FRV: Use generic show_interrupts()
[cris-mirror.git] / block / cfq-iosched.c
blob7785169f3c8f86df03887fe98d9af988b260e8ea
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[0])
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
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 /* Number of sectors dispatched from queue in single dispatch round */
150 unsigned long nr_sectors;
154 * First index in the service_trees.
155 * IDLE is handled separately, so it has negative index
157 enum wl_prio_t {
158 BE_WORKLOAD = 0,
159 RT_WORKLOAD = 1,
160 IDLE_WORKLOAD = 2,
161 CFQ_PRIO_NR,
165 * Second index in the service_trees.
167 enum wl_type_t {
168 ASYNC_WORKLOAD = 0,
169 SYNC_NOIDLE_WORKLOAD = 1,
170 SYNC_WORKLOAD = 2
173 /* This is per cgroup per device grouping structure */
174 struct cfq_group {
175 /* group service_tree member */
176 struct rb_node rb_node;
178 /* group service_tree key */
179 u64 vdisktime;
180 unsigned int weight;
181 unsigned int new_weight;
182 bool needs_update;
184 /* number of cfqq currently on this group */
185 int nr_cfqq;
188 * Per group busy queus average. Useful for workload slice calc. We
189 * create the array for each prio class but at run time it is used
190 * only for RT and BE class and slot for IDLE class remains unused.
191 * This is primarily done to avoid confusion and a gcc warning.
193 unsigned int busy_queues_avg[CFQ_PRIO_NR];
195 * rr lists of queues with requests. We maintain service trees for
196 * RT and BE classes. These trees are subdivided in subclasses
197 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
198 * class there is no subclassification and all the cfq queues go on
199 * a single tree service_tree_idle.
200 * Counts are embedded in the cfq_rb_root
202 struct cfq_rb_root service_trees[2][3];
203 struct cfq_rb_root service_tree_idle;
205 unsigned long saved_workload_slice;
206 enum wl_type_t saved_workload;
207 enum wl_prio_t saved_serving_prio;
208 struct blkio_group blkg;
209 #ifdef CONFIG_CFQ_GROUP_IOSCHED
210 struct hlist_node cfqd_node;
211 int ref;
212 #endif
213 /* number of requests that are on the dispatch list or inside driver */
214 int dispatched;
218 * Per block device queue structure
220 struct cfq_data {
221 struct request_queue *queue;
222 /* Root service tree for cfq_groups */
223 struct cfq_rb_root grp_service_tree;
224 struct cfq_group root_group;
227 * The priority currently being served
229 enum wl_prio_t serving_prio;
230 enum wl_type_t serving_type;
231 unsigned long workload_expires;
232 struct cfq_group *serving_group;
235 * Each priority tree is sorted by next_request position. These
236 * trees are used when determining if two or more queues are
237 * interleaving requests (see cfq_close_cooperator).
239 struct rb_root prio_trees[CFQ_PRIO_LISTS];
241 unsigned int busy_queues;
242 unsigned int busy_sync_queues;
244 int rq_in_driver;
245 int rq_in_flight[2];
248 * queue-depth detection
250 int rq_queued;
251 int hw_tag;
253 * hw_tag can be
254 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
255 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
256 * 0 => no NCQ
258 int hw_tag_est_depth;
259 unsigned int hw_tag_samples;
262 * idle window management
264 struct timer_list idle_slice_timer;
265 struct work_struct unplug_work;
267 struct cfq_queue *active_queue;
268 struct cfq_io_context *active_cic;
271 * async queue for each priority case
273 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
274 struct cfq_queue *async_idle_cfqq;
276 sector_t last_position;
279 * tunables, see top of file
281 unsigned int cfq_quantum;
282 unsigned int cfq_fifo_expire[2];
283 unsigned int cfq_back_penalty;
284 unsigned int cfq_back_max;
285 unsigned int cfq_slice[2];
286 unsigned int cfq_slice_async_rq;
287 unsigned int cfq_slice_idle;
288 unsigned int cfq_group_idle;
289 unsigned int cfq_latency;
291 unsigned int cic_index;
292 struct list_head cic_list;
295 * Fallback dummy cfqq for extreme OOM conditions
297 struct cfq_queue oom_cfqq;
299 unsigned long last_delayed_sync;
301 /* List of cfq groups being managed on this device*/
302 struct hlist_head cfqg_list;
303 struct rcu_head rcu;
306 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
308 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
309 enum wl_prio_t prio,
310 enum wl_type_t type)
312 if (!cfqg)
313 return NULL;
315 if (prio == IDLE_WORKLOAD)
316 return &cfqg->service_tree_idle;
318 return &cfqg->service_trees[prio][type];
321 enum cfqq_state_flags {
322 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
323 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
324 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
325 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
326 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
327 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
328 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
329 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
330 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
331 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
332 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
333 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
334 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
337 #define CFQ_CFQQ_FNS(name) \
338 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
340 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
342 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
344 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
346 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
348 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
351 CFQ_CFQQ_FNS(on_rr);
352 CFQ_CFQQ_FNS(wait_request);
353 CFQ_CFQQ_FNS(must_dispatch);
354 CFQ_CFQQ_FNS(must_alloc_slice);
355 CFQ_CFQQ_FNS(fifo_expire);
356 CFQ_CFQQ_FNS(idle_window);
357 CFQ_CFQQ_FNS(prio_changed);
358 CFQ_CFQQ_FNS(slice_new);
359 CFQ_CFQQ_FNS(sync);
360 CFQ_CFQQ_FNS(coop);
361 CFQ_CFQQ_FNS(split_coop);
362 CFQ_CFQQ_FNS(deep);
363 CFQ_CFQQ_FNS(wait_busy);
364 #undef CFQ_CFQQ_FNS
366 #ifdef CONFIG_CFQ_GROUP_IOSCHED
367 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
368 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
369 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
370 blkg_path(&(cfqq)->cfqg->blkg), ##args);
372 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
373 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
374 blkg_path(&(cfqg)->blkg), ##args); \
376 #else
377 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
378 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
379 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
380 #endif
381 #define cfq_log(cfqd, fmt, args...) \
382 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
384 /* Traverses through cfq group service trees */
385 #define for_each_cfqg_st(cfqg, i, j, st) \
386 for (i = 0; i <= IDLE_WORKLOAD; i++) \
387 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
388 : &cfqg->service_tree_idle; \
389 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
390 (i == IDLE_WORKLOAD && j == 0); \
391 j++, st = i < IDLE_WORKLOAD ? \
392 &cfqg->service_trees[i][j]: NULL) \
395 static inline bool iops_mode(struct cfq_data *cfqd)
398 * If we are not idling on queues and it is a NCQ drive, parallel
399 * execution of requests is on and measuring time is not possible
400 * in most of the cases until and unless we drive shallower queue
401 * depths and that becomes a performance bottleneck. In such cases
402 * switch to start providing fairness in terms of number of IOs.
404 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
405 return true;
406 else
407 return false;
410 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
412 if (cfq_class_idle(cfqq))
413 return IDLE_WORKLOAD;
414 if (cfq_class_rt(cfqq))
415 return RT_WORKLOAD;
416 return BE_WORKLOAD;
420 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
422 if (!cfq_cfqq_sync(cfqq))
423 return ASYNC_WORKLOAD;
424 if (!cfq_cfqq_idle_window(cfqq))
425 return SYNC_NOIDLE_WORKLOAD;
426 return SYNC_WORKLOAD;
429 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
430 struct cfq_data *cfqd,
431 struct cfq_group *cfqg)
433 if (wl == IDLE_WORKLOAD)
434 return cfqg->service_tree_idle.count;
436 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
437 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
438 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
441 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
442 struct cfq_group *cfqg)
444 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
445 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
448 static void cfq_dispatch_insert(struct request_queue *, struct request *);
449 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
450 struct io_context *, gfp_t);
451 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
452 struct io_context *);
454 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
455 bool is_sync)
457 return cic->cfqq[is_sync];
460 static inline void cic_set_cfqq(struct cfq_io_context *cic,
461 struct cfq_queue *cfqq, bool is_sync)
463 cic->cfqq[is_sync] = cfqq;
466 #define CIC_DEAD_KEY 1ul
467 #define CIC_DEAD_INDEX_SHIFT 1
469 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
471 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
474 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
476 struct cfq_data *cfqd = cic->key;
478 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
479 return NULL;
481 return cfqd;
485 * We regard a request as SYNC, if it's either a read or has the SYNC bit
486 * set (in which case it could also be direct WRITE).
488 static inline bool cfq_bio_sync(struct bio *bio)
490 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
494 * scheduler run of queue, if there are requests pending and no one in the
495 * driver that will restart queueing
497 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
499 if (cfqd->busy_queues) {
500 cfq_log(cfqd, "schedule dispatch");
501 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
506 * Scale schedule slice based on io priority. Use the sync time slice only
507 * if a queue is marked sync and has sync io queued. A sync queue with async
508 * io only, should not get full sync slice length.
510 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
511 unsigned short prio)
513 const int base_slice = cfqd->cfq_slice[sync];
515 WARN_ON(prio >= IOPRIO_BE_NR);
517 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
520 static inline int
521 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
523 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
526 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
528 u64 d = delta << CFQ_SERVICE_SHIFT;
530 d = d * BLKIO_WEIGHT_DEFAULT;
531 do_div(d, cfqg->weight);
532 return d;
535 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
537 s64 delta = (s64)(vdisktime - min_vdisktime);
538 if (delta > 0)
539 min_vdisktime = vdisktime;
541 return min_vdisktime;
544 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
546 s64 delta = (s64)(vdisktime - min_vdisktime);
547 if (delta < 0)
548 min_vdisktime = vdisktime;
550 return min_vdisktime;
553 static void update_min_vdisktime(struct cfq_rb_root *st)
555 struct cfq_group *cfqg;
557 if (st->left) {
558 cfqg = rb_entry_cfqg(st->left);
559 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
560 cfqg->vdisktime);
565 * get averaged number of queues of RT/BE priority.
566 * average is updated, with a formula that gives more weight to higher numbers,
567 * to quickly follows sudden increases and decrease slowly
570 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
571 struct cfq_group *cfqg, bool rt)
573 unsigned min_q, max_q;
574 unsigned mult = cfq_hist_divisor - 1;
575 unsigned round = cfq_hist_divisor / 2;
576 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
578 min_q = min(cfqg->busy_queues_avg[rt], busy);
579 max_q = max(cfqg->busy_queues_avg[rt], busy);
580 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
581 cfq_hist_divisor;
582 return cfqg->busy_queues_avg[rt];
585 static inline unsigned
586 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
588 struct cfq_rb_root *st = &cfqd->grp_service_tree;
590 return cfq_target_latency * cfqg->weight / st->total_weight;
593 static inline unsigned
594 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
596 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
597 if (cfqd->cfq_latency) {
599 * interested queues (we consider only the ones with the same
600 * priority class in the cfq group)
602 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
603 cfq_class_rt(cfqq));
604 unsigned sync_slice = cfqd->cfq_slice[1];
605 unsigned expect_latency = sync_slice * iq;
606 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
608 if (expect_latency > group_slice) {
609 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
610 /* scale low_slice according to IO priority
611 * and sync vs async */
612 unsigned low_slice =
613 min(slice, base_low_slice * slice / sync_slice);
614 /* the adapted slice value is scaled to fit all iqs
615 * into the target latency */
616 slice = max(slice * group_slice / expect_latency,
617 low_slice);
620 return slice;
623 static inline void
624 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
626 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
628 cfqq->slice_start = jiffies;
629 cfqq->slice_end = jiffies + slice;
630 cfqq->allocated_slice = slice;
631 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
635 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
636 * isn't valid until the first request from the dispatch is activated
637 * and the slice time set.
639 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
641 if (cfq_cfqq_slice_new(cfqq))
642 return false;
643 if (time_before(jiffies, cfqq->slice_end))
644 return false;
646 return true;
650 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
651 * We choose the request that is closest to the head right now. Distance
652 * behind the head is penalized and only allowed to a certain extent.
654 static struct request *
655 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
657 sector_t s1, s2, d1 = 0, d2 = 0;
658 unsigned long back_max;
659 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
660 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
661 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
663 if (rq1 == NULL || rq1 == rq2)
664 return rq2;
665 if (rq2 == NULL)
666 return rq1;
668 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
669 return rq1;
670 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
671 return rq2;
672 if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
673 return rq1;
674 else if ((rq2->cmd_flags & REQ_META) &&
675 !(rq1->cmd_flags & REQ_META))
676 return rq2;
678 s1 = blk_rq_pos(rq1);
679 s2 = blk_rq_pos(rq2);
682 * by definition, 1KiB is 2 sectors
684 back_max = cfqd->cfq_back_max * 2;
687 * Strict one way elevator _except_ in the case where we allow
688 * short backward seeks which are biased as twice the cost of a
689 * similar forward seek.
691 if (s1 >= last)
692 d1 = s1 - last;
693 else if (s1 + back_max >= last)
694 d1 = (last - s1) * cfqd->cfq_back_penalty;
695 else
696 wrap |= CFQ_RQ1_WRAP;
698 if (s2 >= last)
699 d2 = s2 - last;
700 else if (s2 + back_max >= last)
701 d2 = (last - s2) * cfqd->cfq_back_penalty;
702 else
703 wrap |= CFQ_RQ2_WRAP;
705 /* Found required data */
708 * By doing switch() on the bit mask "wrap" we avoid having to
709 * check two variables for all permutations: --> faster!
711 switch (wrap) {
712 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
713 if (d1 < d2)
714 return rq1;
715 else if (d2 < d1)
716 return rq2;
717 else {
718 if (s1 >= s2)
719 return rq1;
720 else
721 return rq2;
724 case CFQ_RQ2_WRAP:
725 return rq1;
726 case CFQ_RQ1_WRAP:
727 return rq2;
728 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
729 default:
731 * Since both rqs are wrapped,
732 * start with the one that's further behind head
733 * (--> only *one* back seek required),
734 * since back seek takes more time than forward.
736 if (s1 <= s2)
737 return rq1;
738 else
739 return rq2;
744 * The below is leftmost cache rbtree addon
746 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
748 /* Service tree is empty */
749 if (!root->count)
750 return NULL;
752 if (!root->left)
753 root->left = rb_first(&root->rb);
755 if (root->left)
756 return rb_entry(root->left, struct cfq_queue, rb_node);
758 return NULL;
761 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
763 if (!root->left)
764 root->left = rb_first(&root->rb);
766 if (root->left)
767 return rb_entry_cfqg(root->left);
769 return NULL;
772 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
774 rb_erase(n, root);
775 RB_CLEAR_NODE(n);
778 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
780 if (root->left == n)
781 root->left = NULL;
782 rb_erase_init(n, &root->rb);
783 --root->count;
787 * would be nice to take fifo expire time into account as well
789 static struct request *
790 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
791 struct request *last)
793 struct rb_node *rbnext = rb_next(&last->rb_node);
794 struct rb_node *rbprev = rb_prev(&last->rb_node);
795 struct request *next = NULL, *prev = NULL;
797 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
799 if (rbprev)
800 prev = rb_entry_rq(rbprev);
802 if (rbnext)
803 next = rb_entry_rq(rbnext);
804 else {
805 rbnext = rb_first(&cfqq->sort_list);
806 if (rbnext && rbnext != &last->rb_node)
807 next = rb_entry_rq(rbnext);
810 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
813 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
814 struct cfq_queue *cfqq)
817 * just an approximation, should be ok.
819 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
820 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
823 static inline s64
824 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
826 return cfqg->vdisktime - st->min_vdisktime;
829 static void
830 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
832 struct rb_node **node = &st->rb.rb_node;
833 struct rb_node *parent = NULL;
834 struct cfq_group *__cfqg;
835 s64 key = cfqg_key(st, cfqg);
836 int left = 1;
838 while (*node != NULL) {
839 parent = *node;
840 __cfqg = rb_entry_cfqg(parent);
842 if (key < cfqg_key(st, __cfqg))
843 node = &parent->rb_left;
844 else {
845 node = &parent->rb_right;
846 left = 0;
850 if (left)
851 st->left = &cfqg->rb_node;
853 rb_link_node(&cfqg->rb_node, parent, node);
854 rb_insert_color(&cfqg->rb_node, &st->rb);
857 static void
858 cfq_update_group_weight(struct cfq_group *cfqg)
860 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
861 if (cfqg->needs_update) {
862 cfqg->weight = cfqg->new_weight;
863 cfqg->needs_update = false;
867 static void
868 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
870 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
872 cfq_update_group_weight(cfqg);
873 __cfq_group_service_tree_add(st, cfqg);
874 st->total_weight += cfqg->weight;
877 static void
878 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
880 struct cfq_rb_root *st = &cfqd->grp_service_tree;
881 struct cfq_group *__cfqg;
882 struct rb_node *n;
884 cfqg->nr_cfqq++;
885 if (!RB_EMPTY_NODE(&cfqg->rb_node))
886 return;
889 * Currently put the group at the end. Later implement something
890 * so that groups get lesser vtime based on their weights, so that
891 * if group does not loose all if it was not continously backlogged.
893 n = rb_last(&st->rb);
894 if (n) {
895 __cfqg = rb_entry_cfqg(n);
896 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
897 } else
898 cfqg->vdisktime = st->min_vdisktime;
899 cfq_group_service_tree_add(st, cfqg);
902 static void
903 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
905 st->total_weight -= cfqg->weight;
906 if (!RB_EMPTY_NODE(&cfqg->rb_node))
907 cfq_rb_erase(&cfqg->rb_node, st);
910 static void
911 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
913 struct cfq_rb_root *st = &cfqd->grp_service_tree;
915 BUG_ON(cfqg->nr_cfqq < 1);
916 cfqg->nr_cfqq--;
918 /* If there are other cfq queues under this group, don't delete it */
919 if (cfqg->nr_cfqq)
920 return;
922 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
923 cfq_group_service_tree_del(st, cfqg);
924 cfqg->saved_workload_slice = 0;
925 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
928 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
929 unsigned int *unaccounted_time)
931 unsigned int slice_used;
934 * Queue got expired before even a single request completed or
935 * got expired immediately after first request completion.
937 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
939 * Also charge the seek time incurred to the group, otherwise
940 * if there are mutiple queues in the group, each can dispatch
941 * a single request on seeky media and cause lots of seek time
942 * and group will never know it.
944 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
946 } else {
947 slice_used = jiffies - cfqq->slice_start;
948 if (slice_used > cfqq->allocated_slice) {
949 *unaccounted_time = slice_used - cfqq->allocated_slice;
950 slice_used = cfqq->allocated_slice;
952 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
953 *unaccounted_time += cfqq->slice_start -
954 cfqq->dispatch_start;
957 return slice_used;
960 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
961 struct cfq_queue *cfqq)
963 struct cfq_rb_root *st = &cfqd->grp_service_tree;
964 unsigned int used_sl, charge, unaccounted_sl = 0;
965 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
966 - cfqg->service_tree_idle.count;
968 BUG_ON(nr_sync < 0);
969 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
971 if (iops_mode(cfqd))
972 charge = cfqq->slice_dispatch;
973 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
974 charge = cfqq->allocated_slice;
976 /* Can't update vdisktime while group is on service tree */
977 cfq_group_service_tree_del(st, cfqg);
978 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
979 /* If a new weight was requested, update now, off tree */
980 cfq_group_service_tree_add(st, cfqg);
982 /* This group is being expired. Save the context */
983 if (time_after(cfqd->workload_expires, jiffies)) {
984 cfqg->saved_workload_slice = cfqd->workload_expires
985 - jiffies;
986 cfqg->saved_workload = cfqd->serving_type;
987 cfqg->saved_serving_prio = cfqd->serving_prio;
988 } else
989 cfqg->saved_workload_slice = 0;
991 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
992 st->min_vdisktime);
993 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u"
994 " sect=%u", used_sl, cfqq->slice_dispatch, charge,
995 iops_mode(cfqd), cfqq->nr_sectors);
996 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
997 unaccounted_sl);
998 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
1001 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1002 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
1004 if (blkg)
1005 return container_of(blkg, struct cfq_group, blkg);
1006 return NULL;
1009 void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
1010 unsigned int weight)
1012 struct cfq_group *cfqg = cfqg_of_blkg(blkg);
1013 cfqg->new_weight = weight;
1014 cfqg->needs_update = true;
1017 static struct cfq_group *
1018 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
1020 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1021 struct cfq_group *cfqg = NULL;
1022 void *key = cfqd;
1023 int i, j;
1024 struct cfq_rb_root *st;
1025 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1026 unsigned int major, minor;
1028 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1029 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1030 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1031 cfqg->blkg.dev = MKDEV(major, minor);
1032 goto done;
1034 if (cfqg || !create)
1035 goto done;
1037 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1038 if (!cfqg)
1039 goto done;
1041 for_each_cfqg_st(cfqg, i, j, st)
1042 *st = CFQ_RB_ROOT;
1043 RB_CLEAR_NODE(&cfqg->rb_node);
1046 * Take the initial reference that will be released on destroy
1047 * This can be thought of a joint reference by cgroup and
1048 * elevator which will be dropped by either elevator exit
1049 * or cgroup deletion path depending on who is exiting first.
1051 cfqg->ref = 1;
1054 * Add group onto cgroup list. It might happen that bdi->dev is
1055 * not initialized yet. Initialize this new group without major
1056 * and minor info and this info will be filled in once a new thread
1057 * comes for IO. See code above.
1059 if (bdi->dev) {
1060 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1061 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1062 MKDEV(major, minor));
1063 } else
1064 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1067 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1069 /* Add group on cfqd list */
1070 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1072 done:
1073 return cfqg;
1077 * Search for the cfq group current task belongs to. If create = 1, then also
1078 * create the cfq group if it does not exist. request_queue lock must be held.
1080 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1082 struct cgroup *cgroup;
1083 struct cfq_group *cfqg = NULL;
1085 rcu_read_lock();
1086 cgroup = task_cgroup(current, blkio_subsys_id);
1087 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1088 if (!cfqg && create)
1089 cfqg = &cfqd->root_group;
1090 rcu_read_unlock();
1091 return cfqg;
1094 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1096 cfqg->ref++;
1097 return cfqg;
1100 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1102 /* Currently, all async queues are mapped to root group */
1103 if (!cfq_cfqq_sync(cfqq))
1104 cfqg = &cfqq->cfqd->root_group;
1106 cfqq->cfqg = cfqg;
1107 /* cfqq reference on cfqg */
1108 cfqq->cfqg->ref++;
1111 static void cfq_put_cfqg(struct cfq_group *cfqg)
1113 struct cfq_rb_root *st;
1114 int i, j;
1116 BUG_ON(cfqg->ref <= 0);
1117 cfqg->ref--;
1118 if (cfqg->ref)
1119 return;
1120 for_each_cfqg_st(cfqg, i, j, st)
1121 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
1122 kfree(cfqg);
1125 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1127 /* Something wrong if we are trying to remove same group twice */
1128 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1130 hlist_del_init(&cfqg->cfqd_node);
1133 * Put the reference taken at the time of creation so that when all
1134 * queues are gone, group can be destroyed.
1136 cfq_put_cfqg(cfqg);
1139 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1141 struct hlist_node *pos, *n;
1142 struct cfq_group *cfqg;
1144 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1146 * If cgroup removal path got to blk_group first and removed
1147 * it from cgroup list, then it will take care of destroying
1148 * cfqg also.
1150 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1151 cfq_destroy_cfqg(cfqd, cfqg);
1156 * Blk cgroup controller notification saying that blkio_group object is being
1157 * delinked as associated cgroup object is going away. That also means that
1158 * no new IO will come in this group. So get rid of this group as soon as
1159 * any pending IO in the group is finished.
1161 * This function is called under rcu_read_lock(). key is the rcu protected
1162 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1163 * read lock.
1165 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1166 * it should not be NULL as even if elevator was exiting, cgroup deltion
1167 * path got to it first.
1169 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1171 unsigned long flags;
1172 struct cfq_data *cfqd = key;
1174 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1175 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1176 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1179 #else /* GROUP_IOSCHED */
1180 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1182 return &cfqd->root_group;
1185 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1187 return cfqg;
1190 static inline void
1191 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1192 cfqq->cfqg = cfqg;
1195 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1196 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1198 #endif /* GROUP_IOSCHED */
1201 * The cfqd->service_trees holds all pending cfq_queue's that have
1202 * requests waiting to be processed. It is sorted in the order that
1203 * we will service the queues.
1205 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1206 bool add_front)
1208 struct rb_node **p, *parent;
1209 struct cfq_queue *__cfqq;
1210 unsigned long rb_key;
1211 struct cfq_rb_root *service_tree;
1212 int left;
1213 int new_cfqq = 1;
1214 int group_changed = 0;
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_notify_queue_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++;
1375 if (cfq_cfqq_sync(cfqq))
1376 cfqd->busy_sync_queues++;
1378 cfq_resort_rr_list(cfqd, cfqq);
1382 * Called when the cfqq no longer has requests pending, remove it from
1383 * the service tree.
1385 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1387 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1388 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1389 cfq_clear_cfqq_on_rr(cfqq);
1391 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1392 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1393 cfqq->service_tree = NULL;
1395 if (cfqq->p_root) {
1396 rb_erase(&cfqq->p_node, cfqq->p_root);
1397 cfqq->p_root = NULL;
1400 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1401 BUG_ON(!cfqd->busy_queues);
1402 cfqd->busy_queues--;
1403 if (cfq_cfqq_sync(cfqq))
1404 cfqd->busy_sync_queues--;
1408 * rb tree support functions
1410 static void cfq_del_rq_rb(struct request *rq)
1412 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1413 const int sync = rq_is_sync(rq);
1415 BUG_ON(!cfqq->queued[sync]);
1416 cfqq->queued[sync]--;
1418 elv_rb_del(&cfqq->sort_list, rq);
1420 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1422 * Queue will be deleted from service tree when we actually
1423 * expire it later. Right now just remove it from prio tree
1424 * as it is empty.
1426 if (cfqq->p_root) {
1427 rb_erase(&cfqq->p_node, cfqq->p_root);
1428 cfqq->p_root = NULL;
1433 static void cfq_add_rq_rb(struct request *rq)
1435 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1436 struct cfq_data *cfqd = cfqq->cfqd;
1437 struct request *__alias, *prev;
1439 cfqq->queued[rq_is_sync(rq)]++;
1442 * looks a little odd, but the first insert might return an alias.
1443 * if that happens, put the alias on the dispatch list
1445 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1446 cfq_dispatch_insert(cfqd->queue, __alias);
1448 if (!cfq_cfqq_on_rr(cfqq))
1449 cfq_add_cfqq_rr(cfqd, cfqq);
1452 * check if this request is a better next-serve candidate
1454 prev = cfqq->next_rq;
1455 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1458 * adjust priority tree position, if ->next_rq changes
1460 if (prev != cfqq->next_rq)
1461 cfq_prio_tree_add(cfqd, cfqq);
1463 BUG_ON(!cfqq->next_rq);
1466 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1468 elv_rb_del(&cfqq->sort_list, rq);
1469 cfqq->queued[rq_is_sync(rq)]--;
1470 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1471 rq_data_dir(rq), rq_is_sync(rq));
1472 cfq_add_rq_rb(rq);
1473 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1474 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1475 rq_is_sync(rq));
1478 static struct request *
1479 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1481 struct task_struct *tsk = current;
1482 struct cfq_io_context *cic;
1483 struct cfq_queue *cfqq;
1485 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1486 if (!cic)
1487 return NULL;
1489 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1490 if (cfqq) {
1491 sector_t sector = bio->bi_sector + bio_sectors(bio);
1493 return elv_rb_find(&cfqq->sort_list, sector);
1496 return NULL;
1499 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1501 struct cfq_data *cfqd = q->elevator->elevator_data;
1503 cfqd->rq_in_driver++;
1504 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1505 cfqd->rq_in_driver);
1507 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1510 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1512 struct cfq_data *cfqd = q->elevator->elevator_data;
1514 WARN_ON(!cfqd->rq_in_driver);
1515 cfqd->rq_in_driver--;
1516 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1517 cfqd->rq_in_driver);
1520 static void cfq_remove_request(struct request *rq)
1522 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1524 if (cfqq->next_rq == rq)
1525 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1527 list_del_init(&rq->queuelist);
1528 cfq_del_rq_rb(rq);
1530 cfqq->cfqd->rq_queued--;
1531 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1532 rq_data_dir(rq), rq_is_sync(rq));
1533 if (rq->cmd_flags & REQ_META) {
1534 WARN_ON(!cfqq->meta_pending);
1535 cfqq->meta_pending--;
1539 static int cfq_merge(struct request_queue *q, struct request **req,
1540 struct bio *bio)
1542 struct cfq_data *cfqd = q->elevator->elevator_data;
1543 struct request *__rq;
1545 __rq = cfq_find_rq_fmerge(cfqd, bio);
1546 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1547 *req = __rq;
1548 return ELEVATOR_FRONT_MERGE;
1551 return ELEVATOR_NO_MERGE;
1554 static void cfq_merged_request(struct request_queue *q, struct request *req,
1555 int type)
1557 if (type == ELEVATOR_FRONT_MERGE) {
1558 struct cfq_queue *cfqq = RQ_CFQQ(req);
1560 cfq_reposition_rq_rb(cfqq, req);
1564 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1565 struct bio *bio)
1567 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1568 bio_data_dir(bio), cfq_bio_sync(bio));
1571 static void
1572 cfq_merged_requests(struct request_queue *q, struct request *rq,
1573 struct request *next)
1575 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1577 * reposition in fifo if next is older than rq
1579 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1580 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1581 list_move(&rq->queuelist, &next->queuelist);
1582 rq_set_fifo_time(rq, rq_fifo_time(next));
1585 if (cfqq->next_rq == next)
1586 cfqq->next_rq = rq;
1587 cfq_remove_request(next);
1588 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1589 rq_data_dir(next), rq_is_sync(next));
1592 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1593 struct bio *bio)
1595 struct cfq_data *cfqd = q->elevator->elevator_data;
1596 struct cfq_io_context *cic;
1597 struct cfq_queue *cfqq;
1600 * Disallow merge of a sync bio into an async request.
1602 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1603 return false;
1606 * Lookup the cfqq that this bio will be queued with. Allow
1607 * merge only if rq is queued there.
1609 cic = cfq_cic_lookup(cfqd, current->io_context);
1610 if (!cic)
1611 return false;
1613 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1614 return cfqq == RQ_CFQQ(rq);
1617 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1619 del_timer(&cfqd->idle_slice_timer);
1620 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1623 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1624 struct cfq_queue *cfqq)
1626 if (cfqq) {
1627 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1628 cfqd->serving_prio, cfqd->serving_type);
1629 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1630 cfqq->slice_start = 0;
1631 cfqq->dispatch_start = jiffies;
1632 cfqq->allocated_slice = 0;
1633 cfqq->slice_end = 0;
1634 cfqq->slice_dispatch = 0;
1635 cfqq->nr_sectors = 0;
1637 cfq_clear_cfqq_wait_request(cfqq);
1638 cfq_clear_cfqq_must_dispatch(cfqq);
1639 cfq_clear_cfqq_must_alloc_slice(cfqq);
1640 cfq_clear_cfqq_fifo_expire(cfqq);
1641 cfq_mark_cfqq_slice_new(cfqq);
1643 cfq_del_timer(cfqd, cfqq);
1646 cfqd->active_queue = cfqq;
1650 * current cfqq expired its slice (or was too idle), select new one
1652 static void
1653 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1654 bool timed_out)
1656 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1658 if (cfq_cfqq_wait_request(cfqq))
1659 cfq_del_timer(cfqd, cfqq);
1661 cfq_clear_cfqq_wait_request(cfqq);
1662 cfq_clear_cfqq_wait_busy(cfqq);
1665 * If this cfqq is shared between multiple processes, check to
1666 * make sure that those processes are still issuing I/Os within
1667 * the mean seek distance. If not, it may be time to break the
1668 * queues apart again.
1670 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1671 cfq_mark_cfqq_split_coop(cfqq);
1674 * store what was left of this slice, if the queue idled/timed out
1676 if (timed_out) {
1677 if (cfq_cfqq_slice_new(cfqq))
1678 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
1679 else
1680 cfqq->slice_resid = cfqq->slice_end - jiffies;
1681 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1684 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1686 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1687 cfq_del_cfqq_rr(cfqd, cfqq);
1689 cfq_resort_rr_list(cfqd, cfqq);
1691 if (cfqq == cfqd->active_queue)
1692 cfqd->active_queue = NULL;
1694 if (cfqd->active_cic) {
1695 put_io_context(cfqd->active_cic->ioc);
1696 cfqd->active_cic = NULL;
1700 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1702 struct cfq_queue *cfqq = cfqd->active_queue;
1704 if (cfqq)
1705 __cfq_slice_expired(cfqd, cfqq, timed_out);
1709 * Get next queue for service. Unless we have a queue preemption,
1710 * we'll simply select the first cfqq in the service tree.
1712 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1714 struct cfq_rb_root *service_tree =
1715 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1716 cfqd->serving_type);
1718 if (!cfqd->rq_queued)
1719 return NULL;
1721 /* There is nothing to dispatch */
1722 if (!service_tree)
1723 return NULL;
1724 if (RB_EMPTY_ROOT(&service_tree->rb))
1725 return NULL;
1726 return cfq_rb_first(service_tree);
1729 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1731 struct cfq_group *cfqg;
1732 struct cfq_queue *cfqq;
1733 int i, j;
1734 struct cfq_rb_root *st;
1736 if (!cfqd->rq_queued)
1737 return NULL;
1739 cfqg = cfq_get_next_cfqg(cfqd);
1740 if (!cfqg)
1741 return NULL;
1743 for_each_cfqg_st(cfqg, i, j, st)
1744 if ((cfqq = cfq_rb_first(st)) != NULL)
1745 return cfqq;
1746 return NULL;
1750 * Get and set a new active queue for service.
1752 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1753 struct cfq_queue *cfqq)
1755 if (!cfqq)
1756 cfqq = cfq_get_next_queue(cfqd);
1758 __cfq_set_active_queue(cfqd, cfqq);
1759 return cfqq;
1762 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1763 struct request *rq)
1765 if (blk_rq_pos(rq) >= cfqd->last_position)
1766 return blk_rq_pos(rq) - cfqd->last_position;
1767 else
1768 return cfqd->last_position - blk_rq_pos(rq);
1771 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1772 struct request *rq)
1774 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1777 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1778 struct cfq_queue *cur_cfqq)
1780 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1781 struct rb_node *parent, *node;
1782 struct cfq_queue *__cfqq;
1783 sector_t sector = cfqd->last_position;
1785 if (RB_EMPTY_ROOT(root))
1786 return NULL;
1789 * First, if we find a request starting at the end of the last
1790 * request, choose it.
1792 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1793 if (__cfqq)
1794 return __cfqq;
1797 * If the exact sector wasn't found, the parent of the NULL leaf
1798 * will contain the closest sector.
1800 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1801 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1802 return __cfqq;
1804 if (blk_rq_pos(__cfqq->next_rq) < sector)
1805 node = rb_next(&__cfqq->p_node);
1806 else
1807 node = rb_prev(&__cfqq->p_node);
1808 if (!node)
1809 return NULL;
1811 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1812 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1813 return __cfqq;
1815 return NULL;
1819 * cfqd - obvious
1820 * cur_cfqq - passed in so that we don't decide that the current queue is
1821 * closely cooperating with itself.
1823 * So, basically we're assuming that that cur_cfqq has dispatched at least
1824 * one request, and that cfqd->last_position reflects a position on the disk
1825 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1826 * assumption.
1828 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1829 struct cfq_queue *cur_cfqq)
1831 struct cfq_queue *cfqq;
1833 if (cfq_class_idle(cur_cfqq))
1834 return NULL;
1835 if (!cfq_cfqq_sync(cur_cfqq))
1836 return NULL;
1837 if (CFQQ_SEEKY(cur_cfqq))
1838 return NULL;
1841 * Don't search priority tree if it's the only queue in the group.
1843 if (cur_cfqq->cfqg->nr_cfqq == 1)
1844 return NULL;
1847 * We should notice if some of the queues are cooperating, eg
1848 * working closely on the same area of the disk. In that case,
1849 * we can group them together and don't waste time idling.
1851 cfqq = cfqq_close(cfqd, cur_cfqq);
1852 if (!cfqq)
1853 return NULL;
1855 /* If new queue belongs to different cfq_group, don't choose it */
1856 if (cur_cfqq->cfqg != cfqq->cfqg)
1857 return NULL;
1860 * It only makes sense to merge sync queues.
1862 if (!cfq_cfqq_sync(cfqq))
1863 return NULL;
1864 if (CFQQ_SEEKY(cfqq))
1865 return NULL;
1868 * Do not merge queues of different priority classes
1870 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1871 return NULL;
1873 return cfqq;
1877 * Determine whether we should enforce idle window for this queue.
1880 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1882 enum wl_prio_t prio = cfqq_prio(cfqq);
1883 struct cfq_rb_root *service_tree = cfqq->service_tree;
1885 BUG_ON(!service_tree);
1886 BUG_ON(!service_tree->count);
1888 if (!cfqd->cfq_slice_idle)
1889 return false;
1891 /* We never do for idle class queues. */
1892 if (prio == IDLE_WORKLOAD)
1893 return false;
1895 /* We do for queues that were marked with idle window flag. */
1896 if (cfq_cfqq_idle_window(cfqq) &&
1897 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1898 return true;
1901 * Otherwise, we do only if they are the last ones
1902 * in their service tree.
1904 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1905 return true;
1906 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1907 service_tree->count);
1908 return false;
1911 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1913 struct cfq_queue *cfqq = cfqd->active_queue;
1914 struct cfq_io_context *cic;
1915 unsigned long sl, group_idle = 0;
1918 * SSD device without seek penalty, disable idling. But only do so
1919 * for devices that support queuing, otherwise we still have a problem
1920 * with sync vs async workloads.
1922 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1923 return;
1925 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1926 WARN_ON(cfq_cfqq_slice_new(cfqq));
1929 * idle is disabled, either manually or by past process history
1931 if (!cfq_should_idle(cfqd, cfqq)) {
1932 /* no queue idling. Check for group idling */
1933 if (cfqd->cfq_group_idle)
1934 group_idle = cfqd->cfq_group_idle;
1935 else
1936 return;
1940 * still active requests from this queue, don't idle
1942 if (cfqq->dispatched)
1943 return;
1946 * task has exited, don't wait
1948 cic = cfqd->active_cic;
1949 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1950 return;
1953 * If our average think time is larger than the remaining time
1954 * slice, then don't idle. This avoids overrunning the allotted
1955 * time slice.
1957 if (sample_valid(cic->ttime_samples) &&
1958 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1959 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1960 cic->ttime_mean);
1961 return;
1964 /* There are other queues in the group, don't do group idle */
1965 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
1966 return;
1968 cfq_mark_cfqq_wait_request(cfqq);
1970 if (group_idle)
1971 sl = cfqd->cfq_group_idle;
1972 else
1973 sl = cfqd->cfq_slice_idle;
1975 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1976 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1977 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
1978 group_idle ? 1 : 0);
1982 * Move request from internal lists to the request queue dispatch list.
1984 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1986 struct cfq_data *cfqd = q->elevator->elevator_data;
1987 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1989 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1991 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1992 cfq_remove_request(rq);
1993 cfqq->dispatched++;
1994 (RQ_CFQG(rq))->dispatched++;
1995 elv_dispatch_sort(q, rq);
1997 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1998 cfqq->nr_sectors += blk_rq_sectors(rq);
1999 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
2000 rq_data_dir(rq), rq_is_sync(rq));
2004 * return expired entry, or NULL to just start from scratch in rbtree
2006 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2008 struct request *rq = NULL;
2010 if (cfq_cfqq_fifo_expire(cfqq))
2011 return NULL;
2013 cfq_mark_cfqq_fifo_expire(cfqq);
2015 if (list_empty(&cfqq->fifo))
2016 return NULL;
2018 rq = rq_entry_fifo(cfqq->fifo.next);
2019 if (time_before(jiffies, rq_fifo_time(rq)))
2020 rq = NULL;
2022 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2023 return rq;
2026 static inline int
2027 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2029 const int base_rq = cfqd->cfq_slice_async_rq;
2031 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2033 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
2037 * Must be called with the queue_lock held.
2039 static int cfqq_process_refs(struct cfq_queue *cfqq)
2041 int process_refs, io_refs;
2043 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2044 process_refs = cfqq->ref - io_refs;
2045 BUG_ON(process_refs < 0);
2046 return process_refs;
2049 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2051 int process_refs, new_process_refs;
2052 struct cfq_queue *__cfqq;
2055 * If there are no process references on the new_cfqq, then it is
2056 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2057 * chain may have dropped their last reference (not just their
2058 * last process reference).
2060 if (!cfqq_process_refs(new_cfqq))
2061 return;
2063 /* Avoid a circular list and skip interim queue merges */
2064 while ((__cfqq = new_cfqq->new_cfqq)) {
2065 if (__cfqq == cfqq)
2066 return;
2067 new_cfqq = __cfqq;
2070 process_refs = cfqq_process_refs(cfqq);
2071 new_process_refs = cfqq_process_refs(new_cfqq);
2073 * If the process for the cfqq has gone away, there is no
2074 * sense in merging the queues.
2076 if (process_refs == 0 || new_process_refs == 0)
2077 return;
2080 * Merge in the direction of the lesser amount of work.
2082 if (new_process_refs >= process_refs) {
2083 cfqq->new_cfqq = new_cfqq;
2084 new_cfqq->ref += process_refs;
2085 } else {
2086 new_cfqq->new_cfqq = cfqq;
2087 cfqq->ref += new_process_refs;
2091 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2092 struct cfq_group *cfqg, enum wl_prio_t prio)
2094 struct cfq_queue *queue;
2095 int i;
2096 bool key_valid = false;
2097 unsigned long lowest_key = 0;
2098 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2100 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2101 /* select the one with lowest rb_key */
2102 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2103 if (queue &&
2104 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2105 lowest_key = queue->rb_key;
2106 cur_best = i;
2107 key_valid = true;
2111 return cur_best;
2114 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2116 unsigned slice;
2117 unsigned count;
2118 struct cfq_rb_root *st;
2119 unsigned group_slice;
2120 enum wl_prio_t original_prio = cfqd->serving_prio;
2122 /* Choose next priority. RT > BE > IDLE */
2123 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2124 cfqd->serving_prio = RT_WORKLOAD;
2125 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2126 cfqd->serving_prio = BE_WORKLOAD;
2127 else {
2128 cfqd->serving_prio = IDLE_WORKLOAD;
2129 cfqd->workload_expires = jiffies + 1;
2130 return;
2133 if (original_prio != cfqd->serving_prio)
2134 goto new_workload;
2137 * For RT and BE, we have to choose also the type
2138 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2139 * expiration time
2141 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2142 count = st->count;
2145 * check workload expiration, and that we still have other queues ready
2147 if (count && !time_after(jiffies, cfqd->workload_expires))
2148 return;
2150 new_workload:
2151 /* otherwise select new workload type */
2152 cfqd->serving_type =
2153 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2154 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2155 count = st->count;
2158 * the workload slice is computed as a fraction of target latency
2159 * proportional to the number of queues in that workload, over
2160 * all the queues in the same priority class
2162 group_slice = cfq_group_slice(cfqd, cfqg);
2164 slice = group_slice * count /
2165 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2166 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2168 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2169 unsigned int tmp;
2172 * Async queues are currently system wide. Just taking
2173 * proportion of queues with-in same group will lead to higher
2174 * async ratio system wide as generally root group is going
2175 * to have higher weight. A more accurate thing would be to
2176 * calculate system wide asnc/sync ratio.
2178 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2179 tmp = tmp/cfqd->busy_queues;
2180 slice = min_t(unsigned, slice, tmp);
2182 /* async workload slice is scaled down according to
2183 * the sync/async slice ratio. */
2184 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2185 } else
2186 /* sync workload slice is at least 2 * cfq_slice_idle */
2187 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2189 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2190 cfq_log(cfqd, "workload slice:%d", slice);
2191 cfqd->workload_expires = jiffies + slice;
2194 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2196 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2197 struct cfq_group *cfqg;
2199 if (RB_EMPTY_ROOT(&st->rb))
2200 return NULL;
2201 cfqg = cfq_rb_first_group(st);
2202 update_min_vdisktime(st);
2203 return cfqg;
2206 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2208 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2210 cfqd->serving_group = cfqg;
2212 /* Restore the workload type data */
2213 if (cfqg->saved_workload_slice) {
2214 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2215 cfqd->serving_type = cfqg->saved_workload;
2216 cfqd->serving_prio = cfqg->saved_serving_prio;
2217 } else
2218 cfqd->workload_expires = jiffies - 1;
2220 choose_service_tree(cfqd, cfqg);
2224 * Select a queue for service. If we have a current active queue,
2225 * check whether to continue servicing it, or retrieve and set a new one.
2227 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2229 struct cfq_queue *cfqq, *new_cfqq = NULL;
2231 cfqq = cfqd->active_queue;
2232 if (!cfqq)
2233 goto new_queue;
2235 if (!cfqd->rq_queued)
2236 return NULL;
2239 * We were waiting for group to get backlogged. Expire the queue
2241 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2242 goto expire;
2245 * The active queue has run out of time, expire it and select new.
2247 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2249 * If slice had not expired at the completion of last request
2250 * we might not have turned on wait_busy flag. Don't expire
2251 * the queue yet. Allow the group to get backlogged.
2253 * The very fact that we have used the slice, that means we
2254 * have been idling all along on this queue and it should be
2255 * ok to wait for this request to complete.
2257 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2258 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2259 cfqq = NULL;
2260 goto keep_queue;
2261 } else
2262 goto check_group_idle;
2266 * The active queue has requests and isn't expired, allow it to
2267 * dispatch.
2269 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2270 goto keep_queue;
2273 * If another queue has a request waiting within our mean seek
2274 * distance, let it run. The expire code will check for close
2275 * cooperators and put the close queue at the front of the service
2276 * tree. If possible, merge the expiring queue with the new cfqq.
2278 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2279 if (new_cfqq) {
2280 if (!cfqq->new_cfqq)
2281 cfq_setup_merge(cfqq, new_cfqq);
2282 goto expire;
2286 * No requests pending. If the active queue still has requests in
2287 * flight or is idling for a new request, allow either of these
2288 * conditions to happen (or time out) before selecting a new queue.
2290 if (timer_pending(&cfqd->idle_slice_timer)) {
2291 cfqq = NULL;
2292 goto keep_queue;
2296 * This is a deep seek queue, but the device is much faster than
2297 * the queue can deliver, don't idle
2299 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2300 (cfq_cfqq_slice_new(cfqq) ||
2301 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2302 cfq_clear_cfqq_deep(cfqq);
2303 cfq_clear_cfqq_idle_window(cfqq);
2306 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2307 cfqq = NULL;
2308 goto keep_queue;
2312 * If group idle is enabled and there are requests dispatched from
2313 * this group, wait for requests to complete.
2315 check_group_idle:
2316 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
2317 && cfqq->cfqg->dispatched) {
2318 cfqq = NULL;
2319 goto keep_queue;
2322 expire:
2323 cfq_slice_expired(cfqd, 0);
2324 new_queue:
2326 * Current queue expired. Check if we have to switch to a new
2327 * service tree
2329 if (!new_cfqq)
2330 cfq_choose_cfqg(cfqd);
2332 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2333 keep_queue:
2334 return cfqq;
2337 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2339 int dispatched = 0;
2341 while (cfqq->next_rq) {
2342 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2343 dispatched++;
2346 BUG_ON(!list_empty(&cfqq->fifo));
2348 /* By default cfqq is not expired if it is empty. Do it explicitly */
2349 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2350 return dispatched;
2354 * Drain our current requests. Used for barriers and when switching
2355 * io schedulers on-the-fly.
2357 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2359 struct cfq_queue *cfqq;
2360 int dispatched = 0;
2362 /* Expire the timeslice of the current active queue first */
2363 cfq_slice_expired(cfqd, 0);
2364 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2365 __cfq_set_active_queue(cfqd, cfqq);
2366 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2369 BUG_ON(cfqd->busy_queues);
2371 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2372 return dispatched;
2375 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2376 struct cfq_queue *cfqq)
2378 /* the queue hasn't finished any request, can't estimate */
2379 if (cfq_cfqq_slice_new(cfqq))
2380 return true;
2381 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2382 cfqq->slice_end))
2383 return true;
2385 return false;
2388 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2390 unsigned int max_dispatch;
2393 * Drain async requests before we start sync IO
2395 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2396 return false;
2399 * If this is an async queue and we have sync IO in flight, let it wait
2401 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2402 return false;
2404 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2405 if (cfq_class_idle(cfqq))
2406 max_dispatch = 1;
2409 * Does this cfqq already have too much IO in flight?
2411 if (cfqq->dispatched >= max_dispatch) {
2412 bool promote_sync = false;
2414 * idle queue must always only have a single IO in flight
2416 if (cfq_class_idle(cfqq))
2417 return false;
2420 * If there is only one sync queue
2421 * we can ignore async queue here and give the sync
2422 * queue no dispatch limit. The reason is a sync queue can
2423 * preempt async queue, limiting the sync queue doesn't make
2424 * sense. This is useful for aiostress test.
2426 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2427 promote_sync = true;
2430 * We have other queues, don't allow more IO from this one
2432 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2433 !promote_sync)
2434 return false;
2437 * Sole queue user, no limit
2439 if (cfqd->busy_queues == 1 || promote_sync)
2440 max_dispatch = -1;
2441 else
2443 * Normally we start throttling cfqq when cfq_quantum/2
2444 * requests have been dispatched. But we can drive
2445 * deeper queue depths at the beginning of slice
2446 * subjected to upper limit of cfq_quantum.
2447 * */
2448 max_dispatch = cfqd->cfq_quantum;
2452 * Async queues must wait a bit before being allowed dispatch.
2453 * We also ramp up the dispatch depth gradually for async IO,
2454 * based on the last sync IO we serviced
2456 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2457 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2458 unsigned int depth;
2460 depth = last_sync / cfqd->cfq_slice[1];
2461 if (!depth && !cfqq->dispatched)
2462 depth = 1;
2463 if (depth < max_dispatch)
2464 max_dispatch = depth;
2468 * If we're below the current max, allow a dispatch
2470 return cfqq->dispatched < max_dispatch;
2474 * Dispatch a request from cfqq, moving them to the request queue
2475 * dispatch list.
2477 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2479 struct request *rq;
2481 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2483 if (!cfq_may_dispatch(cfqd, cfqq))
2484 return false;
2487 * follow expired path, else get first next available
2489 rq = cfq_check_fifo(cfqq);
2490 if (!rq)
2491 rq = cfqq->next_rq;
2494 * insert request into driver dispatch list
2496 cfq_dispatch_insert(cfqd->queue, rq);
2498 if (!cfqd->active_cic) {
2499 struct cfq_io_context *cic = RQ_CIC(rq);
2501 atomic_long_inc(&cic->ioc->refcount);
2502 cfqd->active_cic = cic;
2505 return true;
2509 * Find the cfqq that we need to service and move a request from that to the
2510 * dispatch list
2512 static int cfq_dispatch_requests(struct request_queue *q, int force)
2514 struct cfq_data *cfqd = q->elevator->elevator_data;
2515 struct cfq_queue *cfqq;
2517 if (!cfqd->busy_queues)
2518 return 0;
2520 if (unlikely(force))
2521 return cfq_forced_dispatch(cfqd);
2523 cfqq = cfq_select_queue(cfqd);
2524 if (!cfqq)
2525 return 0;
2528 * Dispatch a request from this cfqq, if it is allowed
2530 if (!cfq_dispatch_request(cfqd, cfqq))
2531 return 0;
2533 cfqq->slice_dispatch++;
2534 cfq_clear_cfqq_must_dispatch(cfqq);
2537 * expire an async queue immediately if it has used up its slice. idle
2538 * queue always expire after 1 dispatch round.
2540 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2541 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2542 cfq_class_idle(cfqq))) {
2543 cfqq->slice_end = jiffies + 1;
2544 cfq_slice_expired(cfqd, 0);
2547 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2548 return 1;
2552 * task holds one reference to the queue, dropped when task exits. each rq
2553 * in-flight on this queue also holds a reference, dropped when rq is freed.
2555 * Each cfq queue took a reference on the parent group. Drop it now.
2556 * queue lock must be held here.
2558 static void cfq_put_queue(struct cfq_queue *cfqq)
2560 struct cfq_data *cfqd = cfqq->cfqd;
2561 struct cfq_group *cfqg;
2563 BUG_ON(cfqq->ref <= 0);
2565 cfqq->ref--;
2566 if (cfqq->ref)
2567 return;
2569 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2570 BUG_ON(rb_first(&cfqq->sort_list));
2571 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2572 cfqg = cfqq->cfqg;
2574 if (unlikely(cfqd->active_queue == cfqq)) {
2575 __cfq_slice_expired(cfqd, cfqq, 0);
2576 cfq_schedule_dispatch(cfqd);
2579 BUG_ON(cfq_cfqq_on_rr(cfqq));
2580 kmem_cache_free(cfq_pool, cfqq);
2581 cfq_put_cfqg(cfqg);
2585 * Must always be called with the rcu_read_lock() held
2587 static void
2588 __call_for_each_cic(struct io_context *ioc,
2589 void (*func)(struct io_context *, struct cfq_io_context *))
2591 struct cfq_io_context *cic;
2592 struct hlist_node *n;
2594 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2595 func(ioc, cic);
2599 * Call func for each cic attached to this ioc.
2601 static void
2602 call_for_each_cic(struct io_context *ioc,
2603 void (*func)(struct io_context *, struct cfq_io_context *))
2605 rcu_read_lock();
2606 __call_for_each_cic(ioc, func);
2607 rcu_read_unlock();
2610 static void cfq_cic_free_rcu(struct rcu_head *head)
2612 struct cfq_io_context *cic;
2614 cic = container_of(head, struct cfq_io_context, rcu_head);
2616 kmem_cache_free(cfq_ioc_pool, cic);
2617 elv_ioc_count_dec(cfq_ioc_count);
2619 if (ioc_gone) {
2621 * CFQ scheduler is exiting, grab exit lock and check
2622 * the pending io context count. If it hits zero,
2623 * complete ioc_gone and set it back to NULL
2625 spin_lock(&ioc_gone_lock);
2626 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2627 complete(ioc_gone);
2628 ioc_gone = NULL;
2630 spin_unlock(&ioc_gone_lock);
2634 static void cfq_cic_free(struct cfq_io_context *cic)
2636 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2639 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2641 unsigned long flags;
2642 unsigned long dead_key = (unsigned long) cic->key;
2644 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2646 spin_lock_irqsave(&ioc->lock, flags);
2647 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2648 hlist_del_rcu(&cic->cic_list);
2649 spin_unlock_irqrestore(&ioc->lock, flags);
2651 cfq_cic_free(cic);
2655 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2656 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2657 * and ->trim() which is called with the task lock held
2659 static void cfq_free_io_context(struct io_context *ioc)
2662 * ioc->refcount is zero here, or we are called from elv_unregister(),
2663 * so no more cic's are allowed to be linked into this ioc. So it
2664 * should be ok to iterate over the known list, we will see all cic's
2665 * since no new ones are added.
2667 __call_for_each_cic(ioc, cic_free_func);
2670 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2672 struct cfq_queue *__cfqq, *next;
2675 * If this queue was scheduled to merge with another queue, be
2676 * sure to drop the reference taken on that queue (and others in
2677 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2679 __cfqq = cfqq->new_cfqq;
2680 while (__cfqq) {
2681 if (__cfqq == cfqq) {
2682 WARN(1, "cfqq->new_cfqq loop detected\n");
2683 break;
2685 next = __cfqq->new_cfqq;
2686 cfq_put_queue(__cfqq);
2687 __cfqq = next;
2691 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2693 if (unlikely(cfqq == cfqd->active_queue)) {
2694 __cfq_slice_expired(cfqd, cfqq, 0);
2695 cfq_schedule_dispatch(cfqd);
2698 cfq_put_cooperator(cfqq);
2700 cfq_put_queue(cfqq);
2703 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2704 struct cfq_io_context *cic)
2706 struct io_context *ioc = cic->ioc;
2708 list_del_init(&cic->queue_list);
2711 * Make sure dead mark is seen for dead queues
2713 smp_wmb();
2714 cic->key = cfqd_dead_key(cfqd);
2716 if (ioc->ioc_data == cic)
2717 rcu_assign_pointer(ioc->ioc_data, NULL);
2719 if (cic->cfqq[BLK_RW_ASYNC]) {
2720 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2721 cic->cfqq[BLK_RW_ASYNC] = NULL;
2724 if (cic->cfqq[BLK_RW_SYNC]) {
2725 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2726 cic->cfqq[BLK_RW_SYNC] = NULL;
2730 static void cfq_exit_single_io_context(struct io_context *ioc,
2731 struct cfq_io_context *cic)
2733 struct cfq_data *cfqd = cic_to_cfqd(cic);
2735 if (cfqd) {
2736 struct request_queue *q = cfqd->queue;
2737 unsigned long flags;
2739 spin_lock_irqsave(q->queue_lock, flags);
2742 * Ensure we get a fresh copy of the ->key to prevent
2743 * race between exiting task and queue
2745 smp_read_barrier_depends();
2746 if (cic->key == cfqd)
2747 __cfq_exit_single_io_context(cfqd, cic);
2749 spin_unlock_irqrestore(q->queue_lock, flags);
2754 * The process that ioc belongs to has exited, we need to clean up
2755 * and put the internal structures we have that belongs to that process.
2757 static void cfq_exit_io_context(struct io_context *ioc)
2759 call_for_each_cic(ioc, cfq_exit_single_io_context);
2762 static struct cfq_io_context *
2763 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2765 struct cfq_io_context *cic;
2767 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2768 cfqd->queue->node);
2769 if (cic) {
2770 cic->last_end_request = jiffies;
2771 INIT_LIST_HEAD(&cic->queue_list);
2772 INIT_HLIST_NODE(&cic->cic_list);
2773 cic->dtor = cfq_free_io_context;
2774 cic->exit = cfq_exit_io_context;
2775 elv_ioc_count_inc(cfq_ioc_count);
2778 return cic;
2781 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2783 struct task_struct *tsk = current;
2784 int ioprio_class;
2786 if (!cfq_cfqq_prio_changed(cfqq))
2787 return;
2789 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2790 switch (ioprio_class) {
2791 default:
2792 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2793 case IOPRIO_CLASS_NONE:
2795 * no prio set, inherit CPU scheduling settings
2797 cfqq->ioprio = task_nice_ioprio(tsk);
2798 cfqq->ioprio_class = task_nice_ioclass(tsk);
2799 break;
2800 case IOPRIO_CLASS_RT:
2801 cfqq->ioprio = task_ioprio(ioc);
2802 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2803 break;
2804 case IOPRIO_CLASS_BE:
2805 cfqq->ioprio = task_ioprio(ioc);
2806 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2807 break;
2808 case IOPRIO_CLASS_IDLE:
2809 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2810 cfqq->ioprio = 7;
2811 cfq_clear_cfqq_idle_window(cfqq);
2812 break;
2816 * keep track of original prio settings in case we have to temporarily
2817 * elevate the priority of this queue
2819 cfqq->org_ioprio = cfqq->ioprio;
2820 cfqq->org_ioprio_class = cfqq->ioprio_class;
2821 cfq_clear_cfqq_prio_changed(cfqq);
2824 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2826 struct cfq_data *cfqd = cic_to_cfqd(cic);
2827 struct cfq_queue *cfqq;
2828 unsigned long flags;
2830 if (unlikely(!cfqd))
2831 return;
2833 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2835 cfqq = cic->cfqq[BLK_RW_ASYNC];
2836 if (cfqq) {
2837 struct cfq_queue *new_cfqq;
2838 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2839 GFP_ATOMIC);
2840 if (new_cfqq) {
2841 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2842 cfq_put_queue(cfqq);
2846 cfqq = cic->cfqq[BLK_RW_SYNC];
2847 if (cfqq)
2848 cfq_mark_cfqq_prio_changed(cfqq);
2850 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2853 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2855 call_for_each_cic(ioc, changed_ioprio);
2856 ioc->ioprio_changed = 0;
2859 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2860 pid_t pid, bool is_sync)
2862 RB_CLEAR_NODE(&cfqq->rb_node);
2863 RB_CLEAR_NODE(&cfqq->p_node);
2864 INIT_LIST_HEAD(&cfqq->fifo);
2866 cfqq->ref = 0;
2867 cfqq->cfqd = cfqd;
2869 cfq_mark_cfqq_prio_changed(cfqq);
2871 if (is_sync) {
2872 if (!cfq_class_idle(cfqq))
2873 cfq_mark_cfqq_idle_window(cfqq);
2874 cfq_mark_cfqq_sync(cfqq);
2876 cfqq->pid = pid;
2879 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2880 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2882 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2883 struct cfq_data *cfqd = cic_to_cfqd(cic);
2884 unsigned long flags;
2885 struct request_queue *q;
2887 if (unlikely(!cfqd))
2888 return;
2890 q = cfqd->queue;
2892 spin_lock_irqsave(q->queue_lock, flags);
2894 if (sync_cfqq) {
2896 * Drop reference to sync queue. A new sync queue will be
2897 * assigned in new group upon arrival of a fresh request.
2899 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2900 cic_set_cfqq(cic, NULL, 1);
2901 cfq_put_queue(sync_cfqq);
2904 spin_unlock_irqrestore(q->queue_lock, flags);
2907 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2909 call_for_each_cic(ioc, changed_cgroup);
2910 ioc->cgroup_changed = 0;
2912 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2914 static struct cfq_queue *
2915 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2916 struct io_context *ioc, gfp_t gfp_mask)
2918 struct cfq_queue *cfqq, *new_cfqq = NULL;
2919 struct cfq_io_context *cic;
2920 struct cfq_group *cfqg;
2922 retry:
2923 cfqg = cfq_get_cfqg(cfqd, 1);
2924 cic = cfq_cic_lookup(cfqd, ioc);
2925 /* cic always exists here */
2926 cfqq = cic_to_cfqq(cic, is_sync);
2929 * Always try a new alloc if we fell back to the OOM cfqq
2930 * originally, since it should just be a temporary situation.
2932 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2933 cfqq = NULL;
2934 if (new_cfqq) {
2935 cfqq = new_cfqq;
2936 new_cfqq = NULL;
2937 } else if (gfp_mask & __GFP_WAIT) {
2938 spin_unlock_irq(cfqd->queue->queue_lock);
2939 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2940 gfp_mask | __GFP_ZERO,
2941 cfqd->queue->node);
2942 spin_lock_irq(cfqd->queue->queue_lock);
2943 if (new_cfqq)
2944 goto retry;
2945 } else {
2946 cfqq = kmem_cache_alloc_node(cfq_pool,
2947 gfp_mask | __GFP_ZERO,
2948 cfqd->queue->node);
2951 if (cfqq) {
2952 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2953 cfq_init_prio_data(cfqq, ioc);
2954 cfq_link_cfqq_cfqg(cfqq, cfqg);
2955 cfq_log_cfqq(cfqd, cfqq, "alloced");
2956 } else
2957 cfqq = &cfqd->oom_cfqq;
2960 if (new_cfqq)
2961 kmem_cache_free(cfq_pool, new_cfqq);
2963 return cfqq;
2966 static struct cfq_queue **
2967 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2969 switch (ioprio_class) {
2970 case IOPRIO_CLASS_RT:
2971 return &cfqd->async_cfqq[0][ioprio];
2972 case IOPRIO_CLASS_BE:
2973 return &cfqd->async_cfqq[1][ioprio];
2974 case IOPRIO_CLASS_IDLE:
2975 return &cfqd->async_idle_cfqq;
2976 default:
2977 BUG();
2981 static struct cfq_queue *
2982 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2983 gfp_t gfp_mask)
2985 const int ioprio = task_ioprio(ioc);
2986 const int ioprio_class = task_ioprio_class(ioc);
2987 struct cfq_queue **async_cfqq = NULL;
2988 struct cfq_queue *cfqq = NULL;
2990 if (!is_sync) {
2991 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2992 cfqq = *async_cfqq;
2995 if (!cfqq)
2996 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2999 * pin the queue now that it's allocated, scheduler exit will prune it
3001 if (!is_sync && !(*async_cfqq)) {
3002 cfqq->ref++;
3003 *async_cfqq = cfqq;
3006 cfqq->ref++;
3007 return cfqq;
3011 * We drop cfq io contexts lazily, so we may find a dead one.
3013 static void
3014 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
3015 struct cfq_io_context *cic)
3017 unsigned long flags;
3019 WARN_ON(!list_empty(&cic->queue_list));
3020 BUG_ON(cic->key != cfqd_dead_key(cfqd));
3022 spin_lock_irqsave(&ioc->lock, flags);
3024 BUG_ON(ioc->ioc_data == cic);
3026 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
3027 hlist_del_rcu(&cic->cic_list);
3028 spin_unlock_irqrestore(&ioc->lock, flags);
3030 cfq_cic_free(cic);
3033 static struct cfq_io_context *
3034 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3036 struct cfq_io_context *cic;
3037 unsigned long flags;
3039 if (unlikely(!ioc))
3040 return NULL;
3042 rcu_read_lock();
3045 * we maintain a last-hit cache, to avoid browsing over the tree
3047 cic = rcu_dereference(ioc->ioc_data);
3048 if (cic && cic->key == cfqd) {
3049 rcu_read_unlock();
3050 return cic;
3053 do {
3054 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
3055 rcu_read_unlock();
3056 if (!cic)
3057 break;
3058 if (unlikely(cic->key != cfqd)) {
3059 cfq_drop_dead_cic(cfqd, ioc, cic);
3060 rcu_read_lock();
3061 continue;
3064 spin_lock_irqsave(&ioc->lock, flags);
3065 rcu_assign_pointer(ioc->ioc_data, cic);
3066 spin_unlock_irqrestore(&ioc->lock, flags);
3067 break;
3068 } while (1);
3070 return cic;
3074 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3075 * the process specific cfq io context when entered from the block layer.
3076 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3078 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
3079 struct cfq_io_context *cic, gfp_t gfp_mask)
3081 unsigned long flags;
3082 int ret;
3084 ret = radix_tree_preload(gfp_mask);
3085 if (!ret) {
3086 cic->ioc = ioc;
3087 cic->key = cfqd;
3089 spin_lock_irqsave(&ioc->lock, flags);
3090 ret = radix_tree_insert(&ioc->radix_root,
3091 cfqd->cic_index, cic);
3092 if (!ret)
3093 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3094 spin_unlock_irqrestore(&ioc->lock, flags);
3096 radix_tree_preload_end();
3098 if (!ret) {
3099 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3100 list_add(&cic->queue_list, &cfqd->cic_list);
3101 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3105 if (ret)
3106 printk(KERN_ERR "cfq: cic link failed!\n");
3108 return ret;
3112 * Setup general io context and cfq io context. There can be several cfq
3113 * io contexts per general io context, if this process is doing io to more
3114 * than one device managed by cfq.
3116 static struct cfq_io_context *
3117 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3119 struct io_context *ioc = NULL;
3120 struct cfq_io_context *cic;
3122 might_sleep_if(gfp_mask & __GFP_WAIT);
3124 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3125 if (!ioc)
3126 return NULL;
3128 cic = cfq_cic_lookup(cfqd, ioc);
3129 if (cic)
3130 goto out;
3132 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3133 if (cic == NULL)
3134 goto err;
3136 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3137 goto err_free;
3139 out:
3140 smp_read_barrier_depends();
3141 if (unlikely(ioc->ioprio_changed))
3142 cfq_ioc_set_ioprio(ioc);
3144 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3145 if (unlikely(ioc->cgroup_changed))
3146 cfq_ioc_set_cgroup(ioc);
3147 #endif
3148 return cic;
3149 err_free:
3150 cfq_cic_free(cic);
3151 err:
3152 put_io_context(ioc);
3153 return NULL;
3156 static void
3157 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3159 unsigned long elapsed = jiffies - cic->last_end_request;
3160 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3162 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3163 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3164 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3167 static void
3168 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3169 struct request *rq)
3171 sector_t sdist = 0;
3172 sector_t n_sec = blk_rq_sectors(rq);
3173 if (cfqq->last_request_pos) {
3174 if (cfqq->last_request_pos < blk_rq_pos(rq))
3175 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3176 else
3177 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3180 cfqq->seek_history <<= 1;
3181 if (blk_queue_nonrot(cfqd->queue))
3182 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3183 else
3184 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3188 * Disable idle window if the process thinks too long or seeks so much that
3189 * it doesn't matter
3191 static void
3192 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3193 struct cfq_io_context *cic)
3195 int old_idle, enable_idle;
3198 * Don't idle for async or idle io prio class
3200 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3201 return;
3203 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3205 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3206 cfq_mark_cfqq_deep(cfqq);
3208 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3209 enable_idle = 0;
3210 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3211 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3212 enable_idle = 0;
3213 else if (sample_valid(cic->ttime_samples)) {
3214 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3215 enable_idle = 0;
3216 else
3217 enable_idle = 1;
3220 if (old_idle != enable_idle) {
3221 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3222 if (enable_idle)
3223 cfq_mark_cfqq_idle_window(cfqq);
3224 else
3225 cfq_clear_cfqq_idle_window(cfqq);
3230 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3231 * no or if we aren't sure, a 1 will cause a preempt.
3233 static bool
3234 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3235 struct request *rq)
3237 struct cfq_queue *cfqq;
3239 cfqq = cfqd->active_queue;
3240 if (!cfqq)
3241 return false;
3243 if (cfq_class_idle(new_cfqq))
3244 return false;
3246 if (cfq_class_idle(cfqq))
3247 return true;
3250 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3252 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3253 return false;
3256 * if the new request is sync, but the currently running queue is
3257 * not, let the sync request have priority.
3259 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3260 return true;
3262 if (new_cfqq->cfqg != cfqq->cfqg)
3263 return false;
3265 if (cfq_slice_used(cfqq))
3266 return true;
3268 /* Allow preemption only if we are idling on sync-noidle tree */
3269 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3270 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3271 new_cfqq->service_tree->count == 2 &&
3272 RB_EMPTY_ROOT(&cfqq->sort_list))
3273 return true;
3276 * So both queues are sync. Let the new request get disk time if
3277 * it's a metadata request and the current queue is doing regular IO.
3279 if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
3280 return true;
3283 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3285 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3286 return true;
3288 /* An idle queue should not be idle now for some reason */
3289 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3290 return true;
3292 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3293 return false;
3296 * if this request is as-good as one we would expect from the
3297 * current cfqq, let it preempt
3299 if (cfq_rq_close(cfqd, cfqq, rq))
3300 return true;
3302 return false;
3306 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3307 * let it have half of its nominal slice.
3309 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3311 struct cfq_queue *old_cfqq = cfqd->active_queue;
3313 cfq_log_cfqq(cfqd, cfqq, "preempt");
3314 cfq_slice_expired(cfqd, 1);
3317 * workload type is changed, don't save slice, otherwise preempt
3318 * doesn't happen
3320 if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
3321 cfqq->cfqg->saved_workload_slice = 0;
3324 * Put the new queue at the front of the of the current list,
3325 * so we know that it will be selected next.
3327 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3329 cfq_service_tree_add(cfqd, cfqq, 1);
3331 cfqq->slice_end = 0;
3332 cfq_mark_cfqq_slice_new(cfqq);
3336 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3337 * something we should do about it
3339 static void
3340 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3341 struct request *rq)
3343 struct cfq_io_context *cic = RQ_CIC(rq);
3345 cfqd->rq_queued++;
3346 if (rq->cmd_flags & REQ_META)
3347 cfqq->meta_pending++;
3349 cfq_update_io_thinktime(cfqd, cic);
3350 cfq_update_io_seektime(cfqd, cfqq, rq);
3351 cfq_update_idle_window(cfqd, cfqq, cic);
3353 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3355 if (cfqq == cfqd->active_queue) {
3357 * Remember that we saw a request from this process, but
3358 * don't start queuing just yet. Otherwise we risk seeing lots
3359 * of tiny requests, because we disrupt the normal plugging
3360 * and merging. If the request is already larger than a single
3361 * page, let it rip immediately. For that case we assume that
3362 * merging is already done. Ditto for a busy system that
3363 * has other work pending, don't risk delaying until the
3364 * idle timer unplug to continue working.
3366 if (cfq_cfqq_wait_request(cfqq)) {
3367 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3368 cfqd->busy_queues > 1) {
3369 cfq_del_timer(cfqd, cfqq);
3370 cfq_clear_cfqq_wait_request(cfqq);
3371 __blk_run_queue(cfqd->queue, false);
3372 } else {
3373 cfq_blkiocg_update_idle_time_stats(
3374 &cfqq->cfqg->blkg);
3375 cfq_mark_cfqq_must_dispatch(cfqq);
3378 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3380 * not the active queue - expire current slice if it is
3381 * idle and has expired it's mean thinktime or this new queue
3382 * has some old slice time left and is of higher priority or
3383 * this new queue is RT and the current one is BE
3385 cfq_preempt_queue(cfqd, cfqq);
3386 __blk_run_queue(cfqd->queue, false);
3390 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3392 struct cfq_data *cfqd = q->elevator->elevator_data;
3393 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3395 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3396 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3398 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3399 list_add_tail(&rq->queuelist, &cfqq->fifo);
3400 cfq_add_rq_rb(rq);
3401 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3402 &cfqd->serving_group->blkg, rq_data_dir(rq),
3403 rq_is_sync(rq));
3404 cfq_rq_enqueued(cfqd, cfqq, rq);
3408 * Update hw_tag based on peak queue depth over 50 samples under
3409 * sufficient load.
3411 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3413 struct cfq_queue *cfqq = cfqd->active_queue;
3415 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3416 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3418 if (cfqd->hw_tag == 1)
3419 return;
3421 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3422 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3423 return;
3426 * If active queue hasn't enough requests and can idle, cfq might not
3427 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3428 * case
3430 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3431 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3432 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3433 return;
3435 if (cfqd->hw_tag_samples++ < 50)
3436 return;
3438 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3439 cfqd->hw_tag = 1;
3440 else
3441 cfqd->hw_tag = 0;
3444 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3446 struct cfq_io_context *cic = cfqd->active_cic;
3448 /* If the queue already has requests, don't wait */
3449 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3450 return false;
3452 /* If there are other queues in the group, don't wait */
3453 if (cfqq->cfqg->nr_cfqq > 1)
3454 return false;
3456 if (cfq_slice_used(cfqq))
3457 return true;
3459 /* if slice left is less than think time, wait busy */
3460 if (cic && sample_valid(cic->ttime_samples)
3461 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3462 return true;
3465 * If think times is less than a jiffy than ttime_mean=0 and above
3466 * will not be true. It might happen that slice has not expired yet
3467 * but will expire soon (4-5 ns) during select_queue(). To cover the
3468 * case where think time is less than a jiffy, mark the queue wait
3469 * busy if only 1 jiffy is left in the slice.
3471 if (cfqq->slice_end - jiffies == 1)
3472 return true;
3474 return false;
3477 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3479 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3480 struct cfq_data *cfqd = cfqq->cfqd;
3481 const int sync = rq_is_sync(rq);
3482 unsigned long now;
3484 now = jiffies;
3485 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3486 !!(rq->cmd_flags & REQ_NOIDLE));
3488 cfq_update_hw_tag(cfqd);
3490 WARN_ON(!cfqd->rq_in_driver);
3491 WARN_ON(!cfqq->dispatched);
3492 cfqd->rq_in_driver--;
3493 cfqq->dispatched--;
3494 (RQ_CFQG(rq))->dispatched--;
3495 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3496 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3497 rq_data_dir(rq), rq_is_sync(rq));
3499 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3501 if (sync) {
3502 RQ_CIC(rq)->last_end_request = now;
3503 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3504 cfqd->last_delayed_sync = now;
3508 * If this is the active queue, check if it needs to be expired,
3509 * or if we want to idle in case it has no pending requests.
3511 if (cfqd->active_queue == cfqq) {
3512 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3514 if (cfq_cfqq_slice_new(cfqq)) {
3515 cfq_set_prio_slice(cfqd, cfqq);
3516 cfq_clear_cfqq_slice_new(cfqq);
3520 * Should we wait for next request to come in before we expire
3521 * the queue.
3523 if (cfq_should_wait_busy(cfqd, cfqq)) {
3524 unsigned long extend_sl = cfqd->cfq_slice_idle;
3525 if (!cfqd->cfq_slice_idle)
3526 extend_sl = cfqd->cfq_group_idle;
3527 cfqq->slice_end = jiffies + extend_sl;
3528 cfq_mark_cfqq_wait_busy(cfqq);
3529 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3533 * Idling is not enabled on:
3534 * - expired queues
3535 * - idle-priority queues
3536 * - async queues
3537 * - queues with still some requests queued
3538 * - when there is a close cooperator
3540 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3541 cfq_slice_expired(cfqd, 1);
3542 else if (sync && cfqq_empty &&
3543 !cfq_close_cooperator(cfqd, cfqq)) {
3544 cfq_arm_slice_timer(cfqd);
3548 if (!cfqd->rq_in_driver)
3549 cfq_schedule_dispatch(cfqd);
3553 * we temporarily boost lower priority queues if they are holding fs exclusive
3554 * resources. they are boosted to normal prio (CLASS_BE/4)
3556 static void cfq_prio_boost(struct cfq_queue *cfqq)
3558 if (has_fs_excl()) {
3560 * boost idle prio on transactions that would lock out other
3561 * users of the filesystem
3563 if (cfq_class_idle(cfqq))
3564 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3565 if (cfqq->ioprio > IOPRIO_NORM)
3566 cfqq->ioprio = IOPRIO_NORM;
3567 } else {
3569 * unboost the queue (if needed)
3571 cfqq->ioprio_class = cfqq->org_ioprio_class;
3572 cfqq->ioprio = cfqq->org_ioprio;
3576 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3578 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3579 cfq_mark_cfqq_must_alloc_slice(cfqq);
3580 return ELV_MQUEUE_MUST;
3583 return ELV_MQUEUE_MAY;
3586 static int cfq_may_queue(struct request_queue *q, int rw)
3588 struct cfq_data *cfqd = q->elevator->elevator_data;
3589 struct task_struct *tsk = current;
3590 struct cfq_io_context *cic;
3591 struct cfq_queue *cfqq;
3594 * don't force setup of a queue from here, as a call to may_queue
3595 * does not necessarily imply that a request actually will be queued.
3596 * so just lookup a possibly existing queue, or return 'may queue'
3597 * if that fails
3599 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3600 if (!cic)
3601 return ELV_MQUEUE_MAY;
3603 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3604 if (cfqq) {
3605 cfq_init_prio_data(cfqq, cic->ioc);
3606 cfq_prio_boost(cfqq);
3608 return __cfq_may_queue(cfqq);
3611 return ELV_MQUEUE_MAY;
3615 * queue lock held here
3617 static void cfq_put_request(struct request *rq)
3619 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3621 if (cfqq) {
3622 const int rw = rq_data_dir(rq);
3624 BUG_ON(!cfqq->allocated[rw]);
3625 cfqq->allocated[rw]--;
3627 put_io_context(RQ_CIC(rq)->ioc);
3629 rq->elevator_private[0] = NULL;
3630 rq->elevator_private[1] = NULL;
3632 /* Put down rq reference on cfqg */
3633 cfq_put_cfqg(RQ_CFQG(rq));
3634 rq->elevator_private[2] = NULL;
3636 cfq_put_queue(cfqq);
3640 static struct cfq_queue *
3641 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3642 struct cfq_queue *cfqq)
3644 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3645 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3646 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3647 cfq_put_queue(cfqq);
3648 return cic_to_cfqq(cic, 1);
3652 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3653 * was the last process referring to said cfqq.
3655 static struct cfq_queue *
3656 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3658 if (cfqq_process_refs(cfqq) == 1) {
3659 cfqq->pid = current->pid;
3660 cfq_clear_cfqq_coop(cfqq);
3661 cfq_clear_cfqq_split_coop(cfqq);
3662 return cfqq;
3665 cic_set_cfqq(cic, NULL, 1);
3667 cfq_put_cooperator(cfqq);
3669 cfq_put_queue(cfqq);
3670 return NULL;
3673 * Allocate cfq data structures associated with this request.
3675 static int
3676 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3678 struct cfq_data *cfqd = q->elevator->elevator_data;
3679 struct cfq_io_context *cic;
3680 const int rw = rq_data_dir(rq);
3681 const bool is_sync = rq_is_sync(rq);
3682 struct cfq_queue *cfqq;
3683 unsigned long flags;
3685 might_sleep_if(gfp_mask & __GFP_WAIT);
3687 cic = cfq_get_io_context(cfqd, gfp_mask);
3689 spin_lock_irqsave(q->queue_lock, flags);
3691 if (!cic)
3692 goto queue_fail;
3694 new_queue:
3695 cfqq = cic_to_cfqq(cic, is_sync);
3696 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3697 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3698 cic_set_cfqq(cic, cfqq, is_sync);
3699 } else {
3701 * If the queue was seeky for too long, break it apart.
3703 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3704 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3705 cfqq = split_cfqq(cic, cfqq);
3706 if (!cfqq)
3707 goto new_queue;
3711 * Check to see if this queue is scheduled to merge with
3712 * another, closely cooperating queue. The merging of
3713 * queues happens here as it must be done in process context.
3714 * The reference on new_cfqq was taken in merge_cfqqs.
3716 if (cfqq->new_cfqq)
3717 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3720 cfqq->allocated[rw]++;
3722 cfqq->ref++;
3723 rq->elevator_private[0] = cic;
3724 rq->elevator_private[1] = cfqq;
3725 rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
3726 spin_unlock_irqrestore(q->queue_lock, flags);
3727 return 0;
3729 queue_fail:
3730 if (cic)
3731 put_io_context(cic->ioc);
3733 cfq_schedule_dispatch(cfqd);
3734 spin_unlock_irqrestore(q->queue_lock, flags);
3735 cfq_log(cfqd, "set_request fail");
3736 return 1;
3739 static void cfq_kick_queue(struct work_struct *work)
3741 struct cfq_data *cfqd =
3742 container_of(work, struct cfq_data, unplug_work);
3743 struct request_queue *q = cfqd->queue;
3745 spin_lock_irq(q->queue_lock);
3746 __blk_run_queue(cfqd->queue, false);
3747 spin_unlock_irq(q->queue_lock);
3751 * Timer running if the active_queue is currently idling inside its time slice
3753 static void cfq_idle_slice_timer(unsigned long data)
3755 struct cfq_data *cfqd = (struct cfq_data *) data;
3756 struct cfq_queue *cfqq;
3757 unsigned long flags;
3758 int timed_out = 1;
3760 cfq_log(cfqd, "idle timer fired");
3762 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3764 cfqq = cfqd->active_queue;
3765 if (cfqq) {
3766 timed_out = 0;
3769 * We saw a request before the queue expired, let it through
3771 if (cfq_cfqq_must_dispatch(cfqq))
3772 goto out_kick;
3775 * expired
3777 if (cfq_slice_used(cfqq))
3778 goto expire;
3781 * only expire and reinvoke request handler, if there are
3782 * other queues with pending requests
3784 if (!cfqd->busy_queues)
3785 goto out_cont;
3788 * not expired and it has a request pending, let it dispatch
3790 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3791 goto out_kick;
3794 * Queue depth flag is reset only when the idle didn't succeed
3796 cfq_clear_cfqq_deep(cfqq);
3798 expire:
3799 cfq_slice_expired(cfqd, timed_out);
3800 out_kick:
3801 cfq_schedule_dispatch(cfqd);
3802 out_cont:
3803 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3806 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3808 del_timer_sync(&cfqd->idle_slice_timer);
3809 cancel_work_sync(&cfqd->unplug_work);
3812 static void cfq_put_async_queues(struct cfq_data *cfqd)
3814 int i;
3816 for (i = 0; i < IOPRIO_BE_NR; i++) {
3817 if (cfqd->async_cfqq[0][i])
3818 cfq_put_queue(cfqd->async_cfqq[0][i]);
3819 if (cfqd->async_cfqq[1][i])
3820 cfq_put_queue(cfqd->async_cfqq[1][i]);
3823 if (cfqd->async_idle_cfqq)
3824 cfq_put_queue(cfqd->async_idle_cfqq);
3827 static void cfq_cfqd_free(struct rcu_head *head)
3829 kfree(container_of(head, struct cfq_data, rcu));
3832 static void cfq_exit_queue(struct elevator_queue *e)
3834 struct cfq_data *cfqd = e->elevator_data;
3835 struct request_queue *q = cfqd->queue;
3837 cfq_shutdown_timer_wq(cfqd);
3839 spin_lock_irq(q->queue_lock);
3841 if (cfqd->active_queue)
3842 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3844 while (!list_empty(&cfqd->cic_list)) {
3845 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3846 struct cfq_io_context,
3847 queue_list);
3849 __cfq_exit_single_io_context(cfqd, cic);
3852 cfq_put_async_queues(cfqd);
3853 cfq_release_cfq_groups(cfqd);
3854 cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3856 spin_unlock_irq(q->queue_lock);
3858 cfq_shutdown_timer_wq(cfqd);
3860 spin_lock(&cic_index_lock);
3861 ida_remove(&cic_index_ida, cfqd->cic_index);
3862 spin_unlock(&cic_index_lock);
3864 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3865 call_rcu(&cfqd->rcu, cfq_cfqd_free);
3868 static int cfq_alloc_cic_index(void)
3870 int index, error;
3872 do {
3873 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3874 return -ENOMEM;
3876 spin_lock(&cic_index_lock);
3877 error = ida_get_new(&cic_index_ida, &index);
3878 spin_unlock(&cic_index_lock);
3879 if (error && error != -EAGAIN)
3880 return error;
3881 } while (error);
3883 return index;
3886 static void *cfq_init_queue(struct request_queue *q)
3888 struct cfq_data *cfqd;
3889 int i, j;
3890 struct cfq_group *cfqg;
3891 struct cfq_rb_root *st;
3893 i = cfq_alloc_cic_index();
3894 if (i < 0)
3895 return NULL;
3897 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3898 if (!cfqd)
3899 return NULL;
3902 * Don't need take queue_lock in the routine, since we are
3903 * initializing the ioscheduler, and nobody is using cfqd
3905 cfqd->cic_index = i;
3907 /* Init root service tree */
3908 cfqd->grp_service_tree = CFQ_RB_ROOT;
3910 /* Init root group */
3911 cfqg = &cfqd->root_group;
3912 for_each_cfqg_st(cfqg, i, j, st)
3913 *st = CFQ_RB_ROOT;
3914 RB_CLEAR_NODE(&cfqg->rb_node);
3916 /* Give preference to root group over other groups */
3917 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3919 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3921 * Take a reference to root group which we never drop. This is just
3922 * to make sure that cfq_put_cfqg() does not try to kfree root group
3924 cfqg->ref = 1;
3925 rcu_read_lock();
3926 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3927 (void *)cfqd, 0);
3928 rcu_read_unlock();
3929 #endif
3931 * Not strictly needed (since RB_ROOT just clears the node and we
3932 * zeroed cfqd on alloc), but better be safe in case someone decides
3933 * to add magic to the rb code
3935 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3936 cfqd->prio_trees[i] = RB_ROOT;
3939 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3940 * Grab a permanent reference to it, so that the normal code flow
3941 * will not attempt to free it.
3943 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3944 cfqd->oom_cfqq.ref++;
3945 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3947 INIT_LIST_HEAD(&cfqd->cic_list);
3949 cfqd->queue = q;
3951 init_timer(&cfqd->idle_slice_timer);
3952 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3953 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3955 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3957 cfqd->cfq_quantum = cfq_quantum;
3958 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3959 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3960 cfqd->cfq_back_max = cfq_back_max;
3961 cfqd->cfq_back_penalty = cfq_back_penalty;
3962 cfqd->cfq_slice[0] = cfq_slice_async;
3963 cfqd->cfq_slice[1] = cfq_slice_sync;
3964 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3965 cfqd->cfq_slice_idle = cfq_slice_idle;
3966 cfqd->cfq_group_idle = cfq_group_idle;
3967 cfqd->cfq_latency = 1;
3968 cfqd->hw_tag = -1;
3970 * we optimistically start assuming sync ops weren't delayed in last
3971 * second, in order to have larger depth for async operations.
3973 cfqd->last_delayed_sync = jiffies - HZ;
3974 return cfqd;
3977 static void cfq_slab_kill(void)
3980 * Caller already ensured that pending RCU callbacks are completed,
3981 * so we should have no busy allocations at this point.
3983 if (cfq_pool)
3984 kmem_cache_destroy(cfq_pool);
3985 if (cfq_ioc_pool)
3986 kmem_cache_destroy(cfq_ioc_pool);
3989 static int __init cfq_slab_setup(void)
3991 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3992 if (!cfq_pool)
3993 goto fail;
3995 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3996 if (!cfq_ioc_pool)
3997 goto fail;
3999 return 0;
4000 fail:
4001 cfq_slab_kill();
4002 return -ENOMEM;
4006 * sysfs parts below -->
4008 static ssize_t
4009 cfq_var_show(unsigned int var, char *page)
4011 return sprintf(page, "%d\n", var);
4014 static ssize_t
4015 cfq_var_store(unsigned int *var, const char *page, size_t count)
4017 char *p = (char *) page;
4019 *var = simple_strtoul(p, &p, 10);
4020 return count;
4023 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4024 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4026 struct cfq_data *cfqd = e->elevator_data; \
4027 unsigned int __data = __VAR; \
4028 if (__CONV) \
4029 __data = jiffies_to_msecs(__data); \
4030 return cfq_var_show(__data, (page)); \
4032 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4033 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4034 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4035 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4036 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4037 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4038 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4039 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4040 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4041 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4042 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4043 #undef SHOW_FUNCTION
4045 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4046 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4048 struct cfq_data *cfqd = e->elevator_data; \
4049 unsigned int __data; \
4050 int ret = cfq_var_store(&__data, (page), count); \
4051 if (__data < (MIN)) \
4052 __data = (MIN); \
4053 else if (__data > (MAX)) \
4054 __data = (MAX); \
4055 if (__CONV) \
4056 *(__PTR) = msecs_to_jiffies(__data); \
4057 else \
4058 *(__PTR) = __data; \
4059 return ret; \
4061 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4062 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4063 UINT_MAX, 1);
4064 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4065 UINT_MAX, 1);
4066 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4067 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4068 UINT_MAX, 0);
4069 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4070 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4071 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4072 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4073 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4074 UINT_MAX, 0);
4075 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4076 #undef STORE_FUNCTION
4078 #define CFQ_ATTR(name) \
4079 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4081 static struct elv_fs_entry cfq_attrs[] = {
4082 CFQ_ATTR(quantum),
4083 CFQ_ATTR(fifo_expire_sync),
4084 CFQ_ATTR(fifo_expire_async),
4085 CFQ_ATTR(back_seek_max),
4086 CFQ_ATTR(back_seek_penalty),
4087 CFQ_ATTR(slice_sync),
4088 CFQ_ATTR(slice_async),
4089 CFQ_ATTR(slice_async_rq),
4090 CFQ_ATTR(slice_idle),
4091 CFQ_ATTR(group_idle),
4092 CFQ_ATTR(low_latency),
4093 __ATTR_NULL
4096 static struct elevator_type iosched_cfq = {
4097 .ops = {
4098 .elevator_merge_fn = cfq_merge,
4099 .elevator_merged_fn = cfq_merged_request,
4100 .elevator_merge_req_fn = cfq_merged_requests,
4101 .elevator_allow_merge_fn = cfq_allow_merge,
4102 .elevator_bio_merged_fn = cfq_bio_merged,
4103 .elevator_dispatch_fn = cfq_dispatch_requests,
4104 .elevator_add_req_fn = cfq_insert_request,
4105 .elevator_activate_req_fn = cfq_activate_request,
4106 .elevator_deactivate_req_fn = cfq_deactivate_request,
4107 .elevator_completed_req_fn = cfq_completed_request,
4108 .elevator_former_req_fn = elv_rb_former_request,
4109 .elevator_latter_req_fn = elv_rb_latter_request,
4110 .elevator_set_req_fn = cfq_set_request,
4111 .elevator_put_req_fn = cfq_put_request,
4112 .elevator_may_queue_fn = cfq_may_queue,
4113 .elevator_init_fn = cfq_init_queue,
4114 .elevator_exit_fn = cfq_exit_queue,
4115 .trim = cfq_free_io_context,
4117 .elevator_attrs = cfq_attrs,
4118 .elevator_name = "cfq",
4119 .elevator_owner = THIS_MODULE,
4122 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4123 static struct blkio_policy_type blkio_policy_cfq = {
4124 .ops = {
4125 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4126 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4128 .plid = BLKIO_POLICY_PROP,
4130 #else
4131 static struct blkio_policy_type blkio_policy_cfq;
4132 #endif
4134 static int __init cfq_init(void)
4137 * could be 0 on HZ < 1000 setups
4139 if (!cfq_slice_async)
4140 cfq_slice_async = 1;
4141 if (!cfq_slice_idle)
4142 cfq_slice_idle = 1;
4144 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4145 if (!cfq_group_idle)
4146 cfq_group_idle = 1;
4147 #else
4148 cfq_group_idle = 0;
4149 #endif
4150 if (cfq_slab_setup())
4151 return -ENOMEM;
4153 elv_register(&iosched_cfq);
4154 blkio_policy_register(&blkio_policy_cfq);
4156 return 0;
4159 static void __exit cfq_exit(void)
4161 DECLARE_COMPLETION_ONSTACK(all_gone);
4162 blkio_policy_unregister(&blkio_policy_cfq);
4163 elv_unregister(&iosched_cfq);
4164 ioc_gone = &all_gone;
4165 /* ioc_gone's update must be visible before reading ioc_count */
4166 smp_wmb();
4169 * this also protects us from entering cfq_slab_kill() with
4170 * pending RCU callbacks
4172 if (elv_ioc_count_read(cfq_ioc_count))
4173 wait_for_completion(&all_gone);
4174 ida_destroy(&cic_index_ida);
4175 cfq_slab_kill();
4178 module_init(cfq_init);
4179 module_exit(cfq_exit);
4181 MODULE_AUTHOR("Jens Axboe");
4182 MODULE_LICENSE("GPL");
4183 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");