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>
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>
23 /* max queue in one round of service */
24 static const int cfq_quantum
= 8;
25 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max
= 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty
= 2;
30 static const int cfq_slice_sync
= HZ
/ 10;
31 static int cfq_slice_async
= HZ
/ 25;
32 static const int cfq_slice_async_rq
= 2;
33 static int cfq_slice_idle
= HZ
/ 125;
34 static int cfq_group_idle
= HZ
/ 125;
35 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
36 static const int cfq_hist_divisor
= 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
58 ((struct cfq_io_context *) (rq)->elevator_private[0])
59 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
60 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
62 static struct kmem_cache
*cfq_pool
;
63 static struct kmem_cache
*cfq_ioc_pool
;
65 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
66 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
67 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
69 #define sample_valid(samples) ((samples) > 80)
70 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
73 * Most of our rbtree usage is for sorting with min extraction, so
74 * if we cache the leftmost node we don't have to walk down the tree
75 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
76 * move this into the elevator for the rq sorting as well.
82 unsigned total_weight
;
84 struct cfq_ttime ttime
;
86 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
87 .ttime = {.last_end_request = jiffies,},}
90 * Per process-grouping structure
95 /* various state flags, see below */
98 struct cfq_data
*cfqd
;
99 /* service_tree member */
100 struct rb_node rb_node
;
101 /* service_tree key */
102 unsigned long rb_key
;
103 /* prio tree member */
104 struct rb_node p_node
;
105 /* prio tree root we belong to, if any */
106 struct rb_root
*p_root
;
107 /* sorted list of pending requests */
108 struct rb_root sort_list
;
109 /* if fifo isn't expired, next request to serve */
110 struct request
*next_rq
;
111 /* requests queued in sort_list */
113 /* currently allocated requests */
115 /* fifo list of requests in sort_list */
116 struct list_head fifo
;
118 /* time when queue got scheduled in to dispatch first request. */
119 unsigned long dispatch_start
;
120 unsigned int allocated_slice
;
121 unsigned int slice_dispatch
;
122 /* time when first request from queue completed and slice started. */
123 unsigned long slice_start
;
124 unsigned long slice_end
;
127 /* pending priority requests */
129 /* number of requests that are on the dispatch list or inside driver */
132 /* io prio of this group */
133 unsigned short ioprio
, org_ioprio
;
134 unsigned short ioprio_class
;
139 sector_t last_request_pos
;
141 struct cfq_rb_root
*service_tree
;
142 struct cfq_queue
*new_cfqq
;
143 struct cfq_group
*cfqg
;
144 /* Number of sectors dispatched from queue in single dispatch round */
145 unsigned long nr_sectors
;
149 * First index in the service_trees.
150 * IDLE is handled separately, so it has negative index
160 * Second index in the service_trees.
164 SYNC_NOIDLE_WORKLOAD
= 1,
168 /* This is per cgroup per device grouping structure */
170 /* group service_tree member */
171 struct rb_node rb_node
;
173 /* group service_tree key */
176 unsigned int new_weight
;
179 /* number of cfqq currently on this group */
183 * Per group busy queues average. Useful for workload slice calc. We
184 * create the array for each prio class but at run time it is used
185 * only for RT and BE class and slot for IDLE class remains unused.
186 * This is primarily done to avoid confusion and a gcc warning.
188 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
190 * rr lists of queues with requests. We maintain service trees for
191 * RT and BE classes. These trees are subdivided in subclasses
192 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
193 * class there is no subclassification and all the cfq queues go on
194 * a single tree service_tree_idle.
195 * Counts are embedded in the cfq_rb_root
197 struct cfq_rb_root service_trees
[2][3];
198 struct cfq_rb_root service_tree_idle
;
200 unsigned long saved_workload_slice
;
201 enum wl_type_t saved_workload
;
202 enum wl_prio_t saved_serving_prio
;
203 struct blkio_group blkg
;
204 #ifdef CONFIG_CFQ_GROUP_IOSCHED
205 struct hlist_node cfqd_node
;
208 /* number of requests that are on the dispatch list or inside driver */
210 struct cfq_ttime ttime
;
214 * Per block device queue structure
217 struct request_queue
*queue
;
218 /* Root service tree for cfq_groups */
219 struct cfq_rb_root grp_service_tree
;
220 struct cfq_group root_group
;
223 * The priority currently being served
225 enum wl_prio_t serving_prio
;
226 enum wl_type_t serving_type
;
227 unsigned long workload_expires
;
228 struct cfq_group
*serving_group
;
231 * Each priority tree is sorted by next_request position. These
232 * trees are used when determining if two or more queues are
233 * interleaving requests (see cfq_close_cooperator).
235 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
237 unsigned int busy_queues
;
238 unsigned int busy_sync_queues
;
244 * queue-depth detection
250 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
251 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
254 int hw_tag_est_depth
;
255 unsigned int hw_tag_samples
;
258 * idle window management
260 struct timer_list idle_slice_timer
;
261 struct work_struct unplug_work
;
263 struct cfq_queue
*active_queue
;
264 struct cfq_io_context
*active_cic
;
267 * async queue for each priority case
269 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
270 struct cfq_queue
*async_idle_cfqq
;
272 sector_t last_position
;
275 * tunables, see top of file
277 unsigned int cfq_quantum
;
278 unsigned int cfq_fifo_expire
[2];
279 unsigned int cfq_back_penalty
;
280 unsigned int cfq_back_max
;
281 unsigned int cfq_slice
[2];
282 unsigned int cfq_slice_async_rq
;
283 unsigned int cfq_slice_idle
;
284 unsigned int cfq_group_idle
;
285 unsigned int cfq_latency
;
287 struct list_head cic_list
;
290 * Fallback dummy cfqq for extreme OOM conditions
292 struct cfq_queue oom_cfqq
;
294 unsigned long last_delayed_sync
;
296 /* List of cfq groups being managed on this device*/
297 struct hlist_head cfqg_list
;
299 /* Number of groups which are on blkcg->blkg_list */
300 unsigned int nr_blkcg_linked_grps
;
303 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
305 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
312 if (prio
== IDLE_WORKLOAD
)
313 return &cfqg
->service_tree_idle
;
315 return &cfqg
->service_trees
[prio
][type
];
318 enum cfqq_state_flags
{
319 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
320 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
321 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
322 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
323 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
324 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
325 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
326 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
327 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
328 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
329 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
330 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
331 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
334 #define CFQ_CFQQ_FNS(name) \
335 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
337 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
339 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
341 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
343 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
345 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
349 CFQ_CFQQ_FNS(wait_request
);
350 CFQ_CFQQ_FNS(must_dispatch
);
351 CFQ_CFQQ_FNS(must_alloc_slice
);
352 CFQ_CFQQ_FNS(fifo_expire
);
353 CFQ_CFQQ_FNS(idle_window
);
354 CFQ_CFQQ_FNS(prio_changed
);
355 CFQ_CFQQ_FNS(slice_new
);
358 CFQ_CFQQ_FNS(split_coop
);
360 CFQ_CFQQ_FNS(wait_busy
);
363 #ifdef CONFIG_CFQ_GROUP_IOSCHED
364 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
365 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
366 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
367 blkg_path(&(cfqq)->cfqg->blkg), ##args)
369 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
370 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
371 blkg_path(&(cfqg)->blkg), ##args) \
374 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
375 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
376 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
378 #define cfq_log(cfqd, fmt, args...) \
379 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
381 /* Traverses through cfq group service trees */
382 #define for_each_cfqg_st(cfqg, i, j, st) \
383 for (i = 0; i <= IDLE_WORKLOAD; i++) \
384 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
385 : &cfqg->service_tree_idle; \
386 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
387 (i == IDLE_WORKLOAD && j == 0); \
388 j++, st = i < IDLE_WORKLOAD ? \
389 &cfqg->service_trees[i][j]: NULL) \
391 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
392 struct cfq_ttime
*ttime
, bool group_idle
)
395 if (!sample_valid(ttime
->ttime_samples
))
398 slice
= cfqd
->cfq_group_idle
;
400 slice
= cfqd
->cfq_slice_idle
;
401 return ttime
->ttime_mean
> slice
;
404 static inline bool iops_mode(struct cfq_data
*cfqd
)
407 * If we are not idling on queues and it is a NCQ drive, parallel
408 * execution of requests is on and measuring time is not possible
409 * in most of the cases until and unless we drive shallower queue
410 * depths and that becomes a performance bottleneck. In such cases
411 * switch to start providing fairness in terms of number of IOs.
413 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
419 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
421 if (cfq_class_idle(cfqq
))
422 return IDLE_WORKLOAD
;
423 if (cfq_class_rt(cfqq
))
429 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
431 if (!cfq_cfqq_sync(cfqq
))
432 return ASYNC_WORKLOAD
;
433 if (!cfq_cfqq_idle_window(cfqq
))
434 return SYNC_NOIDLE_WORKLOAD
;
435 return SYNC_WORKLOAD
;
438 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
439 struct cfq_data
*cfqd
,
440 struct cfq_group
*cfqg
)
442 if (wl
== IDLE_WORKLOAD
)
443 return cfqg
->service_tree_idle
.count
;
445 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
446 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
447 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
450 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
451 struct cfq_group
*cfqg
)
453 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
454 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
457 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
458 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
459 struct io_context
*, gfp_t
);
460 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
461 struct io_context
*);
463 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
466 return cic
->cfqq
[is_sync
];
469 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
470 struct cfq_queue
*cfqq
, bool is_sync
)
472 cic
->cfqq
[is_sync
] = cfqq
;
475 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_context
*cic
)
477 return cic
->q
->elevator
->elevator_data
;
481 * We regard a request as SYNC, if it's either a read or has the SYNC bit
482 * set (in which case it could also be direct WRITE).
484 static inline bool cfq_bio_sync(struct bio
*bio
)
486 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
490 * scheduler run of queue, if there are requests pending and no one in the
491 * driver that will restart queueing
493 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
495 if (cfqd
->busy_queues
) {
496 cfq_log(cfqd
, "schedule dispatch");
497 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
502 * Scale schedule slice based on io priority. Use the sync time slice only
503 * if a queue is marked sync and has sync io queued. A sync queue with async
504 * io only, should not get full sync slice length.
506 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
509 const int base_slice
= cfqd
->cfq_slice
[sync
];
511 WARN_ON(prio
>= IOPRIO_BE_NR
);
513 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
517 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
519 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
522 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
524 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
526 d
= d
* BLKIO_WEIGHT_DEFAULT
;
527 do_div(d
, cfqg
->weight
);
531 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
533 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
535 min_vdisktime
= vdisktime
;
537 return min_vdisktime
;
540 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
542 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
544 min_vdisktime
= vdisktime
;
546 return min_vdisktime
;
549 static void update_min_vdisktime(struct cfq_rb_root
*st
)
551 struct cfq_group
*cfqg
;
554 cfqg
= rb_entry_cfqg(st
->left
);
555 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
561 * get averaged number of queues of RT/BE priority.
562 * average is updated, with a formula that gives more weight to higher numbers,
563 * to quickly follows sudden increases and decrease slowly
566 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
567 struct cfq_group
*cfqg
, bool rt
)
569 unsigned min_q
, max_q
;
570 unsigned mult
= cfq_hist_divisor
- 1;
571 unsigned round
= cfq_hist_divisor
/ 2;
572 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
574 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
575 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
576 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
578 return cfqg
->busy_queues_avg
[rt
];
581 static inline unsigned
582 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
584 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
586 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
589 static inline unsigned
590 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
592 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
593 if (cfqd
->cfq_latency
) {
595 * interested queues (we consider only the ones with the same
596 * priority class in the cfq group)
598 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
600 unsigned sync_slice
= cfqd
->cfq_slice
[1];
601 unsigned expect_latency
= sync_slice
* iq
;
602 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
604 if (expect_latency
> group_slice
) {
605 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
606 /* scale low_slice according to IO priority
607 * and sync vs async */
609 min(slice
, base_low_slice
* slice
/ sync_slice
);
610 /* the adapted slice value is scaled to fit all iqs
611 * into the target latency */
612 slice
= max(slice
* group_slice
/ expect_latency
,
620 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
622 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
624 cfqq
->slice_start
= jiffies
;
625 cfqq
->slice_end
= jiffies
+ slice
;
626 cfqq
->allocated_slice
= slice
;
627 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
631 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
632 * isn't valid until the first request from the dispatch is activated
633 * and the slice time set.
635 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
637 if (cfq_cfqq_slice_new(cfqq
))
639 if (time_before(jiffies
, cfqq
->slice_end
))
646 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
647 * We choose the request that is closest to the head right now. Distance
648 * behind the head is penalized and only allowed to a certain extent.
650 static struct request
*
651 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
653 sector_t s1
, s2
, d1
= 0, d2
= 0;
654 unsigned long back_max
;
655 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
656 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
657 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
659 if (rq1
== NULL
|| rq1
== rq2
)
664 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
665 return rq_is_sync(rq1
) ? rq1
: rq2
;
667 if ((rq1
->cmd_flags
^ rq2
->cmd_flags
) & REQ_PRIO
)
668 return rq1
->cmd_flags
& REQ_PRIO
? rq1
: rq2
;
670 s1
= blk_rq_pos(rq1
);
671 s2
= blk_rq_pos(rq2
);
674 * by definition, 1KiB is 2 sectors
676 back_max
= cfqd
->cfq_back_max
* 2;
679 * Strict one way elevator _except_ in the case where we allow
680 * short backward seeks which are biased as twice the cost of a
681 * similar forward seek.
685 else if (s1
+ back_max
>= last
)
686 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
688 wrap
|= CFQ_RQ1_WRAP
;
692 else if (s2
+ back_max
>= last
)
693 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
695 wrap
|= CFQ_RQ2_WRAP
;
697 /* Found required data */
700 * By doing switch() on the bit mask "wrap" we avoid having to
701 * check two variables for all permutations: --> faster!
704 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
720 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
723 * Since both rqs are wrapped,
724 * start with the one that's further behind head
725 * (--> only *one* back seek required),
726 * since back seek takes more time than forward.
736 * The below is leftmost cache rbtree addon
738 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
740 /* Service tree is empty */
745 root
->left
= rb_first(&root
->rb
);
748 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
753 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
756 root
->left
= rb_first(&root
->rb
);
759 return rb_entry_cfqg(root
->left
);
764 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
770 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
774 rb_erase_init(n
, &root
->rb
);
779 * would be nice to take fifo expire time into account as well
781 static struct request
*
782 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
783 struct request
*last
)
785 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
786 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
787 struct request
*next
= NULL
, *prev
= NULL
;
789 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
792 prev
= rb_entry_rq(rbprev
);
795 next
= rb_entry_rq(rbnext
);
797 rbnext
= rb_first(&cfqq
->sort_list
);
798 if (rbnext
&& rbnext
!= &last
->rb_node
)
799 next
= rb_entry_rq(rbnext
);
802 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
805 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
806 struct cfq_queue
*cfqq
)
809 * just an approximation, should be ok.
811 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
812 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
816 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
818 return cfqg
->vdisktime
- st
->min_vdisktime
;
822 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
824 struct rb_node
**node
= &st
->rb
.rb_node
;
825 struct rb_node
*parent
= NULL
;
826 struct cfq_group
*__cfqg
;
827 s64 key
= cfqg_key(st
, cfqg
);
830 while (*node
!= NULL
) {
832 __cfqg
= rb_entry_cfqg(parent
);
834 if (key
< cfqg_key(st
, __cfqg
))
835 node
= &parent
->rb_left
;
837 node
= &parent
->rb_right
;
843 st
->left
= &cfqg
->rb_node
;
845 rb_link_node(&cfqg
->rb_node
, parent
, node
);
846 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
850 cfq_update_group_weight(struct cfq_group
*cfqg
)
852 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
853 if (cfqg
->needs_update
) {
854 cfqg
->weight
= cfqg
->new_weight
;
855 cfqg
->needs_update
= false;
860 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
862 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
864 cfq_update_group_weight(cfqg
);
865 __cfq_group_service_tree_add(st
, cfqg
);
866 st
->total_weight
+= cfqg
->weight
;
870 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
872 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
873 struct cfq_group
*__cfqg
;
877 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
881 * Currently put the group at the end. Later implement something
882 * so that groups get lesser vtime based on their weights, so that
883 * if group does not loose all if it was not continuously backlogged.
885 n
= rb_last(&st
->rb
);
887 __cfqg
= rb_entry_cfqg(n
);
888 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
890 cfqg
->vdisktime
= st
->min_vdisktime
;
891 cfq_group_service_tree_add(st
, cfqg
);
895 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
897 st
->total_weight
-= cfqg
->weight
;
898 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
899 cfq_rb_erase(&cfqg
->rb_node
, st
);
903 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
905 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
907 BUG_ON(cfqg
->nr_cfqq
< 1);
910 /* If there are other cfq queues under this group, don't delete it */
914 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
915 cfq_group_service_tree_del(st
, cfqg
);
916 cfqg
->saved_workload_slice
= 0;
917 cfq_blkiocg_update_dequeue_stats(&cfqg
->blkg
, 1);
920 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
921 unsigned int *unaccounted_time
)
923 unsigned int slice_used
;
926 * Queue got expired before even a single request completed or
927 * got expired immediately after first request completion.
929 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
931 * Also charge the seek time incurred to the group, otherwise
932 * if there are mutiple queues in the group, each can dispatch
933 * a single request on seeky media and cause lots of seek time
934 * and group will never know it.
936 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
939 slice_used
= jiffies
- cfqq
->slice_start
;
940 if (slice_used
> cfqq
->allocated_slice
) {
941 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
942 slice_used
= cfqq
->allocated_slice
;
944 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
945 *unaccounted_time
+= cfqq
->slice_start
-
946 cfqq
->dispatch_start
;
952 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
953 struct cfq_queue
*cfqq
)
955 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
956 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
957 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
958 - cfqg
->service_tree_idle
.count
;
961 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
964 charge
= cfqq
->slice_dispatch
;
965 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
966 charge
= cfqq
->allocated_slice
;
968 /* Can't update vdisktime while group is on service tree */
969 cfq_group_service_tree_del(st
, cfqg
);
970 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
971 /* If a new weight was requested, update now, off tree */
972 cfq_group_service_tree_add(st
, cfqg
);
974 /* This group is being expired. Save the context */
975 if (time_after(cfqd
->workload_expires
, jiffies
)) {
976 cfqg
->saved_workload_slice
= cfqd
->workload_expires
978 cfqg
->saved_workload
= cfqd
->serving_type
;
979 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
981 cfqg
->saved_workload_slice
= 0;
983 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
985 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
986 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
987 used_sl
, cfqq
->slice_dispatch
, charge
,
988 iops_mode(cfqd
), cfqq
->nr_sectors
);
989 cfq_blkiocg_update_timeslice_used(&cfqg
->blkg
, used_sl
,
991 cfq_blkiocg_set_start_empty_time(&cfqg
->blkg
);
994 #ifdef CONFIG_CFQ_GROUP_IOSCHED
995 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
998 return container_of(blkg
, struct cfq_group
, blkg
);
1002 static void cfq_update_blkio_group_weight(void *key
, struct blkio_group
*blkg
,
1003 unsigned int weight
)
1005 struct cfq_group
*cfqg
= cfqg_of_blkg(blkg
);
1006 cfqg
->new_weight
= weight
;
1007 cfqg
->needs_update
= true;
1010 static void cfq_init_add_cfqg_lists(struct cfq_data
*cfqd
,
1011 struct cfq_group
*cfqg
, struct blkio_cgroup
*blkcg
)
1013 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1014 unsigned int major
, minor
;
1017 * Add group onto cgroup list. It might happen that bdi->dev is
1018 * not initialized yet. Initialize this new group without major
1019 * and minor info and this info will be filled in once a new thread
1023 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1024 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1025 (void *)cfqd
, MKDEV(major
, minor
));
1027 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1030 cfqd
->nr_blkcg_linked_grps
++;
1031 cfqg
->weight
= blkcg_get_weight(blkcg
, cfqg
->blkg
.dev
);
1033 /* Add group on cfqd list */
1034 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
1038 * Should be called from sleepable context. No request queue lock as per
1039 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1040 * from sleepable context.
1042 static struct cfq_group
* cfq_alloc_cfqg(struct cfq_data
*cfqd
)
1044 struct cfq_group
*cfqg
= NULL
;
1046 struct cfq_rb_root
*st
;
1048 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
1052 for_each_cfqg_st(cfqg
, i
, j
, st
)
1054 RB_CLEAR_NODE(&cfqg
->rb_node
);
1056 cfqg
->ttime
.last_end_request
= jiffies
;
1059 * Take the initial reference that will be released on destroy
1060 * This can be thought of a joint reference by cgroup and
1061 * elevator which will be dropped by either elevator exit
1062 * or cgroup deletion path depending on who is exiting first.
1066 ret
= blkio_alloc_blkg_stats(&cfqg
->blkg
);
1075 static struct cfq_group
*
1076 cfq_find_cfqg(struct cfq_data
*cfqd
, struct blkio_cgroup
*blkcg
)
1078 struct cfq_group
*cfqg
= NULL
;
1080 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1081 unsigned int major
, minor
;
1084 * This is the common case when there are no blkio cgroups.
1085 * Avoid lookup in this case
1087 if (blkcg
== &blkio_root_cgroup
)
1088 cfqg
= &cfqd
->root_group
;
1090 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
1092 if (cfqg
&& !cfqg
->blkg
.dev
&& bdi
->dev
&& dev_name(bdi
->dev
)) {
1093 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1094 cfqg
->blkg
.dev
= MKDEV(major
, minor
);
1101 * Search for the cfq group current task belongs to. request_queue lock must
1104 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1106 struct blkio_cgroup
*blkcg
;
1107 struct cfq_group
*cfqg
= NULL
, *__cfqg
= NULL
;
1108 struct request_queue
*q
= cfqd
->queue
;
1111 blkcg
= task_blkio_cgroup(current
);
1112 cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1119 * Need to allocate a group. Allocation of group also needs allocation
1120 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1121 * we need to drop rcu lock and queue_lock before we call alloc.
1123 * Not taking any queue reference here and assuming that queue is
1124 * around by the time we return. CFQ queue allocation code does
1125 * the same. It might be racy though.
1129 spin_unlock_irq(q
->queue_lock
);
1131 cfqg
= cfq_alloc_cfqg(cfqd
);
1133 spin_lock_irq(q
->queue_lock
);
1136 blkcg
= task_blkio_cgroup(current
);
1139 * If some other thread already allocated the group while we were
1140 * not holding queue lock, free up the group
1142 __cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1151 cfqg
= &cfqd
->root_group
;
1153 cfq_init_add_cfqg_lists(cfqd
, cfqg
, blkcg
);
1158 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1164 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1166 /* Currently, all async queues are mapped to root group */
1167 if (!cfq_cfqq_sync(cfqq
))
1168 cfqg
= &cfqq
->cfqd
->root_group
;
1171 /* cfqq reference on cfqg */
1175 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1177 struct cfq_rb_root
*st
;
1180 BUG_ON(cfqg
->ref
<= 0);
1184 for_each_cfqg_st(cfqg
, i
, j
, st
)
1185 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
));
1186 free_percpu(cfqg
->blkg
.stats_cpu
);
1190 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1192 /* Something wrong if we are trying to remove same group twice */
1193 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1195 hlist_del_init(&cfqg
->cfqd_node
);
1197 BUG_ON(cfqd
->nr_blkcg_linked_grps
<= 0);
1198 cfqd
->nr_blkcg_linked_grps
--;
1201 * Put the reference taken at the time of creation so that when all
1202 * queues are gone, group can be destroyed.
1207 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1209 struct hlist_node
*pos
, *n
;
1210 struct cfq_group
*cfqg
;
1212 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1214 * If cgroup removal path got to blk_group first and removed
1215 * it from cgroup list, then it will take care of destroying
1218 if (!cfq_blkiocg_del_blkio_group(&cfqg
->blkg
))
1219 cfq_destroy_cfqg(cfqd
, cfqg
);
1224 * Blk cgroup controller notification saying that blkio_group object is being
1225 * delinked as associated cgroup object is going away. That also means that
1226 * no new IO will come in this group. So get rid of this group as soon as
1227 * any pending IO in the group is finished.
1229 * This function is called under rcu_read_lock(). key is the rcu protected
1230 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1233 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1234 * it should not be NULL as even if elevator was exiting, cgroup deltion
1235 * path got to it first.
1237 static void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1239 unsigned long flags
;
1240 struct cfq_data
*cfqd
= key
;
1242 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1243 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1244 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1247 #else /* GROUP_IOSCHED */
1248 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1250 return &cfqd
->root_group
;
1253 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1259 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1263 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1264 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1266 #endif /* GROUP_IOSCHED */
1269 * The cfqd->service_trees holds all pending cfq_queue's that have
1270 * requests waiting to be processed. It is sorted in the order that
1271 * we will service the queues.
1273 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1276 struct rb_node
**p
, *parent
;
1277 struct cfq_queue
*__cfqq
;
1278 unsigned long rb_key
;
1279 struct cfq_rb_root
*service_tree
;
1283 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1285 if (cfq_class_idle(cfqq
)) {
1286 rb_key
= CFQ_IDLE_DELAY
;
1287 parent
= rb_last(&service_tree
->rb
);
1288 if (parent
&& parent
!= &cfqq
->rb_node
) {
1289 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1290 rb_key
+= __cfqq
->rb_key
;
1293 } else if (!add_front
) {
1295 * Get our rb key offset. Subtract any residual slice
1296 * value carried from last service. A negative resid
1297 * count indicates slice overrun, and this should position
1298 * the next service time further away in the tree.
1300 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1301 rb_key
-= cfqq
->slice_resid
;
1302 cfqq
->slice_resid
= 0;
1305 __cfqq
= cfq_rb_first(service_tree
);
1306 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1309 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1312 * same position, nothing more to do
1314 if (rb_key
== cfqq
->rb_key
&&
1315 cfqq
->service_tree
== service_tree
)
1318 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1319 cfqq
->service_tree
= NULL
;
1324 cfqq
->service_tree
= service_tree
;
1325 p
= &service_tree
->rb
.rb_node
;
1330 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1333 * sort by key, that represents service time.
1335 if (time_before(rb_key
, __cfqq
->rb_key
))
1338 n
= &(*p
)->rb_right
;
1346 service_tree
->left
= &cfqq
->rb_node
;
1348 cfqq
->rb_key
= rb_key
;
1349 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1350 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1351 service_tree
->count
++;
1352 if (add_front
|| !new_cfqq
)
1354 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
1357 static struct cfq_queue
*
1358 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1359 sector_t sector
, struct rb_node
**ret_parent
,
1360 struct rb_node
***rb_link
)
1362 struct rb_node
**p
, *parent
;
1363 struct cfq_queue
*cfqq
= NULL
;
1371 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1374 * Sort strictly based on sector. Smallest to the left,
1375 * largest to the right.
1377 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1378 n
= &(*p
)->rb_right
;
1379 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1387 *ret_parent
= parent
;
1393 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1395 struct rb_node
**p
, *parent
;
1396 struct cfq_queue
*__cfqq
;
1399 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1400 cfqq
->p_root
= NULL
;
1403 if (cfq_class_idle(cfqq
))
1408 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1409 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1410 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1412 rb_link_node(&cfqq
->p_node
, parent
, p
);
1413 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1415 cfqq
->p_root
= NULL
;
1419 * Update cfqq's position in the service tree.
1421 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1424 * Resorting requires the cfqq to be on the RR list already.
1426 if (cfq_cfqq_on_rr(cfqq
)) {
1427 cfq_service_tree_add(cfqd
, cfqq
, 0);
1428 cfq_prio_tree_add(cfqd
, cfqq
);
1433 * add to busy list of queues for service, trying to be fair in ordering
1434 * the pending list according to last request service
1436 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1438 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1439 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1440 cfq_mark_cfqq_on_rr(cfqq
);
1441 cfqd
->busy_queues
++;
1442 if (cfq_cfqq_sync(cfqq
))
1443 cfqd
->busy_sync_queues
++;
1445 cfq_resort_rr_list(cfqd
, cfqq
);
1449 * Called when the cfqq no longer has requests pending, remove it from
1452 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1454 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1455 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1456 cfq_clear_cfqq_on_rr(cfqq
);
1458 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1459 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1460 cfqq
->service_tree
= NULL
;
1463 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1464 cfqq
->p_root
= NULL
;
1467 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
1468 BUG_ON(!cfqd
->busy_queues
);
1469 cfqd
->busy_queues
--;
1470 if (cfq_cfqq_sync(cfqq
))
1471 cfqd
->busy_sync_queues
--;
1475 * rb tree support functions
1477 static void cfq_del_rq_rb(struct request
*rq
)
1479 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1480 const int sync
= rq_is_sync(rq
);
1482 BUG_ON(!cfqq
->queued
[sync
]);
1483 cfqq
->queued
[sync
]--;
1485 elv_rb_del(&cfqq
->sort_list
, rq
);
1487 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1489 * Queue will be deleted from service tree when we actually
1490 * expire it later. Right now just remove it from prio tree
1494 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1495 cfqq
->p_root
= NULL
;
1500 static void cfq_add_rq_rb(struct request
*rq
)
1502 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1503 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1504 struct request
*prev
;
1506 cfqq
->queued
[rq_is_sync(rq
)]++;
1508 elv_rb_add(&cfqq
->sort_list
, rq
);
1510 if (!cfq_cfqq_on_rr(cfqq
))
1511 cfq_add_cfqq_rr(cfqd
, cfqq
);
1514 * check if this request is a better next-serve candidate
1516 prev
= cfqq
->next_rq
;
1517 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1520 * adjust priority tree position, if ->next_rq changes
1522 if (prev
!= cfqq
->next_rq
)
1523 cfq_prio_tree_add(cfqd
, cfqq
);
1525 BUG_ON(!cfqq
->next_rq
);
1528 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1530 elv_rb_del(&cfqq
->sort_list
, rq
);
1531 cfqq
->queued
[rq_is_sync(rq
)]--;
1532 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1533 rq_data_dir(rq
), rq_is_sync(rq
));
1535 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
1536 &cfqq
->cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
1540 static struct request
*
1541 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1543 struct task_struct
*tsk
= current
;
1544 struct cfq_io_context
*cic
;
1545 struct cfq_queue
*cfqq
;
1547 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1551 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1553 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1555 return elv_rb_find(&cfqq
->sort_list
, sector
);
1561 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1563 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1565 cfqd
->rq_in_driver
++;
1566 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1567 cfqd
->rq_in_driver
);
1569 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1572 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1574 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1576 WARN_ON(!cfqd
->rq_in_driver
);
1577 cfqd
->rq_in_driver
--;
1578 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1579 cfqd
->rq_in_driver
);
1582 static void cfq_remove_request(struct request
*rq
)
1584 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1586 if (cfqq
->next_rq
== rq
)
1587 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1589 list_del_init(&rq
->queuelist
);
1592 cfqq
->cfqd
->rq_queued
--;
1593 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1594 rq_data_dir(rq
), rq_is_sync(rq
));
1595 if (rq
->cmd_flags
& REQ_PRIO
) {
1596 WARN_ON(!cfqq
->prio_pending
);
1597 cfqq
->prio_pending
--;
1601 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1604 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1605 struct request
*__rq
;
1607 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1608 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1610 return ELEVATOR_FRONT_MERGE
;
1613 return ELEVATOR_NO_MERGE
;
1616 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1619 if (type
== ELEVATOR_FRONT_MERGE
) {
1620 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1622 cfq_reposition_rq_rb(cfqq
, req
);
1626 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1629 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req
))->blkg
,
1630 bio_data_dir(bio
), cfq_bio_sync(bio
));
1634 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1635 struct request
*next
)
1637 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1639 * reposition in fifo if next is older than rq
1641 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1642 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1643 list_move(&rq
->queuelist
, &next
->queuelist
);
1644 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1647 if (cfqq
->next_rq
== next
)
1649 cfq_remove_request(next
);
1650 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq
))->blkg
,
1651 rq_data_dir(next
), rq_is_sync(next
));
1654 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1657 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1658 struct cfq_io_context
*cic
;
1659 struct cfq_queue
*cfqq
;
1662 * Disallow merge of a sync bio into an async request.
1664 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1668 * Lookup the cfqq that this bio will be queued with and allow
1669 * merge only if rq is queued there. This function can be called
1670 * from plug merge without queue_lock. In such cases, ioc of @rq
1671 * and %current are guaranteed to be equal. Avoid lookup which
1672 * requires queue_lock by using @rq's cic.
1674 if (current
->io_context
== RQ_CIC(rq
)->ioc
) {
1677 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1682 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1683 return cfqq
== RQ_CFQQ(rq
);
1686 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1688 del_timer(&cfqd
->idle_slice_timer
);
1689 cfq_blkiocg_update_idle_time_stats(&cfqq
->cfqg
->blkg
);
1692 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1693 struct cfq_queue
*cfqq
)
1696 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
1697 cfqd
->serving_prio
, cfqd
->serving_type
);
1698 cfq_blkiocg_update_avg_queue_size_stats(&cfqq
->cfqg
->blkg
);
1699 cfqq
->slice_start
= 0;
1700 cfqq
->dispatch_start
= jiffies
;
1701 cfqq
->allocated_slice
= 0;
1702 cfqq
->slice_end
= 0;
1703 cfqq
->slice_dispatch
= 0;
1704 cfqq
->nr_sectors
= 0;
1706 cfq_clear_cfqq_wait_request(cfqq
);
1707 cfq_clear_cfqq_must_dispatch(cfqq
);
1708 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1709 cfq_clear_cfqq_fifo_expire(cfqq
);
1710 cfq_mark_cfqq_slice_new(cfqq
);
1712 cfq_del_timer(cfqd
, cfqq
);
1715 cfqd
->active_queue
= cfqq
;
1719 * current cfqq expired its slice (or was too idle), select new one
1722 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1725 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1727 if (cfq_cfqq_wait_request(cfqq
))
1728 cfq_del_timer(cfqd
, cfqq
);
1730 cfq_clear_cfqq_wait_request(cfqq
);
1731 cfq_clear_cfqq_wait_busy(cfqq
);
1734 * If this cfqq is shared between multiple processes, check to
1735 * make sure that those processes are still issuing I/Os within
1736 * the mean seek distance. If not, it may be time to break the
1737 * queues apart again.
1739 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
1740 cfq_mark_cfqq_split_coop(cfqq
);
1743 * store what was left of this slice, if the queue idled/timed out
1746 if (cfq_cfqq_slice_new(cfqq
))
1747 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
1749 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1750 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1753 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1755 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1756 cfq_del_cfqq_rr(cfqd
, cfqq
);
1758 cfq_resort_rr_list(cfqd
, cfqq
);
1760 if (cfqq
== cfqd
->active_queue
)
1761 cfqd
->active_queue
= NULL
;
1763 if (cfqd
->active_cic
) {
1764 put_io_context(cfqd
->active_cic
->ioc
, cfqd
->queue
);
1765 cfqd
->active_cic
= NULL
;
1769 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1771 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1774 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1778 * Get next queue for service. Unless we have a queue preemption,
1779 * we'll simply select the first cfqq in the service tree.
1781 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1783 struct cfq_rb_root
*service_tree
=
1784 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1785 cfqd
->serving_type
);
1787 if (!cfqd
->rq_queued
)
1790 /* There is nothing to dispatch */
1793 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1795 return cfq_rb_first(service_tree
);
1798 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1800 struct cfq_group
*cfqg
;
1801 struct cfq_queue
*cfqq
;
1803 struct cfq_rb_root
*st
;
1805 if (!cfqd
->rq_queued
)
1808 cfqg
= cfq_get_next_cfqg(cfqd
);
1812 for_each_cfqg_st(cfqg
, i
, j
, st
)
1813 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1819 * Get and set a new active queue for service.
1821 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1822 struct cfq_queue
*cfqq
)
1825 cfqq
= cfq_get_next_queue(cfqd
);
1827 __cfq_set_active_queue(cfqd
, cfqq
);
1831 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1834 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1835 return blk_rq_pos(rq
) - cfqd
->last_position
;
1837 return cfqd
->last_position
- blk_rq_pos(rq
);
1840 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1843 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
1846 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1847 struct cfq_queue
*cur_cfqq
)
1849 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1850 struct rb_node
*parent
, *node
;
1851 struct cfq_queue
*__cfqq
;
1852 sector_t sector
= cfqd
->last_position
;
1854 if (RB_EMPTY_ROOT(root
))
1858 * First, if we find a request starting at the end of the last
1859 * request, choose it.
1861 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1866 * If the exact sector wasn't found, the parent of the NULL leaf
1867 * will contain the closest sector.
1869 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1870 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1873 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1874 node
= rb_next(&__cfqq
->p_node
);
1876 node
= rb_prev(&__cfqq
->p_node
);
1880 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1881 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1889 * cur_cfqq - passed in so that we don't decide that the current queue is
1890 * closely cooperating with itself.
1892 * So, basically we're assuming that that cur_cfqq has dispatched at least
1893 * one request, and that cfqd->last_position reflects a position on the disk
1894 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1897 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1898 struct cfq_queue
*cur_cfqq
)
1900 struct cfq_queue
*cfqq
;
1902 if (cfq_class_idle(cur_cfqq
))
1904 if (!cfq_cfqq_sync(cur_cfqq
))
1906 if (CFQQ_SEEKY(cur_cfqq
))
1910 * Don't search priority tree if it's the only queue in the group.
1912 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1916 * We should notice if some of the queues are cooperating, eg
1917 * working closely on the same area of the disk. In that case,
1918 * we can group them together and don't waste time idling.
1920 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1924 /* If new queue belongs to different cfq_group, don't choose it */
1925 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1929 * It only makes sense to merge sync queues.
1931 if (!cfq_cfqq_sync(cfqq
))
1933 if (CFQQ_SEEKY(cfqq
))
1937 * Do not merge queues of different priority classes
1939 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1946 * Determine whether we should enforce idle window for this queue.
1949 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1951 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1952 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1954 BUG_ON(!service_tree
);
1955 BUG_ON(!service_tree
->count
);
1957 if (!cfqd
->cfq_slice_idle
)
1960 /* We never do for idle class queues. */
1961 if (prio
== IDLE_WORKLOAD
)
1964 /* We do for queues that were marked with idle window flag. */
1965 if (cfq_cfqq_idle_window(cfqq
) &&
1966 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1970 * Otherwise, we do only if they are the last ones
1971 * in their service tree.
1973 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
1974 !cfq_io_thinktime_big(cfqd
, &service_tree
->ttime
, false))
1976 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
1977 service_tree
->count
);
1981 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1983 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1984 struct cfq_io_context
*cic
;
1985 unsigned long sl
, group_idle
= 0;
1988 * SSD device without seek penalty, disable idling. But only do so
1989 * for devices that support queuing, otherwise we still have a problem
1990 * with sync vs async workloads.
1992 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1995 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1996 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1999 * idle is disabled, either manually or by past process history
2001 if (!cfq_should_idle(cfqd
, cfqq
)) {
2002 /* no queue idling. Check for group idling */
2003 if (cfqd
->cfq_group_idle
)
2004 group_idle
= cfqd
->cfq_group_idle
;
2010 * still active requests from this queue, don't idle
2012 if (cfqq
->dispatched
)
2016 * task has exited, don't wait
2018 cic
= cfqd
->active_cic
;
2019 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
2023 * If our average think time is larger than the remaining time
2024 * slice, then don't idle. This avoids overrunning the allotted
2027 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2028 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2029 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2030 cic
->ttime
.ttime_mean
);
2034 /* There are other queues in the group, don't do group idle */
2035 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2038 cfq_mark_cfqq_wait_request(cfqq
);
2041 sl
= cfqd
->cfq_group_idle
;
2043 sl
= cfqd
->cfq_slice_idle
;
2045 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2046 cfq_blkiocg_update_set_idle_time_stats(&cfqq
->cfqg
->blkg
);
2047 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2048 group_idle
? 1 : 0);
2052 * Move request from internal lists to the request queue dispatch list.
2054 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2056 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2057 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2059 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2061 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2062 cfq_remove_request(rq
);
2064 (RQ_CFQG(rq
))->dispatched
++;
2065 elv_dispatch_sort(q
, rq
);
2067 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2068 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2069 cfq_blkiocg_update_dispatch_stats(&cfqq
->cfqg
->blkg
, blk_rq_bytes(rq
),
2070 rq_data_dir(rq
), rq_is_sync(rq
));
2074 * return expired entry, or NULL to just start from scratch in rbtree
2076 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2078 struct request
*rq
= NULL
;
2080 if (cfq_cfqq_fifo_expire(cfqq
))
2083 cfq_mark_cfqq_fifo_expire(cfqq
);
2085 if (list_empty(&cfqq
->fifo
))
2088 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2089 if (time_before(jiffies
, rq_fifo_time(rq
)))
2092 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2097 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2099 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2101 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2103 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2107 * Must be called with the queue_lock held.
2109 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2111 int process_refs
, io_refs
;
2113 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2114 process_refs
= cfqq
->ref
- io_refs
;
2115 BUG_ON(process_refs
< 0);
2116 return process_refs
;
2119 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2121 int process_refs
, new_process_refs
;
2122 struct cfq_queue
*__cfqq
;
2125 * If there are no process references on the new_cfqq, then it is
2126 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2127 * chain may have dropped their last reference (not just their
2128 * last process reference).
2130 if (!cfqq_process_refs(new_cfqq
))
2133 /* Avoid a circular list and skip interim queue merges */
2134 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2140 process_refs
= cfqq_process_refs(cfqq
);
2141 new_process_refs
= cfqq_process_refs(new_cfqq
);
2143 * If the process for the cfqq has gone away, there is no
2144 * sense in merging the queues.
2146 if (process_refs
== 0 || new_process_refs
== 0)
2150 * Merge in the direction of the lesser amount of work.
2152 if (new_process_refs
>= process_refs
) {
2153 cfqq
->new_cfqq
= new_cfqq
;
2154 new_cfqq
->ref
+= process_refs
;
2156 new_cfqq
->new_cfqq
= cfqq
;
2157 cfqq
->ref
+= new_process_refs
;
2161 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2162 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2164 struct cfq_queue
*queue
;
2166 bool key_valid
= false;
2167 unsigned long lowest_key
= 0;
2168 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2170 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2171 /* select the one with lowest rb_key */
2172 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2174 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2175 lowest_key
= queue
->rb_key
;
2184 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2188 struct cfq_rb_root
*st
;
2189 unsigned group_slice
;
2190 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2192 /* Choose next priority. RT > BE > IDLE */
2193 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2194 cfqd
->serving_prio
= RT_WORKLOAD
;
2195 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2196 cfqd
->serving_prio
= BE_WORKLOAD
;
2198 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2199 cfqd
->workload_expires
= jiffies
+ 1;
2203 if (original_prio
!= cfqd
->serving_prio
)
2207 * For RT and BE, we have to choose also the type
2208 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2211 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2215 * check workload expiration, and that we still have other queues ready
2217 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2221 /* otherwise select new workload type */
2222 cfqd
->serving_type
=
2223 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2224 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2228 * the workload slice is computed as a fraction of target latency
2229 * proportional to the number of queues in that workload, over
2230 * all the queues in the same priority class
2232 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2234 slice
= group_slice
* count
/
2235 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2236 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2238 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2242 * Async queues are currently system wide. Just taking
2243 * proportion of queues with-in same group will lead to higher
2244 * async ratio system wide as generally root group is going
2245 * to have higher weight. A more accurate thing would be to
2246 * calculate system wide asnc/sync ratio.
2248 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2249 tmp
= tmp
/cfqd
->busy_queues
;
2250 slice
= min_t(unsigned, slice
, tmp
);
2252 /* async workload slice is scaled down according to
2253 * the sync/async slice ratio. */
2254 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2256 /* sync workload slice is at least 2 * cfq_slice_idle */
2257 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2259 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2260 cfq_log(cfqd
, "workload slice:%d", slice
);
2261 cfqd
->workload_expires
= jiffies
+ slice
;
2264 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2266 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2267 struct cfq_group
*cfqg
;
2269 if (RB_EMPTY_ROOT(&st
->rb
))
2271 cfqg
= cfq_rb_first_group(st
);
2272 update_min_vdisktime(st
);
2276 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2278 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2280 cfqd
->serving_group
= cfqg
;
2282 /* Restore the workload type data */
2283 if (cfqg
->saved_workload_slice
) {
2284 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2285 cfqd
->serving_type
= cfqg
->saved_workload
;
2286 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2288 cfqd
->workload_expires
= jiffies
- 1;
2290 choose_service_tree(cfqd
, cfqg
);
2294 * Select a queue for service. If we have a current active queue,
2295 * check whether to continue servicing it, or retrieve and set a new one.
2297 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2299 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2301 cfqq
= cfqd
->active_queue
;
2305 if (!cfqd
->rq_queued
)
2309 * We were waiting for group to get backlogged. Expire the queue
2311 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2315 * The active queue has run out of time, expire it and select new.
2317 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2319 * If slice had not expired at the completion of last request
2320 * we might not have turned on wait_busy flag. Don't expire
2321 * the queue yet. Allow the group to get backlogged.
2323 * The very fact that we have used the slice, that means we
2324 * have been idling all along on this queue and it should be
2325 * ok to wait for this request to complete.
2327 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2328 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2332 goto check_group_idle
;
2336 * The active queue has requests and isn't expired, allow it to
2339 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2343 * If another queue has a request waiting within our mean seek
2344 * distance, let it run. The expire code will check for close
2345 * cooperators and put the close queue at the front of the service
2346 * tree. If possible, merge the expiring queue with the new cfqq.
2348 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2350 if (!cfqq
->new_cfqq
)
2351 cfq_setup_merge(cfqq
, new_cfqq
);
2356 * No requests pending. If the active queue still has requests in
2357 * flight or is idling for a new request, allow either of these
2358 * conditions to happen (or time out) before selecting a new queue.
2360 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2366 * This is a deep seek queue, but the device is much faster than
2367 * the queue can deliver, don't idle
2369 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2370 (cfq_cfqq_slice_new(cfqq
) ||
2371 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2372 cfq_clear_cfqq_deep(cfqq
);
2373 cfq_clear_cfqq_idle_window(cfqq
);
2376 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2382 * If group idle is enabled and there are requests dispatched from
2383 * this group, wait for requests to complete.
2386 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
2387 cfqq
->cfqg
->dispatched
&&
2388 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
2394 cfq_slice_expired(cfqd
, 0);
2397 * Current queue expired. Check if we have to switch to a new
2401 cfq_choose_cfqg(cfqd
);
2403 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2408 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2412 while (cfqq
->next_rq
) {
2413 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2417 BUG_ON(!list_empty(&cfqq
->fifo
));
2419 /* By default cfqq is not expired if it is empty. Do it explicitly */
2420 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2425 * Drain our current requests. Used for barriers and when switching
2426 * io schedulers on-the-fly.
2428 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2430 struct cfq_queue
*cfqq
;
2433 /* Expire the timeslice of the current active queue first */
2434 cfq_slice_expired(cfqd
, 0);
2435 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2436 __cfq_set_active_queue(cfqd
, cfqq
);
2437 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2440 BUG_ON(cfqd
->busy_queues
);
2442 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2446 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2447 struct cfq_queue
*cfqq
)
2449 /* the queue hasn't finished any request, can't estimate */
2450 if (cfq_cfqq_slice_new(cfqq
))
2452 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2459 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2461 unsigned int max_dispatch
;
2464 * Drain async requests before we start sync IO
2466 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2470 * If this is an async queue and we have sync IO in flight, let it wait
2472 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2475 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2476 if (cfq_class_idle(cfqq
))
2480 * Does this cfqq already have too much IO in flight?
2482 if (cfqq
->dispatched
>= max_dispatch
) {
2483 bool promote_sync
= false;
2485 * idle queue must always only have a single IO in flight
2487 if (cfq_class_idle(cfqq
))
2491 * If there is only one sync queue
2492 * we can ignore async queue here and give the sync
2493 * queue no dispatch limit. The reason is a sync queue can
2494 * preempt async queue, limiting the sync queue doesn't make
2495 * sense. This is useful for aiostress test.
2497 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
2498 promote_sync
= true;
2501 * We have other queues, don't allow more IO from this one
2503 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
2508 * Sole queue user, no limit
2510 if (cfqd
->busy_queues
== 1 || promote_sync
)
2514 * Normally we start throttling cfqq when cfq_quantum/2
2515 * requests have been dispatched. But we can drive
2516 * deeper queue depths at the beginning of slice
2517 * subjected to upper limit of cfq_quantum.
2519 max_dispatch
= cfqd
->cfq_quantum
;
2523 * Async queues must wait a bit before being allowed dispatch.
2524 * We also ramp up the dispatch depth gradually for async IO,
2525 * based on the last sync IO we serviced
2527 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2528 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2531 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2532 if (!depth
&& !cfqq
->dispatched
)
2534 if (depth
< max_dispatch
)
2535 max_dispatch
= depth
;
2539 * If we're below the current max, allow a dispatch
2541 return cfqq
->dispatched
< max_dispatch
;
2545 * Dispatch a request from cfqq, moving them to the request queue
2548 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2552 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2554 if (!cfq_may_dispatch(cfqd
, cfqq
))
2558 * follow expired path, else get first next available
2560 rq
= cfq_check_fifo(cfqq
);
2565 * insert request into driver dispatch list
2567 cfq_dispatch_insert(cfqd
->queue
, rq
);
2569 if (!cfqd
->active_cic
) {
2570 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2572 atomic_long_inc(&cic
->ioc
->refcount
);
2573 cfqd
->active_cic
= cic
;
2580 * Find the cfqq that we need to service and move a request from that to the
2583 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2585 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2586 struct cfq_queue
*cfqq
;
2588 if (!cfqd
->busy_queues
)
2591 if (unlikely(force
))
2592 return cfq_forced_dispatch(cfqd
);
2594 cfqq
= cfq_select_queue(cfqd
);
2599 * Dispatch a request from this cfqq, if it is allowed
2601 if (!cfq_dispatch_request(cfqd
, cfqq
))
2604 cfqq
->slice_dispatch
++;
2605 cfq_clear_cfqq_must_dispatch(cfqq
);
2608 * expire an async queue immediately if it has used up its slice. idle
2609 * queue always expire after 1 dispatch round.
2611 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2612 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2613 cfq_class_idle(cfqq
))) {
2614 cfqq
->slice_end
= jiffies
+ 1;
2615 cfq_slice_expired(cfqd
, 0);
2618 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2623 * task holds one reference to the queue, dropped when task exits. each rq
2624 * in-flight on this queue also holds a reference, dropped when rq is freed.
2626 * Each cfq queue took a reference on the parent group. Drop it now.
2627 * queue lock must be held here.
2629 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2631 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2632 struct cfq_group
*cfqg
;
2634 BUG_ON(cfqq
->ref
<= 0);
2640 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2641 BUG_ON(rb_first(&cfqq
->sort_list
));
2642 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2645 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2646 __cfq_slice_expired(cfqd
, cfqq
, 0);
2647 cfq_schedule_dispatch(cfqd
);
2650 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2651 kmem_cache_free(cfq_pool
, cfqq
);
2655 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2657 kmem_cache_free(cfq_ioc_pool
,
2658 container_of(head
, struct cfq_io_context
, rcu_head
));
2661 static void cfq_cic_free(struct cfq_io_context
*cic
)
2663 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2666 static void cfq_release_cic(struct cfq_io_context
*cic
)
2668 struct io_context
*ioc
= cic
->ioc
;
2670 radix_tree_delete(&ioc
->radix_root
, cic
->q
->id
);
2671 hlist_del(&cic
->cic_list
);
2675 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2677 struct cfq_queue
*__cfqq
, *next
;
2680 * If this queue was scheduled to merge with another queue, be
2681 * sure to drop the reference taken on that queue (and others in
2682 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2684 __cfqq
= cfqq
->new_cfqq
;
2686 if (__cfqq
== cfqq
) {
2687 WARN(1, "cfqq->new_cfqq loop detected\n");
2690 next
= __cfqq
->new_cfqq
;
2691 cfq_put_queue(__cfqq
);
2696 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2698 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2699 __cfq_slice_expired(cfqd
, cfqq
, 0);
2700 cfq_schedule_dispatch(cfqd
);
2703 cfq_put_cooperator(cfqq
);
2705 cfq_put_queue(cfqq
);
2708 static void cfq_exit_cic(struct cfq_io_context
*cic
)
2710 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2711 struct io_context
*ioc
= cic
->ioc
;
2713 list_del_init(&cic
->queue_list
);
2716 * Both setting lookup hint to and clearing it from @cic are done
2717 * under queue_lock. If it's not pointing to @cic now, it never
2718 * will. Hint assignment itself can race safely.
2720 if (rcu_dereference_raw(ioc
->ioc_data
) == cic
)
2721 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2723 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2724 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2725 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2728 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2729 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2730 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2734 static struct cfq_io_context
*
2735 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2737 struct cfq_io_context
*cic
;
2739 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2742 cic
->ttime
.last_end_request
= jiffies
;
2743 INIT_LIST_HEAD(&cic
->queue_list
);
2744 INIT_HLIST_NODE(&cic
->cic_list
);
2745 cic
->exit
= cfq_exit_cic
;
2746 cic
->release
= cfq_release_cic
;
2752 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2754 struct task_struct
*tsk
= current
;
2757 if (!cfq_cfqq_prio_changed(cfqq
))
2760 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2761 switch (ioprio_class
) {
2763 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2764 case IOPRIO_CLASS_NONE
:
2766 * no prio set, inherit CPU scheduling settings
2768 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2769 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2771 case IOPRIO_CLASS_RT
:
2772 cfqq
->ioprio
= task_ioprio(ioc
);
2773 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2775 case IOPRIO_CLASS_BE
:
2776 cfqq
->ioprio
= task_ioprio(ioc
);
2777 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2779 case IOPRIO_CLASS_IDLE
:
2780 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2782 cfq_clear_cfqq_idle_window(cfqq
);
2787 * keep track of original prio settings in case we have to temporarily
2788 * elevate the priority of this queue
2790 cfqq
->org_ioprio
= cfqq
->ioprio
;
2791 cfq_clear_cfqq_prio_changed(cfqq
);
2794 static void changed_ioprio(struct cfq_io_context
*cic
)
2796 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2797 struct cfq_queue
*cfqq
;
2799 if (unlikely(!cfqd
))
2802 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2804 struct cfq_queue
*new_cfqq
;
2805 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2808 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2809 cfq_put_queue(cfqq
);
2813 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2815 cfq_mark_cfqq_prio_changed(cfqq
);
2818 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2819 pid_t pid
, bool is_sync
)
2821 RB_CLEAR_NODE(&cfqq
->rb_node
);
2822 RB_CLEAR_NODE(&cfqq
->p_node
);
2823 INIT_LIST_HEAD(&cfqq
->fifo
);
2828 cfq_mark_cfqq_prio_changed(cfqq
);
2831 if (!cfq_class_idle(cfqq
))
2832 cfq_mark_cfqq_idle_window(cfqq
);
2833 cfq_mark_cfqq_sync(cfqq
);
2838 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2839 static void changed_cgroup(struct cfq_io_context
*cic
)
2841 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2842 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2843 struct request_queue
*q
;
2845 if (unlikely(!cfqd
))
2852 * Drop reference to sync queue. A new sync queue will be
2853 * assigned in new group upon arrival of a fresh request.
2855 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2856 cic_set_cfqq(cic
, NULL
, 1);
2857 cfq_put_queue(sync_cfqq
);
2860 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2862 static struct cfq_queue
*
2863 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2864 struct io_context
*ioc
, gfp_t gfp_mask
)
2866 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2867 struct cfq_io_context
*cic
;
2868 struct cfq_group
*cfqg
;
2871 cfqg
= cfq_get_cfqg(cfqd
);
2872 cic
= cfq_cic_lookup(cfqd
, ioc
);
2873 /* cic always exists here */
2874 cfqq
= cic_to_cfqq(cic
, is_sync
);
2877 * Always try a new alloc if we fell back to the OOM cfqq
2878 * originally, since it should just be a temporary situation.
2880 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2885 } else if (gfp_mask
& __GFP_WAIT
) {
2886 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2887 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2888 gfp_mask
| __GFP_ZERO
,
2890 spin_lock_irq(cfqd
->queue
->queue_lock
);
2894 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2895 gfp_mask
| __GFP_ZERO
,
2900 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2901 cfq_init_prio_data(cfqq
, ioc
);
2902 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2903 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2905 cfqq
= &cfqd
->oom_cfqq
;
2909 kmem_cache_free(cfq_pool
, new_cfqq
);
2914 static struct cfq_queue
**
2915 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2917 switch (ioprio_class
) {
2918 case IOPRIO_CLASS_RT
:
2919 return &cfqd
->async_cfqq
[0][ioprio
];
2920 case IOPRIO_CLASS_BE
:
2921 return &cfqd
->async_cfqq
[1][ioprio
];
2922 case IOPRIO_CLASS_IDLE
:
2923 return &cfqd
->async_idle_cfqq
;
2929 static struct cfq_queue
*
2930 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2933 const int ioprio
= task_ioprio(ioc
);
2934 const int ioprio_class
= task_ioprio_class(ioc
);
2935 struct cfq_queue
**async_cfqq
= NULL
;
2936 struct cfq_queue
*cfqq
= NULL
;
2939 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2944 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2947 * pin the queue now that it's allocated, scheduler exit will prune it
2949 if (!is_sync
&& !(*async_cfqq
)) {
2959 * cfq_cic_lookup - lookup cfq_io_context
2960 * @cfqd: the associated cfq_data
2961 * @ioc: the associated io_context
2963 * Look up cfq_io_context associated with @cfqd - @ioc pair. Must be
2964 * called with queue_lock held.
2966 static struct cfq_io_context
*
2967 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
2969 struct request_queue
*q
= cfqd
->queue
;
2970 struct cfq_io_context
*cic
;
2972 lockdep_assert_held(cfqd
->queue
->queue_lock
);
2977 * cic's are indexed from @ioc using radix tree and hint pointer,
2978 * both of which are protected with RCU. All removals are done
2979 * holding both q and ioc locks, and we're holding q lock - if we
2980 * find a cic which points to us, it's guaranteed to be valid.
2983 cic
= rcu_dereference(ioc
->ioc_data
);
2984 if (cic
&& cic
->q
== q
)
2987 cic
= radix_tree_lookup(&ioc
->radix_root
, cfqd
->queue
->id
);
2988 if (cic
&& cic
->q
== q
)
2989 rcu_assign_pointer(ioc
->ioc_data
, cic
); /* allowed to race */
2998 * cfq_create_cic - create and link a cfq_io_context
2999 * @cfqd: cfqd of interest
3000 * @gfp_mask: allocation mask
3002 * Make sure cfq_io_context linking %current->io_context and @cfqd exists.
3003 * If ioc and/or cic doesn't exist, they will be created using @gfp_mask.
3005 static int cfq_create_cic(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3007 struct request_queue
*q
= cfqd
->queue
;
3008 struct cfq_io_context
*cic
= NULL
;
3009 struct io_context
*ioc
;
3012 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3014 /* allocate stuff */
3015 ioc
= current_io_context(gfp_mask
, q
->node
);
3019 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
3023 ret
= radix_tree_preload(gfp_mask
);
3028 cic
->q
= cfqd
->queue
;
3030 /* lock both q and ioc and try to link @cic */
3031 spin_lock_irq(q
->queue_lock
);
3032 spin_lock(&ioc
->lock
);
3034 ret
= radix_tree_insert(&ioc
->radix_root
, q
->id
, cic
);
3036 hlist_add_head(&cic
->cic_list
, &ioc
->cic_list
);
3037 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
3039 } else if (ret
== -EEXIST
) {
3040 /* someone else already did it */
3044 spin_unlock(&ioc
->lock
);
3045 spin_unlock_irq(q
->queue_lock
);
3047 radix_tree_preload_end();
3050 printk(KERN_ERR
"cfq: cic link failed!\n");
3057 * cfq_get_io_context - acquire cfq_io_context and bump refcnt on io_context
3058 * @cfqd: cfqd to setup cic for
3059 * @gfp_mask: allocation mask
3061 * Return cfq_io_context associating @cfqd and %current->io_context and
3062 * bump refcnt on io_context. If ioc or cic doesn't exist, they're created
3065 * Must be called under queue_lock which may be released and re-acquired.
3066 * This function also may sleep depending on @gfp_mask.
3068 static struct cfq_io_context
*
3069 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3071 struct request_queue
*q
= cfqd
->queue
;
3072 struct cfq_io_context
*cic
= NULL
;
3073 struct io_context
*ioc
;
3076 lockdep_assert_held(q
->queue_lock
);
3080 ioc
= current
->io_context
;
3082 cic
= cfq_cic_lookup(cfqd
, ioc
);
3087 /* slow path - unlock, create missing ones and retry */
3088 spin_unlock_irq(q
->queue_lock
);
3089 err
= cfq_create_cic(cfqd
, gfp_mask
);
3090 spin_lock_irq(q
->queue_lock
);
3095 /* bump @ioc's refcnt and handle changed notifications */
3096 get_io_context(ioc
);
3098 if (unlikely(cic
->changed
)) {
3099 if (test_and_clear_bit(CIC_IOPRIO_CHANGED
, &cic
->changed
))
3100 changed_ioprio(cic
);
3101 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3102 if (test_and_clear_bit(CIC_CGROUP_CHANGED
, &cic
->changed
))
3103 changed_cgroup(cic
);
3111 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
3113 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
3114 elapsed
= min(elapsed
, 2UL * slice_idle
);
3116 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
3117 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
3118 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
3122 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3123 struct cfq_io_context
*cic
)
3125 if (cfq_cfqq_sync(cfqq
)) {
3126 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
3127 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
3128 cfqd
->cfq_slice_idle
);
3130 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3131 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
3136 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3140 sector_t n_sec
= blk_rq_sectors(rq
);
3141 if (cfqq
->last_request_pos
) {
3142 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3143 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3145 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3148 cfqq
->seek_history
<<= 1;
3149 if (blk_queue_nonrot(cfqd
->queue
))
3150 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3152 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3156 * Disable idle window if the process thinks too long or seeks so much that
3160 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3161 struct cfq_io_context
*cic
)
3163 int old_idle
, enable_idle
;
3166 * Don't idle for async or idle io prio class
3168 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3171 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3173 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3174 cfq_mark_cfqq_deep(cfqq
);
3176 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3178 else if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3179 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3181 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3182 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3188 if (old_idle
!= enable_idle
) {
3189 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3191 cfq_mark_cfqq_idle_window(cfqq
);
3193 cfq_clear_cfqq_idle_window(cfqq
);
3198 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3199 * no or if we aren't sure, a 1 will cause a preempt.
3202 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3205 struct cfq_queue
*cfqq
;
3207 cfqq
= cfqd
->active_queue
;
3211 if (cfq_class_idle(new_cfqq
))
3214 if (cfq_class_idle(cfqq
))
3218 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3220 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3224 * if the new request is sync, but the currently running queue is
3225 * not, let the sync request have priority.
3227 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3230 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3233 if (cfq_slice_used(cfqq
))
3236 /* Allow preemption only if we are idling on sync-noidle tree */
3237 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3238 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3239 new_cfqq
->service_tree
->count
== 2 &&
3240 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3244 * So both queues are sync. Let the new request get disk time if
3245 * it's a metadata request and the current queue is doing regular IO.
3247 if ((rq
->cmd_flags
& REQ_PRIO
) && !cfqq
->prio_pending
)
3251 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3253 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3256 /* An idle queue should not be idle now for some reason */
3257 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3260 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3264 * if this request is as-good as one we would expect from the
3265 * current cfqq, let it preempt
3267 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3274 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3275 * let it have half of its nominal slice.
3277 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3279 struct cfq_queue
*old_cfqq
= cfqd
->active_queue
;
3281 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3282 cfq_slice_expired(cfqd
, 1);
3285 * workload type is changed, don't save slice, otherwise preempt
3288 if (cfqq_type(old_cfqq
) != cfqq_type(cfqq
))
3289 cfqq
->cfqg
->saved_workload_slice
= 0;
3292 * Put the new queue at the front of the of the current list,
3293 * so we know that it will be selected next.
3295 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3297 cfq_service_tree_add(cfqd
, cfqq
, 1);
3299 cfqq
->slice_end
= 0;
3300 cfq_mark_cfqq_slice_new(cfqq
);
3304 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3305 * something we should do about it
3308 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3311 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3314 if (rq
->cmd_flags
& REQ_PRIO
)
3315 cfqq
->prio_pending
++;
3317 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3318 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3319 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3321 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3323 if (cfqq
== cfqd
->active_queue
) {
3325 * Remember that we saw a request from this process, but
3326 * don't start queuing just yet. Otherwise we risk seeing lots
3327 * of tiny requests, because we disrupt the normal plugging
3328 * and merging. If the request is already larger than a single
3329 * page, let it rip immediately. For that case we assume that
3330 * merging is already done. Ditto for a busy system that
3331 * has other work pending, don't risk delaying until the
3332 * idle timer unplug to continue working.
3334 if (cfq_cfqq_wait_request(cfqq
)) {
3335 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3336 cfqd
->busy_queues
> 1) {
3337 cfq_del_timer(cfqd
, cfqq
);
3338 cfq_clear_cfqq_wait_request(cfqq
);
3339 __blk_run_queue(cfqd
->queue
);
3341 cfq_blkiocg_update_idle_time_stats(
3343 cfq_mark_cfqq_must_dispatch(cfqq
);
3346 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3348 * not the active queue - expire current slice if it is
3349 * idle and has expired it's mean thinktime or this new queue
3350 * has some old slice time left and is of higher priority or
3351 * this new queue is RT and the current one is BE
3353 cfq_preempt_queue(cfqd
, cfqq
);
3354 __blk_run_queue(cfqd
->queue
);
3358 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3360 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3361 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3363 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3364 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3366 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3367 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3369 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
3370 &cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
3372 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3376 * Update hw_tag based on peak queue depth over 50 samples under
3379 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3381 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3383 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3384 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3386 if (cfqd
->hw_tag
== 1)
3389 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3390 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3394 * If active queue hasn't enough requests and can idle, cfq might not
3395 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3398 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3399 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3400 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3403 if (cfqd
->hw_tag_samples
++ < 50)
3406 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3412 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3414 struct cfq_io_context
*cic
= cfqd
->active_cic
;
3416 /* If the queue already has requests, don't wait */
3417 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3420 /* If there are other queues in the group, don't wait */
3421 if (cfqq
->cfqg
->nr_cfqq
> 1)
3424 /* the only queue in the group, but think time is big */
3425 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3428 if (cfq_slice_used(cfqq
))
3431 /* if slice left is less than think time, wait busy */
3432 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3433 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
3437 * If think times is less than a jiffy than ttime_mean=0 and above
3438 * will not be true. It might happen that slice has not expired yet
3439 * but will expire soon (4-5 ns) during select_queue(). To cover the
3440 * case where think time is less than a jiffy, mark the queue wait
3441 * busy if only 1 jiffy is left in the slice.
3443 if (cfqq
->slice_end
- jiffies
== 1)
3449 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3451 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3452 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3453 const int sync
= rq_is_sync(rq
);
3457 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3458 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3460 cfq_update_hw_tag(cfqd
);
3462 WARN_ON(!cfqd
->rq_in_driver
);
3463 WARN_ON(!cfqq
->dispatched
);
3464 cfqd
->rq_in_driver
--;
3466 (RQ_CFQG(rq
))->dispatched
--;
3467 cfq_blkiocg_update_completion_stats(&cfqq
->cfqg
->blkg
,
3468 rq_start_time_ns(rq
), rq_io_start_time_ns(rq
),
3469 rq_data_dir(rq
), rq_is_sync(rq
));
3471 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3474 struct cfq_rb_root
*service_tree
;
3476 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
3478 if (cfq_cfqq_on_rr(cfqq
))
3479 service_tree
= cfqq
->service_tree
;
3481 service_tree
= service_tree_for(cfqq
->cfqg
,
3482 cfqq_prio(cfqq
), cfqq_type(cfqq
));
3483 service_tree
->ttime
.last_end_request
= now
;
3484 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3485 cfqd
->last_delayed_sync
= now
;
3488 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3489 cfqq
->cfqg
->ttime
.last_end_request
= now
;
3493 * If this is the active queue, check if it needs to be expired,
3494 * or if we want to idle in case it has no pending requests.
3496 if (cfqd
->active_queue
== cfqq
) {
3497 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3499 if (cfq_cfqq_slice_new(cfqq
)) {
3500 cfq_set_prio_slice(cfqd
, cfqq
);
3501 cfq_clear_cfqq_slice_new(cfqq
);
3505 * Should we wait for next request to come in before we expire
3508 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3509 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3510 if (!cfqd
->cfq_slice_idle
)
3511 extend_sl
= cfqd
->cfq_group_idle
;
3512 cfqq
->slice_end
= jiffies
+ extend_sl
;
3513 cfq_mark_cfqq_wait_busy(cfqq
);
3514 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3518 * Idling is not enabled on:
3520 * - idle-priority queues
3522 * - queues with still some requests queued
3523 * - when there is a close cooperator
3525 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3526 cfq_slice_expired(cfqd
, 1);
3527 else if (sync
&& cfqq_empty
&&
3528 !cfq_close_cooperator(cfqd
, cfqq
)) {
3529 cfq_arm_slice_timer(cfqd
);
3533 if (!cfqd
->rq_in_driver
)
3534 cfq_schedule_dispatch(cfqd
);
3537 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3539 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3540 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3541 return ELV_MQUEUE_MUST
;
3544 return ELV_MQUEUE_MAY
;
3547 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3549 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3550 struct task_struct
*tsk
= current
;
3551 struct cfq_io_context
*cic
;
3552 struct cfq_queue
*cfqq
;
3555 * don't force setup of a queue from here, as a call to may_queue
3556 * does not necessarily imply that a request actually will be queued.
3557 * so just lookup a possibly existing queue, or return 'may queue'
3560 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3562 return ELV_MQUEUE_MAY
;
3564 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3566 cfq_init_prio_data(cfqq
, cic
->ioc
);
3568 return __cfq_may_queue(cfqq
);
3571 return ELV_MQUEUE_MAY
;
3575 * queue lock held here
3577 static void cfq_put_request(struct request
*rq
)
3579 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3582 const int rw
= rq_data_dir(rq
);
3584 BUG_ON(!cfqq
->allocated
[rw
]);
3585 cfqq
->allocated
[rw
]--;
3587 put_io_context(RQ_CIC(rq
)->ioc
, cfqq
->cfqd
->queue
);
3589 rq
->elevator_private
[0] = NULL
;
3590 rq
->elevator_private
[1] = NULL
;
3592 /* Put down rq reference on cfqg */
3593 cfq_put_cfqg(RQ_CFQG(rq
));
3594 rq
->elevator_private
[2] = NULL
;
3596 cfq_put_queue(cfqq
);
3600 static struct cfq_queue
*
3601 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3602 struct cfq_queue
*cfqq
)
3604 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3605 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3606 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3607 cfq_put_queue(cfqq
);
3608 return cic_to_cfqq(cic
, 1);
3612 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3613 * was the last process referring to said cfqq.
3615 static struct cfq_queue
*
3616 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3618 if (cfqq_process_refs(cfqq
) == 1) {
3619 cfqq
->pid
= current
->pid
;
3620 cfq_clear_cfqq_coop(cfqq
);
3621 cfq_clear_cfqq_split_coop(cfqq
);
3625 cic_set_cfqq(cic
, NULL
, 1);
3627 cfq_put_cooperator(cfqq
);
3629 cfq_put_queue(cfqq
);
3633 * Allocate cfq data structures associated with this request.
3636 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3638 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3639 struct cfq_io_context
*cic
;
3640 const int rw
= rq_data_dir(rq
);
3641 const bool is_sync
= rq_is_sync(rq
);
3642 struct cfq_queue
*cfqq
;
3644 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3646 spin_lock_irq(q
->queue_lock
);
3647 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3652 cfqq
= cic_to_cfqq(cic
, is_sync
);
3653 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3654 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3655 cic_set_cfqq(cic
, cfqq
, is_sync
);
3658 * If the queue was seeky for too long, break it apart.
3660 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3661 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3662 cfqq
= split_cfqq(cic
, cfqq
);
3668 * Check to see if this queue is scheduled to merge with
3669 * another, closely cooperating queue. The merging of
3670 * queues happens here as it must be done in process context.
3671 * The reference on new_cfqq was taken in merge_cfqqs.
3674 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3677 cfqq
->allocated
[rw
]++;
3680 rq
->elevator_private
[0] = cic
;
3681 rq
->elevator_private
[1] = cfqq
;
3682 rq
->elevator_private
[2] = cfq_ref_get_cfqg(cfqq
->cfqg
);
3683 spin_unlock_irq(q
->queue_lock
);
3687 cfq_schedule_dispatch(cfqd
);
3688 spin_unlock_irq(q
->queue_lock
);
3689 cfq_log(cfqd
, "set_request fail");
3693 static void cfq_kick_queue(struct work_struct
*work
)
3695 struct cfq_data
*cfqd
=
3696 container_of(work
, struct cfq_data
, unplug_work
);
3697 struct request_queue
*q
= cfqd
->queue
;
3699 spin_lock_irq(q
->queue_lock
);
3700 __blk_run_queue(cfqd
->queue
);
3701 spin_unlock_irq(q
->queue_lock
);
3705 * Timer running if the active_queue is currently idling inside its time slice
3707 static void cfq_idle_slice_timer(unsigned long data
)
3709 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3710 struct cfq_queue
*cfqq
;
3711 unsigned long flags
;
3714 cfq_log(cfqd
, "idle timer fired");
3716 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3718 cfqq
= cfqd
->active_queue
;
3723 * We saw a request before the queue expired, let it through
3725 if (cfq_cfqq_must_dispatch(cfqq
))
3731 if (cfq_slice_used(cfqq
))
3735 * only expire and reinvoke request handler, if there are
3736 * other queues with pending requests
3738 if (!cfqd
->busy_queues
)
3742 * not expired and it has a request pending, let it dispatch
3744 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3748 * Queue depth flag is reset only when the idle didn't succeed
3750 cfq_clear_cfqq_deep(cfqq
);
3753 cfq_slice_expired(cfqd
, timed_out
);
3755 cfq_schedule_dispatch(cfqd
);
3757 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3760 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3762 del_timer_sync(&cfqd
->idle_slice_timer
);
3763 cancel_work_sync(&cfqd
->unplug_work
);
3766 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3770 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3771 if (cfqd
->async_cfqq
[0][i
])
3772 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3773 if (cfqd
->async_cfqq
[1][i
])
3774 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3777 if (cfqd
->async_idle_cfqq
)
3778 cfq_put_queue(cfqd
->async_idle_cfqq
);
3781 static void cfq_exit_queue(struct elevator_queue
*e
)
3783 struct cfq_data
*cfqd
= e
->elevator_data
;
3784 struct request_queue
*q
= cfqd
->queue
;
3787 cfq_shutdown_timer_wq(cfqd
);
3789 spin_lock_irq(q
->queue_lock
);
3791 if (cfqd
->active_queue
)
3792 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3794 while (!list_empty(&cfqd
->cic_list
)) {
3795 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3796 struct cfq_io_context
,
3798 struct io_context
*ioc
= cic
->ioc
;
3800 spin_lock(&ioc
->lock
);
3802 cfq_release_cic(cic
);
3803 spin_unlock(&ioc
->lock
);
3806 cfq_put_async_queues(cfqd
);
3807 cfq_release_cfq_groups(cfqd
);
3810 * If there are groups which we could not unlink from blkcg list,
3811 * wait for a rcu period for them to be freed.
3813 if (cfqd
->nr_blkcg_linked_grps
)
3816 spin_unlock_irq(q
->queue_lock
);
3818 cfq_shutdown_timer_wq(cfqd
);
3821 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3822 * Do this wait only if there are other unlinked groups out
3823 * there. This can happen if cgroup deletion path claimed the
3824 * responsibility of cleaning up a group before queue cleanup code
3827 * Do not call synchronize_rcu() unconditionally as there are drivers
3828 * which create/delete request queue hundreds of times during scan/boot
3829 * and synchronize_rcu() can take significant time and slow down boot.
3834 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3835 /* Free up per cpu stats for root group */
3836 free_percpu(cfqd
->root_group
.blkg
.stats_cpu
);
3841 static void *cfq_init_queue(struct request_queue
*q
)
3843 struct cfq_data
*cfqd
;
3845 struct cfq_group
*cfqg
;
3846 struct cfq_rb_root
*st
;
3848 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3852 /* Init root service tree */
3853 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3855 /* Init root group */
3856 cfqg
= &cfqd
->root_group
;
3857 for_each_cfqg_st(cfqg
, i
, j
, st
)
3859 RB_CLEAR_NODE(&cfqg
->rb_node
);
3861 /* Give preference to root group over other groups */
3862 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3864 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3866 * Set root group reference to 2. One reference will be dropped when
3867 * all groups on cfqd->cfqg_list are being deleted during queue exit.
3868 * Other reference will remain there as we don't want to delete this
3869 * group as it is statically allocated and gets destroyed when
3870 * throtl_data goes away.
3874 if (blkio_alloc_blkg_stats(&cfqg
->blkg
)) {
3882 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
,
3885 cfqd
->nr_blkcg_linked_grps
++;
3887 /* Add group on cfqd->cfqg_list */
3888 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
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 cfqd
->oom_cfqq
.ref
++;
3905 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3907 INIT_LIST_HEAD(&cfqd
->cic_list
);
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;
3930 * we optimistically start assuming sync ops weren't delayed in last
3931 * second, in order to have larger depth for async operations.
3933 cfqd
->last_delayed_sync
= jiffies
- HZ
;
3937 static void cfq_slab_kill(void)
3940 * Caller already ensured that pending RCU callbacks are completed,
3941 * so we should have no busy allocations at this point.
3944 kmem_cache_destroy(cfq_pool
);
3946 kmem_cache_destroy(cfq_ioc_pool
);
3949 static int __init
cfq_slab_setup(void)
3951 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3955 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3966 * sysfs parts below -->
3969 cfq_var_show(unsigned int var
, char *page
)
3971 return sprintf(page
, "%d\n", var
);
3975 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3977 char *p
= (char *) page
;
3979 *var
= simple_strtoul(p
, &p
, 10);
3983 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3984 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3986 struct cfq_data *cfqd = e->elevator_data; \
3987 unsigned int __data = __VAR; \
3989 __data = jiffies_to_msecs(__data); \
3990 return cfq_var_show(__data, (page)); \
3992 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3993 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3994 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3995 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3996 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3997 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3998 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
3999 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4000 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4001 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4002 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4003 #undef SHOW_FUNCTION
4005 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4006 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4008 struct cfq_data *cfqd = e->elevator_data; \
4009 unsigned int __data; \
4010 int ret = cfq_var_store(&__data, (page), count); \
4011 if (__data < (MIN)) \
4013 else if (__data > (MAX)) \
4016 *(__PTR) = msecs_to_jiffies(__data); \
4018 *(__PTR) = __data; \
4021 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4022 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4024 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4026 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4027 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4029 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4030 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4031 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4032 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4033 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4035 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4036 #undef STORE_FUNCTION
4038 #define CFQ_ATTR(name) \
4039 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4041 static struct elv_fs_entry cfq_attrs
[] = {
4043 CFQ_ATTR(fifo_expire_sync
),
4044 CFQ_ATTR(fifo_expire_async
),
4045 CFQ_ATTR(back_seek_max
),
4046 CFQ_ATTR(back_seek_penalty
),
4047 CFQ_ATTR(slice_sync
),
4048 CFQ_ATTR(slice_async
),
4049 CFQ_ATTR(slice_async_rq
),
4050 CFQ_ATTR(slice_idle
),
4051 CFQ_ATTR(group_idle
),
4052 CFQ_ATTR(low_latency
),
4056 static struct elevator_type iosched_cfq
= {
4058 .elevator_merge_fn
= cfq_merge
,
4059 .elevator_merged_fn
= cfq_merged_request
,
4060 .elevator_merge_req_fn
= cfq_merged_requests
,
4061 .elevator_allow_merge_fn
= cfq_allow_merge
,
4062 .elevator_bio_merged_fn
= cfq_bio_merged
,
4063 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4064 .elevator_add_req_fn
= cfq_insert_request
,
4065 .elevator_activate_req_fn
= cfq_activate_request
,
4066 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4067 .elevator_completed_req_fn
= cfq_completed_request
,
4068 .elevator_former_req_fn
= elv_rb_former_request
,
4069 .elevator_latter_req_fn
= elv_rb_latter_request
,
4070 .elevator_set_req_fn
= cfq_set_request
,
4071 .elevator_put_req_fn
= cfq_put_request
,
4072 .elevator_may_queue_fn
= cfq_may_queue
,
4073 .elevator_init_fn
= cfq_init_queue
,
4074 .elevator_exit_fn
= cfq_exit_queue
,
4076 .elevator_attrs
= cfq_attrs
,
4077 .elevator_name
= "cfq",
4078 .elevator_owner
= THIS_MODULE
,
4081 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4082 static struct blkio_policy_type blkio_policy_cfq
= {
4084 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
4085 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
4087 .plid
= BLKIO_POLICY_PROP
,
4090 static struct blkio_policy_type blkio_policy_cfq
;
4093 static int __init
cfq_init(void)
4096 * could be 0 on HZ < 1000 setups
4098 if (!cfq_slice_async
)
4099 cfq_slice_async
= 1;
4100 if (!cfq_slice_idle
)
4103 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4104 if (!cfq_group_idle
)
4109 if (cfq_slab_setup())
4112 elv_register(&iosched_cfq
);
4113 blkio_policy_register(&blkio_policy_cfq
);
4118 static void __exit
cfq_exit(void)
4120 blkio_policy_unregister(&blkio_policy_cfq
);
4121 elv_unregister(&iosched_cfq
);
4122 rcu_barrier(); /* make sure all cic RCU frees are complete */
4126 module_init(cfq_init
);
4127 module_exit(cfq_exit
);
4129 MODULE_AUTHOR("Jens Axboe");
4130 MODULE_LICENSE("GPL");
4131 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");