drivers/video/matrox/matroxfb_maven.c: fix unsigned return type
[linux/fpc-iii.git] / block / cfq-iosched.c
blob4cd59b0d7c15b2b0df8c6e7323afe5cd51359969
1 /*
2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8 */
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
17 #include "cfq.h"
20 * tunables
22 /* max queue in one round of service */
23 static const int cfq_quantum = 8;
24 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
25 /* maximum backwards seek, in KiB */
26 static const int cfq_back_max = 16 * 1024;
27 /* penalty of a backwards seek */
28 static const int cfq_back_penalty = 2;
29 static const int cfq_slice_sync = HZ / 10;
30 static int cfq_slice_async = HZ / 25;
31 static const int cfq_slice_async_rq = 2;
32 static int cfq_slice_idle = HZ / 125;
33 static int cfq_group_idle = HZ / 125;
34 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
35 static const int cfq_hist_divisor = 4;
38 * offset from end of service tree
40 #define CFQ_IDLE_DELAY (HZ / 5)
43 * below this threshold, we consider thinktime immediate
45 #define CFQ_MIN_TT (2)
47 #define CFQ_SLICE_SCALE (5)
48 #define CFQ_HW_QUEUE_MIN (5)
49 #define CFQ_SERVICE_SHIFT 12
51 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
52 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
53 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
54 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
56 #define RQ_CIC(rq) \
57 ((struct cfq_io_context *) (rq)->elevator_private)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
61 static struct kmem_cache *cfq_pool;
62 static struct kmem_cache *cfq_ioc_pool;
64 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
65 static struct completion *ioc_gone;
66 static DEFINE_SPINLOCK(ioc_gone_lock);
68 static DEFINE_SPINLOCK(cic_index_lock);
69 static DEFINE_IDA(cic_index_ida);
71 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
72 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
73 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
75 #define sample_valid(samples) ((samples) > 80)
76 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
84 struct cfq_rb_root {
85 struct rb_root rb;
86 struct rb_node *left;
87 unsigned count;
88 unsigned total_weight;
89 u64 min_vdisktime;
90 struct rb_node *active;
92 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
93 .count = 0, .min_vdisktime = 0, }
96 * Per process-grouping structure
98 struct cfq_queue {
99 /* reference count */
100 atomic_t ref;
101 /* various state flags, see below */
102 unsigned int flags;
103 /* parent cfq_data */
104 struct cfq_data *cfqd;
105 /* service_tree member */
106 struct rb_node rb_node;
107 /* service_tree key */
108 unsigned long rb_key;
109 /* prio tree member */
110 struct rb_node p_node;
111 /* prio tree root we belong to, if any */
112 struct rb_root *p_root;
113 /* sorted list of pending requests */
114 struct rb_root sort_list;
115 /* if fifo isn't expired, next request to serve */
116 struct request *next_rq;
117 /* requests queued in sort_list */
118 int queued[2];
119 /* currently allocated requests */
120 int allocated[2];
121 /* fifo list of requests in sort_list */
122 struct list_head fifo;
124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start;
126 unsigned int allocated_slice;
127 unsigned int slice_dispatch;
128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start;
130 unsigned long slice_end;
131 long slice_resid;
133 /* pending metadata requests */
134 int meta_pending;
135 /* number of requests that are on the dispatch list or inside driver */
136 int dispatched;
138 /* io prio of this group */
139 unsigned short ioprio, org_ioprio;
140 unsigned short ioprio_class, org_ioprio_class;
142 pid_t pid;
144 u32 seek_history;
145 sector_t last_request_pos;
147 struct cfq_rb_root *service_tree;
148 struct cfq_queue *new_cfqq;
149 struct cfq_group *cfqg;
150 struct cfq_group *orig_cfqg;
151 /* Number of sectors dispatched from queue in single dispatch round */
152 unsigned long nr_sectors;
156 * First index in the service_trees.
157 * IDLE is handled separately, so it has negative index
159 enum wl_prio_t {
160 BE_WORKLOAD = 0,
161 RT_WORKLOAD = 1,
162 IDLE_WORKLOAD = 2,
163 CFQ_PRIO_NR,
167 * Second index in the service_trees.
169 enum wl_type_t {
170 ASYNC_WORKLOAD = 0,
171 SYNC_NOIDLE_WORKLOAD = 1,
172 SYNC_WORKLOAD = 2
175 /* This is per cgroup per device grouping structure */
176 struct cfq_group {
177 /* group service_tree member */
178 struct rb_node rb_node;
180 /* group service_tree key */
181 u64 vdisktime;
182 unsigned int weight;
183 bool on_st;
185 /* number of cfqq currently on this group */
186 int nr_cfqq;
189 * Per group busy queus average. Useful for workload slice calc. We
190 * create the array for each prio class but at run time it is used
191 * only for RT and BE class and slot for IDLE class remains unused.
192 * This is primarily done to avoid confusion and a gcc warning.
194 unsigned int busy_queues_avg[CFQ_PRIO_NR];
196 * rr lists of queues with requests. We maintain service trees for
197 * RT and BE classes. These trees are subdivided in subclasses
198 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
199 * class there is no subclassification and all the cfq queues go on
200 * a single tree service_tree_idle.
201 * Counts are embedded in the cfq_rb_root
203 struct cfq_rb_root service_trees[2][3];
204 struct cfq_rb_root service_tree_idle;
206 unsigned long saved_workload_slice;
207 enum wl_type_t saved_workload;
208 enum wl_prio_t saved_serving_prio;
209 struct blkio_group blkg;
210 #ifdef CONFIG_CFQ_GROUP_IOSCHED
211 struct hlist_node cfqd_node;
212 atomic_t ref;
213 #endif
214 /* number of requests that are on the dispatch list or inside driver */
215 int dispatched;
219 * Per block device queue structure
221 struct cfq_data {
222 struct request_queue *queue;
223 /* Root service tree for cfq_groups */
224 struct cfq_rb_root grp_service_tree;
225 struct cfq_group root_group;
228 * The priority currently being served
230 enum wl_prio_t serving_prio;
231 enum wl_type_t serving_type;
232 unsigned long workload_expires;
233 struct cfq_group *serving_group;
236 * Each priority tree is sorted by next_request position. These
237 * trees are used when determining if two or more queues are
238 * interleaving requests (see cfq_close_cooperator).
240 struct rb_root prio_trees[CFQ_PRIO_LISTS];
242 unsigned int busy_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;
290 unsigned int cfq_group_isolation;
292 unsigned int cic_index;
293 struct list_head cic_list;
296 * Fallback dummy cfqq for extreme OOM conditions
298 struct cfq_queue oom_cfqq;
300 unsigned long last_delayed_sync;
302 /* List of cfq groups being managed on this device*/
303 struct hlist_head cfqg_list;
304 struct rcu_head rcu;
307 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
309 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
310 enum wl_prio_t prio,
311 enum wl_type_t type)
313 if (!cfqg)
314 return NULL;
316 if (prio == IDLE_WORKLOAD)
317 return &cfqg->service_tree_idle;
319 return &cfqg->service_trees[prio][type];
322 enum cfqq_state_flags {
323 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
324 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
325 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
326 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
327 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
328 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
329 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
330 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
331 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
332 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
333 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
334 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
335 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
338 #define CFQ_CFQQ_FNS(name) \
339 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
341 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
343 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
345 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
347 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
349 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
352 CFQ_CFQQ_FNS(on_rr);
353 CFQ_CFQQ_FNS(wait_request);
354 CFQ_CFQQ_FNS(must_dispatch);
355 CFQ_CFQQ_FNS(must_alloc_slice);
356 CFQ_CFQQ_FNS(fifo_expire);
357 CFQ_CFQQ_FNS(idle_window);
358 CFQ_CFQQ_FNS(prio_changed);
359 CFQ_CFQQ_FNS(slice_new);
360 CFQ_CFQQ_FNS(sync);
361 CFQ_CFQQ_FNS(coop);
362 CFQ_CFQQ_FNS(split_coop);
363 CFQ_CFQQ_FNS(deep);
364 CFQ_CFQQ_FNS(wait_busy);
365 #undef CFQ_CFQQ_FNS
367 #ifdef CONFIG_CFQ_GROUP_IOSCHED
368 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
369 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
370 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
371 blkg_path(&(cfqq)->cfqg->blkg), ##args);
373 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
374 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
375 blkg_path(&(cfqg)->blkg), ##args); \
377 #else
378 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
379 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
380 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
381 #endif
382 #define cfq_log(cfqd, fmt, args...) \
383 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
385 /* Traverses through cfq group service trees */
386 #define for_each_cfqg_st(cfqg, i, j, st) \
387 for (i = 0; i <= IDLE_WORKLOAD; i++) \
388 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
389 : &cfqg->service_tree_idle; \
390 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
391 (i == IDLE_WORKLOAD && j == 0); \
392 j++, st = i < IDLE_WORKLOAD ? \
393 &cfqg->service_trees[i][j]: NULL) \
396 static inline bool iops_mode(struct cfq_data *cfqd)
399 * If we are not idling on queues and it is a NCQ drive, parallel
400 * execution of requests is on and measuring time is not possible
401 * in most of the cases until and unless we drive shallower queue
402 * depths and that becomes a performance bottleneck. In such cases
403 * switch to start providing fairness in terms of number of IOs.
405 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
406 return true;
407 else
408 return false;
411 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
413 if (cfq_class_idle(cfqq))
414 return IDLE_WORKLOAD;
415 if (cfq_class_rt(cfqq))
416 return RT_WORKLOAD;
417 return BE_WORKLOAD;
421 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
423 if (!cfq_cfqq_sync(cfqq))
424 return ASYNC_WORKLOAD;
425 if (!cfq_cfqq_idle_window(cfqq))
426 return SYNC_NOIDLE_WORKLOAD;
427 return SYNC_WORKLOAD;
430 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
431 struct cfq_data *cfqd,
432 struct cfq_group *cfqg)
434 if (wl == IDLE_WORKLOAD)
435 return cfqg->service_tree_idle.count;
437 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
438 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
439 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
442 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
443 struct cfq_group *cfqg)
445 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
446 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
449 static void cfq_dispatch_insert(struct request_queue *, struct request *);
450 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
451 struct io_context *, gfp_t);
452 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
453 struct io_context *);
455 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
456 bool is_sync)
458 return cic->cfqq[is_sync];
461 static inline void cic_set_cfqq(struct cfq_io_context *cic,
462 struct cfq_queue *cfqq, bool is_sync)
464 cic->cfqq[is_sync] = cfqq;
467 #define CIC_DEAD_KEY 1ul
468 #define CIC_DEAD_INDEX_SHIFT 1
470 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
472 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
475 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
477 struct cfq_data *cfqd = cic->key;
479 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
480 return NULL;
482 return cfqd;
486 * We regard a request as SYNC, if it's either a read or has the SYNC bit
487 * set (in which case it could also be direct WRITE).
489 static inline bool cfq_bio_sync(struct bio *bio)
491 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
495 * scheduler run of queue, if there are requests pending and no one in the
496 * driver that will restart queueing
498 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
500 if (cfqd->busy_queues) {
501 cfq_log(cfqd, "schedule dispatch");
502 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
506 static int cfq_queue_empty(struct request_queue *q)
508 struct cfq_data *cfqd = q->elevator->elevator_data;
510 return !cfqd->rq_queued;
514 * Scale schedule slice based on io priority. Use the sync time slice only
515 * if a queue is marked sync and has sync io queued. A sync queue with async
516 * io only, should not get full sync slice length.
518 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
519 unsigned short prio)
521 const int base_slice = cfqd->cfq_slice[sync];
523 WARN_ON(prio >= IOPRIO_BE_NR);
525 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
528 static inline int
529 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
531 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
534 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
536 u64 d = delta << CFQ_SERVICE_SHIFT;
538 d = d * BLKIO_WEIGHT_DEFAULT;
539 do_div(d, cfqg->weight);
540 return d;
543 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
545 s64 delta = (s64)(vdisktime - min_vdisktime);
546 if (delta > 0)
547 min_vdisktime = vdisktime;
549 return min_vdisktime;
552 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
554 s64 delta = (s64)(vdisktime - min_vdisktime);
555 if (delta < 0)
556 min_vdisktime = vdisktime;
558 return min_vdisktime;
561 static void update_min_vdisktime(struct cfq_rb_root *st)
563 u64 vdisktime = st->min_vdisktime;
564 struct cfq_group *cfqg;
566 if (st->active) {
567 cfqg = rb_entry_cfqg(st->active);
568 vdisktime = cfqg->vdisktime;
571 if (st->left) {
572 cfqg = rb_entry_cfqg(st->left);
573 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
576 st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
580 * get averaged number of queues of RT/BE priority.
581 * average is updated, with a formula that gives more weight to higher numbers,
582 * to quickly follows sudden increases and decrease slowly
585 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
586 struct cfq_group *cfqg, bool rt)
588 unsigned min_q, max_q;
589 unsigned mult = cfq_hist_divisor - 1;
590 unsigned round = cfq_hist_divisor / 2;
591 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
593 min_q = min(cfqg->busy_queues_avg[rt], busy);
594 max_q = max(cfqg->busy_queues_avg[rt], busy);
595 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
596 cfq_hist_divisor;
597 return cfqg->busy_queues_avg[rt];
600 static inline unsigned
601 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
603 struct cfq_rb_root *st = &cfqd->grp_service_tree;
605 return cfq_target_latency * cfqg->weight / st->total_weight;
608 static inline void
609 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
611 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
612 if (cfqd->cfq_latency) {
614 * interested queues (we consider only the ones with the same
615 * priority class in the cfq group)
617 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
618 cfq_class_rt(cfqq));
619 unsigned sync_slice = cfqd->cfq_slice[1];
620 unsigned expect_latency = sync_slice * iq;
621 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
623 if (expect_latency > group_slice) {
624 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
625 /* scale low_slice according to IO priority
626 * and sync vs async */
627 unsigned low_slice =
628 min(slice, base_low_slice * slice / sync_slice);
629 /* the adapted slice value is scaled to fit all iqs
630 * into the target latency */
631 slice = max(slice * group_slice / expect_latency,
632 low_slice);
635 cfqq->slice_start = jiffies;
636 cfqq->slice_end = jiffies + slice;
637 cfqq->allocated_slice = slice;
638 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
642 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
643 * isn't valid until the first request from the dispatch is activated
644 * and the slice time set.
646 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
648 if (cfq_cfqq_slice_new(cfqq))
649 return 0;
650 if (time_before(jiffies, cfqq->slice_end))
651 return 0;
653 return 1;
657 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
658 * We choose the request that is closest to the head right now. Distance
659 * behind the head is penalized and only allowed to a certain extent.
661 static struct request *
662 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
664 sector_t s1, s2, d1 = 0, d2 = 0;
665 unsigned long back_max;
666 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
667 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
668 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
670 if (rq1 == NULL || rq1 == rq2)
671 return rq2;
672 if (rq2 == NULL)
673 return rq1;
675 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
676 return rq1;
677 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
678 return rq2;
679 if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
680 return rq1;
681 else if ((rq2->cmd_flags & REQ_META) &&
682 !(rq1->cmd_flags & REQ_META))
683 return rq2;
685 s1 = blk_rq_pos(rq1);
686 s2 = blk_rq_pos(rq2);
689 * by definition, 1KiB is 2 sectors
691 back_max = cfqd->cfq_back_max * 2;
694 * Strict one way elevator _except_ in the case where we allow
695 * short backward seeks which are biased as twice the cost of a
696 * similar forward seek.
698 if (s1 >= last)
699 d1 = s1 - last;
700 else if (s1 + back_max >= last)
701 d1 = (last - s1) * cfqd->cfq_back_penalty;
702 else
703 wrap |= CFQ_RQ1_WRAP;
705 if (s2 >= last)
706 d2 = s2 - last;
707 else if (s2 + back_max >= last)
708 d2 = (last - s2) * cfqd->cfq_back_penalty;
709 else
710 wrap |= CFQ_RQ2_WRAP;
712 /* Found required data */
715 * By doing switch() on the bit mask "wrap" we avoid having to
716 * check two variables for all permutations: --> faster!
718 switch (wrap) {
719 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
720 if (d1 < d2)
721 return rq1;
722 else if (d2 < d1)
723 return rq2;
724 else {
725 if (s1 >= s2)
726 return rq1;
727 else
728 return rq2;
731 case CFQ_RQ2_WRAP:
732 return rq1;
733 case CFQ_RQ1_WRAP:
734 return rq2;
735 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
736 default:
738 * Since both rqs are wrapped,
739 * start with the one that's further behind head
740 * (--> only *one* back seek required),
741 * since back seek takes more time than forward.
743 if (s1 <= s2)
744 return rq1;
745 else
746 return rq2;
751 * The below is leftmost cache rbtree addon
753 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
755 /* Service tree is empty */
756 if (!root->count)
757 return NULL;
759 if (!root->left)
760 root->left = rb_first(&root->rb);
762 if (root->left)
763 return rb_entry(root->left, struct cfq_queue, rb_node);
765 return NULL;
768 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
770 if (!root->left)
771 root->left = rb_first(&root->rb);
773 if (root->left)
774 return rb_entry_cfqg(root->left);
776 return NULL;
779 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
781 rb_erase(n, root);
782 RB_CLEAR_NODE(n);
785 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
787 if (root->left == n)
788 root->left = NULL;
789 rb_erase_init(n, &root->rb);
790 --root->count;
794 * would be nice to take fifo expire time into account as well
796 static struct request *
797 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
798 struct request *last)
800 struct rb_node *rbnext = rb_next(&last->rb_node);
801 struct rb_node *rbprev = rb_prev(&last->rb_node);
802 struct request *next = NULL, *prev = NULL;
804 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
806 if (rbprev)
807 prev = rb_entry_rq(rbprev);
809 if (rbnext)
810 next = rb_entry_rq(rbnext);
811 else {
812 rbnext = rb_first(&cfqq->sort_list);
813 if (rbnext && rbnext != &last->rb_node)
814 next = rb_entry_rq(rbnext);
817 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
820 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
821 struct cfq_queue *cfqq)
824 * just an approximation, should be ok.
826 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
827 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
830 static inline s64
831 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
833 return cfqg->vdisktime - st->min_vdisktime;
836 static void
837 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
839 struct rb_node **node = &st->rb.rb_node;
840 struct rb_node *parent = NULL;
841 struct cfq_group *__cfqg;
842 s64 key = cfqg_key(st, cfqg);
843 int left = 1;
845 while (*node != NULL) {
846 parent = *node;
847 __cfqg = rb_entry_cfqg(parent);
849 if (key < cfqg_key(st, __cfqg))
850 node = &parent->rb_left;
851 else {
852 node = &parent->rb_right;
853 left = 0;
857 if (left)
858 st->left = &cfqg->rb_node;
860 rb_link_node(&cfqg->rb_node, parent, node);
861 rb_insert_color(&cfqg->rb_node, &st->rb);
864 static void
865 cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
867 struct cfq_rb_root *st = &cfqd->grp_service_tree;
868 struct cfq_group *__cfqg;
869 struct rb_node *n;
871 cfqg->nr_cfqq++;
872 if (cfqg->on_st)
873 return;
876 * Currently put the group at the end. Later implement something
877 * so that groups get lesser vtime based on their weights, so that
878 * if group does not loose all if it was not continously backlogged.
880 n = rb_last(&st->rb);
881 if (n) {
882 __cfqg = rb_entry_cfqg(n);
883 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
884 } else
885 cfqg->vdisktime = st->min_vdisktime;
887 __cfq_group_service_tree_add(st, cfqg);
888 cfqg->on_st = true;
889 st->total_weight += cfqg->weight;
892 static void
893 cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
895 struct cfq_rb_root *st = &cfqd->grp_service_tree;
897 if (st->active == &cfqg->rb_node)
898 st->active = NULL;
900 BUG_ON(cfqg->nr_cfqq < 1);
901 cfqg->nr_cfqq--;
903 /* If there are other cfq queues under this group, don't delete it */
904 if (cfqg->nr_cfqq)
905 return;
907 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
908 cfqg->on_st = false;
909 st->total_weight -= cfqg->weight;
910 if (!RB_EMPTY_NODE(&cfqg->rb_node))
911 cfq_rb_erase(&cfqg->rb_node, st);
912 cfqg->saved_workload_slice = 0;
913 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
916 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
918 unsigned int slice_used;
921 * Queue got expired before even a single request completed or
922 * got expired immediately after first request completion.
924 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
926 * Also charge the seek time incurred to the group, otherwise
927 * if there are mutiple queues in the group, each can dispatch
928 * a single request on seeky media and cause lots of seek time
929 * and group will never know it.
931 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
933 } else {
934 slice_used = jiffies - cfqq->slice_start;
935 if (slice_used > cfqq->allocated_slice)
936 slice_used = cfqq->allocated_slice;
939 return slice_used;
942 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
943 struct cfq_queue *cfqq)
945 struct cfq_rb_root *st = &cfqd->grp_service_tree;
946 unsigned int used_sl, charge;
947 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
948 - cfqg->service_tree_idle.count;
950 BUG_ON(nr_sync < 0);
951 used_sl = charge = cfq_cfqq_slice_usage(cfqq);
953 if (iops_mode(cfqd))
954 charge = cfqq->slice_dispatch;
955 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
956 charge = cfqq->allocated_slice;
958 /* Can't update vdisktime while group is on service tree */
959 cfq_rb_erase(&cfqg->rb_node, st);
960 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
961 __cfq_group_service_tree_add(st, cfqg);
963 /* This group is being expired. Save the context */
964 if (time_after(cfqd->workload_expires, jiffies)) {
965 cfqg->saved_workload_slice = cfqd->workload_expires
966 - jiffies;
967 cfqg->saved_workload = cfqd->serving_type;
968 cfqg->saved_serving_prio = cfqd->serving_prio;
969 } else
970 cfqg->saved_workload_slice = 0;
972 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
973 st->min_vdisktime);
974 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u"
975 " sect=%u", used_sl, cfqq->slice_dispatch, charge,
976 iops_mode(cfqd), cfqq->nr_sectors);
977 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
978 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
981 #ifdef CONFIG_CFQ_GROUP_IOSCHED
982 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
984 if (blkg)
985 return container_of(blkg, struct cfq_group, blkg);
986 return NULL;
989 void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
990 unsigned int weight)
992 cfqg_of_blkg(blkg)->weight = weight;
995 static struct cfq_group *
996 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
998 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
999 struct cfq_group *cfqg = NULL;
1000 void *key = cfqd;
1001 int i, j;
1002 struct cfq_rb_root *st;
1003 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1004 unsigned int major, minor;
1006 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1007 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
1008 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1009 cfqg->blkg.dev = MKDEV(major, minor);
1010 goto done;
1012 if (cfqg || !create)
1013 goto done;
1015 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1016 if (!cfqg)
1017 goto done;
1019 for_each_cfqg_st(cfqg, i, j, st)
1020 *st = CFQ_RB_ROOT;
1021 RB_CLEAR_NODE(&cfqg->rb_node);
1024 * Take the initial reference that will be released on destroy
1025 * This can be thought of a joint reference by cgroup and
1026 * elevator which will be dropped by either elevator exit
1027 * or cgroup deletion path depending on who is exiting first.
1029 atomic_set(&cfqg->ref, 1);
1032 * Add group onto cgroup list. It might happen that bdi->dev is
1033 * not initiliazed yet. Initialize this new group without major
1034 * and minor info and this info will be filled in once a new thread
1035 * comes for IO. See code above.
1037 if (bdi->dev) {
1038 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
1039 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1040 MKDEV(major, minor));
1041 } else
1042 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
1045 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1047 /* Add group on cfqd list */
1048 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1050 done:
1051 return cfqg;
1055 * Search for the cfq group current task belongs to. If create = 1, then also
1056 * create the cfq group if it does not exist. request_queue lock must be held.
1058 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1060 struct cgroup *cgroup;
1061 struct cfq_group *cfqg = NULL;
1063 rcu_read_lock();
1064 cgroup = task_cgroup(current, blkio_subsys_id);
1065 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1066 if (!cfqg && create)
1067 cfqg = &cfqd->root_group;
1068 rcu_read_unlock();
1069 return cfqg;
1072 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1074 atomic_inc(&cfqg->ref);
1075 return cfqg;
1078 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1080 /* Currently, all async queues are mapped to root group */
1081 if (!cfq_cfqq_sync(cfqq))
1082 cfqg = &cfqq->cfqd->root_group;
1084 cfqq->cfqg = cfqg;
1085 /* cfqq reference on cfqg */
1086 atomic_inc(&cfqq->cfqg->ref);
1089 static void cfq_put_cfqg(struct cfq_group *cfqg)
1091 struct cfq_rb_root *st;
1092 int i, j;
1094 BUG_ON(atomic_read(&cfqg->ref) <= 0);
1095 if (!atomic_dec_and_test(&cfqg->ref))
1096 return;
1097 for_each_cfqg_st(cfqg, i, j, st)
1098 BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
1099 kfree(cfqg);
1102 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1104 /* Something wrong if we are trying to remove same group twice */
1105 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1107 hlist_del_init(&cfqg->cfqd_node);
1110 * Put the reference taken at the time of creation so that when all
1111 * queues are gone, group can be destroyed.
1113 cfq_put_cfqg(cfqg);
1116 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1118 struct hlist_node *pos, *n;
1119 struct cfq_group *cfqg;
1121 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1123 * If cgroup removal path got to blk_group first and removed
1124 * it from cgroup list, then it will take care of destroying
1125 * cfqg also.
1127 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
1128 cfq_destroy_cfqg(cfqd, cfqg);
1133 * Blk cgroup controller notification saying that blkio_group object is being
1134 * delinked as associated cgroup object is going away. That also means that
1135 * no new IO will come in this group. So get rid of this group as soon as
1136 * any pending IO in the group is finished.
1138 * This function is called under rcu_read_lock(). key is the rcu protected
1139 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1140 * read lock.
1142 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1143 * it should not be NULL as even if elevator was exiting, cgroup deltion
1144 * path got to it first.
1146 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1148 unsigned long flags;
1149 struct cfq_data *cfqd = key;
1151 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1152 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1153 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1156 #else /* GROUP_IOSCHED */
1157 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1159 return &cfqd->root_group;
1162 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1164 return cfqg;
1167 static inline void
1168 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1169 cfqq->cfqg = cfqg;
1172 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1173 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1175 #endif /* GROUP_IOSCHED */
1178 * The cfqd->service_trees holds all pending cfq_queue's that have
1179 * requests waiting to be processed. It is sorted in the order that
1180 * we will service the queues.
1182 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1183 bool add_front)
1185 struct rb_node **p, *parent;
1186 struct cfq_queue *__cfqq;
1187 unsigned long rb_key;
1188 struct cfq_rb_root *service_tree;
1189 int left;
1190 int new_cfqq = 1;
1191 int group_changed = 0;
1193 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1194 if (!cfqd->cfq_group_isolation
1195 && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
1196 && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
1197 /* Move this cfq to root group */
1198 cfq_log_cfqq(cfqd, cfqq, "moving to root group");
1199 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1200 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1201 cfqq->orig_cfqg = cfqq->cfqg;
1202 cfqq->cfqg = &cfqd->root_group;
1203 atomic_inc(&cfqd->root_group.ref);
1204 group_changed = 1;
1205 } else if (!cfqd->cfq_group_isolation
1206 && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
1207 /* cfqq is sequential now needs to go to its original group */
1208 BUG_ON(cfqq->cfqg != &cfqd->root_group);
1209 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1210 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1211 cfq_put_cfqg(cfqq->cfqg);
1212 cfqq->cfqg = cfqq->orig_cfqg;
1213 cfqq->orig_cfqg = NULL;
1214 group_changed = 1;
1215 cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
1217 #endif
1219 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1220 cfqq_type(cfqq));
1221 if (cfq_class_idle(cfqq)) {
1222 rb_key = CFQ_IDLE_DELAY;
1223 parent = rb_last(&service_tree->rb);
1224 if (parent && parent != &cfqq->rb_node) {
1225 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1226 rb_key += __cfqq->rb_key;
1227 } else
1228 rb_key += jiffies;
1229 } else if (!add_front) {
1231 * Get our rb key offset. Subtract any residual slice
1232 * value carried from last service. A negative resid
1233 * count indicates slice overrun, and this should position
1234 * the next service time further away in the tree.
1236 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1237 rb_key -= cfqq->slice_resid;
1238 cfqq->slice_resid = 0;
1239 } else {
1240 rb_key = -HZ;
1241 __cfqq = cfq_rb_first(service_tree);
1242 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1245 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1246 new_cfqq = 0;
1248 * same position, nothing more to do
1250 if (rb_key == cfqq->rb_key &&
1251 cfqq->service_tree == service_tree)
1252 return;
1254 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1255 cfqq->service_tree = NULL;
1258 left = 1;
1259 parent = NULL;
1260 cfqq->service_tree = service_tree;
1261 p = &service_tree->rb.rb_node;
1262 while (*p) {
1263 struct rb_node **n;
1265 parent = *p;
1266 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1269 * sort by key, that represents service time.
1271 if (time_before(rb_key, __cfqq->rb_key))
1272 n = &(*p)->rb_left;
1273 else {
1274 n = &(*p)->rb_right;
1275 left = 0;
1278 p = n;
1281 if (left)
1282 service_tree->left = &cfqq->rb_node;
1284 cfqq->rb_key = rb_key;
1285 rb_link_node(&cfqq->rb_node, parent, p);
1286 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1287 service_tree->count++;
1288 if ((add_front || !new_cfqq) && !group_changed)
1289 return;
1290 cfq_group_service_tree_add(cfqd, cfqq->cfqg);
1293 static struct cfq_queue *
1294 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1295 sector_t sector, struct rb_node **ret_parent,
1296 struct rb_node ***rb_link)
1298 struct rb_node **p, *parent;
1299 struct cfq_queue *cfqq = NULL;
1301 parent = NULL;
1302 p = &root->rb_node;
1303 while (*p) {
1304 struct rb_node **n;
1306 parent = *p;
1307 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1310 * Sort strictly based on sector. Smallest to the left,
1311 * largest to the right.
1313 if (sector > blk_rq_pos(cfqq->next_rq))
1314 n = &(*p)->rb_right;
1315 else if (sector < blk_rq_pos(cfqq->next_rq))
1316 n = &(*p)->rb_left;
1317 else
1318 break;
1319 p = n;
1320 cfqq = NULL;
1323 *ret_parent = parent;
1324 if (rb_link)
1325 *rb_link = p;
1326 return cfqq;
1329 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1331 struct rb_node **p, *parent;
1332 struct cfq_queue *__cfqq;
1334 if (cfqq->p_root) {
1335 rb_erase(&cfqq->p_node, cfqq->p_root);
1336 cfqq->p_root = NULL;
1339 if (cfq_class_idle(cfqq))
1340 return;
1341 if (!cfqq->next_rq)
1342 return;
1344 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1345 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1346 blk_rq_pos(cfqq->next_rq), &parent, &p);
1347 if (!__cfqq) {
1348 rb_link_node(&cfqq->p_node, parent, p);
1349 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1350 } else
1351 cfqq->p_root = NULL;
1355 * Update cfqq's position in the service tree.
1357 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1360 * Resorting requires the cfqq to be on the RR list already.
1362 if (cfq_cfqq_on_rr(cfqq)) {
1363 cfq_service_tree_add(cfqd, cfqq, 0);
1364 cfq_prio_tree_add(cfqd, cfqq);
1369 * add to busy list of queues for service, trying to be fair in ordering
1370 * the pending list according to last request service
1372 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1374 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1375 BUG_ON(cfq_cfqq_on_rr(cfqq));
1376 cfq_mark_cfqq_on_rr(cfqq);
1377 cfqd->busy_queues++;
1379 cfq_resort_rr_list(cfqd, cfqq);
1383 * Called when the cfqq no longer has requests pending, remove it from
1384 * the service tree.
1386 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1388 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1389 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1390 cfq_clear_cfqq_on_rr(cfqq);
1392 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1393 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1394 cfqq->service_tree = NULL;
1396 if (cfqq->p_root) {
1397 rb_erase(&cfqq->p_node, cfqq->p_root);
1398 cfqq->p_root = NULL;
1401 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1402 BUG_ON(!cfqd->busy_queues);
1403 cfqd->busy_queues--;
1407 * rb tree support functions
1409 static void cfq_del_rq_rb(struct request *rq)
1411 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1412 const int sync = rq_is_sync(rq);
1414 BUG_ON(!cfqq->queued[sync]);
1415 cfqq->queued[sync]--;
1417 elv_rb_del(&cfqq->sort_list, rq);
1419 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1421 * Queue will be deleted from service tree when we actually
1422 * expire it later. Right now just remove it from prio tree
1423 * as it is empty.
1425 if (cfqq->p_root) {
1426 rb_erase(&cfqq->p_node, cfqq->p_root);
1427 cfqq->p_root = NULL;
1432 static void cfq_add_rq_rb(struct request *rq)
1434 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1435 struct cfq_data *cfqd = cfqq->cfqd;
1436 struct request *__alias, *prev;
1438 cfqq->queued[rq_is_sync(rq)]++;
1441 * looks a little odd, but the first insert might return an alias.
1442 * if that happens, put the alias on the dispatch list
1444 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1445 cfq_dispatch_insert(cfqd->queue, __alias);
1447 if (!cfq_cfqq_on_rr(cfqq))
1448 cfq_add_cfqq_rr(cfqd, cfqq);
1451 * check if this request is a better next-serve candidate
1453 prev = cfqq->next_rq;
1454 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1457 * adjust priority tree position, if ->next_rq changes
1459 if (prev != cfqq->next_rq)
1460 cfq_prio_tree_add(cfqd, cfqq);
1462 BUG_ON(!cfqq->next_rq);
1465 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1467 elv_rb_del(&cfqq->sort_list, rq);
1468 cfqq->queued[rq_is_sync(rq)]--;
1469 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1470 rq_data_dir(rq), rq_is_sync(rq));
1471 cfq_add_rq_rb(rq);
1472 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1473 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1474 rq_is_sync(rq));
1477 static struct request *
1478 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1480 struct task_struct *tsk = current;
1481 struct cfq_io_context *cic;
1482 struct cfq_queue *cfqq;
1484 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1485 if (!cic)
1486 return NULL;
1488 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1489 if (cfqq) {
1490 sector_t sector = bio->bi_sector + bio_sectors(bio);
1492 return elv_rb_find(&cfqq->sort_list, sector);
1495 return NULL;
1498 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1500 struct cfq_data *cfqd = q->elevator->elevator_data;
1502 cfqd->rq_in_driver++;
1503 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1504 cfqd->rq_in_driver);
1506 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1509 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1511 struct cfq_data *cfqd = q->elevator->elevator_data;
1513 WARN_ON(!cfqd->rq_in_driver);
1514 cfqd->rq_in_driver--;
1515 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1516 cfqd->rq_in_driver);
1519 static void cfq_remove_request(struct request *rq)
1521 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1523 if (cfqq->next_rq == rq)
1524 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1526 list_del_init(&rq->queuelist);
1527 cfq_del_rq_rb(rq);
1529 cfqq->cfqd->rq_queued--;
1530 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1531 rq_data_dir(rq), rq_is_sync(rq));
1532 if (rq->cmd_flags & REQ_META) {
1533 WARN_ON(!cfqq->meta_pending);
1534 cfqq->meta_pending--;
1538 static int cfq_merge(struct request_queue *q, struct request **req,
1539 struct bio *bio)
1541 struct cfq_data *cfqd = q->elevator->elevator_data;
1542 struct request *__rq;
1544 __rq = cfq_find_rq_fmerge(cfqd, bio);
1545 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1546 *req = __rq;
1547 return ELEVATOR_FRONT_MERGE;
1550 return ELEVATOR_NO_MERGE;
1553 static void cfq_merged_request(struct request_queue *q, struct request *req,
1554 int type)
1556 if (type == ELEVATOR_FRONT_MERGE) {
1557 struct cfq_queue *cfqq = RQ_CFQQ(req);
1559 cfq_reposition_rq_rb(cfqq, req);
1563 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1564 struct bio *bio)
1566 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1567 bio_data_dir(bio), cfq_bio_sync(bio));
1570 static void
1571 cfq_merged_requests(struct request_queue *q, struct request *rq,
1572 struct request *next)
1574 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1576 * reposition in fifo if next is older than rq
1578 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1579 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1580 list_move(&rq->queuelist, &next->queuelist);
1581 rq_set_fifo_time(rq, rq_fifo_time(next));
1584 if (cfqq->next_rq == next)
1585 cfqq->next_rq = rq;
1586 cfq_remove_request(next);
1587 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1588 rq_data_dir(next), rq_is_sync(next));
1591 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1592 struct bio *bio)
1594 struct cfq_data *cfqd = q->elevator->elevator_data;
1595 struct cfq_io_context *cic;
1596 struct cfq_queue *cfqq;
1599 * Disallow merge of a sync bio into an async request.
1601 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1602 return false;
1605 * Lookup the cfqq that this bio will be queued with. Allow
1606 * merge only if rq is queued there.
1608 cic = cfq_cic_lookup(cfqd, current->io_context);
1609 if (!cic)
1610 return false;
1612 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1613 return cfqq == RQ_CFQQ(rq);
1616 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1618 del_timer(&cfqd->idle_slice_timer);
1619 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1622 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1623 struct cfq_queue *cfqq)
1625 if (cfqq) {
1626 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1627 cfqd->serving_prio, cfqd->serving_type);
1628 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1629 cfqq->slice_start = 0;
1630 cfqq->dispatch_start = jiffies;
1631 cfqq->allocated_slice = 0;
1632 cfqq->slice_end = 0;
1633 cfqq->slice_dispatch = 0;
1634 cfqq->nr_sectors = 0;
1636 cfq_clear_cfqq_wait_request(cfqq);
1637 cfq_clear_cfqq_must_dispatch(cfqq);
1638 cfq_clear_cfqq_must_alloc_slice(cfqq);
1639 cfq_clear_cfqq_fifo_expire(cfqq);
1640 cfq_mark_cfqq_slice_new(cfqq);
1642 cfq_del_timer(cfqd, cfqq);
1645 cfqd->active_queue = cfqq;
1649 * current cfqq expired its slice (or was too idle), select new one
1651 static void
1652 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1653 bool timed_out)
1655 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1657 if (cfq_cfqq_wait_request(cfqq))
1658 cfq_del_timer(cfqd, cfqq);
1660 cfq_clear_cfqq_wait_request(cfqq);
1661 cfq_clear_cfqq_wait_busy(cfqq);
1664 * If this cfqq is shared between multiple processes, check to
1665 * make sure that those processes are still issuing I/Os within
1666 * the mean seek distance. If not, it may be time to break the
1667 * queues apart again.
1669 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1670 cfq_mark_cfqq_split_coop(cfqq);
1673 * store what was left of this slice, if the queue idled/timed out
1675 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
1676 cfqq->slice_resid = cfqq->slice_end - jiffies;
1677 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1680 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1682 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1683 cfq_del_cfqq_rr(cfqd, cfqq);
1685 cfq_resort_rr_list(cfqd, cfqq);
1687 if (cfqq == cfqd->active_queue)
1688 cfqd->active_queue = NULL;
1690 if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
1691 cfqd->grp_service_tree.active = NULL;
1693 if (cfqd->active_cic) {
1694 put_io_context(cfqd->active_cic->ioc);
1695 cfqd->active_cic = NULL;
1699 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1701 struct cfq_queue *cfqq = cfqd->active_queue;
1703 if (cfqq)
1704 __cfq_slice_expired(cfqd, cfqq, timed_out);
1708 * Get next queue for service. Unless we have a queue preemption,
1709 * we'll simply select the first cfqq in the service tree.
1711 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1713 struct cfq_rb_root *service_tree =
1714 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1715 cfqd->serving_type);
1717 if (!cfqd->rq_queued)
1718 return NULL;
1720 /* There is nothing to dispatch */
1721 if (!service_tree)
1722 return NULL;
1723 if (RB_EMPTY_ROOT(&service_tree->rb))
1724 return NULL;
1725 return cfq_rb_first(service_tree);
1728 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1730 struct cfq_group *cfqg;
1731 struct cfq_queue *cfqq;
1732 int i, j;
1733 struct cfq_rb_root *st;
1735 if (!cfqd->rq_queued)
1736 return NULL;
1738 cfqg = cfq_get_next_cfqg(cfqd);
1739 if (!cfqg)
1740 return NULL;
1742 for_each_cfqg_st(cfqg, i, j, st)
1743 if ((cfqq = cfq_rb_first(st)) != NULL)
1744 return cfqq;
1745 return NULL;
1749 * Get and set a new active queue for service.
1751 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1752 struct cfq_queue *cfqq)
1754 if (!cfqq)
1755 cfqq = cfq_get_next_queue(cfqd);
1757 __cfq_set_active_queue(cfqd, cfqq);
1758 return cfqq;
1761 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1762 struct request *rq)
1764 if (blk_rq_pos(rq) >= cfqd->last_position)
1765 return blk_rq_pos(rq) - cfqd->last_position;
1766 else
1767 return cfqd->last_position - blk_rq_pos(rq);
1770 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1771 struct request *rq)
1773 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1776 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1777 struct cfq_queue *cur_cfqq)
1779 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1780 struct rb_node *parent, *node;
1781 struct cfq_queue *__cfqq;
1782 sector_t sector = cfqd->last_position;
1784 if (RB_EMPTY_ROOT(root))
1785 return NULL;
1788 * First, if we find a request starting at the end of the last
1789 * request, choose it.
1791 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1792 if (__cfqq)
1793 return __cfqq;
1796 * If the exact sector wasn't found, the parent of the NULL leaf
1797 * will contain the closest sector.
1799 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1800 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1801 return __cfqq;
1803 if (blk_rq_pos(__cfqq->next_rq) < sector)
1804 node = rb_next(&__cfqq->p_node);
1805 else
1806 node = rb_prev(&__cfqq->p_node);
1807 if (!node)
1808 return NULL;
1810 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1811 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1812 return __cfqq;
1814 return NULL;
1818 * cfqd - obvious
1819 * cur_cfqq - passed in so that we don't decide that the current queue is
1820 * closely cooperating with itself.
1822 * So, basically we're assuming that that cur_cfqq has dispatched at least
1823 * one request, and that cfqd->last_position reflects a position on the disk
1824 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1825 * assumption.
1827 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1828 struct cfq_queue *cur_cfqq)
1830 struct cfq_queue *cfqq;
1832 if (cfq_class_idle(cur_cfqq))
1833 return NULL;
1834 if (!cfq_cfqq_sync(cur_cfqq))
1835 return NULL;
1836 if (CFQQ_SEEKY(cur_cfqq))
1837 return NULL;
1840 * Don't search priority tree if it's the only queue in the group.
1842 if (cur_cfqq->cfqg->nr_cfqq == 1)
1843 return NULL;
1846 * We should notice if some of the queues are cooperating, eg
1847 * working closely on the same area of the disk. In that case,
1848 * we can group them together and don't waste time idling.
1850 cfqq = cfqq_close(cfqd, cur_cfqq);
1851 if (!cfqq)
1852 return NULL;
1854 /* If new queue belongs to different cfq_group, don't choose it */
1855 if (cur_cfqq->cfqg != cfqq->cfqg)
1856 return NULL;
1859 * It only makes sense to merge sync queues.
1861 if (!cfq_cfqq_sync(cfqq))
1862 return NULL;
1863 if (CFQQ_SEEKY(cfqq))
1864 return NULL;
1867 * Do not merge queues of different priority classes
1869 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1870 return NULL;
1872 return cfqq;
1876 * Determine whether we should enforce idle window for this queue.
1879 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1881 enum wl_prio_t prio = cfqq_prio(cfqq);
1882 struct cfq_rb_root *service_tree = cfqq->service_tree;
1884 BUG_ON(!service_tree);
1885 BUG_ON(!service_tree->count);
1887 if (!cfqd->cfq_slice_idle)
1888 return false;
1890 /* We never do for idle class queues. */
1891 if (prio == IDLE_WORKLOAD)
1892 return false;
1894 /* We do for queues that were marked with idle window flag. */
1895 if (cfq_cfqq_idle_window(cfqq) &&
1896 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1897 return true;
1900 * Otherwise, we do only if they are the last ones
1901 * in their service tree.
1903 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1904 return 1;
1905 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1906 service_tree->count);
1907 return 0;
1910 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1912 struct cfq_queue *cfqq = cfqd->active_queue;
1913 struct cfq_io_context *cic;
1914 unsigned long sl, group_idle = 0;
1917 * SSD device without seek penalty, disable idling. But only do so
1918 * for devices that support queuing, otherwise we still have a problem
1919 * with sync vs async workloads.
1921 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1922 return;
1924 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1925 WARN_ON(cfq_cfqq_slice_new(cfqq));
1928 * idle is disabled, either manually or by past process history
1930 if (!cfq_should_idle(cfqd, cfqq)) {
1931 /* no queue idling. Check for group idling */
1932 if (cfqd->cfq_group_idle)
1933 group_idle = cfqd->cfq_group_idle;
1934 else
1935 return;
1939 * still active requests from this queue, don't idle
1941 if (cfqq->dispatched)
1942 return;
1945 * task has exited, don't wait
1947 cic = cfqd->active_cic;
1948 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1949 return;
1952 * If our average think time is larger than the remaining time
1953 * slice, then don't idle. This avoids overrunning the allotted
1954 * time slice.
1956 if (sample_valid(cic->ttime_samples) &&
1957 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1958 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1959 cic->ttime_mean);
1960 return;
1963 /* There are other queues in the group, don't do group idle */
1964 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
1965 return;
1967 cfq_mark_cfqq_wait_request(cfqq);
1969 if (group_idle)
1970 sl = cfqd->cfq_group_idle;
1971 else
1972 sl = cfqd->cfq_slice_idle;
1974 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1975 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1976 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
1977 group_idle ? 1 : 0);
1981 * Move request from internal lists to the request queue dispatch list.
1983 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1985 struct cfq_data *cfqd = q->elevator->elevator_data;
1986 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1988 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1990 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1991 cfq_remove_request(rq);
1992 cfqq->dispatched++;
1993 (RQ_CFQG(rq))->dispatched++;
1994 elv_dispatch_sort(q, rq);
1996 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1997 cfqq->nr_sectors += blk_rq_sectors(rq);
1998 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
1999 rq_data_dir(rq), rq_is_sync(rq));
2003 * return expired entry, or NULL to just start from scratch in rbtree
2005 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2007 struct request *rq = NULL;
2009 if (cfq_cfqq_fifo_expire(cfqq))
2010 return NULL;
2012 cfq_mark_cfqq_fifo_expire(cfqq);
2014 if (list_empty(&cfqq->fifo))
2015 return NULL;
2017 rq = rq_entry_fifo(cfqq->fifo.next);
2018 if (time_before(jiffies, rq_fifo_time(rq)))
2019 rq = NULL;
2021 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2022 return rq;
2025 static inline int
2026 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2028 const int base_rq = cfqd->cfq_slice_async_rq;
2030 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2032 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
2036 * Must be called with the queue_lock held.
2038 static int cfqq_process_refs(struct cfq_queue *cfqq)
2040 int process_refs, io_refs;
2042 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2043 process_refs = atomic_read(&cfqq->ref) - io_refs;
2044 BUG_ON(process_refs < 0);
2045 return process_refs;
2048 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2050 int process_refs, new_process_refs;
2051 struct cfq_queue *__cfqq;
2054 * If there are no process references on the new_cfqq, then it is
2055 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2056 * chain may have dropped their last reference (not just their
2057 * last process reference).
2059 if (!cfqq_process_refs(new_cfqq))
2060 return;
2062 /* Avoid a circular list and skip interim queue merges */
2063 while ((__cfqq = new_cfqq->new_cfqq)) {
2064 if (__cfqq == cfqq)
2065 return;
2066 new_cfqq = __cfqq;
2069 process_refs = cfqq_process_refs(cfqq);
2070 new_process_refs = cfqq_process_refs(new_cfqq);
2072 * If the process for the cfqq has gone away, there is no
2073 * sense in merging the queues.
2075 if (process_refs == 0 || new_process_refs == 0)
2076 return;
2079 * Merge in the direction of the lesser amount of work.
2081 if (new_process_refs >= process_refs) {
2082 cfqq->new_cfqq = new_cfqq;
2083 atomic_add(process_refs, &new_cfqq->ref);
2084 } else {
2085 new_cfqq->new_cfqq = cfqq;
2086 atomic_add(new_process_refs, &cfqq->ref);
2090 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2091 struct cfq_group *cfqg, enum wl_prio_t prio)
2093 struct cfq_queue *queue;
2094 int i;
2095 bool key_valid = false;
2096 unsigned long lowest_key = 0;
2097 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2099 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2100 /* select the one with lowest rb_key */
2101 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2102 if (queue &&
2103 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2104 lowest_key = queue->rb_key;
2105 cur_best = i;
2106 key_valid = true;
2110 return cur_best;
2113 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2115 unsigned slice;
2116 unsigned count;
2117 struct cfq_rb_root *st;
2118 unsigned group_slice;
2120 if (!cfqg) {
2121 cfqd->serving_prio = IDLE_WORKLOAD;
2122 cfqd->workload_expires = jiffies + 1;
2123 return;
2126 /* Choose next priority. RT > BE > IDLE */
2127 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2128 cfqd->serving_prio = RT_WORKLOAD;
2129 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2130 cfqd->serving_prio = BE_WORKLOAD;
2131 else {
2132 cfqd->serving_prio = IDLE_WORKLOAD;
2133 cfqd->workload_expires = jiffies + 1;
2134 return;
2138 * For RT and BE, we have to choose also the type
2139 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2140 * expiration time
2142 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2143 count = st->count;
2146 * check workload expiration, and that we still have other queues ready
2148 if (count && !time_after(jiffies, cfqd->workload_expires))
2149 return;
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 st->active = &cfqg->rb_node;
2203 update_min_vdisktime(st);
2204 return cfqg;
2207 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2209 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2211 cfqd->serving_group = cfqg;
2213 /* Restore the workload type data */
2214 if (cfqg->saved_workload_slice) {
2215 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2216 cfqd->serving_type = cfqg->saved_workload;
2217 cfqd->serving_prio = cfqg->saved_serving_prio;
2218 } else
2219 cfqd->workload_expires = jiffies - 1;
2221 choose_service_tree(cfqd, cfqg);
2225 * Select a queue for service. If we have a current active queue,
2226 * check whether to continue servicing it, or retrieve and set a new one.
2228 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2230 struct cfq_queue *cfqq, *new_cfqq = NULL;
2232 cfqq = cfqd->active_queue;
2233 if (!cfqq)
2234 goto new_queue;
2236 if (!cfqd->rq_queued)
2237 return NULL;
2240 * We were waiting for group to get backlogged. Expire the queue
2242 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2243 goto expire;
2246 * The active queue has run out of time, expire it and select new.
2248 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2250 * If slice had not expired at the completion of last request
2251 * we might not have turned on wait_busy flag. Don't expire
2252 * the queue yet. Allow the group to get backlogged.
2254 * The very fact that we have used the slice, that means we
2255 * have been idling all along on this queue and it should be
2256 * ok to wait for this request to complete.
2258 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2259 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2260 cfqq = NULL;
2261 goto keep_queue;
2262 } else
2263 goto check_group_idle;
2267 * The active queue has requests and isn't expired, allow it to
2268 * dispatch.
2270 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2271 goto keep_queue;
2274 * If another queue has a request waiting within our mean seek
2275 * distance, let it run. The expire code will check for close
2276 * cooperators and put the close queue at the front of the service
2277 * tree. If possible, merge the expiring queue with the new cfqq.
2279 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2280 if (new_cfqq) {
2281 if (!cfqq->new_cfqq)
2282 cfq_setup_merge(cfqq, new_cfqq);
2283 goto expire;
2287 * No requests pending. If the active queue still has requests in
2288 * flight or is idling for a new request, allow either of these
2289 * conditions to happen (or time out) before selecting a new queue.
2291 if (timer_pending(&cfqd->idle_slice_timer)) {
2292 cfqq = NULL;
2293 goto keep_queue;
2296 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2297 cfqq = NULL;
2298 goto keep_queue;
2302 * If group idle is enabled and there are requests dispatched from
2303 * this group, wait for requests to complete.
2305 check_group_idle:
2306 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
2307 && cfqq->cfqg->dispatched) {
2308 cfqq = NULL;
2309 goto keep_queue;
2312 expire:
2313 cfq_slice_expired(cfqd, 0);
2314 new_queue:
2316 * Current queue expired. Check if we have to switch to a new
2317 * service tree
2319 if (!new_cfqq)
2320 cfq_choose_cfqg(cfqd);
2322 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2323 keep_queue:
2324 return cfqq;
2327 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2329 int dispatched = 0;
2331 while (cfqq->next_rq) {
2332 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2333 dispatched++;
2336 BUG_ON(!list_empty(&cfqq->fifo));
2338 /* By default cfqq is not expired if it is empty. Do it explicitly */
2339 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2340 return dispatched;
2344 * Drain our current requests. Used for barriers and when switching
2345 * io schedulers on-the-fly.
2347 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2349 struct cfq_queue *cfqq;
2350 int dispatched = 0;
2352 /* Expire the timeslice of the current active queue first */
2353 cfq_slice_expired(cfqd, 0);
2354 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2355 __cfq_set_active_queue(cfqd, cfqq);
2356 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2359 BUG_ON(cfqd->busy_queues);
2361 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2362 return dispatched;
2365 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2366 struct cfq_queue *cfqq)
2368 /* the queue hasn't finished any request, can't estimate */
2369 if (cfq_cfqq_slice_new(cfqq))
2370 return 1;
2371 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2372 cfqq->slice_end))
2373 return 1;
2375 return 0;
2378 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2380 unsigned int max_dispatch;
2383 * Drain async requests before we start sync IO
2385 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2386 return false;
2389 * If this is an async queue and we have sync IO in flight, let it wait
2391 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2392 return false;
2394 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2395 if (cfq_class_idle(cfqq))
2396 max_dispatch = 1;
2399 * Does this cfqq already have too much IO in flight?
2401 if (cfqq->dispatched >= max_dispatch) {
2403 * idle queue must always only have a single IO in flight
2405 if (cfq_class_idle(cfqq))
2406 return false;
2409 * We have other queues, don't allow more IO from this one
2411 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
2412 return false;
2415 * Sole queue user, no limit
2417 if (cfqd->busy_queues == 1)
2418 max_dispatch = -1;
2419 else
2421 * Normally we start throttling cfqq when cfq_quantum/2
2422 * requests have been dispatched. But we can drive
2423 * deeper queue depths at the beginning of slice
2424 * subjected to upper limit of cfq_quantum.
2425 * */
2426 max_dispatch = cfqd->cfq_quantum;
2430 * Async queues must wait a bit before being allowed dispatch.
2431 * We also ramp up the dispatch depth gradually for async IO,
2432 * based on the last sync IO we serviced
2434 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2435 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2436 unsigned int depth;
2438 depth = last_sync / cfqd->cfq_slice[1];
2439 if (!depth && !cfqq->dispatched)
2440 depth = 1;
2441 if (depth < max_dispatch)
2442 max_dispatch = depth;
2446 * If we're below the current max, allow a dispatch
2448 return cfqq->dispatched < max_dispatch;
2452 * Dispatch a request from cfqq, moving them to the request queue
2453 * dispatch list.
2455 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2457 struct request *rq;
2459 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2461 if (!cfq_may_dispatch(cfqd, cfqq))
2462 return false;
2465 * follow expired path, else get first next available
2467 rq = cfq_check_fifo(cfqq);
2468 if (!rq)
2469 rq = cfqq->next_rq;
2472 * insert request into driver dispatch list
2474 cfq_dispatch_insert(cfqd->queue, rq);
2476 if (!cfqd->active_cic) {
2477 struct cfq_io_context *cic = RQ_CIC(rq);
2479 atomic_long_inc(&cic->ioc->refcount);
2480 cfqd->active_cic = cic;
2483 return true;
2487 * Find the cfqq that we need to service and move a request from that to the
2488 * dispatch list
2490 static int cfq_dispatch_requests(struct request_queue *q, int force)
2492 struct cfq_data *cfqd = q->elevator->elevator_data;
2493 struct cfq_queue *cfqq;
2495 if (!cfqd->busy_queues)
2496 return 0;
2498 if (unlikely(force))
2499 return cfq_forced_dispatch(cfqd);
2501 cfqq = cfq_select_queue(cfqd);
2502 if (!cfqq)
2503 return 0;
2506 * Dispatch a request from this cfqq, if it is allowed
2508 if (!cfq_dispatch_request(cfqd, cfqq))
2509 return 0;
2511 cfqq->slice_dispatch++;
2512 cfq_clear_cfqq_must_dispatch(cfqq);
2515 * expire an async queue immediately if it has used up its slice. idle
2516 * queue always expire after 1 dispatch round.
2518 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2519 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2520 cfq_class_idle(cfqq))) {
2521 cfqq->slice_end = jiffies + 1;
2522 cfq_slice_expired(cfqd, 0);
2525 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2526 return 1;
2530 * task holds one reference to the queue, dropped when task exits. each rq
2531 * in-flight on this queue also holds a reference, dropped when rq is freed.
2533 * Each cfq queue took a reference on the parent group. Drop it now.
2534 * queue lock must be held here.
2536 static void cfq_put_queue(struct cfq_queue *cfqq)
2538 struct cfq_data *cfqd = cfqq->cfqd;
2539 struct cfq_group *cfqg, *orig_cfqg;
2541 BUG_ON(atomic_read(&cfqq->ref) <= 0);
2543 if (!atomic_dec_and_test(&cfqq->ref))
2544 return;
2546 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2547 BUG_ON(rb_first(&cfqq->sort_list));
2548 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2549 cfqg = cfqq->cfqg;
2550 orig_cfqg = cfqq->orig_cfqg;
2552 if (unlikely(cfqd->active_queue == cfqq)) {
2553 __cfq_slice_expired(cfqd, cfqq, 0);
2554 cfq_schedule_dispatch(cfqd);
2557 BUG_ON(cfq_cfqq_on_rr(cfqq));
2558 kmem_cache_free(cfq_pool, cfqq);
2559 cfq_put_cfqg(cfqg);
2560 if (orig_cfqg)
2561 cfq_put_cfqg(orig_cfqg);
2565 * Must always be called with the rcu_read_lock() held
2567 static void
2568 __call_for_each_cic(struct io_context *ioc,
2569 void (*func)(struct io_context *, struct cfq_io_context *))
2571 struct cfq_io_context *cic;
2572 struct hlist_node *n;
2574 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2575 func(ioc, cic);
2579 * Call func for each cic attached to this ioc.
2581 static void
2582 call_for_each_cic(struct io_context *ioc,
2583 void (*func)(struct io_context *, struct cfq_io_context *))
2585 rcu_read_lock();
2586 __call_for_each_cic(ioc, func);
2587 rcu_read_unlock();
2590 static void cfq_cic_free_rcu(struct rcu_head *head)
2592 struct cfq_io_context *cic;
2594 cic = container_of(head, struct cfq_io_context, rcu_head);
2596 kmem_cache_free(cfq_ioc_pool, cic);
2597 elv_ioc_count_dec(cfq_ioc_count);
2599 if (ioc_gone) {
2601 * CFQ scheduler is exiting, grab exit lock and check
2602 * the pending io context count. If it hits zero,
2603 * complete ioc_gone and set it back to NULL
2605 spin_lock(&ioc_gone_lock);
2606 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2607 complete(ioc_gone);
2608 ioc_gone = NULL;
2610 spin_unlock(&ioc_gone_lock);
2614 static void cfq_cic_free(struct cfq_io_context *cic)
2616 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2619 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2621 unsigned long flags;
2622 unsigned long dead_key = (unsigned long) cic->key;
2624 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2626 spin_lock_irqsave(&ioc->lock, flags);
2627 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
2628 hlist_del_rcu(&cic->cic_list);
2629 spin_unlock_irqrestore(&ioc->lock, flags);
2631 cfq_cic_free(cic);
2635 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2636 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2637 * and ->trim() which is called with the task lock held
2639 static void cfq_free_io_context(struct io_context *ioc)
2642 * ioc->refcount is zero here, or we are called from elv_unregister(),
2643 * so no more cic's are allowed to be linked into this ioc. So it
2644 * should be ok to iterate over the known list, we will see all cic's
2645 * since no new ones are added.
2647 __call_for_each_cic(ioc, cic_free_func);
2650 static void cfq_put_cooperator(struct cfq_queue *cfqq)
2652 struct cfq_queue *__cfqq, *next;
2655 * If this queue was scheduled to merge with another queue, be
2656 * sure to drop the reference taken on that queue (and others in
2657 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2659 __cfqq = cfqq->new_cfqq;
2660 while (__cfqq) {
2661 if (__cfqq == cfqq) {
2662 WARN(1, "cfqq->new_cfqq loop detected\n");
2663 break;
2665 next = __cfqq->new_cfqq;
2666 cfq_put_queue(__cfqq);
2667 __cfqq = next;
2671 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2673 if (unlikely(cfqq == cfqd->active_queue)) {
2674 __cfq_slice_expired(cfqd, cfqq, 0);
2675 cfq_schedule_dispatch(cfqd);
2678 cfq_put_cooperator(cfqq);
2680 cfq_put_queue(cfqq);
2683 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2684 struct cfq_io_context *cic)
2686 struct io_context *ioc = cic->ioc;
2688 list_del_init(&cic->queue_list);
2691 * Make sure dead mark is seen for dead queues
2693 smp_wmb();
2694 cic->key = cfqd_dead_key(cfqd);
2696 if (ioc->ioc_data == cic)
2697 rcu_assign_pointer(ioc->ioc_data, NULL);
2699 if (cic->cfqq[BLK_RW_ASYNC]) {
2700 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2701 cic->cfqq[BLK_RW_ASYNC] = NULL;
2704 if (cic->cfqq[BLK_RW_SYNC]) {
2705 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2706 cic->cfqq[BLK_RW_SYNC] = NULL;
2710 static void cfq_exit_single_io_context(struct io_context *ioc,
2711 struct cfq_io_context *cic)
2713 struct cfq_data *cfqd = cic_to_cfqd(cic);
2715 if (cfqd) {
2716 struct request_queue *q = cfqd->queue;
2717 unsigned long flags;
2719 spin_lock_irqsave(q->queue_lock, flags);
2722 * Ensure we get a fresh copy of the ->key to prevent
2723 * race between exiting task and queue
2725 smp_read_barrier_depends();
2726 if (cic->key == cfqd)
2727 __cfq_exit_single_io_context(cfqd, cic);
2729 spin_unlock_irqrestore(q->queue_lock, flags);
2734 * The process that ioc belongs to has exited, we need to clean up
2735 * and put the internal structures we have that belongs to that process.
2737 static void cfq_exit_io_context(struct io_context *ioc)
2739 call_for_each_cic(ioc, cfq_exit_single_io_context);
2742 static struct cfq_io_context *
2743 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2745 struct cfq_io_context *cic;
2747 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2748 cfqd->queue->node);
2749 if (cic) {
2750 cic->last_end_request = jiffies;
2751 INIT_LIST_HEAD(&cic->queue_list);
2752 INIT_HLIST_NODE(&cic->cic_list);
2753 cic->dtor = cfq_free_io_context;
2754 cic->exit = cfq_exit_io_context;
2755 elv_ioc_count_inc(cfq_ioc_count);
2758 return cic;
2761 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2763 struct task_struct *tsk = current;
2764 int ioprio_class;
2766 if (!cfq_cfqq_prio_changed(cfqq))
2767 return;
2769 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2770 switch (ioprio_class) {
2771 default:
2772 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2773 case IOPRIO_CLASS_NONE:
2775 * no prio set, inherit CPU scheduling settings
2777 cfqq->ioprio = task_nice_ioprio(tsk);
2778 cfqq->ioprio_class = task_nice_ioclass(tsk);
2779 break;
2780 case IOPRIO_CLASS_RT:
2781 cfqq->ioprio = task_ioprio(ioc);
2782 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2783 break;
2784 case IOPRIO_CLASS_BE:
2785 cfqq->ioprio = task_ioprio(ioc);
2786 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2787 break;
2788 case IOPRIO_CLASS_IDLE:
2789 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2790 cfqq->ioprio = 7;
2791 cfq_clear_cfqq_idle_window(cfqq);
2792 break;
2796 * keep track of original prio settings in case we have to temporarily
2797 * elevate the priority of this queue
2799 cfqq->org_ioprio = cfqq->ioprio;
2800 cfqq->org_ioprio_class = cfqq->ioprio_class;
2801 cfq_clear_cfqq_prio_changed(cfqq);
2804 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2806 struct cfq_data *cfqd = cic_to_cfqd(cic);
2807 struct cfq_queue *cfqq;
2808 unsigned long flags;
2810 if (unlikely(!cfqd))
2811 return;
2813 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2815 cfqq = cic->cfqq[BLK_RW_ASYNC];
2816 if (cfqq) {
2817 struct cfq_queue *new_cfqq;
2818 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2819 GFP_ATOMIC);
2820 if (new_cfqq) {
2821 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2822 cfq_put_queue(cfqq);
2826 cfqq = cic->cfqq[BLK_RW_SYNC];
2827 if (cfqq)
2828 cfq_mark_cfqq_prio_changed(cfqq);
2830 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2833 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2835 call_for_each_cic(ioc, changed_ioprio);
2836 ioc->ioprio_changed = 0;
2839 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2840 pid_t pid, bool is_sync)
2842 RB_CLEAR_NODE(&cfqq->rb_node);
2843 RB_CLEAR_NODE(&cfqq->p_node);
2844 INIT_LIST_HEAD(&cfqq->fifo);
2846 atomic_set(&cfqq->ref, 0);
2847 cfqq->cfqd = cfqd;
2849 cfq_mark_cfqq_prio_changed(cfqq);
2851 if (is_sync) {
2852 if (!cfq_class_idle(cfqq))
2853 cfq_mark_cfqq_idle_window(cfqq);
2854 cfq_mark_cfqq_sync(cfqq);
2856 cfqq->pid = pid;
2859 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2860 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2862 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2863 struct cfq_data *cfqd = cic_to_cfqd(cic);
2864 unsigned long flags;
2865 struct request_queue *q;
2867 if (unlikely(!cfqd))
2868 return;
2870 q = cfqd->queue;
2872 spin_lock_irqsave(q->queue_lock, flags);
2874 if (sync_cfqq) {
2876 * Drop reference to sync queue. A new sync queue will be
2877 * assigned in new group upon arrival of a fresh request.
2879 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2880 cic_set_cfqq(cic, NULL, 1);
2881 cfq_put_queue(sync_cfqq);
2884 spin_unlock_irqrestore(q->queue_lock, flags);
2887 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2889 call_for_each_cic(ioc, changed_cgroup);
2890 ioc->cgroup_changed = 0;
2892 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2894 static struct cfq_queue *
2895 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2896 struct io_context *ioc, gfp_t gfp_mask)
2898 struct cfq_queue *cfqq, *new_cfqq = NULL;
2899 struct cfq_io_context *cic;
2900 struct cfq_group *cfqg;
2902 retry:
2903 cfqg = cfq_get_cfqg(cfqd, 1);
2904 cic = cfq_cic_lookup(cfqd, ioc);
2905 /* cic always exists here */
2906 cfqq = cic_to_cfqq(cic, is_sync);
2909 * Always try a new alloc if we fell back to the OOM cfqq
2910 * originally, since it should just be a temporary situation.
2912 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2913 cfqq = NULL;
2914 if (new_cfqq) {
2915 cfqq = new_cfqq;
2916 new_cfqq = NULL;
2917 } else if (gfp_mask & __GFP_WAIT) {
2918 spin_unlock_irq(cfqd->queue->queue_lock);
2919 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2920 gfp_mask | __GFP_ZERO,
2921 cfqd->queue->node);
2922 spin_lock_irq(cfqd->queue->queue_lock);
2923 if (new_cfqq)
2924 goto retry;
2925 } else {
2926 cfqq = kmem_cache_alloc_node(cfq_pool,
2927 gfp_mask | __GFP_ZERO,
2928 cfqd->queue->node);
2931 if (cfqq) {
2932 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2933 cfq_init_prio_data(cfqq, ioc);
2934 cfq_link_cfqq_cfqg(cfqq, cfqg);
2935 cfq_log_cfqq(cfqd, cfqq, "alloced");
2936 } else
2937 cfqq = &cfqd->oom_cfqq;
2940 if (new_cfqq)
2941 kmem_cache_free(cfq_pool, new_cfqq);
2943 return cfqq;
2946 static struct cfq_queue **
2947 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2949 switch (ioprio_class) {
2950 case IOPRIO_CLASS_RT:
2951 return &cfqd->async_cfqq[0][ioprio];
2952 case IOPRIO_CLASS_BE:
2953 return &cfqd->async_cfqq[1][ioprio];
2954 case IOPRIO_CLASS_IDLE:
2955 return &cfqd->async_idle_cfqq;
2956 default:
2957 BUG();
2961 static struct cfq_queue *
2962 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2963 gfp_t gfp_mask)
2965 const int ioprio = task_ioprio(ioc);
2966 const int ioprio_class = task_ioprio_class(ioc);
2967 struct cfq_queue **async_cfqq = NULL;
2968 struct cfq_queue *cfqq = NULL;
2970 if (!is_sync) {
2971 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2972 cfqq = *async_cfqq;
2975 if (!cfqq)
2976 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2979 * pin the queue now that it's allocated, scheduler exit will prune it
2981 if (!is_sync && !(*async_cfqq)) {
2982 atomic_inc(&cfqq->ref);
2983 *async_cfqq = cfqq;
2986 atomic_inc(&cfqq->ref);
2987 return cfqq;
2991 * We drop cfq io contexts lazily, so we may find a dead one.
2993 static void
2994 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
2995 struct cfq_io_context *cic)
2997 unsigned long flags;
2999 WARN_ON(!list_empty(&cic->queue_list));
3000 BUG_ON(cic->key != cfqd_dead_key(cfqd));
3002 spin_lock_irqsave(&ioc->lock, flags);
3004 BUG_ON(ioc->ioc_data == cic);
3006 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
3007 hlist_del_rcu(&cic->cic_list);
3008 spin_unlock_irqrestore(&ioc->lock, flags);
3010 cfq_cic_free(cic);
3013 static struct cfq_io_context *
3014 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
3016 struct cfq_io_context *cic;
3017 unsigned long flags;
3019 if (unlikely(!ioc))
3020 return NULL;
3022 rcu_read_lock();
3025 * we maintain a last-hit cache, to avoid browsing over the tree
3027 cic = rcu_dereference(ioc->ioc_data);
3028 if (cic && cic->key == cfqd) {
3029 rcu_read_unlock();
3030 return cic;
3033 do {
3034 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
3035 rcu_read_unlock();
3036 if (!cic)
3037 break;
3038 if (unlikely(cic->key != cfqd)) {
3039 cfq_drop_dead_cic(cfqd, ioc, cic);
3040 rcu_read_lock();
3041 continue;
3044 spin_lock_irqsave(&ioc->lock, flags);
3045 rcu_assign_pointer(ioc->ioc_data, cic);
3046 spin_unlock_irqrestore(&ioc->lock, flags);
3047 break;
3048 } while (1);
3050 return cic;
3054 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3055 * the process specific cfq io context when entered from the block layer.
3056 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3058 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
3059 struct cfq_io_context *cic, gfp_t gfp_mask)
3061 unsigned long flags;
3062 int ret;
3064 ret = radix_tree_preload(gfp_mask);
3065 if (!ret) {
3066 cic->ioc = ioc;
3067 cic->key = cfqd;
3069 spin_lock_irqsave(&ioc->lock, flags);
3070 ret = radix_tree_insert(&ioc->radix_root,
3071 cfqd->cic_index, cic);
3072 if (!ret)
3073 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
3074 spin_unlock_irqrestore(&ioc->lock, flags);
3076 radix_tree_preload_end();
3078 if (!ret) {
3079 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3080 list_add(&cic->queue_list, &cfqd->cic_list);
3081 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3085 if (ret)
3086 printk(KERN_ERR "cfq: cic link failed!\n");
3088 return ret;
3092 * Setup general io context and cfq io context. There can be several cfq
3093 * io contexts per general io context, if this process is doing io to more
3094 * than one device managed by cfq.
3096 static struct cfq_io_context *
3097 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3099 struct io_context *ioc = NULL;
3100 struct cfq_io_context *cic;
3102 might_sleep_if(gfp_mask & __GFP_WAIT);
3104 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3105 if (!ioc)
3106 return NULL;
3108 cic = cfq_cic_lookup(cfqd, ioc);
3109 if (cic)
3110 goto out;
3112 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3113 if (cic == NULL)
3114 goto err;
3116 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3117 goto err_free;
3119 out:
3120 smp_read_barrier_depends();
3121 if (unlikely(ioc->ioprio_changed))
3122 cfq_ioc_set_ioprio(ioc);
3124 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3125 if (unlikely(ioc->cgroup_changed))
3126 cfq_ioc_set_cgroup(ioc);
3127 #endif
3128 return cic;
3129 err_free:
3130 cfq_cic_free(cic);
3131 err:
3132 put_io_context(ioc);
3133 return NULL;
3136 static void
3137 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3139 unsigned long elapsed = jiffies - cic->last_end_request;
3140 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3142 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3143 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3144 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3147 static void
3148 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3149 struct request *rq)
3151 sector_t sdist = 0;
3152 sector_t n_sec = blk_rq_sectors(rq);
3153 if (cfqq->last_request_pos) {
3154 if (cfqq->last_request_pos < blk_rq_pos(rq))
3155 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3156 else
3157 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3160 cfqq->seek_history <<= 1;
3161 if (blk_queue_nonrot(cfqd->queue))
3162 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3163 else
3164 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3168 * Disable idle window if the process thinks too long or seeks so much that
3169 * it doesn't matter
3171 static void
3172 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3173 struct cfq_io_context *cic)
3175 int old_idle, enable_idle;
3178 * Don't idle for async or idle io prio class
3180 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3181 return;
3183 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3185 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3186 cfq_mark_cfqq_deep(cfqq);
3188 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3189 enable_idle = 0;
3190 else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3191 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3192 enable_idle = 0;
3193 else if (sample_valid(cic->ttime_samples)) {
3194 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3195 enable_idle = 0;
3196 else
3197 enable_idle = 1;
3200 if (old_idle != enable_idle) {
3201 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3202 if (enable_idle)
3203 cfq_mark_cfqq_idle_window(cfqq);
3204 else
3205 cfq_clear_cfqq_idle_window(cfqq);
3210 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3211 * no or if we aren't sure, a 1 will cause a preempt.
3213 static bool
3214 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3215 struct request *rq)
3217 struct cfq_queue *cfqq;
3219 cfqq = cfqd->active_queue;
3220 if (!cfqq)
3221 return false;
3223 if (cfq_class_idle(new_cfqq))
3224 return false;
3226 if (cfq_class_idle(cfqq))
3227 return true;
3230 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3232 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3233 return false;
3236 * if the new request is sync, but the currently running queue is
3237 * not, let the sync request have priority.
3239 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3240 return true;
3242 if (new_cfqq->cfqg != cfqq->cfqg)
3243 return false;
3245 if (cfq_slice_used(cfqq))
3246 return true;
3248 /* Allow preemption only if we are idling on sync-noidle tree */
3249 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3250 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3251 new_cfqq->service_tree->count == 2 &&
3252 RB_EMPTY_ROOT(&cfqq->sort_list))
3253 return true;
3256 * So both queues are sync. Let the new request get disk time if
3257 * it's a metadata request and the current queue is doing regular IO.
3259 if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
3260 return true;
3263 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3265 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3266 return true;
3268 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3269 return false;
3272 * if this request is as-good as one we would expect from the
3273 * current cfqq, let it preempt
3275 if (cfq_rq_close(cfqd, cfqq, rq))
3276 return true;
3278 return false;
3282 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3283 * let it have half of its nominal slice.
3285 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3287 cfq_log_cfqq(cfqd, cfqq, "preempt");
3288 cfq_slice_expired(cfqd, 1);
3291 * Put the new queue at the front of the of the current list,
3292 * so we know that it will be selected next.
3294 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3296 cfq_service_tree_add(cfqd, cfqq, 1);
3298 cfqq->slice_end = 0;
3299 cfq_mark_cfqq_slice_new(cfqq);
3303 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3304 * something we should do about it
3306 static void
3307 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3308 struct request *rq)
3310 struct cfq_io_context *cic = RQ_CIC(rq);
3312 cfqd->rq_queued++;
3313 if (rq->cmd_flags & REQ_META)
3314 cfqq->meta_pending++;
3316 cfq_update_io_thinktime(cfqd, cic);
3317 cfq_update_io_seektime(cfqd, cfqq, rq);
3318 cfq_update_idle_window(cfqd, cfqq, cic);
3320 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3322 if (cfqq == cfqd->active_queue) {
3324 * Remember that we saw a request from this process, but
3325 * don't start queuing just yet. Otherwise we risk seeing lots
3326 * of tiny requests, because we disrupt the normal plugging
3327 * and merging. If the request is already larger than a single
3328 * page, let it rip immediately. For that case we assume that
3329 * merging is already done. Ditto for a busy system that
3330 * has other work pending, don't risk delaying until the
3331 * idle timer unplug to continue working.
3333 if (cfq_cfqq_wait_request(cfqq)) {
3334 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3335 cfqd->busy_queues > 1) {
3336 cfq_del_timer(cfqd, cfqq);
3337 cfq_clear_cfqq_wait_request(cfqq);
3338 __blk_run_queue(cfqd->queue);
3339 } else {
3340 cfq_blkiocg_update_idle_time_stats(
3341 &cfqq->cfqg->blkg);
3342 cfq_mark_cfqq_must_dispatch(cfqq);
3345 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3347 * not the active queue - expire current slice if it is
3348 * idle and has expired it's mean thinktime or this new queue
3349 * has some old slice time left and is of higher priority or
3350 * this new queue is RT and the current one is BE
3352 cfq_preempt_queue(cfqd, cfqq);
3353 __blk_run_queue(cfqd->queue);
3357 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3359 struct cfq_data *cfqd = q->elevator->elevator_data;
3360 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3362 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3363 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3365 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3366 list_add_tail(&rq->queuelist, &cfqq->fifo);
3367 cfq_add_rq_rb(rq);
3368 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3369 &cfqd->serving_group->blkg, rq_data_dir(rq),
3370 rq_is_sync(rq));
3371 cfq_rq_enqueued(cfqd, cfqq, rq);
3375 * Update hw_tag based on peak queue depth over 50 samples under
3376 * sufficient load.
3378 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3380 struct cfq_queue *cfqq = cfqd->active_queue;
3382 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3383 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3385 if (cfqd->hw_tag == 1)
3386 return;
3388 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3389 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3390 return;
3393 * If active queue hasn't enough requests and can idle, cfq might not
3394 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3395 * case
3397 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3398 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3399 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3400 return;
3402 if (cfqd->hw_tag_samples++ < 50)
3403 return;
3405 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3406 cfqd->hw_tag = 1;
3407 else
3408 cfqd->hw_tag = 0;
3411 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3413 struct cfq_io_context *cic = cfqd->active_cic;
3415 /* If there are other queues in the group, don't wait */
3416 if (cfqq->cfqg->nr_cfqq > 1)
3417 return false;
3419 if (cfq_slice_used(cfqq))
3420 return true;
3422 /* if slice left is less than think time, wait busy */
3423 if (cic && sample_valid(cic->ttime_samples)
3424 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3425 return true;
3428 * If think times is less than a jiffy than ttime_mean=0 and above
3429 * will not be true. It might happen that slice has not expired yet
3430 * but will expire soon (4-5 ns) during select_queue(). To cover the
3431 * case where think time is less than a jiffy, mark the queue wait
3432 * busy if only 1 jiffy is left in the slice.
3434 if (cfqq->slice_end - jiffies == 1)
3435 return true;
3437 return false;
3440 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3442 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3443 struct cfq_data *cfqd = cfqq->cfqd;
3444 const int sync = rq_is_sync(rq);
3445 unsigned long now;
3447 now = jiffies;
3448 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3449 !!(rq->cmd_flags & REQ_NOIDLE));
3451 cfq_update_hw_tag(cfqd);
3453 WARN_ON(!cfqd->rq_in_driver);
3454 WARN_ON(!cfqq->dispatched);
3455 cfqd->rq_in_driver--;
3456 cfqq->dispatched--;
3457 (RQ_CFQG(rq))->dispatched--;
3458 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3459 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3460 rq_data_dir(rq), rq_is_sync(rq));
3462 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3464 if (sync) {
3465 RQ_CIC(rq)->last_end_request = now;
3466 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3467 cfqd->last_delayed_sync = now;
3471 * If this is the active queue, check if it needs to be expired,
3472 * or if we want to idle in case it has no pending requests.
3474 if (cfqd->active_queue == cfqq) {
3475 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3477 if (cfq_cfqq_slice_new(cfqq)) {
3478 cfq_set_prio_slice(cfqd, cfqq);
3479 cfq_clear_cfqq_slice_new(cfqq);
3483 * Should we wait for next request to come in before we expire
3484 * the queue.
3486 if (cfq_should_wait_busy(cfqd, cfqq)) {
3487 unsigned long extend_sl = cfqd->cfq_slice_idle;
3488 if (!cfqd->cfq_slice_idle)
3489 extend_sl = cfqd->cfq_group_idle;
3490 cfqq->slice_end = jiffies + extend_sl;
3491 cfq_mark_cfqq_wait_busy(cfqq);
3492 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3496 * Idling is not enabled on:
3497 * - expired queues
3498 * - idle-priority queues
3499 * - async queues
3500 * - queues with still some requests queued
3501 * - when there is a close cooperator
3503 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3504 cfq_slice_expired(cfqd, 1);
3505 else if (sync && cfqq_empty &&
3506 !cfq_close_cooperator(cfqd, cfqq)) {
3507 cfq_arm_slice_timer(cfqd);
3511 if (!cfqd->rq_in_driver)
3512 cfq_schedule_dispatch(cfqd);
3516 * we temporarily boost lower priority queues if they are holding fs exclusive
3517 * resources. they are boosted to normal prio (CLASS_BE/4)
3519 static void cfq_prio_boost(struct cfq_queue *cfqq)
3521 if (has_fs_excl()) {
3523 * boost idle prio on transactions that would lock out other
3524 * users of the filesystem
3526 if (cfq_class_idle(cfqq))
3527 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3528 if (cfqq->ioprio > IOPRIO_NORM)
3529 cfqq->ioprio = IOPRIO_NORM;
3530 } else {
3532 * unboost the queue (if needed)
3534 cfqq->ioprio_class = cfqq->org_ioprio_class;
3535 cfqq->ioprio = cfqq->org_ioprio;
3539 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3541 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3542 cfq_mark_cfqq_must_alloc_slice(cfqq);
3543 return ELV_MQUEUE_MUST;
3546 return ELV_MQUEUE_MAY;
3549 static int cfq_may_queue(struct request_queue *q, int rw)
3551 struct cfq_data *cfqd = q->elevator->elevator_data;
3552 struct task_struct *tsk = current;
3553 struct cfq_io_context *cic;
3554 struct cfq_queue *cfqq;
3557 * don't force setup of a queue from here, as a call to may_queue
3558 * does not necessarily imply that a request actually will be queued.
3559 * so just lookup a possibly existing queue, or return 'may queue'
3560 * if that fails
3562 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3563 if (!cic)
3564 return ELV_MQUEUE_MAY;
3566 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3567 if (cfqq) {
3568 cfq_init_prio_data(cfqq, cic->ioc);
3569 cfq_prio_boost(cfqq);
3571 return __cfq_may_queue(cfqq);
3574 return ELV_MQUEUE_MAY;
3578 * queue lock held here
3580 static void cfq_put_request(struct request *rq)
3582 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3584 if (cfqq) {
3585 const int rw = rq_data_dir(rq);
3587 BUG_ON(!cfqq->allocated[rw]);
3588 cfqq->allocated[rw]--;
3590 put_io_context(RQ_CIC(rq)->ioc);
3592 rq->elevator_private = NULL;
3593 rq->elevator_private2 = NULL;
3595 /* Put down rq reference on cfqg */
3596 cfq_put_cfqg(RQ_CFQG(rq));
3597 rq->elevator_private3 = NULL;
3599 cfq_put_queue(cfqq);
3603 static struct cfq_queue *
3604 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3605 struct cfq_queue *cfqq)
3607 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3608 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3609 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3610 cfq_put_queue(cfqq);
3611 return cic_to_cfqq(cic, 1);
3615 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3616 * was the last process referring to said cfqq.
3618 static struct cfq_queue *
3619 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3621 if (cfqq_process_refs(cfqq) == 1) {
3622 cfqq->pid = current->pid;
3623 cfq_clear_cfqq_coop(cfqq);
3624 cfq_clear_cfqq_split_coop(cfqq);
3625 return cfqq;
3628 cic_set_cfqq(cic, NULL, 1);
3630 cfq_put_cooperator(cfqq);
3632 cfq_put_queue(cfqq);
3633 return NULL;
3636 * Allocate cfq data structures associated with this request.
3638 static int
3639 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3641 struct cfq_data *cfqd = q->elevator->elevator_data;
3642 struct cfq_io_context *cic;
3643 const int rw = rq_data_dir(rq);
3644 const bool is_sync = rq_is_sync(rq);
3645 struct cfq_queue *cfqq;
3646 unsigned long flags;
3648 might_sleep_if(gfp_mask & __GFP_WAIT);
3650 cic = cfq_get_io_context(cfqd, gfp_mask);
3652 spin_lock_irqsave(q->queue_lock, flags);
3654 if (!cic)
3655 goto queue_fail;
3657 new_queue:
3658 cfqq = cic_to_cfqq(cic, is_sync);
3659 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3660 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3661 cic_set_cfqq(cic, cfqq, is_sync);
3662 } else {
3664 * If the queue was seeky for too long, break it apart.
3666 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3667 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3668 cfqq = split_cfqq(cic, cfqq);
3669 if (!cfqq)
3670 goto new_queue;
3674 * Check to see if this queue is scheduled to merge with
3675 * another, closely cooperating queue. The merging of
3676 * queues happens here as it must be done in process context.
3677 * The reference on new_cfqq was taken in merge_cfqqs.
3679 if (cfqq->new_cfqq)
3680 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3683 cfqq->allocated[rw]++;
3684 atomic_inc(&cfqq->ref);
3686 spin_unlock_irqrestore(q->queue_lock, flags);
3688 rq->elevator_private = cic;
3689 rq->elevator_private2 = cfqq;
3690 rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
3691 return 0;
3693 queue_fail:
3694 if (cic)
3695 put_io_context(cic->ioc);
3697 cfq_schedule_dispatch(cfqd);
3698 spin_unlock_irqrestore(q->queue_lock, flags);
3699 cfq_log(cfqd, "set_request fail");
3700 return 1;
3703 static void cfq_kick_queue(struct work_struct *work)
3705 struct cfq_data *cfqd =
3706 container_of(work, struct cfq_data, unplug_work);
3707 struct request_queue *q = cfqd->queue;
3709 spin_lock_irq(q->queue_lock);
3710 __blk_run_queue(cfqd->queue);
3711 spin_unlock_irq(q->queue_lock);
3715 * Timer running if the active_queue is currently idling inside its time slice
3717 static void cfq_idle_slice_timer(unsigned long data)
3719 struct cfq_data *cfqd = (struct cfq_data *) data;
3720 struct cfq_queue *cfqq;
3721 unsigned long flags;
3722 int timed_out = 1;
3724 cfq_log(cfqd, "idle timer fired");
3726 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3728 cfqq = cfqd->active_queue;
3729 if (cfqq) {
3730 timed_out = 0;
3733 * We saw a request before the queue expired, let it through
3735 if (cfq_cfqq_must_dispatch(cfqq))
3736 goto out_kick;
3739 * expired
3741 if (cfq_slice_used(cfqq))
3742 goto expire;
3745 * only expire and reinvoke request handler, if there are
3746 * other queues with pending requests
3748 if (!cfqd->busy_queues)
3749 goto out_cont;
3752 * not expired and it has a request pending, let it dispatch
3754 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3755 goto out_kick;
3758 * Queue depth flag is reset only when the idle didn't succeed
3760 cfq_clear_cfqq_deep(cfqq);
3762 expire:
3763 cfq_slice_expired(cfqd, timed_out);
3764 out_kick:
3765 cfq_schedule_dispatch(cfqd);
3766 out_cont:
3767 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3770 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3772 del_timer_sync(&cfqd->idle_slice_timer);
3773 cancel_work_sync(&cfqd->unplug_work);
3776 static void cfq_put_async_queues(struct cfq_data *cfqd)
3778 int i;
3780 for (i = 0; i < IOPRIO_BE_NR; i++) {
3781 if (cfqd->async_cfqq[0][i])
3782 cfq_put_queue(cfqd->async_cfqq[0][i]);
3783 if (cfqd->async_cfqq[1][i])
3784 cfq_put_queue(cfqd->async_cfqq[1][i]);
3787 if (cfqd->async_idle_cfqq)
3788 cfq_put_queue(cfqd->async_idle_cfqq);
3791 static void cfq_cfqd_free(struct rcu_head *head)
3793 kfree(container_of(head, struct cfq_data, rcu));
3796 static void cfq_exit_queue(struct elevator_queue *e)
3798 struct cfq_data *cfqd = e->elevator_data;
3799 struct request_queue *q = cfqd->queue;
3801 cfq_shutdown_timer_wq(cfqd);
3803 spin_lock_irq(q->queue_lock);
3805 if (cfqd->active_queue)
3806 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3808 while (!list_empty(&cfqd->cic_list)) {
3809 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3810 struct cfq_io_context,
3811 queue_list);
3813 __cfq_exit_single_io_context(cfqd, cic);
3816 cfq_put_async_queues(cfqd);
3817 cfq_release_cfq_groups(cfqd);
3818 cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3820 spin_unlock_irq(q->queue_lock);
3822 cfq_shutdown_timer_wq(cfqd);
3824 spin_lock(&cic_index_lock);
3825 ida_remove(&cic_index_ida, cfqd->cic_index);
3826 spin_unlock(&cic_index_lock);
3828 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3829 call_rcu(&cfqd->rcu, cfq_cfqd_free);
3832 static int cfq_alloc_cic_index(void)
3834 int index, error;
3836 do {
3837 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3838 return -ENOMEM;
3840 spin_lock(&cic_index_lock);
3841 error = ida_get_new(&cic_index_ida, &index);
3842 spin_unlock(&cic_index_lock);
3843 if (error && error != -EAGAIN)
3844 return error;
3845 } while (error);
3847 return index;
3850 static void *cfq_init_queue(struct request_queue *q)
3852 struct cfq_data *cfqd;
3853 int i, j;
3854 struct cfq_group *cfqg;
3855 struct cfq_rb_root *st;
3857 i = cfq_alloc_cic_index();
3858 if (i < 0)
3859 return NULL;
3861 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3862 if (!cfqd)
3863 return NULL;
3865 cfqd->cic_index = i;
3867 /* Init root service tree */
3868 cfqd->grp_service_tree = CFQ_RB_ROOT;
3870 /* Init root group */
3871 cfqg = &cfqd->root_group;
3872 for_each_cfqg_st(cfqg, i, j, st)
3873 *st = CFQ_RB_ROOT;
3874 RB_CLEAR_NODE(&cfqg->rb_node);
3876 /* Give preference to root group over other groups */
3877 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3879 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3881 * Take a reference to root group which we never drop. This is just
3882 * to make sure that cfq_put_cfqg() does not try to kfree root group
3884 atomic_set(&cfqg->ref, 1);
3885 rcu_read_lock();
3886 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3887 (void *)cfqd, 0);
3888 rcu_read_unlock();
3889 #endif
3891 * Not strictly needed (since RB_ROOT just clears the node and we
3892 * zeroed cfqd on alloc), but better be safe in case someone decides
3893 * to add magic to the rb code
3895 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3896 cfqd->prio_trees[i] = RB_ROOT;
3899 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3900 * Grab a permanent reference to it, so that the normal code flow
3901 * will not attempt to free it.
3903 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3904 atomic_inc(&cfqd->oom_cfqq.ref);
3905 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3907 INIT_LIST_HEAD(&cfqd->cic_list);
3909 cfqd->queue = q;
3911 init_timer(&cfqd->idle_slice_timer);
3912 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3913 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3915 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3917 cfqd->cfq_quantum = cfq_quantum;
3918 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3919 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3920 cfqd->cfq_back_max = cfq_back_max;
3921 cfqd->cfq_back_penalty = cfq_back_penalty;
3922 cfqd->cfq_slice[0] = cfq_slice_async;
3923 cfqd->cfq_slice[1] = cfq_slice_sync;
3924 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3925 cfqd->cfq_slice_idle = cfq_slice_idle;
3926 cfqd->cfq_group_idle = cfq_group_idle;
3927 cfqd->cfq_latency = 1;
3928 cfqd->cfq_group_isolation = 0;
3929 cfqd->hw_tag = -1;
3931 * we optimistically start assuming sync ops weren't delayed in last
3932 * second, in order to have larger depth for async operations.
3934 cfqd->last_delayed_sync = jiffies - HZ;
3935 return cfqd;
3938 static void cfq_slab_kill(void)
3941 * Caller already ensured that pending RCU callbacks are completed,
3942 * so we should have no busy allocations at this point.
3944 if (cfq_pool)
3945 kmem_cache_destroy(cfq_pool);
3946 if (cfq_ioc_pool)
3947 kmem_cache_destroy(cfq_ioc_pool);
3950 static int __init cfq_slab_setup(void)
3952 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3953 if (!cfq_pool)
3954 goto fail;
3956 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3957 if (!cfq_ioc_pool)
3958 goto fail;
3960 return 0;
3961 fail:
3962 cfq_slab_kill();
3963 return -ENOMEM;
3967 * sysfs parts below -->
3969 static ssize_t
3970 cfq_var_show(unsigned int var, char *page)
3972 return sprintf(page, "%d\n", var);
3975 static ssize_t
3976 cfq_var_store(unsigned int *var, const char *page, size_t count)
3978 char *p = (char *) page;
3980 *var = simple_strtoul(p, &p, 10);
3981 return count;
3984 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3985 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3987 struct cfq_data *cfqd = e->elevator_data; \
3988 unsigned int __data = __VAR; \
3989 if (__CONV) \
3990 __data = jiffies_to_msecs(__data); \
3991 return cfq_var_show(__data, (page)); \
3993 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
3994 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3995 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
3996 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3997 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
3998 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
3999 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4000 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4001 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4002 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4003 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4004 SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
4005 #undef SHOW_FUNCTION
4007 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4008 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4010 struct cfq_data *cfqd = e->elevator_data; \
4011 unsigned int __data; \
4012 int ret = cfq_var_store(&__data, (page), count); \
4013 if (__data < (MIN)) \
4014 __data = (MIN); \
4015 else if (__data > (MAX)) \
4016 __data = (MAX); \
4017 if (__CONV) \
4018 *(__PTR) = msecs_to_jiffies(__data); \
4019 else \
4020 *(__PTR) = __data; \
4021 return ret; \
4023 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4024 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4025 UINT_MAX, 1);
4026 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4027 UINT_MAX, 1);
4028 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4029 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4030 UINT_MAX, 0);
4031 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4032 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4033 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4034 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4035 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4036 UINT_MAX, 0);
4037 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4038 STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
4039 #undef STORE_FUNCTION
4041 #define CFQ_ATTR(name) \
4042 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4044 static struct elv_fs_entry cfq_attrs[] = {
4045 CFQ_ATTR(quantum),
4046 CFQ_ATTR(fifo_expire_sync),
4047 CFQ_ATTR(fifo_expire_async),
4048 CFQ_ATTR(back_seek_max),
4049 CFQ_ATTR(back_seek_penalty),
4050 CFQ_ATTR(slice_sync),
4051 CFQ_ATTR(slice_async),
4052 CFQ_ATTR(slice_async_rq),
4053 CFQ_ATTR(slice_idle),
4054 CFQ_ATTR(group_idle),
4055 CFQ_ATTR(low_latency),
4056 CFQ_ATTR(group_isolation),
4057 __ATTR_NULL
4060 static struct elevator_type iosched_cfq = {
4061 .ops = {
4062 .elevator_merge_fn = cfq_merge,
4063 .elevator_merged_fn = cfq_merged_request,
4064 .elevator_merge_req_fn = cfq_merged_requests,
4065 .elevator_allow_merge_fn = cfq_allow_merge,
4066 .elevator_bio_merged_fn = cfq_bio_merged,
4067 .elevator_dispatch_fn = cfq_dispatch_requests,
4068 .elevator_add_req_fn = cfq_insert_request,
4069 .elevator_activate_req_fn = cfq_activate_request,
4070 .elevator_deactivate_req_fn = cfq_deactivate_request,
4071 .elevator_queue_empty_fn = cfq_queue_empty,
4072 .elevator_completed_req_fn = cfq_completed_request,
4073 .elevator_former_req_fn = elv_rb_former_request,
4074 .elevator_latter_req_fn = elv_rb_latter_request,
4075 .elevator_set_req_fn = cfq_set_request,
4076 .elevator_put_req_fn = cfq_put_request,
4077 .elevator_may_queue_fn = cfq_may_queue,
4078 .elevator_init_fn = cfq_init_queue,
4079 .elevator_exit_fn = cfq_exit_queue,
4080 .trim = cfq_free_io_context,
4082 .elevator_attrs = cfq_attrs,
4083 .elevator_name = "cfq",
4084 .elevator_owner = THIS_MODULE,
4087 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4088 static struct blkio_policy_type blkio_policy_cfq = {
4089 .ops = {
4090 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4091 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4093 .plid = BLKIO_POLICY_PROP,
4095 #else
4096 static struct blkio_policy_type blkio_policy_cfq;
4097 #endif
4099 static int __init cfq_init(void)
4102 * could be 0 on HZ < 1000 setups
4104 if (!cfq_slice_async)
4105 cfq_slice_async = 1;
4106 if (!cfq_slice_idle)
4107 cfq_slice_idle = 1;
4109 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4110 if (!cfq_group_idle)
4111 cfq_group_idle = 1;
4112 #else
4113 cfq_group_idle = 0;
4114 #endif
4115 if (cfq_slab_setup())
4116 return -ENOMEM;
4118 elv_register(&iosched_cfq);
4119 blkio_policy_register(&blkio_policy_cfq);
4121 return 0;
4124 static void __exit cfq_exit(void)
4126 DECLARE_COMPLETION_ONSTACK(all_gone);
4127 blkio_policy_unregister(&blkio_policy_cfq);
4128 elv_unregister(&iosched_cfq);
4129 ioc_gone = &all_gone;
4130 /* ioc_gone's update must be visible before reading ioc_count */
4131 smp_wmb();
4134 * this also protects us from entering cfq_slab_kill() with
4135 * pending RCU callbacks
4137 if (elv_ioc_count_read(cfq_ioc_count))
4138 wait_for_completion(&all_gone);
4139 ida_destroy(&cic_index_ida);
4140 cfq_slab_kill();
4143 module_init(cfq_init);
4144 module_exit(cfq_exit);
4146 MODULE_AUTHOR("Jens Axboe");
4147 MODULE_LICENSE("GPL");
4148 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");