527 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1528 rq_data_dir(rq), rq_is_sync(rq));
1529 if (rq->cmd_flags & REQ_META) {
1530 WARN_ON(!cfqq->meta_pending);
1531 cfqq->meta_pending--;
1535 static int cfq_merge(struct request_queue *q, struct request **req,
1536 struct bio *bio)
1538 struct cfq_data *cfqd = q->elevator->elevator_data;
1539 struct request *__rq;
1541 __rq = cfq_find_rq_fmerge(cfqd, bio);
1542 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1543 *req = __rq;
1544 return ELEVATOR_FRONT_MERGE;
1547 return ELEVATOR_NO_MERGE;
1550 static void cfq_merged_request(struct request_queue *q, struct request *req,
1551 int type)
1553 if (type == ELEVATOR_FRONT_MERGE) {
1554 struct cfq_queue *cfqq = RQ_CFQQ(req);
1556 cfq_reposition_rq_rb(cfqq, req);
1560 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1561 struct bio *bio)
1563 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1564 bio_data_dir(bio), cfq_bio_sync(bio));
1567 static void
1568 cfq_merged_requests(struct request_queue *q, struct request *rq,
1569 struct request *next)
1571 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1573 * reposition in fifo if next is older than rq
1575 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1576 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1577 list_move(&rq->queuelist, &next->queuelist);
1578 rq_set_fifo_time(rq, rq_fifo_time(next));
1581 if (cfqq->next_rq == next)
1582 cfqq->next_rq = rq;
1583 cfq_remove_request(next);
1584 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1585 rq_data_dir(next), rq_is_sync(next));
1588 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1589 struct bio *bio)
1591 struct cfq_data *cfqd = q->elevator->elevator_data;
1592 struct cfq_io_context *cic;
1593 struct cfq_queue *cfqq;
1596 * Disallow merge of a sync bio into an async request.
1598 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1599 return false;
1602 * Lookup the cfqq that this bio will be queued with. Allow
1603 * merge only if rq is queued there.
1605 cic = cfq_cic_lookup(cfqd, current->io_context);
1606 if (!cic)
1607 return false;
1609 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1610 return cfqq == RQ_CFQQ(rq);
1613 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1615 del_timer(&cfqd->idle_slice_timer);
1616 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1619 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1620 struct cfq_queue *cfqq)
1622 if (cfqq) {
1623 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1624 cfqd->serving_prio, cfqd->serving_type);
1625 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1626 cfqq->slice_start = 0;
1627 cfqq->dispatch_start = jiffies;
1628 cfqq->allocated_slice = 0;
1629 cfqq->slice_end = 0;
1630 cfqq->slice_dispatch = 0;
1631 cfqq->nr_sectors = 0;
1633 cfq_clear_cfqq_wait_request(cfqq);
1634 cfq_clear_cfqq_must_dispatch(cfqq);
1635 cfq_clear_cfqq_must_alloc_slice(cfqq);
1636 cfq_clear_cfqq_fifo_expire(cfqq);
1637 cfq_mark_cfqq_slice_new(cfqq);
1639 cfq_del_timer(cfqd, cfqq);
1642 cfqd->active_queue = cfqq;
1646 * current cfqq expired its slice (or was too idle), select new one
1648 static void
1649 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1650 bool timed_out)
1652 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1654 if (cfq_cfqq_wait_request(cfqq))
1655 cfq_del_timer(cfqd, cfqq);
1657 cfq_clear_cfqq_wait_request(cfqq);
1658 cfq_clear_cfqq_wait_busy(cfqq);
1661 * If this cfqq is shared between multiple processes, check to
1662 * make sure that those processes are still issuing I/Os within
1663 * the mean seek distance. If not, it may be time to break the
1664 * queues apart again.
1666 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1667 cfq_mark_cfqq_split_coop(cfqq);
1670 * store what was left of this slice, if the queue idled/timed out
1672 if (timed_out) {
1673 if (cfq_cfqq_slice_new(cfqq))
1674 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1675 else
1676 cfqq->slice_resid = cfqq->slice_end - jiffies;
1677 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1680 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1682 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1683 cfq_del_cfqq_rr(cfqd, cfqq);
1685 cfq_resort_rr_list(cfqd, cfqq);
1687 if (cfqq == cfqd->active_queue)
1688 cfqd->active_queue = NULL;
1690 if (cfqd->active_cic) {
1691 put_io_context(cfqd->active_cic->ioc);
1692 cfqd->active_cic = NULL;
1696 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1698 struct cfq_queue *cfqq = cfqd->active_queue;
1700 if (cfqq)
1701 __cfq_slice_expired(cfqd, cfqq, timed_out);
1705 * Get next queue for service. Unless we have a queue preemption,
1706 * we'll simply select the first cfqq in the service tree.
1708 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1710 struct cfq_rb_root *service_tree =
1711 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1712 cfqd->serving_type);
1714 if (!cfqd->rq_queued)
1715 return NULL;
1717 /* There is nothing to dispatch */
1718 if (!service_tree)
1719 return NULL;
1720 if (RB_EMPTY_ROOT(&service_tree->rb))
1721 return NULL;
1722 return cfq_rb_first(service_tree);
1725 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1727 struct cfq_group *cfqg;
1728 struct cfq_queue *cfqq;
1729 int i, j;
1730 struct cfq_rb_root *st;
1732 if (!cfqd->rq_queued)
1733 return NULL;
1735 cfqg = cfq_get_next_cfqg(cfqd);
1736 if (!cfqg)
1737 return NULL;
1739 for_each_cfqg_st(cfqg, i, j, st)
1740 if ((cfqq = cfq_rb_first(st)) != NULL)
1741 return cfqq;
1742 return NULL;
1746 * Get and set a new active queue for service.
1748 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1749 struct cfq_queue *cfqq)
1751 if (!cfqq)
1752 cfqq = cfq_get_next_queue(cfqd);
1754 __cfq_set_active_queue(cfqd, cfqq);
1755 return cfqq;
1758 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1759 struct request *rq)
1761 if (blk_rq_pos(rq) >= cfqd->last_position)
1762 return blk_rq_pos(rq) - cfqd->last_position;
1763 else
1764 return cfqd->last_position - blk_rq_pos(rq);
1767 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1768 struct request *rq)
1770 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1773 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1774 struct cfq_queue *cur_cfqq)
1776 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1777 struct rb_node *parent, *node;
1778 struct cfq_queue *__cfqq;
1779 sector_t sector = cfqd->last_position;
1781 if (RB_EMPTY_ROOT(root))
1782 return NULL;
1785 * First, if we find a request starting at the end of the last
1786 * request, choose it.
1788 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1789 if (__cfqq)
1790 return __cfqq;
1793 * If the exact sector wasn't found, the parent of the NULL leaf
1794 * will contain the closest sector.
1796 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1797 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1798 return __cfqq;
1800 if (blk_rq_pos(__cfqq->next_rq) < sector)
1801 node = rb_next(&__cfqq->p_node);
1802 else
1803 node = rb_prev(&__cfqq->p_node);
1804 if (!node)
1805 return NULL;
1807 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1808 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1809 return __cfqq;
1811 return NULL;
1815 * cfqd - obvious
1816 * cur_cfqq - passed in so that we don't decide that the current queue is
1817 * closely cooperating with itself.
1819 * So, basically we're assuming that that cur_cfqq has dispatched at least
1820 * one request, and that cfqd->last_position reflects a position on the disk
1821 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1822 * assumption.
1824 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1825 struct cfq_queue *cur_cfqq)
1827 struct cfq_queue *cfqq;
1829 if (cfq_class_idle(cur_cfqq))
1830 return NULL;
1831 if (!cfq_cfqq_sync(cur_cfqq))
1832 return NULL;
1833 if (CFQQ_SEEKY(cur_cfqq))
1834 return NULL;
1837 * Don't search priority tree if it's the only queue in the group.
1839 if (cur_cfqq->cfqg->nr_cfqq == 1)
1840 return NULL;
1843 * We should notice if some of the queues are cooperating, eg
1844 * working closely on the same area of the disk. In that case,
1845 * we can group them together and don't waste time idling.
1847 cfqq = cfqq_close(cfqd, cur_cfqq);
1848 if (!cfqq)
1849 return NULL;
1851 /* If new queue belongs to different cfq_group, don't choose it */
1852 if (cur_cfqq->cfqg != cfqq->cfqg)
1853 return NULL;
1856 * It only makes sense to merge sync queues.
1858 if (!cfq_cfqq_sync(cfqq))
1859 return NULL;
1860 if (CFQQ_SEEKY(cfqq))
1861 return NULL;
1864 * Do not merge queues of different priority classes
1866 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1867 return NULL;
1869 return cfqq;
1873 * Determine whether we should enforce idle window for this queue.
1876 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1878 enum wl_prio_t prio = cfqq_prio(cfqq);
1879 struct cfq_rb_root *service_tree = cfqq->service_tree;
1881 BUG_ON(!service_tree);
1882 BUG_ON(!service_tree->count);
1884 if (!cfqd->cfq_slice_idle)
1885 return false;
1887 /* We never do for idle class queues. */
1888 if (prio == IDLE_WORKLOAD)
1889 return false;
1891 /* We do for queues that were marked with idle window flag. */
1892 if (cfq_cfqq_idle_window(cfqq) &&
1893 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1894 return true;
1897 * Otherwise, we do only if they are the last ones
1898 * in their service tree.
1900 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1901 return true;
1902 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1903 service_tree->count);
1904 return false;
1907 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1909 struct cfq_queue *cfqq = cfqd->active_queue;
1910 struct cfq_io_context *cic;
1911 unsigned long sl, group_idle = 0;
1914 * SSD device without seek penalty, disable idling. But only do so
1915 * for devices that support queuing, otherwise we still have a problem
1916 * with sync vs async workloads.
1918 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1919 return;
1921 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1922 WARN_ON(cfq_cfqq_slice_new(cfqq));
1925 * idle is disabled, either manually or by past process history
1927 if (!cfq_should_idle(cfqd, cfqq)) {
1928 /* no queue idling. Check for group idling */
1929 if (cfqd->cfq_group_idle)
1930 group_idle = cfqd->cfq_group_idle;
1931 else
1932 return;
1936 * still active requests from this queue, don't idle
1938 if (cfqq->dispatched)
1939 return;
1942 * task has exited, don't wait
1944 cic = cfqd->active_cic;
1945 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1946 return;
1949 * If our average think time is larger than the remaining time
1950 * slice, then don't idle. This avoids overrunning the allotted
1951 * time slice.
1953 if (sample_valid(cic->ttime_samples) &&
1954 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1955 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1956 cic->ttime_mean);
1957 return;
1960 /* There are other queues in the group, don't do group idle */
1961 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
1962 return;
1964 cfq_mark_cfqq_wait_request(cfqq);
1966 if (group_idle)
1967 sl = cfqd->cfq_group_idle;
1968 else
1969 sl = cfqd->cfq_slice_idle;
1971 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1972 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1973 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
1974 group_idle ? 1 : 0);
1978 * Move request from internal lists to the request queue dispatch list.
1980 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1982 struct cfq_data *cfqd = q->elevator->elevator_data;
1983 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1985 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1987 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1988 cfq_remove_request(rq);
1989 cfqq->dispatched++;
1990 (RQ_CFQG(rq))->dispatched++;
1991 elv_dispatch_sort(q, rq);
1993 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1994 cfqq->nr_sectors += blk_rq_sectors(rq);
1995 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
1996 rq_data_dir(rq), rq_is_sync(rq));
2000 * return expired entry, or NULL to just start from scratch in rbtree
2002 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2004 struct request *rq = NULL;
2006 if (cfq_cfqq_fifo_expire(cfqq))
2007 return NULL;
2009 cfq_mark_cfqq_fifo_expire(cfqq);
2011 if (list_empty(&cfqq->fifo))
2012 return NULL;
2014 rq = rq_entry_fifo(cfqq->fifo.next);
2015 if (time_before(jiffies, rq_fifo_time(rq)))
2016 rq = NULL;
2018 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2019 return rq;
2022 static inline int
2023 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2025 const int base_rq = cfqd->cfq_slice_async_rq;
2027 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2029 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
2033 * Must be called with the queue_lock held.
2035 static int cfqq_process_refs(struct cfq_queue *cfqq)
2037 int process_refs, io_refs;
2039 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2040 process_refs = cfqq->ref - io_refs;
2041 BUG_ON(process_refs < 0);
2042 return process_refs;
2045 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2047 int process_refs, new_process_refs;
2048 struct cfq_queue *__cfqq;
2051 * If there are no process references on the new_cfqq, then it is
2052 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2053 * chain may have dropped their last reference (not just their
2054 * last process reference).
2056 if (!cfqq_process_refs(new_cfqq))
2057 return;
2059 /* Avoid a circular list and skip interim queue merges */
2060 while ((__cfqq = new_cfqq->new_cfqq)) {
2061 if (__cfqq == cfqq)
2062 return;
2063 new_cfqq = __cfqq;
2066 process_refs = cfqq_process_refs(cfqq);
2067 new_process_refs = cfqq_process_refs(new_cfqq);
2069 * If the process for the cfqq has gone away, there is no
2070 * sense in merging the queues.
2072 if (process_refs == 0 || new_process_refs == 0)
2073 return;
2076 * Merge in the direction of the lesser amount of work.
2078 if (new_process_refs >= process_refs) {
2079 cfqq->new_cfqq = new_cfqq;
2080 new_cfqq->ref += process_refs;
2081 } else {
2082 new_cfqq->new_cfqq = cfqq;
2083 cfqq->ref += new_process_refs;
2087 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2088 struct cfq_group *cfqg, enum wl_prio_t prio)
2090 struct cfq_queue *queue;
2091 int i;
2092 bool key_valid = false;
2093 unsigned long lowest_key = 0;
2094 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2096 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2097 /* select the one with lowest rb_key */
2098 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2099 if (queue &&
2100 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2101 lowest_key = queue->rb_key;
2102 cur_best = i;
2103 key_valid = true;
2107 return cur_best;
2110 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2112 unsigned slice;
2113 unsigned count;
2114 struct cfq_rb_root *st;
2115 unsigned group_slice;
2116 enum wl_prio_t original_prio = cfqd->serving_prio;
2118 /* Choose next priority. RT > BE > IDLE */
2119 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2120 cfqd->serving_prio = RT_WORKLOAD;
2121 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2122 cfqd->serving_prio = BE_WORKLOAD;
2123 else {
2124 cfqd->serving_prio = IDLE_WORKLOAD;
2125 cfqd->workload_expires = jiffies + 1;
2126 return;
2129 if (original_prio != cfqd->serving_prio)
2130 goto new_workload;
2133 * For RT and BE, we have to choose also the type
2134 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2135 * expiration time
2137 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2138 count = st->count;
2141 * check workload expiration, and that we still have other queues ready
2143 if (count && !time_after(jiffies, cfqd->workload_expires))
2144 return;
2146 new_workload:
2147 /* otherwise select new workload type */
2148 cfqd->serving_type =
2149 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2150 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2151 count = st->count;
2154 * the workload slice is computed as a fraction of target latency
2155 * proportional to the number of queues in that workload, over
2156 * all the queues in the same priority class
2158 group_slice = cfq_group_slice(cfqd, cfqg);
2160 slice = group_slice * count /
2161 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2162 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2164 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2165 unsigned int tmp;
2168 * Async queues are currently system wide. Just taking
2169 * proportion of queues with-in same group will lead to higher
2170 * async ratio system wide as generally root group is going
2171 * to have higher weight. A more accurate thing would be to
2172 * calculate system wide asnc/sync ratio.
2174 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2175 tmp = tmp/cfqd->busy_queues;
2176 slice = min_t(unsigned, slice, tmp);
2178 /* async workload slice is scaled down according to
2179 * the sync/async slice ratio. */
2180 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2181 } else
2182 /* sync workload slice is at least 2 * cfq_slice_idle */
2183 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2185 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2186 cfq_log(cfqd, "workload slice:%d", slice);
2187 cfqd->workload_expires = jiffies + slice;
2190 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2192 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2193 struct cfq_group *cfqg;
2195 if (RB_EMPTY_ROOT(&st->rb))
2196 return NULL;
2197 cfqg = cfq_rb_first_group(st);
2198 update_min_vdisktime(st);
2199 return cfqg;
2202 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2204 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2206 cfqd->serving_group = cfqg;
2208 /* Restore the workload type data */
2209 if (cfqg->saved_workload_slice) {
2210 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2211 cfqd->serving_type = cfqg->saved_workload;
2212 cfqd->serving_prio = cfqg->saved_serving_prio;
2213 } else
2214 cfqd->workload_expires = jiffies - 1;
2216 choose_service_tree(cfqd, cfqg);
2220 * Select a queue for service. If we have a current active queue,
2221 * check whether to continue servicing it, or retrieve and set a new one.
2223 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2225 struct cfq_queue *cfqq, *new_cfqq = NULL;
2227 cfqq = cfqd->active_queue;
2228 if (!cfqq)
2229 goto new_queue;
2231 if (!cfqd->rq_queued)
2232 return NULL;
2235 * We were waiting for group to get backlogged. Expire the queue
2237 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2238 goto expire;
2241 * The active queue has run out of time, expire it and select new.
2243 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2245 * If slice had not expired at the completion of last request
2246 * we might not have turned on wait_busy flag. Don't expire
2247 * the queue yet. Allow the group to get backlogged.
2249 * The very fact that we have used the slice, that means we
2250 * have been idling all along on this queue and it should be
2251 * ok to wait for this request to complete.
2253 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2254 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2255 cfqq = NULL;
2256 goto keep_queue;
2257 } else
2258 goto check_group_idle;
2262 * The active queue has requests and isn't expired, allow it to
2263 * dispatch.
2265 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2266 goto keep_queue;
2269 * If another queue has a request waiting within our mean seek
2270 * distance, let it run. The expire code will check for close
2271 * cooperators and put the close queue at the front of the service
2272 * tree. If possible, merge the expiring queue with the new cfqq.
2274 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2275 if (new_cfqq) {
2276 if (!cfqq->new_cfqq)
2277 cfq_setup_merge(cfqq, new_cfqq);
2278 goto expire;
2282 * No requests pending. If the active queue still has requests in
2283 * flight or is idling for a new request, allow either of these
2284 * conditions to happen (or time out) before selecting a new queue.
2286 if (timer_pending(&cfqd->idle_slice_timer)) {
2287 cfqq = NULL;
2288 goto keep_queue;
2292 * This is a deep seek queue, but the device is much faster than
2293 * the queue can deliver, don't idle
2295 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2296 (cfq_cfqq_slice_new(cfqq) ||
2297 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2298 cfq_clear_cfqq_deep(cfqq);
2299 cfq_clear_cfqq_idle_window(cfqq);
2302 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2303 cfqq = NULL;
2304 goto keep_queue;
2308 * If group idle is enabled and there are requests dispatched from
2309 * this group, wait for requests to complete.
2311 check_group_idle:
2312 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
2313 && cfqq->cfqg->dispatched) {
2314 cfqq = NULL;
2315 goto keep_queue;
2318 expire:
2319 cfq_slice_expired(cfqd, 0);
2320 new_queue:
2322 * Current queue expired. Check if we have to switch to a new
2323 * service tree
2325 if (!new_cfqq)
2326 cfq_choose_cfqg(cfqd);
2328 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2329 keep_queue:
2330 return cfqq;
2333 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2335 int dispatched = 0;
2337 while (cfqq->next_rq) {
2338 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2339 dispatched++;
2342 BUG_ON(!list_empty(&cfqq->fifo));
2344 /* By default cfqq is not expired if it is empty. Do it explicitly */
2345 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2346 return dispatched;
2350 * Drain our current requests. Used for barriers and when switching
2351 * io schedulers on-the-fly.
2353 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2355 struct cfq_queue *cfqq;
2356 int dispatched = 0;
2358 /* Expire the timeslice of the current active queue first */
2359 cfq_slice_expired(cfqd, 0);
2360 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2361 __cfq_set_active_queue(cfqd, cfqq);
2362 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2365 BUG_ON(cfqd->busy_queues);
2367 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2368 return dispatched;
2371 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2372 struct cfq_queue *cfqq)
2374 /* the queue hasn't finished any request, can't estimate */
2375 if (cfq_cfqq_slice_new(cfqq))
2376 return true;
2377 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2378 cfqq->slice_end))
2379 return true;
2381 return false;
2384 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2386 unsigned int max_dispatch;
2389 * Drain async requests before we start sync IO
2391 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2392 return false;
2395 * If this is an async queue and we have sync IO in flight, let it wait
2397 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2398 return false;
2400 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2401 if (cfq_class_idle(cfqq))
2402 max_dispatch = 1;
2405 * Does this cfqq already have too much IO in flight?
2407 if (cfqq->dispatched >= max_dispatch) {
2409 * idle queue must always only have a single IO in flight
2411 if (cfq_class_idle(cfqq))
2412 return false;
2415 * We have other queues, don't allow more IO from this one
2417 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
2418 return false;
2421 * Sole queue user, no limit
2423 if (cfqd->busy_queues == 1)
2424 max_dispatch = -1;
2425 else
2427 * Normally we start throttling cfqq when cfq_quantum/2
2428 * requests have been dispatched. But we can drive
2429 * deeper queue depths at the beginning of slice
2430 * subjected to upper limit of cfq_quantum.
2431 * */
2432 max_dispatch = cfqd->cfq_quantum;
2436 * Async queues must wait a bit before being allowed dispatch.
2437 * We also ramp up the dispatch depth gradually for async IO,
2438 * based on the last sync IO we serviced
2440 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2441 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2442 unsigned int depth;
2444 depth = last_sync / cfqd->cfq_slice[1];
2445 if (!depth && !cfqq->dispatched)
2446 depth = 1;
2447 if (depth < max_dispatch)
2448 max_dispatch = depth;
2452 * If we're below the current max, allow a dispatch
2454 return cfqq->dispatched < max_dispatch;
2458 * Dispatch a request from cfqq, moving them to the request queue
2459 * dispatch list.
2461 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2463 struct request *rq;
2465 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2467 if (!cfq_may_dispatch(cfqd, cfqq))
2468 return false;
2471 * follow expired path, else get first next available
2473 rq = cfq_check_fifo(cfqq);
2474 if (!rq)
2475 rq = cfqq->next_rq;
2478 * insert request into driver dispatch list
2480 cfq_dispatch_insert(cfqd->queue, rq);
2482 if (!cfqd->active_cic) {
2483 struct cfq_io_context *cic = RQ_CIC(rq);
2485 atomic_long_inc(&cic->ioc->refcount);
2486 cfqd->active_cic = cic;
2489 return true;
2493 * Find the cfqq that we need to service and move a request from that to the
2494 * dispatch list
2496 static int cfq_dispatch_requests(struct request_queue *q, int force)
2498 struct cfq_data *cfqd = q->elevator->elevator_data;
2499 struct cfq_queue *cfqq;
2501 if (!cfqd->busy_queues)
2502 return 0;
2504 if (unlikely(force))
2505 return cfq_forced_dispatch(cfqd);
2507 cfqq = cfq_select_queue(cfqd);
2508 if (!cfqq)
2509 return 0;
2512 * Dispatch a request from this cfqq, if it is allowed
2514 if (!cfq_dispatch_request(cfqd, cfqq))
2515 return 0;
2517 cfqq->slice_dispatch++;
2518 cfq_clear_cfqq_must_dispatch(cfqq);
2521 * expire an async queue immediately if it has used up its slice. idle
2522 * queue always expire after 1 dispatch round.
2524 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2525 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2526 cfq_class_idle(cfqq))) {
2527 cfqq->slice_end = jiffies + 1;
2528 cfq_slice_expired(cfqd, 0);
2531 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2532 return 1;
2536 * task holds one reference to the queue, dropped when task exits. each rq
2537 * in-flight on this queue also holds a reference, dropped when rq is freed.
2539 * Each cfq queue took a reference on the parent group. Drop it now.
2540 * queue lock must be held here.
2542 static void cfq_put_queue(struct cfq_queue *cfqq)
2544 struct cfq_data *cfqd = cfqq->cfqd;
2545 struct cfq_group *cfqg, *orig_cfqg;
2547 BUG_ON(cfqq->ref <= 0);
2549 cfqq->ref--;
2550 if (cfqq->ref)
2551 return;
2553 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2554 BUG_ON(rb_first(&cfqq->sort_list));
2555 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2556 cfqg = cfqq->cfqg;
2557 orig_cfqg = cfqq->orig_cfqg;
2559 if (unlikely(cfqd->active_queue == cfqq)) {
2560 __cfq_slice_expired(cfqd, cfqq, 0);
2561 cfq_schedule_dispatch(cfqd);
2564 BUG_ON(cfq_cfqq_on_rr(cfqq));
2565 kmem_cache_free(cfq_pool, cfqq);
2566 cfq_put_cfqg(cfqg);
2567 if (orig_cfqg)
2568 cfq_put_cfqg(orig_cfqg);
2572 * Must always be called with the rcu_read_lock() held
2574 static void
2575 __call_for_each_cic(struct io_context *ioc,
2576 void (*func)(struct io_context *, struct cfq_io_context *))
2578 struct cfq_io_context *cic;
2579 struct hlist_node *n;
2581 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2582 func(ioc, cic);
2586 * Call func for each cic attached to this ioc.
2588 static void
2589 call_for_each_cic(struct io_context *ioc,
2590 void (*func)(struct io_context *, struct cfq_io_context *))
2592 rcu_read_lock();
2593 __call_for_each_cic(ioc, func);
2594 rcu_read_unlock();
2597 static void cfq_cic_free_rcu(struct rcu_head *head)
2599 struct cfq_io_context *cic;
2601 cic = container_of(head, struct cfq_io_context, rcu_head);
2603 kmem_cache_free(cfq_ioc_pool, cic);
2604 elv_ioc_count_dec(cfq_ioc_count);
2606 if (ioc_gone) {
2608 * CFQ scheduler is exiting, grab exit lock and check
2609 * the pending io context count. If it hits zero,
2610 * complete ioc_gone and set it back to NULL
2612 spin_lock(&ioc_gone_lock);
2613 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2614 complete(ioc_gone);
2615 ioc_gone = NULL;
2617 spin_unlock(&ioc_gone_lock);
2621 static void cfq_cic_free(struct cfq_io_context *cic)
2623 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2626 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2628 unsigned long flags;
2629 unsigned long dead_key = (unsigned long) cic->key;
2631 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2633 spin_lock_irqsave(&ioc->lock, flags);
2634 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2635 hlist_del_rcu(&cic->cic_list);
2636 spin_unlock_irqrestore(&ioc->lock, flags);
2638 cfq_cic_free(cic);
2642 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2643 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2644 * and ->trim() which is called with the task lock held
2646 static void cfq_free_io_context(struct io_context *ioc)
2649 * ioc->refcount is zero here, or we are called from elv_unregister(),
2650 * so no more cic's are allowed to be linked into this ioc. So it
2651 * should be ok to iterate over the known list, we will see all cic's
2652 * since no new ones are added.
2654 __call_for_each_cic(ioc, cic_free_func);
2657 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2659 struct cfq_queue *__cfqq, *next;
2662 * If this queue was scheduled to merge with another queue, be
2663 * sure to drop the reference taken on that queue (and others in
2664 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2666 __cfqq = cfqq->new_cfqq;
2667 while (__cfqq) {
2668 if (__cfqq == cfqq) {
2669 WARN(1, "cfqq->new_cfqq loop detected\n");
2670 break;
2672 next = __cfqq->new_cfqq;
2673 cfq_put_queue(__cfqq);
2674 __cfqq = next;
2678 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2680 if (unlikely(cfqq == cfqd->active_queue)) {
2681 __cfq_slice_expired(cfqd, cfqq, 0);
2682 cfq_schedule_dispatch(cfqd);
2685 cfq_put_cooperator(cfqq);
2687 cfq_put_queue(cfqq);
2690 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2691 struct cfq_io_context *cic)
2693 struct io_context *ioc = cic->ioc;
2695 list_del_init(&cic->queue_list);
2698 * Make sure dead mark is seen for dead queues
2700 smp_wmb();
2701 cic->key = cfqd_dead_key(cfqd);
2703 if (ioc->ioc_data == cic)
2704 rcu_assign_pointer(ioc->ioc_data, NULL);
2706 if (cic->cfqq[BLK_RW_ASYNC]) {
2707 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2708 cic->cfqq[BLK_RW_ASYNC] = NULL;
2711 if (cic->cfqq[BLK_RW_SYNC]) {
2712 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2713 cic->cfqq[BLK_RW_SYNC] = NULL;
2717 static void cfq_exit_single_io_context(struct io_context *ioc,
2718 struct cfq_io_context *cic)
2720 struct cfq_data *cfqd = cic_to_cfqd(cic);
2722 if (cfqd) {
2723 struct request_queue *q = cfqd->queue;
2724 unsigned long flags;
2726 spin_lock_irqsave(q->queue_lock, flags);
2729 * Ensure we get a fresh copy of the ->key to prevent
2730 * race between exiting task and queue
2732 smp_read_barrier_depends();
2733 if (cic->key == cfqd)
2734 __cfq_exit_single_io_context(cfqd, cic);
2736 spin_unlock_irqrestore(q->queue_lock, flags);
2741 * The process that ioc belongs to has exited, we need to clean up
2742 * and put the internal structures we have that belongs to that process.
2744 static void cfq_exit_io_context(struct io_context *ioc)
2746 call_for_each_cic(ioc, cfq_exit_single_io_context);
2749 static struct cfq_io_context *
2750 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2752 struct cfq_io_context *cic;
2754 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2755 cfqd->queue->node);
2756 if (cic) {
2757 cic->last_end_request = jiffies;
2758 INIT_LIST_HEAD(&cic->queue_list);
2759 INIT_HLIST_NODE(&cic->cic_list);
2760 cic->dtor = cfq_free_io_context;
2761 cic->exit = cfq_exit_io_context;
2762 elv_ioc_count_inc(cfq_ioc_count);
2765 return cic;
2768 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2770 struct task_struct *tsk = current;
2771 int ioprio_class;
2773 if (!cfq_cfqq_prio_changed(cfqq))
2774 return;
2776 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2777 switch (ioprio_class) {
2778 default:
2779 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2780 case IOPRIO_CLASS_NONE:
2782 * no prio set, inherit CPU scheduling settings
2784 cfqq->ioprio = task_nice_ioprio(tsk);
2785 cfqq->ioprio_class = task_nice_ioclass(tsk);
2786 break;
2787 case IOPRIO_CLASS_RT:
2788 cfqq->ioprio = task_ioprio(ioc);
2789 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2790 break;
2791 case IOPRIO_CLASS_BE:
2792 cfqq->ioprio = task_ioprio(ioc);
2793 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2794 break;
2795 case IOPRIO_CLASS_IDLE:
2796 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2797 cfqq->ioprio = 7;
2798 cfq_clear_cfqq_idle_window(cfqq);
2799 break;
2803 * keep track of original prio settings in case we have to temporarily
2804 * elevate the priority of this queue
2806 cfqq->org_ioprio = cfqq->ioprio;
2807 cfqq->org_ioprio_class = cfqq->ioprio_class;
2808 cfq_clear_cfqq_prio_changed(cfqq);
2811 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2813 struct cfq_data *cfqd = cic_to_cfqd(cic);
2814 struct cfq_queue *cfqq;
2815 unsigned long flags;
2817 if (unlikely(!cfqd))
2818 return;
2820 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2822 cfqq = cic->cfqq[BLK_RW_ASYNC];
2823 if (cfqq) {
2824 struct cfq_queue *new_cfqq;
2825 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2826 GFP_ATOMIC);
2827 if (new_cfqq) {
2828 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2829 cfq_put_queue(cfqq);
2833 cfqq = cic->cfqq[BLK_RW_SYNC];
2834 if (cfqq)
2835 cfq_mark_cfqq_prio_changed(cfqq);
2837 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2840 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2842 call_for_each_cic(ioc, changed_ioprio);
2843 ioc->ioprio_changed = 0;
2846 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2847 pid_t pid, bool is_sync)
2849 RB_CLEAR_NODE(&cfqq->rb_node);
2850 RB_CLEAR_NODE(&cfqq->p_node);
2851 INIT_LIST_HEAD(&cfqq->fifo);
2853 cfqq->ref = 0;
2854 cfqq->cfqd = cfqd;
2856 cfq_mark_cfqq_prio_changed(cfqq);
2858 if (is_sync) {
2859 if (!cfq_class_idle(cfqq))
2860 cfq_mark_cfqq_idle_window(cfqq);
2861 cfq_mark_cfqq_sync(cfqq);
2863 cfqq->pid = pid;
2866 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2867 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2869 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2870 struct cfq_data *cfqd = cic_to_cfqd(cic);
2871 unsigned long flags;
2872 struct request_queue *q;
2874 if (unlikely(!cfqd))
2875 return;
2877 q = cfqd->queue;
2879 spin_lock_irqsave(q->queue_lock, flags);
2881 if (sync_cfqq) {
2883 * Drop reference to sync queue. A new sync queue will be
2884 * assigned in new group upon arrival of a fresh request.
2886 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2887 cic_set_cfqq(cic, NULL, 1);
2888 cfq_put_queue(sync_cfqq);
2891 spin_unlock_irqrestore(q->queue_lock, flags);
2894 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2896 call_for_each_cic(ioc, changed_cgroup);
2897 ioc->cgroup_changed = 0;
2899 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2901 static struct cfq_queue *
2902 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2903 struct io_context *ioc, gfp_t gfp_mask)
2905 struct cfq_queue *cfqq, *new_cfqq = NULL;
2906 struct cfq_io_context *cic;
2907 struct cfq_group *cfqg;
2909 retry:
2910 cfqg = cfq_get_cfqg(cfqd, 1);
2911 cic = cfq_cic_lookup(cfqd, ioc);
2912 /* cic always exists here */
2913 cfqq = cic_to_cfqq(cic, is_sync);
2916 * Always try a new alloc if we fell back to the OOM cfqq
2917 * originally, since it should just be a temporary situation.
2919 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2920 cfqq = NULL;
2921 if (new_cfqq) {
2922 cfqq = new_cfqq;
2923 new_cfqq = NULL;
2924 } else if (gfp_mask & __GFP_WAIT) {
2925 spin_unlock_irq(cfqd->queue->queue_lock);
2926 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2927 gfp_mask | __GFP_ZERO,
2928 cfqd->queue->node);
2929 spin_lock_irq(cfqd->queue->queue_lock);
2930 if (new_cfqq)
2931 goto retry;
2932 } else {
2933 cfqq = kmem_cache_alloc_node(cfq_pool,
2934 gfp_mask | __GFP_ZERO,
2935 cfqd->queue->node);
2938 if (cfqq) {
2939 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2940 cfq_init_prio_data(cfqq, ioc);
2941 cfq_link_cfqq_cfqg(cfqq, cfqg);
2942 cfq_log_cfqq(cfqd, cfqq, "alloced");
2943 } else
2944 cfqq = &cfqd->oom_cfqq;
2947 if (new_cfqq)
2948 kmem_cache_free(cfq_pool, new_cfqq);
2950 return cfqq;
2953 static struct cfq_queue **
2954 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2956 switch (ioprio_class) {
2957 case IOPRIO_CLASS_RT:
2958 return &cfqd->async_cfqq[0][ioprio];
2959 case IOPRIO_CLASS_BE:
2960 return &cfqd->async_cfqq[1][ioprio];
2961 case IOPRIO_CLASS_IDLE:
2962 return &cfqd->async_idle_cfqq;
2963 default:
2964 BUG();
2968 static struct cfq_queue *
2969 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2970 gfp_t gfp_mask)
2972 const int ioprio = task_ioprio(ioc);
2973 const int ioprio_class = task_ioprio_class(ioc);
2974 struct cfq_queue **async_cfqq = NULL;
2975 struct cfq_queue *cfqq = NULL;
2977 if (!is_sync) {
2978 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2979 cfqq = *async_cfqq;
2982 if (!cfqq)
2983 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2986 * pin the queue now that it's allocated, scheduler exit will prune it
2988 if (!is_sync && !(*async_cfqq)) {
2989 cfqq->ref++;
2990 *async_cfqq = cfqq;
2993 cfqq->ref++;
2994 return cfqq;
2998 * We drop cfq io contexts lazily, so we may find a dead one.
3000 static void
3001 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
3002 struct cfq_io_context *cic)
3004 unsigned long flags;
3006 WARN_ON(!list_empty(&cic->queue_list));
3007 BUG_ON(cic->key != cfqd_dead_key(cfqd));
3009 spin_lock_irqsave(&ioc->lock, flags);
3011 BUG_ON(ioc->ioc_data == cic);
3013 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
3014 hlist_del_rcu(&cic->cic_list);
3015 spin_unlock_irqrestore(&ioc->lock, flags);
3017 cfq_cic_free(cic);
3020 static struct cfq_io_context *
3021 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3023 struct cfq_io_context *cic;
3024 unsigned long flags;
3026 if (unlikely(!ioc))
3027 return NULL;
3029 rcu_read_lock();
3032 * we maintain a last-hit cache, to avoid browsing over the tree
3034 cic = rcu_dereference(ioc->ioc_data);
3035 if (cic && cic->key == cfqd) {
3036 rcu_read_unlock();
3037 return cic;
3040 do {
3041 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
3042 rcu_read_unlock();
3043 if (!cic)
3044 break;
3045 if (unlikely(cic->key != cfqd)) {
3046 cfq_drop_dead_cic(cfqd, ioc, cic);
3047 rcu_read_lock();
3048 continue;
3051 spin_lock_irqsave(&ioc->lock, flags);
3052 rcu_assign_pointer(ioc->ioc_data, cic);
3053 spin_unlock_irqrestore(&ioc->lock, flags);
3054 break;
3055 } while (1);
3057 return cic;
3061 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3062 * the process specific cfq io context when entered from the block layer.
3063 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3065 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
3066 struct cfq_io_context *cic, gfp_t gfp_mask)
3068 unsigned long flags;
3069 int ret;
3071 ret = radix_tree_preload(gfp_mask);
3072 if (!ret) {
3073 cic->ioc = ioc;
3074 cic->key = cfqd;
3076 spin_lock_irqsave(&ioc->lock, flags);
3077 ret = radix_tree_insert(&ioc->radix_root,
3078 cfqd->cic_index, cic);
3079 if (!ret)
3080 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3081 spin_unlock_irqrestore(&ioc->lock, flags);
3083 radix_tree_preload_end();
3085 if (!ret) {
3086 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3087 list_add(&cic->queue_list, &cfqd->cic_list);
3088 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3092 if (ret)
3093 printk(KERN_ERR "cfq: cic link failed!\n");
3095 return ret;
3099 * Setup general io context and cfq io context. There can be several cfq
3100 * io contexts per general io context, if this process is doing io to more
3101 * than one device managed by cfq.
3103 static struct cfq_io_context *
3104 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3106 struct io_context *ioc = NULL;
3107 struct cfq_io_context *cic;
3109 might_sleep_if(gfp_mask & __GFP_WAIT);
3111 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3112 if (!ioc)
3113 return NULL;
3115 cic = cfq_cic_lookup(cfqd, ioc);
3116 if (cic)
3117 goto out;
3119 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3120 if (cic == NULL)
3121 goto err;
3123 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3124 goto err_free;
3126 out:
3127 smp_read_barrier_depends();
3128 if (unlikely(ioc->ioprio_changed))
3129 cfq_ioc_set_ioprio(ioc);
3131 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3132 if (unlikely(ioc->cgroup_changed))
3133 cfq_ioc_set_cgroup(ioc);
3134 #endif
3135 return cic;
3136 err_free:
3137 cfq_cic_free(cic);
3138 err:
3139 put_io_context(ioc);
3140 return NULL;
3143 static void
3144 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3146 unsigned long elapsed = jiffies - cic->last_end_request;
3147 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3149 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3150 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3151 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3154 static void
3155 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3156 struct request *rq)
3158 sector_t sdist = 0;
3159 sector_t n_sec = blk_rq_sectors(rq);
3160 if (cfqq->last_request_pos) {
3161 if (cfqq->last_request_pos < blk_rq_pos(rq))
3162 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3163 else
3164 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3167 cfqq->seek_history <<= 1;
3168 if (blk_queue_nonrot(cfqd->queue))
3169 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3170 else
3171 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3175 * Disable idle window if the process thinks too long or seeks so much that
3176 * it doesn't matter
3178 static void
3179 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3180 struct cfq_io_context *cic)
3182 int old_idle, enable_idle;
3185 * Don't idle for async or idle io prio class
3187 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3188 return;
3190 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3192 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3193 cfq_mark_cfqq_deep(cfqq);
3195 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3196 enable_idle = 0;
3197 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3198 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3199 enable_idle = 0;
3200 else if (sample_valid(cic->ttime_samples)) {
3201 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3202 enable_idle = 0;
3203 else
3204 enable_idle = 1;
3207 if (old_idle != enable_idle) {
3208 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3209 if (enable_idle)
3210 cfq_mark_cfqq_idle_window(cfqq);
3211 else
3212 cfq_clear_cfqq_idle_window(cfqq);
3217 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3218 * no or if we aren't sure, a 1 will cause a preempt.
3220 static bool
3221 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3222 struct request *rq)
3224 struct cfq_queue *cfqq;
3226 cfqq = cfqd->active_queue;
3227 if (!cfqq)
3228 return false;
3230 if (cfq_class_idle(new_cfqq))
3231 return false;
3233 if (cfq_class_idle(cfqq))
3234 return true;
3237 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3239 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3240 return false;
3243 * if the new request is sync, but the currently running queue is
3244 * not, let the sync request have priority.
3246 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3247 return true;
3249 if (new_cfqq->cfqg != cfqq->cfqg)
3250 return false;
3252 if (cfq_slice_used(cfqq))
3253 return true;
3255 /* Allow preemption only if we are idling on sync-noidle tree */
3256 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3257 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3258 new_cfqq->service_tree->count == 2 &&
3259 RB_EMPTY_ROOT(&cfqq->sort_list))
3260 return true;
3263 * So both queues are sync. Let the new request get disk time if
3264 * it's a metadata request and the current queue is doing regular IO.
3266 if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
3267 return true;
3270 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3272 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3273 return true;
3275 /* An idle queue should not be idle now for some reason */
3276 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3277 return true;
3279 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3280 return false;
3283 * if this request is as-good as one we would expect from the
3284 * current cfqq, let it preempt
3286 if (cfq_rq_close(cfqd, cfqq, rq))
3287 return true;
3289 return false;
3293 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3294 * let it have half of its nominal slice.
3296 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3298 struct cfq_queue *old_cfqq = cfqd->active_queue;
3300 cfq_log_cfqq(cfqd, cfqq, "preempt");
3301 cfq_slice_expired(cfqd, 1);
3304 * workload type is changed, don't save slice, otherwise preempt
3305 * doesn't happen
3307 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3308 cfqq->cfqg->saved_workload_slice = 0;
3311 * Put the new queue at the front of the of the current list,
3312 * so we know that it will be selected next.
3314 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3316 cfq_service_tree_add(cfqd, cfqq, 1);
3318 cfqq->slice_end = 0;
3319 cfq_mark_cfqq_slice_new(cfqq);
3323 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3324 * something we should do about it
3326 static void
3327 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3328 struct request *rq)
3330 struct cfq_io_context *cic = RQ_CIC(rq);
3332 cfqd->rq_queued++;
3333 if (rq->cmd_flags & REQ_META)
3334 cfqq->meta_pending++;
3336 cfq_update_io_thinktime(cfqd, cic);
3337 cfq_update_io_seektime(cfqd, cfqq, rq);
3338 cfq_update_idle_window(cfqd, cfqq, cic);
3340 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3342 if (cfqq == cfqd->active_queue) {
3344 * Remember that we saw a request from this process, but
3345 * don't start queuing just yet. Otherwise we risk seeing lots
3346 * of tiny requests, because we disrupt the normal plugging
3347 * and merging. If the request is already larger than a single
3348 * page, let it rip immediately. For that case we assume that
3349 * merging is already done. Ditto for a busy system that
3350 * has other work pending, don't risk delaying until the
3351 * idle timer unplug to continue working.
3353 if (cfq_cfqq_wait_request(cfqq)) {
3354 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3355 cfqd->busy_queues > 1) {
3356 cfq_del_timer(cfqd, cfqq);
3357 cfq_clear_cfqq_wait_request(cfqq);
3358 __blk_run_queue(cfqd->queue, false);
3359 } else {
3360 cfq_blkiocg_update_idle_time_stats(
3361 &cfqq->cfqg->blkg);
3362 cfq_mark_cfqq_must_dispatch(cfqq);
3365 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3367 * not the active queue - expire current slice if it is
3368 * idle and has expired it's mean thinktime or this new queue
3369 * has some old slice time left and is of higher priority or
3370 * this new queue is RT and the current one is BE
3372 cfq_preempt_queue(cfqd, cfqq);
3373 __blk_run_queue(cfqd->queue, false);
3377 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3379 struct cfq_data *cfqd = q->elevator->elevator_data;
3380 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3382 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3383 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3385 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3386 list_add_tail(&rq->queuelist, &cfqq->fifo);
3387 cfq_add_rq_rb(rq);
3388 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3389 &cfqd->serving_group->blkg, rq_data_dir(rq),
3390 rq_is_sync(rq));
3391 cfq_rq_enqueued(cfqd, cfqq, rq);
3395 * Update hw_tag based on peak queue depth over 50 samples under
3396 * sufficient load.
3398 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3400 struct cfq_queue *cfqq = cfqd->active_queue;
3402 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3403 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3405 if (cfqd->hw_tag == 1)
3406 return;
3408 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3409 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3410 return;
3413 * If active queue hasn't enough requests and can idle, cfq might not
3414 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3415 * case
3417 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3418 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3419 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3420 return;
3422 if (cfqd->hw_tag_samples++ < 50)
3423 return;
3425 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3426 cfqd->hw_tag = 1;
3427 else
3428 cfqd->hw_tag = 0;
3431 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3433 struct cfq_io_context *cic = cfqd->active_cic;
3435 /* If the queue already has requests, don't wait */
3436 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3437 return false;
3439 /* If there are other queues in the group, don't wait */
3440 if (cfqq->cfqg->nr_cfqq > 1)
3441 return false;
3443 if (cfq_slice_used(cfqq))
3444 return true;
3446 /* if slice left is less than think time, wait busy */
3447 if (cic && sample_valid(cic->ttime_samples)
3448 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3449 return true;
3452 * If think times is less than a jiffy than ttime_mean=0 and above
3453 * will not be true. It might happen that slice has not expired yet
3454 * but will expire soon (4-5 ns) during select_queue(). To cover the
3455 * case where think time is less than a jiffy, mark the queue wait
3456 * busy if only 1 jiffy is left in the slice.
3458 if (cfqq->slice_end - jiffies == 1)
3459 return true;
3461 return false;
3464 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3466 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3467 struct cfq_data *cfqd = cfqq->cfqd;
3468 const int sync = rq_is_sync(rq);
3469 unsigned long now;
3471 now = jiffies;
3472 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3473 !!(rq->cmd_flags & REQ_NOIDLE));
3475 cfq_update_hw_tag(cfqd);
3477 WARN_ON(!cfqd->rq_in_driver);
3478 WARN_ON(!cfqq->dispatched);
3479 cfqd->rq_in_driver--;
3480 cfqq->dispatched--;
3481 (RQ_CFQG(rq))->dispatched--;
3482 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3483 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3484 rq_data_dir(rq), rq_is_sync(rq));
3486 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3488 if (sync) {
3489 RQ_CIC(rq)->last_end_request = now;
3490 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3491 cfqd->last_delayed_sync = now;
3495 * If this is the active queue, check if it needs to be expired,
3496 * or if we want to idle in case it has no pending requests.
3498 if (cfqd->active_queue == cfqq) {
3499 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3501 if (cfq_cfqq_slice_new(cfqq)) {
3502 cfq_set_prio_slice(cfqd, cfqq);
3503 cfq_clear_cfqq_slice_new(cfqq);
3507 * Should we wait for next request to come in before we expire
3508 * the queue.
3510 if (cfq_should_wait_busy(cfqd, cfqq)) {
3511 unsigned long extend_sl = cfqd->cfq_slice_idle;
3512 if (!cfqd->cfq_slice_idle)
3513 extend_sl = cfqd->cfq_group_idle;
3514 cfqq->slice_end = jiffies + extend_sl;
3515 cfq_mark_cfqq_wait_busy(cfqq);
3516 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3520 * Idling is not enabled on:
3521 * - expired queues
3522 * - idle-priority queues
3523 * - async queues
3524 * - queues with still some requests queued
3525 * - when there is a close cooperator
3527 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3528 cfq_slice_expired(cfqd, 1);
3529 else if (sync && cfqq_empty &&
3530 !cfq_close_cooperator(cfqd, cfqq)) {
3531 cfq_arm_slice_timer(cfqd);
3535 if (!cfqd->rq_in_driver)
3536 cfq_schedule_dispatch(cfqd);
3540 * we temporarily boost lower priority queues if they are holding fs exclusive
3541 * resources. they are boosted to normal prio (CLASS_BE/4)
3543 static void cfq_prio_boost(struct cfq_queue *cfqq)
3545 if (has_fs_excl()) {
3547 * boost idle prio on transactions that would lock out other
3548 * users of the filesystem
3550 if (cfq_class_idle(cfqq))
3551 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3552 if (cfqq->ioprio > IOPRIO_NORM)
3553 cfqq->ioprio = IOPRIO_NORM;
3554 } else {
3556 * unboost the queue (if needed)
3558 cfqq->ioprio_class = cfqq->org_ioprio_class;
3559 cfqq->ioprio = cfqq->org_ioprio;
3563 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3565 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3566 cfq_mark_cfqq_must_alloc_slice(cfqq);
3567 return ELV_MQUEUE_MUST;
3570 return ELV_MQUEUE_MAY;
3573 static int cfq_may_queue(struct request_queue *q, int rw)
3575 struct cfq_data *cfqd = q->elevator->elevator_data;
3576 struct task_struct *tsk = current;
3577 struct cfq_io_context *cic;
3578 struct cfq_queue *cfqq;
3581 * don't force setup of a queue from here, as a call to may_queue
3582 * does not necessarily imply that a request actually will be queued.
3583 * so just lookup a possibly existing queue, or return 'may queue'
3584 * if that fails
3586 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3587 if (!cic)
3588 return ELV_MQUEUE_MAY;
3590 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3591 if (cfqq) {
3592 cfq_init_prio_data(cfqq, cic->ioc);
3593 cfq_prio_boost(cfqq);
3595 return __cfq_may_queue(cfqq);
3598 return ELV_MQUEUE_MAY;
3602 * queue lock held here
3604 static void cfq_put_request(struct request *rq)
3606 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3608 if (cfqq) {
3609 const int rw = rq_data_dir(rq);
3611 BUG_ON(!cfqq->allocated[rw]);
3612 cfqq->allocated[rw]--;
3614 put_io_context(RQ_CIC(rq)->ioc);
3616 rq->elevator_private = NULL;
3617 rq->elevator_private2 = NULL;
3619 /* Put down rq reference on cfqg */
3620 cfq_put_cfqg(RQ_CFQG(rq));
3621 rq->elevator_private3 = NULL;
3623 cfq_put_queue(cfqq);
3627 static struct cfq_queue *
3628 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3629 struct cfq_queue *cfqq)
3631 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3632 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3633 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3634 cfq_put_queue(cfqq);
3635 return cic_to_cfqq(cic, 1);
3639 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3640 * was the last process referring to said cfqq.
3642 static struct cfq_queue *
3643 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3645 if (cfqq_process_refs(cfqq) == 1) {
3646 cfqq->pid = current->pid;
3647 cfq_clear_cfqq_coop(cfqq);
3648 cfq_clear_cfqq_split_coop(cfqq);
3649 return cfqq;
3652 cic_set_cfqq(cic, NULL, 1);
3654 cfq_put_cooperator(cfqq);
3656 cfq_put_queue(cfqq);
3657 return NULL;
3660 * Allocate cfq data structures associated with this request.
3662 static int
3663 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3665 struct cfq_data *cfqd = q->elevator->elevator_data;
3666 struct cfq_io_context *cic;
3667 const int rw = rq_data_dir(rq);
3668 const bool is_sync = rq_is_sync(rq);
3669 struct cfq_queue *cfqq;
3670 unsigned long flags;
3672 might_sleep_if(gfp_mask & __GFP_WAIT);
3674 cic = cfq_get_io_context(cfqd, gfp_mask);
3676 spin_lock_irqsave(q->queue_lock, flags);
3678 if (!cic)
3679 goto queue_fail;
3681 new_queue:
3682 cfqq = cic_to_cfqq(cic, is_sync);
3683 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3684 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3685 cic_set_cfqq(cic, cfqq, is_sync);
3686 } else {
3688 * If the queue was seeky for too long, break it apart.
3690 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3691 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3692 cfqq = split_cfqq(cic, cfqq);
3693 if (!cfqq)
3694 goto new_queue;
3698 * Check to see if this queue is scheduled to merge with
3699 * another, closely cooperating queue. The merging of
3700 * queues happens here as it must be done in process context.
3701 * The reference on new_cfqq was taken in merge_cfqqs.
3703 if (cfqq->new_cfqq)
3704 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3707 cfqq->allocated[rw]++;
3708 cfqq->ref++;
3709 rq->elevator_private = cic;
3710 rq->elevator_private2 = cfqq;
3711 rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
3713 spin_unlock_irqrestore(q->queue_lock, flags);
3715 return 0;
3717 queue_fail:
3718 if (cic)
3719 put_io_context(cic->ioc);
3721 cfq_schedule_dispatch(cfqd);
3722 spin_unlock_irqrestore(q->queue_lock, flags);
3723 cfq_log(cfqd, "set_request fail");
3724 return 1;
3727 static void cfq_kick_queue(struct work_struct *work)
3729 struct cfq_data *cfqd =
3730 container_of(work, struct cfq_data, unplug_work);
3731 struct request_queue *q = cfqd->queue;
3733 spin_lock_irq(q->queue_lock);
3734 __blk_run_queue(cfqd->queue, false);
3735 spin_unlock_irq(q->queue_lock);
3739 * Timer running if the active_queue is currently idling inside its time slice
3741 static void cfq_idle_slice_timer(unsigned long data)
3743 struct cfq_data *cfqd = (struct cfq_data *) data;
3744 struct cfq_queue *cfqq;
3745 unsigned long flags;
3746 int timed_out = 1;
3748 cfq_log(cfqd, "idle timer fired");
3750 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3752 cfqq = cfqd->active_queue;
3753 if (cfqq) {
3754 timed_out = 0;
3757 * We saw a request before the queue expired, let it through
3759 if (cfq_cfqq_must_dispatch(cfqq))
3760 goto out_kick;
3763 * expired
3765 if (cfq_slice_used(cfqq))
3766 goto expire;
3769 * only expire and reinvoke request handler, if there are
3770 * other queues with pending requests
3772 if (!cfqd->busy_queues)
3773 goto out_cont;
3776 * not expired and it has a request pending, let it dispatch
3778 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3779 goto out_kick;
3782 * Queue depth flag is reset only when the idle didn't succeed
3784 cfq_clear_cfqq_deep(cfqq);
3786 expire:
3787 cfq_slice_expired(cfqd, timed_out);
3788 out_kick:
3789 cfq_schedule_dispatch(cfqd);
3790 out_cont:
3791 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3794 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3796 del_timer_sync(&cfqd->idle_slice_timer);
3797 cancel_work_sync(&cfqd->unplug_work);
3800 static void cfq_put_async_queues(struct cfq_data *cfqd)
3802 int i;
3804 for (i = 0; i < IOPRIO_BE_NR; i++) {
3805 if (cfqd->async_cfqq[0][i])
3806 cfq_put_queue(cfqd->async_cfqq[0][i]);
3807 if (cfqd->async_cfqq[1][i])
3808 cfq_put_queue(cfqd->async_cfqq[1][i]);
3811 if (cfqd->async_idle_cfqq)
3812 cfq_put_queue(cfqd->async_idle_cfqq);
3815 static void cfq_cfqd_free(struct rcu_head *head)
3817 kfree(container_of(head, struct cfq_data, rcu));
3820 static void cfq_exit_queue(struct elevator_queue *e)
3822 struct cfq_data *cfqd = e->elevator_data;
3823 struct request_queue *q = cfqd->queue;
3825 cfq_shutdown_timer_wq(cfqd);
3827 spin_lock_irq(q->queue_lock);
3829 if (cfqd->active_queue)
3830 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3832 while (!list_empty(&cfqd->cic_list)) {
3833 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3834 struct cfq_io_context,
3835 queue_list);
3837 __cfq_exit_single_io_context(cfqd, cic);
3840 cfq_put_async_queues(cfqd);
3841 cfq_release_cfq_groups(cfqd);
3842 cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3844 spin_unlock_irq(q->queue_lock);
3846 cfq_shutdown_timer_wq(cfqd);
3848 spin_lock(&cic_index_lock);
3849 ida_remove(&cic_index_ida, cfqd->cic_index);
3850 spin_unlock(&cic_index_lock);
3852 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3853 call_rcu(&cfqd->rcu, cfq_cfqd_free);
3856 static int cfq_alloc_cic_index(void)
3858 int index, error;
3860 do {
3861 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3862 return -ENOMEM;
3864 spin_lock(&cic_index_lock);
3865 error = ida_get_new(&cic_index_ida, &index);
3866 spin_unlock(&cic_index_lock);
3867 if (error && error != -EAGAIN)
3868 return error;
3869 } while (error);
3871 return index;
3874 static void *cfq_init_queue(struct request_queue *q)
3876 struct cfq_data *cfqd;
3877 int i, j;
3878 struct cfq_group *cfqg;
3879 struct cfq_rb_root *st;
3881 i = cfq_alloc_cic_index();
3882 if (i < 0)
3883 return NULL;
3885 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3886 if (!cfqd)
3887 return NULL;
3890 * Don't need take queue_lock in the routine, since we are
3891 * initializing the ioscheduler, and nobody is using cfqd
3893 cfqd->cic_index = i;
3895 /* Init root service tree */
3896 cfqd->grp_service_tree = CFQ_RB_ROOT;
3898 /* Init root group */
3899 cfqg = &cfqd->root_group;
3900 for_each_cfqg_st(cfqg, i, j, st)
3901 *st = CFQ_RB_ROOT;
3902 RB_CLEAR_NODE(&cfqg->rb_node);
3904 /* Give preference to root group over other groups */
3905 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3907 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3909 * Take a reference to root group which we never drop. This is just
3910 * to make sure that cfq_put_cfqg() does not try to kfree root group
3912 cfqg->ref = 1;
3913 rcu_read_lock();
3914 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3915 (void *)cfqd, 0);
3916 rcu_read_unlock();
3917 #endif
3919 * Not strictly needed (since RB_ROOT just clears the node and we
3920 * zeroed cfqd on alloc), but better be safe in case someone decides
3921 * to add magic to the rb code
3923 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3924 cfqd->prio_trees[i] = RB_ROOT;
3927 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3928 * Grab a permanent reference to it, so that the normal code flow
3929 * will not attempt to free it.
3931 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3932 cfqd->oom_cfqq.ref++;
3933 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3935 INIT_LIST_HEAD(&cfqd->cic_list);
3937 cfqd->queue = q;
3939 init_timer(&cfqd->idle_slice_timer);
3940 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3941 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3943 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3945 cfqd->cfq_quantum = cfq_quantum;
3946 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3947 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3948 cfqd->cfq_back_max = cfq_back_max;
3949 cfqd->cfq_back_penalty = cfq_back_penalty;
3950 cfqd->cfq_slice[0] = cfq_slice_async;
3951 cfqd->cfq_slice[1] = cfq_slice_sync;
3952 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3953 cfqd->cfq_slice_idle = cfq_slice_idle;
3954 cfqd->cfq_group_idle = cfq_group_idle;
3955 cfqd->cfq_latency = 1;
3956 cfqd->cfq_group_isolation = 0;
3957 cfqd->hw_tag = -1;
3959 * we optimistically start assuming sync ops weren't delayed in last
3960 * second, in order to have larger depth for async operations.
3962 cfqd->last_delayed_sync = jiffies - HZ;
3963 return cfqd;
3966 static void cfq_slab_kill(void)
3969 * Caller already ensured that pending RCU callbacks are completed,
3970 * so we should have no busy allocations at this point.
3972 if (cfq_pool)
3973 kmem_cache_destroy(cfq_pool);
3974 if (cfq_ioc_pool)
3975 kmem_cache_destroy(cfq_ioc_pool);
3978 static int __init cfq_slab_setup(void)
3980 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3981 if (!cfq_pool)
3982 goto fail;
3984 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3985 if (!cfq_ioc_pool)
3986 goto fail;
3988 return 0;
3989 fail:
3990 cfq_slab_kill();
3991 return -ENOMEM;
3995 * sysfs parts below -->
3997 static ssize_t
3998 cfq_var_show(unsigned int var, char *page)
4000 return sprintf(page, "%d\n", var);
4003 static ssize_t
4004 cfq_var_store(unsigned int *var, const char *page, size_t count)
4006 char *p = (char *) page;
4008 *var = simple_strtoul(p, &p, 10);
4009 return count;
4012 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4013 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4015 struct cfq_data *cfqd = e->elevator_data; \
4016 unsigned int __data = __VAR; \
4017 if (__CONV) \
4018 __data = jiffies_to_msecs(__data); \
4019 return cfq_var_show(__data, (page)); \
4021 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4022 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4023 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4024 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4025 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4026 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4027 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4028 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4029 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4030 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4031 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4032 SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
4033 #undef SHOW_FUNCTION
4035 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4036 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4038 struct cfq_data *cfqd = e->elevator_data; \
4039 unsigned int __data; \
4040 int ret = cfq_var_store(&__data, (page), count); \
4041 if (__data < (MIN)) \
4042 __data = (MIN); \
4043 else if (__data > (MAX)) \
4044 __data = (MAX); \
4045 if (__CONV) \
4046 *(__PTR) = msecs_to_jiffies(__data); \
4047 else \
4048 *(__PTR) = __data; \
4049 return ret; \
4051 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4052 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4053 UINT_MAX, 1);
4054 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4055 UINT_MAX, 1);
4056 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4057 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4058 UINT_MAX, 0);
4059 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4060 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4061 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4062 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4063 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4064 UINT_MAX, 0);
4065 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4066 STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
4067 #undef STORE_FUNCTION
4069 #define CFQ_ATTR(name) \
4070 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4072 static struct elv_fs_entry cfq_attrs[] = {
4073 CFQ_ATTR(quantum),
4074 CFQ_ATTR(fifo_expire_sync),
4075 CFQ_ATTR(fifo_expire_async),
4076 CFQ_ATTR(back_seek_max),
4077 CFQ_ATTR(back_seek_penalty),
4078 CFQ_ATTR(slice_sync),
4079 CFQ_ATTR(slice_async),
4080 CFQ_ATTR(slice_async_rq),
4081 CFQ_ATTR(slice_idle),
4082 CFQ_ATTR(group_idle),
4083 CFQ_ATTR(low_latency),
4084 CFQ_ATTR(group_isolation),
4085 __ATTR_NULL
4088 static struct elevator_type iosched_cfq = {
4089 .ops = {
4090 .elevator_merge_fn = cfq_merge,
4091 .elevator_merged_fn = cfq_merged_request,
4092 .elevator_merge_req_fn = cfq_merged_requests,
4093 .elevator_allow_merge_fn = cfq_allow_merge,
4094 .elevator_bio_merged_fn = cfq_bio_merged,
4095 .elevator_dispatch_fn = cfq_dispatch_requests,
4096 .elevator_add_req_fn = cfq_insert_request,
4097 .elevator_activate_req_fn = cfq_activate_request,
4098 .elevator_deactivate_req_fn = cfq_deactivate_request,
4099 .elevator_queue_empty_fn = cfq_queue_empty,
4100 .elevator_completed_req_fn = cfq_completed_request,
4101 .elevator_former_req_fn = elv_rb_former_request,
4102 .elevator_latter_req_fn = elv_rb_latter_request,
4103 .elevator_set_req_fn = cfq_set_request,
4104 .elevator_put_req_fn = cfq_put_request,
4105 .elevator_may_queue_fn = cfq_may_queue,
4106 .elevator_init_fn = cfq_init_queue,
4107 .elevator_exit_fn = cfq_exit_queue,
4108 .trim = cfq_free_io_context,
4110 .elevator_attrs = cfq_attrs,
4111 .elevator_name = "cfq",
4112 .elevator_owner = THIS_MODULE,
4115 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4116 static struct blkio_policy_type blkio_policy_cfq = {
4117 .ops = {
4118 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4119 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4121 .plid = BLKIO_POLICY_PROP,
4123 #else
4124 static struct blkio_policy_type blkio_policy_cfq;
4125 #endif
4127 static int __init cfq_init(void)
4130 * could be 0 on HZ < 1000 setups
4132 if (!cfq_slice_async)
4133 cfq_slice_async = 1;
4134 if (!cfq_slice_idle)
4135 cfq_slice_idle = 1;
4137 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4138 if (!cfq_group_idle)
4139 cfq_group_idle = 1;
4140 #else
4141 cfq_group_idle = 0;
4142 #endif
4143 if (cfq_slab_setup())
4144 return -ENOMEM;
4146 elv_register(&iosched_cfq);
4147 blkio_policy_register(&blkio_policy_cfq);
4149 return 0;
4152 static void __exit cfq_exit(void)
4154 DECLARE_COMPLETION_ONSTACK(all_gone);
4155 blkio_policy_unregister(&blkio_policy_cfq);
4156 elv_unregister(&iosched_cfq);
4157 ioc_gone = &all_gone;
4158 /* ioc_gone's update must be visible before reading ioc_count */
4159 smp_wmb();
4162 * this also protects us from entering cfq_slab_kill() with
4163 * pending RCU callbacks
4165 if (elv_ioc_count_read(cfq_ioc_count))
4166 wait_for_completion(&all_gone);
4167 ida_destroy(&cic_index_ida);
4168 cfq_slab_kill();
4171 module_init(cfq_init);
4172 module_exit(cfq_exit);
4174 MODULE_AUTHOR("Jens Axboe");
4175 MODULE_LICENSE("GPL");
4176 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");