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/blkdev.h>
11 #include <linux/elevator.h>
12 #include <linux/jiffies.h>
13 #include <linux/rbtree.h>
14 #include <linux/ioprio.h>
15 #include <linux/blktrace_api.h>
16 #include "blk-cgroup.h"
21 /* max queue in one round of service */
22 static const int cfq_quantum
= 4;
23 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
24 /* maximum backwards seek, in KiB */
25 static const int cfq_back_max
= 16 * 1024;
26 /* penalty of a backwards seek */
27 static const int cfq_back_penalty
= 2;
28 static const int cfq_slice_sync
= HZ
/ 10;
29 static int cfq_slice_async
= HZ
/ 25;
30 static const int cfq_slice_async_rq
= 2;
31 static int cfq_slice_idle
= HZ
/ 125;
32 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
33 static const int cfq_hist_divisor
= 4;
36 * offset from end of service tree
38 #define CFQ_IDLE_DELAY (HZ / 5)
41 * below this threshold, we consider thinktime immediate
43 #define CFQ_MIN_TT (2)
46 * Allow merged cfqqs to perform this amount of seeky I/O before
47 * deciding to break the queues up again.
49 #define CFQQ_COOP_TOUT (HZ)
51 #define CFQ_SLICE_SCALE (5)
52 #define CFQ_HW_QUEUE_MIN (5)
53 #define CFQ_SERVICE_SHIFT 12
56 ((struct cfq_io_context *) (rq)->elevator_private)
57 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
59 static struct kmem_cache
*cfq_pool
;
60 static struct kmem_cache
*cfq_ioc_pool
;
62 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count
);
63 static struct completion
*ioc_gone
;
64 static DEFINE_SPINLOCK(ioc_gone_lock
);
66 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
67 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
68 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
70 #define sample_valid(samples) ((samples) > 80)
71 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
74 * Most of our rbtree usage is for sorting with min extraction, so
75 * if we cache the leftmost node we don't have to walk down the tree
76 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
77 * move this into the elevator for the rq sorting as well.
84 struct rb_node
*active
;
85 unsigned total_weight
;
87 #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
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 /* time when first request from queue completed and slice started. */
122 unsigned long slice_start
;
123 unsigned long slice_end
;
125 unsigned int slice_dispatch
;
127 /* pending metadata 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
, org_ioprio_class
;
136 unsigned int seek_samples
;
139 sector_t last_request_pos
;
140 unsigned long seeky_start
;
144 struct cfq_rb_root
*service_tree
;
145 struct cfq_queue
*new_cfqq
;
146 struct cfq_group
*cfqg
;
147 struct cfq_group
*orig_cfqg
;
148 /* Sectors dispatched in current dispatch round */
149 unsigned long nr_sectors
;
153 * First index in the service_trees.
154 * IDLE is handled separately, so it has negative index
163 * Second index in the service_trees.
167 SYNC_NOIDLE_WORKLOAD
= 1,
171 /* This is per cgroup per device grouping structure */
173 /* group service_tree member */
174 struct rb_node rb_node
;
176 /* group service_tree key */
181 /* number of cfqq currently on this group */
184 /* Per group busy queus average. Useful for workload slice calc. */
185 unsigned int busy_queues_avg
[2];
187 * rr lists of queues with requests, onle rr for each priority class.
188 * Counts are embedded in the cfq_rb_root
190 struct cfq_rb_root service_trees
[2][3];
191 struct cfq_rb_root service_tree_idle
;
193 unsigned long saved_workload_slice
;
194 enum wl_type_t saved_workload
;
195 enum wl_prio_t saved_serving_prio
;
196 struct blkio_group blkg
;
197 #ifdef CONFIG_CFQ_GROUP_IOSCHED
198 struct hlist_node cfqd_node
;
204 * Per block device queue structure
207 struct request_queue
*queue
;
208 /* Root service tree for cfq_groups */
209 struct cfq_rb_root grp_service_tree
;
210 struct cfq_group root_group
;
213 * The priority currently being served
215 enum wl_prio_t serving_prio
;
216 enum wl_type_t serving_type
;
217 unsigned long workload_expires
;
218 struct cfq_group
*serving_group
;
219 bool noidle_tree_requires_idle
;
222 * Each priority tree is sorted by next_request position. These
223 * trees are used when determining if two or more queues are
224 * interleaving requests (see cfq_close_cooperator).
226 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
228 unsigned int busy_queues
;
234 * queue-depth detection
240 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
241 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
244 int hw_tag_est_depth
;
245 unsigned int hw_tag_samples
;
248 * idle window management
250 struct timer_list idle_slice_timer
;
251 struct work_struct unplug_work
;
253 struct cfq_queue
*active_queue
;
254 struct cfq_io_context
*active_cic
;
257 * async queue for each priority case
259 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
260 struct cfq_queue
*async_idle_cfqq
;
262 sector_t last_position
;
265 * tunables, see top of file
267 unsigned int cfq_quantum
;
268 unsigned int cfq_fifo_expire
[2];
269 unsigned int cfq_back_penalty
;
270 unsigned int cfq_back_max
;
271 unsigned int cfq_slice
[2];
272 unsigned int cfq_slice_async_rq
;
273 unsigned int cfq_slice_idle
;
274 unsigned int cfq_latency
;
275 unsigned int cfq_group_isolation
;
277 struct list_head cic_list
;
280 * Fallback dummy cfqq for extreme OOM conditions
282 struct cfq_queue oom_cfqq
;
284 unsigned long last_delayed_sync
;
286 /* List of cfq groups being managed on this device*/
287 struct hlist_head cfqg_list
;
291 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
293 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
300 if (prio
== IDLE_WORKLOAD
)
301 return &cfqg
->service_tree_idle
;
303 return &cfqg
->service_trees
[prio
][type
];
306 enum cfqq_state_flags
{
307 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
308 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
309 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
310 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
311 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
312 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
313 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
314 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
315 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
316 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
317 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
318 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
321 #define CFQ_CFQQ_FNS(name) \
322 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
324 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
326 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
328 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
330 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
332 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
336 CFQ_CFQQ_FNS(wait_request
);
337 CFQ_CFQQ_FNS(must_dispatch
);
338 CFQ_CFQQ_FNS(must_alloc_slice
);
339 CFQ_CFQQ_FNS(fifo_expire
);
340 CFQ_CFQQ_FNS(idle_window
);
341 CFQ_CFQQ_FNS(prio_changed
);
342 CFQ_CFQQ_FNS(slice_new
);
346 CFQ_CFQQ_FNS(wait_busy
);
349 #ifdef CONFIG_DEBUG_CFQ_IOSCHED
350 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
351 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
352 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
353 blkg_path(&(cfqq)->cfqg->blkg), ##args);
355 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
356 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
357 blkg_path(&(cfqg)->blkg), ##args); \
360 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
361 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
362 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
364 #define cfq_log(cfqd, fmt, args...) \
365 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
367 /* Traverses through cfq group service trees */
368 #define for_each_cfqg_st(cfqg, i, j, st) \
369 for (i = 0; i <= IDLE_WORKLOAD; i++) \
370 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
371 : &cfqg->service_tree_idle; \
372 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
373 (i == IDLE_WORKLOAD && j == 0); \
374 j++, st = i < IDLE_WORKLOAD ? \
375 &cfqg->service_trees[i][j]: NULL) \
378 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
380 if (cfq_class_idle(cfqq
))
381 return IDLE_WORKLOAD
;
382 if (cfq_class_rt(cfqq
))
388 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
390 if (!cfq_cfqq_sync(cfqq
))
391 return ASYNC_WORKLOAD
;
392 if (!cfq_cfqq_idle_window(cfqq
))
393 return SYNC_NOIDLE_WORKLOAD
;
394 return SYNC_WORKLOAD
;
397 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
398 struct cfq_data
*cfqd
,
399 struct cfq_group
*cfqg
)
401 if (wl
== IDLE_WORKLOAD
)
402 return cfqg
->service_tree_idle
.count
;
404 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
405 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
406 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
409 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
410 struct cfq_group
*cfqg
)
412 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
413 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
416 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
417 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
418 struct io_context
*, gfp_t
);
419 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
420 struct io_context
*);
422 static inline int rq_in_driver(struct cfq_data
*cfqd
)
424 return cfqd
->rq_in_driver
[0] + cfqd
->rq_in_driver
[1];
427 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
430 return cic
->cfqq
[is_sync
];
433 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
434 struct cfq_queue
*cfqq
, bool is_sync
)
436 cic
->cfqq
[is_sync
] = cfqq
;
440 * We regard a request as SYNC, if it's either a read or has the SYNC bit
441 * set (in which case it could also be direct WRITE).
443 static inline bool cfq_bio_sync(struct bio
*bio
)
445 return bio_data_dir(bio
) == READ
|| bio_rw_flagged(bio
, BIO_RW_SYNCIO
);
449 * scheduler run of queue, if there are requests pending and no one in the
450 * driver that will restart queueing
452 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
454 if (cfqd
->busy_queues
) {
455 cfq_log(cfqd
, "schedule dispatch");
456 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
460 static int cfq_queue_empty(struct request_queue
*q
)
462 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
464 return !cfqd
->rq_queued
;
468 * Scale schedule slice based on io priority. Use the sync time slice only
469 * if a queue is marked sync and has sync io queued. A sync queue with async
470 * io only, should not get full sync slice length.
472 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
475 const int base_slice
= cfqd
->cfq_slice
[sync
];
477 WARN_ON(prio
>= IOPRIO_BE_NR
);
479 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
483 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
485 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
488 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
490 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
492 d
= d
* BLKIO_WEIGHT_DEFAULT
;
493 do_div(d
, cfqg
->weight
);
497 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
499 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
501 min_vdisktime
= vdisktime
;
503 return min_vdisktime
;
506 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
508 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
510 min_vdisktime
= vdisktime
;
512 return min_vdisktime
;
515 static void update_min_vdisktime(struct cfq_rb_root
*st
)
517 u64 vdisktime
= st
->min_vdisktime
;
518 struct cfq_group
*cfqg
;
521 cfqg
= rb_entry_cfqg(st
->active
);
522 vdisktime
= cfqg
->vdisktime
;
526 cfqg
= rb_entry_cfqg(st
->left
);
527 vdisktime
= min_vdisktime(vdisktime
, cfqg
->vdisktime
);
530 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
, vdisktime
);
534 * get averaged number of queues of RT/BE priority.
535 * average is updated, with a formula that gives more weight to higher numbers,
536 * to quickly follows sudden increases and decrease slowly
539 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
540 struct cfq_group
*cfqg
, bool rt
)
542 unsigned min_q
, max_q
;
543 unsigned mult
= cfq_hist_divisor
- 1;
544 unsigned round
= cfq_hist_divisor
/ 2;
545 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
547 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
548 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
549 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
551 return cfqg
->busy_queues_avg
[rt
];
554 static inline unsigned
555 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
557 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
559 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
563 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
565 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
566 if (cfqd
->cfq_latency
) {
568 * interested queues (we consider only the ones with the same
569 * priority class in the cfq group)
571 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
573 unsigned sync_slice
= cfqd
->cfq_slice
[1];
574 unsigned expect_latency
= sync_slice
* iq
;
575 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
577 if (expect_latency
> group_slice
) {
578 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
579 /* scale low_slice according to IO priority
580 * and sync vs async */
582 min(slice
, base_low_slice
* slice
/ sync_slice
);
583 /* the adapted slice value is scaled to fit all iqs
584 * into the target latency */
585 slice
= max(slice
* group_slice
/ expect_latency
,
589 cfqq
->slice_start
= jiffies
;
590 cfqq
->slice_end
= jiffies
+ slice
;
591 cfqq
->allocated_slice
= slice
;
592 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
596 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
597 * isn't valid until the first request from the dispatch is activated
598 * and the slice time set.
600 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
602 if (cfq_cfqq_slice_new(cfqq
))
604 if (time_before(jiffies
, cfqq
->slice_end
))
611 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
612 * We choose the request that is closest to the head right now. Distance
613 * behind the head is penalized and only allowed to a certain extent.
615 static struct request
*
616 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
618 sector_t s1
, s2
, d1
= 0, d2
= 0;
619 unsigned long back_max
;
620 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
621 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
622 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
624 if (rq1
== NULL
|| rq1
== rq2
)
629 if (rq_is_sync(rq1
) && !rq_is_sync(rq2
))
631 else if (rq_is_sync(rq2
) && !rq_is_sync(rq1
))
633 if (rq_is_meta(rq1
) && !rq_is_meta(rq2
))
635 else if (rq_is_meta(rq2
) && !rq_is_meta(rq1
))
638 s1
= blk_rq_pos(rq1
);
639 s2
= blk_rq_pos(rq2
);
642 * by definition, 1KiB is 2 sectors
644 back_max
= cfqd
->cfq_back_max
* 2;
647 * Strict one way elevator _except_ in the case where we allow
648 * short backward seeks which are biased as twice the cost of a
649 * similar forward seek.
653 else if (s1
+ back_max
>= last
)
654 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
656 wrap
|= CFQ_RQ1_WRAP
;
660 else if (s2
+ back_max
>= last
)
661 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
663 wrap
|= CFQ_RQ2_WRAP
;
665 /* Found required data */
668 * By doing switch() on the bit mask "wrap" we avoid having to
669 * check two variables for all permutations: --> faster!
672 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
688 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
691 * Since both rqs are wrapped,
692 * start with the one that's further behind head
693 * (--> only *one* back seek required),
694 * since back seek takes more time than forward.
704 * The below is leftmost cache rbtree addon
706 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
708 /* Service tree is empty */
713 root
->left
= rb_first(&root
->rb
);
716 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
721 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
724 root
->left
= rb_first(&root
->rb
);
727 return rb_entry_cfqg(root
->left
);
732 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
738 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
742 rb_erase_init(n
, &root
->rb
);
747 * would be nice to take fifo expire time into account as well
749 static struct request
*
750 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
751 struct request
*last
)
753 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
754 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
755 struct request
*next
= NULL
, *prev
= NULL
;
757 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
760 prev
= rb_entry_rq(rbprev
);
763 next
= rb_entry_rq(rbnext
);
765 rbnext
= rb_first(&cfqq
->sort_list
);
766 if (rbnext
&& rbnext
!= &last
->rb_node
)
767 next
= rb_entry_rq(rbnext
);
770 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
773 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
774 struct cfq_queue
*cfqq
)
777 * just an approximation, should be ok.
779 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
780 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
784 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
786 return cfqg
->vdisktime
- st
->min_vdisktime
;
790 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
792 struct rb_node
**node
= &st
->rb
.rb_node
;
793 struct rb_node
*parent
= NULL
;
794 struct cfq_group
*__cfqg
;
795 s64 key
= cfqg_key(st
, cfqg
);
798 while (*node
!= NULL
) {
800 __cfqg
= rb_entry_cfqg(parent
);
802 if (key
< cfqg_key(st
, __cfqg
))
803 node
= &parent
->rb_left
;
805 node
= &parent
->rb_right
;
811 st
->left
= &cfqg
->rb_node
;
813 rb_link_node(&cfqg
->rb_node
, parent
, node
);
814 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
818 cfq_group_service_tree_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
820 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
821 struct cfq_group
*__cfqg
;
829 * Currently put the group at the end. Later implement something
830 * so that groups get lesser vtime based on their weights, so that
831 * if group does not loose all if it was not continously backlogged.
833 n
= rb_last(&st
->rb
);
835 __cfqg
= rb_entry_cfqg(n
);
836 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
838 cfqg
->vdisktime
= st
->min_vdisktime
;
840 __cfq_group_service_tree_add(st
, cfqg
);
842 st
->total_weight
+= cfqg
->weight
;
846 cfq_group_service_tree_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
848 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
850 if (st
->active
== &cfqg
->rb_node
)
853 BUG_ON(cfqg
->nr_cfqq
< 1);
856 /* If there are other cfq queues under this group, don't delete it */
860 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
862 st
->total_weight
-= cfqg
->weight
;
863 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
864 cfq_rb_erase(&cfqg
->rb_node
, st
);
865 cfqg
->saved_workload_slice
= 0;
866 blkiocg_update_blkio_group_dequeue_stats(&cfqg
->blkg
, 1);
869 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
)
871 unsigned int slice_used
;
874 * Queue got expired before even a single request completed or
875 * got expired immediately after first request completion.
877 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
879 * Also charge the seek time incurred to the group, otherwise
880 * if there are mutiple queues in the group, each can dispatch
881 * a single request on seeky media and cause lots of seek time
882 * and group will never know it.
884 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
887 slice_used
= jiffies
- cfqq
->slice_start
;
888 if (slice_used
> cfqq
->allocated_slice
)
889 slice_used
= cfqq
->allocated_slice
;
892 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "sl_used=%u sect=%lu", slice_used
,
897 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
898 struct cfq_queue
*cfqq
)
900 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
901 unsigned int used_sl
, charge_sl
;
902 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
903 - cfqg
->service_tree_idle
.count
;
906 used_sl
= charge_sl
= cfq_cfqq_slice_usage(cfqq
);
908 if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
909 charge_sl
= cfqq
->allocated_slice
;
911 /* Can't update vdisktime while group is on service tree */
912 cfq_rb_erase(&cfqg
->rb_node
, st
);
913 cfqg
->vdisktime
+= cfq_scale_slice(charge_sl
, cfqg
);
914 __cfq_group_service_tree_add(st
, cfqg
);
916 /* This group is being expired. Save the context */
917 if (time_after(cfqd
->workload_expires
, jiffies
)) {
918 cfqg
->saved_workload_slice
= cfqd
->workload_expires
920 cfqg
->saved_workload
= cfqd
->serving_type
;
921 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
923 cfqg
->saved_workload_slice
= 0;
925 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
927 blkiocg_update_blkio_group_stats(&cfqg
->blkg
, used_sl
,
931 #ifdef CONFIG_CFQ_GROUP_IOSCHED
932 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
935 return container_of(blkg
, struct cfq_group
, blkg
);
940 cfq_update_blkio_group_weight(struct blkio_group
*blkg
, unsigned int weight
)
942 cfqg_of_blkg(blkg
)->weight
= weight
;
945 static struct cfq_group
*
946 cfq_find_alloc_cfqg(struct cfq_data
*cfqd
, struct cgroup
*cgroup
, int create
)
948 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgroup
);
949 struct cfq_group
*cfqg
= NULL
;
952 struct cfq_rb_root
*st
;
953 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
954 unsigned int major
, minor
;
956 /* Do we need to take this reference */
957 if (!blkiocg_css_tryget(blkcg
))
960 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
964 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
968 cfqg
->weight
= blkcg
->weight
;
969 for_each_cfqg_st(cfqg
, i
, j
, st
)
971 RB_CLEAR_NODE(&cfqg
->rb_node
);
974 * Take the initial reference that will be released on destroy
975 * This can be thought of a joint reference by cgroup and
976 * elevator which will be dropped by either elevator exit
977 * or cgroup deletion path depending on who is exiting first.
979 atomic_set(&cfqg
->ref
, 1);
981 /* Add group onto cgroup list */
982 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
983 blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
, (void *)cfqd
,
984 MKDEV(major
, minor
));
986 /* Add group on cfqd list */
987 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
990 blkiocg_css_put(blkcg
);
995 * Search for the cfq group current task belongs to. If create = 1, then also
996 * create the cfq group if it does not exist. request_queue lock must be held.
998 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1000 struct cgroup
*cgroup
;
1001 struct cfq_group
*cfqg
= NULL
;
1004 cgroup
= task_cgroup(current
, blkio_subsys_id
);
1005 cfqg
= cfq_find_alloc_cfqg(cfqd
, cgroup
, create
);
1006 if (!cfqg
&& create
)
1007 cfqg
= &cfqd
->root_group
;
1012 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1014 /* Currently, all async queues are mapped to root group */
1015 if (!cfq_cfqq_sync(cfqq
))
1016 cfqg
= &cfqq
->cfqd
->root_group
;
1019 /* cfqq reference on cfqg */
1020 atomic_inc(&cfqq
->cfqg
->ref
);
1023 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1025 struct cfq_rb_root
*st
;
1028 BUG_ON(atomic_read(&cfqg
->ref
) <= 0);
1029 if (!atomic_dec_and_test(&cfqg
->ref
))
1031 for_each_cfqg_st(cfqg
, i
, j
, st
)
1032 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
) || st
->active
!= NULL
);
1036 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1038 /* Something wrong if we are trying to remove same group twice */
1039 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1041 hlist_del_init(&cfqg
->cfqd_node
);
1044 * Put the reference taken at the time of creation so that when all
1045 * queues are gone, group can be destroyed.
1050 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1052 struct hlist_node
*pos
, *n
;
1053 struct cfq_group
*cfqg
;
1055 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1057 * If cgroup removal path got to blk_group first and removed
1058 * it from cgroup list, then it will take care of destroying
1061 if (!blkiocg_del_blkio_group(&cfqg
->blkg
))
1062 cfq_destroy_cfqg(cfqd
, cfqg
);
1067 * Blk cgroup controller notification saying that blkio_group object is being
1068 * delinked as associated cgroup object is going away. That also means that
1069 * no new IO will come in this group. So get rid of this group as soon as
1070 * any pending IO in the group is finished.
1072 * This function is called under rcu_read_lock(). key is the rcu protected
1073 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1076 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1077 * it should not be NULL as even if elevator was exiting, cgroup deltion
1078 * path got to it first.
1080 void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1082 unsigned long flags
;
1083 struct cfq_data
*cfqd
= key
;
1085 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1086 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1087 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1090 #else /* GROUP_IOSCHED */
1091 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1093 return &cfqd
->root_group
;
1096 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1100 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1101 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1103 #endif /* GROUP_IOSCHED */
1106 * The cfqd->service_trees holds all pending cfq_queue's that have
1107 * requests waiting to be processed. It is sorted in the order that
1108 * we will service the queues.
1110 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1113 struct rb_node
**p
, *parent
;
1114 struct cfq_queue
*__cfqq
;
1115 unsigned long rb_key
;
1116 struct cfq_rb_root
*service_tree
;
1119 int group_changed
= 0;
1121 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1122 if (!cfqd
->cfq_group_isolation
1123 && cfqq_type(cfqq
) == SYNC_NOIDLE_WORKLOAD
1124 && cfqq
->cfqg
&& cfqq
->cfqg
!= &cfqd
->root_group
) {
1125 /* Move this cfq to root group */
1126 cfq_log_cfqq(cfqd
, cfqq
, "moving to root group");
1127 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1128 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1129 cfqq
->orig_cfqg
= cfqq
->cfqg
;
1130 cfqq
->cfqg
= &cfqd
->root_group
;
1131 atomic_inc(&cfqd
->root_group
.ref
);
1133 } else if (!cfqd
->cfq_group_isolation
1134 && cfqq_type(cfqq
) == SYNC_WORKLOAD
&& cfqq
->orig_cfqg
) {
1135 /* cfqq is sequential now needs to go to its original group */
1136 BUG_ON(cfqq
->cfqg
!= &cfqd
->root_group
);
1137 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1138 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1139 cfq_put_cfqg(cfqq
->cfqg
);
1140 cfqq
->cfqg
= cfqq
->orig_cfqg
;
1141 cfqq
->orig_cfqg
= NULL
;
1143 cfq_log_cfqq(cfqd
, cfqq
, "moved to origin group");
1147 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1149 if (cfq_class_idle(cfqq
)) {
1150 rb_key
= CFQ_IDLE_DELAY
;
1151 parent
= rb_last(&service_tree
->rb
);
1152 if (parent
&& parent
!= &cfqq
->rb_node
) {
1153 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1154 rb_key
+= __cfqq
->rb_key
;
1157 } else if (!add_front
) {
1159 * Get our rb key offset. Subtract any residual slice
1160 * value carried from last service. A negative resid
1161 * count indicates slice overrun, and this should position
1162 * the next service time further away in the tree.
1164 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1165 rb_key
-= cfqq
->slice_resid
;
1166 cfqq
->slice_resid
= 0;
1169 __cfqq
= cfq_rb_first(service_tree
);
1170 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1173 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1176 * same position, nothing more to do
1178 if (rb_key
== cfqq
->rb_key
&&
1179 cfqq
->service_tree
== service_tree
)
1182 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1183 cfqq
->service_tree
= NULL
;
1188 cfqq
->service_tree
= service_tree
;
1189 p
= &service_tree
->rb
.rb_node
;
1194 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1197 * sort by key, that represents service time.
1199 if (time_before(rb_key
, __cfqq
->rb_key
))
1202 n
= &(*p
)->rb_right
;
1210 service_tree
->left
= &cfqq
->rb_node
;
1212 cfqq
->rb_key
= rb_key
;
1213 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1214 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1215 service_tree
->count
++;
1216 if ((add_front
|| !new_cfqq
) && !group_changed
)
1218 cfq_group_service_tree_add(cfqd
, cfqq
->cfqg
);
1221 static struct cfq_queue
*
1222 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1223 sector_t sector
, struct rb_node
**ret_parent
,
1224 struct rb_node
***rb_link
)
1226 struct rb_node
**p
, *parent
;
1227 struct cfq_queue
*cfqq
= NULL
;
1235 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1238 * Sort strictly based on sector. Smallest to the left,
1239 * largest to the right.
1241 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1242 n
= &(*p
)->rb_right
;
1243 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1251 *ret_parent
= parent
;
1257 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1259 struct rb_node
**p
, *parent
;
1260 struct cfq_queue
*__cfqq
;
1263 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1264 cfqq
->p_root
= NULL
;
1267 if (cfq_class_idle(cfqq
))
1272 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1273 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1274 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1276 rb_link_node(&cfqq
->p_node
, parent
, p
);
1277 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1279 cfqq
->p_root
= NULL
;
1283 * Update cfqq's position in the service tree.
1285 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1288 * Resorting requires the cfqq to be on the RR list already.
1290 if (cfq_cfqq_on_rr(cfqq
)) {
1291 cfq_service_tree_add(cfqd
, cfqq
, 0);
1292 cfq_prio_tree_add(cfqd
, cfqq
);
1297 * add to busy list of queues for service, trying to be fair in ordering
1298 * the pending list according to last request service
1300 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1302 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1303 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1304 cfq_mark_cfqq_on_rr(cfqq
);
1305 cfqd
->busy_queues
++;
1307 cfq_resort_rr_list(cfqd
, cfqq
);
1311 * Called when the cfqq no longer has requests pending, remove it from
1314 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1316 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1317 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1318 cfq_clear_cfqq_on_rr(cfqq
);
1320 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1321 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1322 cfqq
->service_tree
= NULL
;
1325 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1326 cfqq
->p_root
= NULL
;
1329 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1330 BUG_ON(!cfqd
->busy_queues
);
1331 cfqd
->busy_queues
--;
1335 * rb tree support functions
1337 static void cfq_del_rq_rb(struct request
*rq
)
1339 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1340 const int sync
= rq_is_sync(rq
);
1342 BUG_ON(!cfqq
->queued
[sync
]);
1343 cfqq
->queued
[sync
]--;
1345 elv_rb_del(&cfqq
->sort_list
, rq
);
1347 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1349 * Queue will be deleted from service tree when we actually
1350 * expire it later. Right now just remove it from prio tree
1354 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1355 cfqq
->p_root
= NULL
;
1360 static void cfq_add_rq_rb(struct request
*rq
)
1362 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1363 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1364 struct request
*__alias
, *prev
;
1366 cfqq
->queued
[rq_is_sync(rq
)]++;
1369 * looks a little odd, but the first insert might return an alias.
1370 * if that happens, put the alias on the dispatch list
1372 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
1373 cfq_dispatch_insert(cfqd
->queue
, __alias
);
1375 if (!cfq_cfqq_on_rr(cfqq
))
1376 cfq_add_cfqq_rr(cfqd
, cfqq
);
1379 * check if this request is a better next-serve candidate
1381 prev
= cfqq
->next_rq
;
1382 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1385 * adjust priority tree position, if ->next_rq changes
1387 if (prev
!= cfqq
->next_rq
)
1388 cfq_prio_tree_add(cfqd
, cfqq
);
1390 BUG_ON(!cfqq
->next_rq
);
1393 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1395 elv_rb_del(&cfqq
->sort_list
, rq
);
1396 cfqq
->queued
[rq_is_sync(rq
)]--;
1400 static struct request
*
1401 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1403 struct task_struct
*tsk
= current
;
1404 struct cfq_io_context
*cic
;
1405 struct cfq_queue
*cfqq
;
1407 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1411 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1413 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1415 return elv_rb_find(&cfqq
->sort_list
, sector
);
1421 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1423 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1425 cfqd
->rq_in_driver
[rq_is_sync(rq
)]++;
1426 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1427 rq_in_driver(cfqd
));
1429 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1432 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1434 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1435 const int sync
= rq_is_sync(rq
);
1437 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
1438 cfqd
->rq_in_driver
[sync
]--;
1439 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1440 rq_in_driver(cfqd
));
1443 static void cfq_remove_request(struct request
*rq
)
1445 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1447 if (cfqq
->next_rq
== rq
)
1448 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1450 list_del_init(&rq
->queuelist
);
1453 cfqq
->cfqd
->rq_queued
--;
1454 if (rq_is_meta(rq
)) {
1455 WARN_ON(!cfqq
->meta_pending
);
1456 cfqq
->meta_pending
--;
1460 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1463 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1464 struct request
*__rq
;
1466 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1467 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1469 return ELEVATOR_FRONT_MERGE
;
1472 return ELEVATOR_NO_MERGE
;
1475 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1478 if (type
== ELEVATOR_FRONT_MERGE
) {
1479 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1481 cfq_reposition_rq_rb(cfqq
, req
);
1486 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1487 struct request
*next
)
1489 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1491 * reposition in fifo if next is older than rq
1493 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1494 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1495 list_move(&rq
->queuelist
, &next
->queuelist
);
1496 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1499 if (cfqq
->next_rq
== next
)
1501 cfq_remove_request(next
);
1504 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1507 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1508 struct cfq_io_context
*cic
;
1509 struct cfq_queue
*cfqq
;
1512 * Disallow merge of a sync bio into an async request.
1514 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1518 * Lookup the cfqq that this bio will be queued with. Allow
1519 * merge only if rq is queued there.
1521 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1525 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1526 return cfqq
== RQ_CFQQ(rq
);
1529 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1530 struct cfq_queue
*cfqq
)
1533 cfq_log_cfqq(cfqd
, cfqq
, "set_active");
1534 cfqq
->slice_start
= 0;
1535 cfqq
->dispatch_start
= jiffies
;
1536 cfqq
->allocated_slice
= 0;
1537 cfqq
->slice_end
= 0;
1538 cfqq
->slice_dispatch
= 0;
1539 cfqq
->nr_sectors
= 0;
1541 cfq_clear_cfqq_wait_request(cfqq
);
1542 cfq_clear_cfqq_must_dispatch(cfqq
);
1543 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1544 cfq_clear_cfqq_fifo_expire(cfqq
);
1545 cfq_mark_cfqq_slice_new(cfqq
);
1547 del_timer(&cfqd
->idle_slice_timer
);
1550 cfqd
->active_queue
= cfqq
;
1554 * current cfqq expired its slice (or was too idle), select new one
1557 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1560 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1562 if (cfq_cfqq_wait_request(cfqq
))
1563 del_timer(&cfqd
->idle_slice_timer
);
1565 cfq_clear_cfqq_wait_request(cfqq
);
1566 cfq_clear_cfqq_wait_busy(cfqq
);
1569 * store what was left of this slice, if the queue idled/timed out
1571 if (timed_out
&& !cfq_cfqq_slice_new(cfqq
)) {
1572 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1573 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1576 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1578 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1579 cfq_del_cfqq_rr(cfqd
, cfqq
);
1581 cfq_resort_rr_list(cfqd
, cfqq
);
1583 if (cfqq
== cfqd
->active_queue
)
1584 cfqd
->active_queue
= NULL
;
1586 if (&cfqq
->cfqg
->rb_node
== cfqd
->grp_service_tree
.active
)
1587 cfqd
->grp_service_tree
.active
= NULL
;
1589 if (cfqd
->active_cic
) {
1590 put_io_context(cfqd
->active_cic
->ioc
);
1591 cfqd
->active_cic
= NULL
;
1595 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1597 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1600 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1604 * Get next queue for service. Unless we have a queue preemption,
1605 * we'll simply select the first cfqq in the service tree.
1607 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1609 struct cfq_rb_root
*service_tree
=
1610 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1611 cfqd
->serving_type
);
1613 if (!cfqd
->rq_queued
)
1616 /* There is nothing to dispatch */
1619 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1621 return cfq_rb_first(service_tree
);
1624 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1626 struct cfq_group
*cfqg
;
1627 struct cfq_queue
*cfqq
;
1629 struct cfq_rb_root
*st
;
1631 if (!cfqd
->rq_queued
)
1634 cfqg
= cfq_get_next_cfqg(cfqd
);
1638 for_each_cfqg_st(cfqg
, i
, j
, st
)
1639 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1645 * Get and set a new active queue for service.
1647 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1648 struct cfq_queue
*cfqq
)
1651 cfqq
= cfq_get_next_queue(cfqd
);
1653 __cfq_set_active_queue(cfqd
, cfqq
);
1657 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1660 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1661 return blk_rq_pos(rq
) - cfqd
->last_position
;
1663 return cfqd
->last_position
- blk_rq_pos(rq
);
1666 #define CFQQ_SEEK_THR 8 * 1024
1667 #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
1669 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1670 struct request
*rq
, bool for_preempt
)
1672 sector_t sdist
= cfqq
->seek_mean
;
1674 if (!sample_valid(cfqq
->seek_samples
))
1675 sdist
= CFQQ_SEEK_THR
;
1677 /* if seek_mean is big, using it as close criteria is meaningless */
1678 if (sdist
> CFQQ_SEEK_THR
&& !for_preempt
)
1679 sdist
= CFQQ_SEEK_THR
;
1681 return cfq_dist_from_last(cfqd
, rq
) <= sdist
;
1684 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1685 struct cfq_queue
*cur_cfqq
)
1687 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1688 struct rb_node
*parent
, *node
;
1689 struct cfq_queue
*__cfqq
;
1690 sector_t sector
= cfqd
->last_position
;
1692 if (RB_EMPTY_ROOT(root
))
1696 * First, if we find a request starting at the end of the last
1697 * request, choose it.
1699 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1704 * If the exact sector wasn't found, the parent of the NULL leaf
1705 * will contain the closest sector.
1707 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1708 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
, false))
1711 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1712 node
= rb_next(&__cfqq
->p_node
);
1714 node
= rb_prev(&__cfqq
->p_node
);
1718 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1719 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
, false))
1727 * cur_cfqq - passed in so that we don't decide that the current queue is
1728 * closely cooperating with itself.
1730 * So, basically we're assuming that that cur_cfqq has dispatched at least
1731 * one request, and that cfqd->last_position reflects a position on the disk
1732 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1735 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1736 struct cfq_queue
*cur_cfqq
)
1738 struct cfq_queue
*cfqq
;
1740 if (!cfq_cfqq_sync(cur_cfqq
))
1742 if (CFQQ_SEEKY(cur_cfqq
))
1746 * Don't search priority tree if it's the only queue in the group.
1748 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1752 * We should notice if some of the queues are cooperating, eg
1753 * working closely on the same area of the disk. In that case,
1754 * we can group them together and don't waste time idling.
1756 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1760 /* If new queue belongs to different cfq_group, don't choose it */
1761 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1765 * It only makes sense to merge sync queues.
1767 if (!cfq_cfqq_sync(cfqq
))
1769 if (CFQQ_SEEKY(cfqq
))
1773 * Do not merge queues of different priority classes
1775 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1782 * Determine whether we should enforce idle window for this queue.
1785 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1787 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1788 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1790 BUG_ON(!service_tree
);
1791 BUG_ON(!service_tree
->count
);
1793 /* We never do for idle class queues. */
1794 if (prio
== IDLE_WORKLOAD
)
1797 /* We do for queues that were marked with idle window flag. */
1798 if (cfq_cfqq_idle_window(cfqq
) &&
1799 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1803 * Otherwise, we do only if they are the last ones
1804 * in their service tree.
1806 return service_tree
->count
== 1;
1809 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1811 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1812 struct cfq_io_context
*cic
;
1816 * SSD device without seek penalty, disable idling. But only do so
1817 * for devices that support queuing, otherwise we still have a problem
1818 * with sync vs async workloads.
1820 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1823 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1824 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1827 * idle is disabled, either manually or by past process history
1829 if (!cfqd
->cfq_slice_idle
|| !cfq_should_idle(cfqd
, cfqq
))
1833 * still active requests from this queue, don't idle
1835 if (cfqq
->dispatched
)
1839 * task has exited, don't wait
1841 cic
= cfqd
->active_cic
;
1842 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1846 * If our average think time is larger than the remaining time
1847 * slice, then don't idle. This avoids overrunning the allotted
1850 if (sample_valid(cic
->ttime_samples
) &&
1851 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
1854 cfq_mark_cfqq_wait_request(cfqq
);
1856 sl
= cfqd
->cfq_slice_idle
;
1858 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1859 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu", sl
);
1863 * Move request from internal lists to the request queue dispatch list.
1865 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1867 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1868 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1870 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1872 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1873 cfq_remove_request(rq
);
1875 elv_dispatch_sort(q
, rq
);
1877 if (cfq_cfqq_sync(cfqq
))
1878 cfqd
->sync_flight
++;
1879 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
1883 * return expired entry, or NULL to just start from scratch in rbtree
1885 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1887 struct request
*rq
= NULL
;
1889 if (cfq_cfqq_fifo_expire(cfqq
))
1892 cfq_mark_cfqq_fifo_expire(cfqq
);
1894 if (list_empty(&cfqq
->fifo
))
1897 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
1898 if (time_before(jiffies
, rq_fifo_time(rq
)))
1901 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
1906 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1908 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1910 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1912 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1916 * Must be called with the queue_lock held.
1918 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
1920 int process_refs
, io_refs
;
1922 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
1923 process_refs
= atomic_read(&cfqq
->ref
) - io_refs
;
1924 BUG_ON(process_refs
< 0);
1925 return process_refs
;
1928 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
1930 int process_refs
, new_process_refs
;
1931 struct cfq_queue
*__cfqq
;
1933 /* Avoid a circular list and skip interim queue merges */
1934 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
1940 process_refs
= cfqq_process_refs(cfqq
);
1942 * If the process for the cfqq has gone away, there is no
1943 * sense in merging the queues.
1945 if (process_refs
== 0)
1949 * Merge in the direction of the lesser amount of work.
1951 new_process_refs
= cfqq_process_refs(new_cfqq
);
1952 if (new_process_refs
>= process_refs
) {
1953 cfqq
->new_cfqq
= new_cfqq
;
1954 atomic_add(process_refs
, &new_cfqq
->ref
);
1956 new_cfqq
->new_cfqq
= cfqq
;
1957 atomic_add(new_process_refs
, &cfqq
->ref
);
1961 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
1962 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
1964 struct cfq_queue
*queue
;
1966 bool key_valid
= false;
1967 unsigned long lowest_key
= 0;
1968 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
1970 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
1971 /* select the one with lowest rb_key */
1972 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
1974 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
1975 lowest_key
= queue
->rb_key
;
1984 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1988 struct cfq_rb_root
*st
;
1989 unsigned group_slice
;
1992 cfqd
->serving_prio
= IDLE_WORKLOAD
;
1993 cfqd
->workload_expires
= jiffies
+ 1;
1997 /* Choose next priority. RT > BE > IDLE */
1998 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
1999 cfqd
->serving_prio
= RT_WORKLOAD
;
2000 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2001 cfqd
->serving_prio
= BE_WORKLOAD
;
2003 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2004 cfqd
->workload_expires
= jiffies
+ 1;
2009 * For RT and BE, we have to choose also the type
2010 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2013 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2017 * check workload expiration, and that we still have other queues ready
2019 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2022 /* otherwise select new workload type */
2023 cfqd
->serving_type
=
2024 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2025 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2029 * the workload slice is computed as a fraction of target latency
2030 * proportional to the number of queues in that workload, over
2031 * all the queues in the same priority class
2033 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2035 slice
= group_slice
* count
/
2036 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2037 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2039 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2043 * Async queues are currently system wide. Just taking
2044 * proportion of queues with-in same group will lead to higher
2045 * async ratio system wide as generally root group is going
2046 * to have higher weight. A more accurate thing would be to
2047 * calculate system wide asnc/sync ratio.
2049 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2050 tmp
= tmp
/cfqd
->busy_queues
;
2051 slice
= min_t(unsigned, slice
, tmp
);
2053 /* async workload slice is scaled down according to
2054 * the sync/async slice ratio. */
2055 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2057 /* sync workload slice is at least 2 * cfq_slice_idle */
2058 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2060 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2061 cfqd
->workload_expires
= jiffies
+ slice
;
2062 cfqd
->noidle_tree_requires_idle
= false;
2065 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2067 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2068 struct cfq_group
*cfqg
;
2070 if (RB_EMPTY_ROOT(&st
->rb
))
2072 cfqg
= cfq_rb_first_group(st
);
2073 st
->active
= &cfqg
->rb_node
;
2074 update_min_vdisktime(st
);
2078 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2080 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2082 cfqd
->serving_group
= cfqg
;
2084 /* Restore the workload type data */
2085 if (cfqg
->saved_workload_slice
) {
2086 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2087 cfqd
->serving_type
= cfqg
->saved_workload
;
2088 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2090 cfqd
->workload_expires
= jiffies
- 1;
2092 choose_service_tree(cfqd
, cfqg
);
2096 * Select a queue for service. If we have a current active queue,
2097 * check whether to continue servicing it, or retrieve and set a new one.
2099 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2101 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2103 cfqq
= cfqd
->active_queue
;
2107 if (!cfqd
->rq_queued
)
2111 * We were waiting for group to get backlogged. Expire the queue
2113 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2117 * The active queue has run out of time, expire it and select new.
2119 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2121 * If slice had not expired at the completion of last request
2122 * we might not have turned on wait_busy flag. Don't expire
2123 * the queue yet. Allow the group to get backlogged.
2125 * The very fact that we have used the slice, that means we
2126 * have been idling all along on this queue and it should be
2127 * ok to wait for this request to complete.
2129 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2130 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2138 * The active queue has requests and isn't expired, allow it to
2141 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2145 * If another queue has a request waiting within our mean seek
2146 * distance, let it run. The expire code will check for close
2147 * cooperators and put the close queue at the front of the service
2148 * tree. If possible, merge the expiring queue with the new cfqq.
2150 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2152 if (!cfqq
->new_cfqq
)
2153 cfq_setup_merge(cfqq
, new_cfqq
);
2158 * No requests pending. If the active queue still has requests in
2159 * flight or is idling for a new request, allow either of these
2160 * conditions to happen (or time out) before selecting a new queue.
2162 if (timer_pending(&cfqd
->idle_slice_timer
) ||
2163 (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
))) {
2169 cfq_slice_expired(cfqd
, 0);
2172 * Current queue expired. Check if we have to switch to a new
2176 cfq_choose_cfqg(cfqd
);
2178 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2183 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2187 while (cfqq
->next_rq
) {
2188 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2192 BUG_ON(!list_empty(&cfqq
->fifo
));
2194 /* By default cfqq is not expired if it is empty. Do it explicitly */
2195 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2200 * Drain our current requests. Used for barriers and when switching
2201 * io schedulers on-the-fly.
2203 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2205 struct cfq_queue
*cfqq
;
2208 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
)
2209 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2211 cfq_slice_expired(cfqd
, 0);
2212 BUG_ON(cfqd
->busy_queues
);
2214 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2218 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2220 unsigned int max_dispatch
;
2223 * Drain async requests before we start sync IO
2225 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_driver
[BLK_RW_ASYNC
])
2229 * If this is an async queue and we have sync IO in flight, let it wait
2231 if (cfqd
->sync_flight
&& !cfq_cfqq_sync(cfqq
))
2234 max_dispatch
= cfqd
->cfq_quantum
;
2235 if (cfq_class_idle(cfqq
))
2239 * Does this cfqq already have too much IO in flight?
2241 if (cfqq
->dispatched
>= max_dispatch
) {
2243 * idle queue must always only have a single IO in flight
2245 if (cfq_class_idle(cfqq
))
2249 * We have other queues, don't allow more IO from this one
2251 if (cfqd
->busy_queues
> 1)
2255 * Sole queue user, no limit
2261 * Async queues must wait a bit before being allowed dispatch.
2262 * We also ramp up the dispatch depth gradually for async IO,
2263 * based on the last sync IO we serviced
2265 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2266 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2269 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2270 if (!depth
&& !cfqq
->dispatched
)
2272 if (depth
< max_dispatch
)
2273 max_dispatch
= depth
;
2277 * If we're below the current max, allow a dispatch
2279 return cfqq
->dispatched
< max_dispatch
;
2283 * Dispatch a request from cfqq, moving them to the request queue
2286 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2290 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2292 if (!cfq_may_dispatch(cfqd
, cfqq
))
2296 * follow expired path, else get first next available
2298 rq
= cfq_check_fifo(cfqq
);
2303 * insert request into driver dispatch list
2305 cfq_dispatch_insert(cfqd
->queue
, rq
);
2307 if (!cfqd
->active_cic
) {
2308 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2310 atomic_long_inc(&cic
->ioc
->refcount
);
2311 cfqd
->active_cic
= cic
;
2318 * Find the cfqq that we need to service and move a request from that to the
2321 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2323 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2324 struct cfq_queue
*cfqq
;
2326 if (!cfqd
->busy_queues
)
2329 if (unlikely(force
))
2330 return cfq_forced_dispatch(cfqd
);
2332 cfqq
= cfq_select_queue(cfqd
);
2337 * Dispatch a request from this cfqq, if it is allowed
2339 if (!cfq_dispatch_request(cfqd
, cfqq
))
2342 cfqq
->slice_dispatch
++;
2343 cfq_clear_cfqq_must_dispatch(cfqq
);
2346 * expire an async queue immediately if it has used up its slice. idle
2347 * queue always expire after 1 dispatch round.
2349 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2350 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2351 cfq_class_idle(cfqq
))) {
2352 cfqq
->slice_end
= jiffies
+ 1;
2353 cfq_slice_expired(cfqd
, 0);
2356 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2361 * task holds one reference to the queue, dropped when task exits. each rq
2362 * in-flight on this queue also holds a reference, dropped when rq is freed.
2364 * Each cfq queue took a reference on the parent group. Drop it now.
2365 * queue lock must be held here.
2367 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2369 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2370 struct cfq_group
*cfqg
, *orig_cfqg
;
2372 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
2374 if (!atomic_dec_and_test(&cfqq
->ref
))
2377 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2378 BUG_ON(rb_first(&cfqq
->sort_list
));
2379 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2381 orig_cfqg
= cfqq
->orig_cfqg
;
2383 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2384 __cfq_slice_expired(cfqd
, cfqq
, 0);
2385 cfq_schedule_dispatch(cfqd
);
2388 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2389 kmem_cache_free(cfq_pool
, cfqq
);
2392 cfq_put_cfqg(orig_cfqg
);
2396 * Must always be called with the rcu_read_lock() held
2399 __call_for_each_cic(struct io_context
*ioc
,
2400 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2402 struct cfq_io_context
*cic
;
2403 struct hlist_node
*n
;
2405 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
2410 * Call func for each cic attached to this ioc.
2413 call_for_each_cic(struct io_context
*ioc
,
2414 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2417 __call_for_each_cic(ioc
, func
);
2421 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2423 struct cfq_io_context
*cic
;
2425 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
2427 kmem_cache_free(cfq_ioc_pool
, cic
);
2428 elv_ioc_count_dec(cfq_ioc_count
);
2432 * CFQ scheduler is exiting, grab exit lock and check
2433 * the pending io context count. If it hits zero,
2434 * complete ioc_gone and set it back to NULL
2436 spin_lock(&ioc_gone_lock
);
2437 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
2441 spin_unlock(&ioc_gone_lock
);
2445 static void cfq_cic_free(struct cfq_io_context
*cic
)
2447 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2450 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2452 unsigned long flags
;
2454 BUG_ON(!cic
->dead_key
);
2456 spin_lock_irqsave(&ioc
->lock
, flags
);
2457 radix_tree_delete(&ioc
->radix_root
, cic
->dead_key
);
2458 hlist_del_rcu(&cic
->cic_list
);
2459 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2465 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2466 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2467 * and ->trim() which is called with the task lock held
2469 static void cfq_free_io_context(struct io_context
*ioc
)
2472 * ioc->refcount is zero here, or we are called from elv_unregister(),
2473 * so no more cic's are allowed to be linked into this ioc. So it
2474 * should be ok to iterate over the known list, we will see all cic's
2475 * since no new ones are added.
2477 __call_for_each_cic(ioc
, cic_free_func
);
2480 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2482 struct cfq_queue
*__cfqq
, *next
;
2484 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2485 __cfq_slice_expired(cfqd
, cfqq
, 0);
2486 cfq_schedule_dispatch(cfqd
);
2490 * If this queue was scheduled to merge with another queue, be
2491 * sure to drop the reference taken on that queue (and others in
2492 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2494 __cfqq
= cfqq
->new_cfqq
;
2496 if (__cfqq
== cfqq
) {
2497 WARN(1, "cfqq->new_cfqq loop detected\n");
2500 next
= __cfqq
->new_cfqq
;
2501 cfq_put_queue(__cfqq
);
2505 cfq_put_queue(cfqq
);
2508 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
2509 struct cfq_io_context
*cic
)
2511 struct io_context
*ioc
= cic
->ioc
;
2513 list_del_init(&cic
->queue_list
);
2516 * Make sure key == NULL is seen for dead queues
2519 cic
->dead_key
= (unsigned long) cic
->key
;
2522 if (ioc
->ioc_data
== cic
)
2523 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2525 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2526 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2527 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2530 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2531 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2532 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2536 static void cfq_exit_single_io_context(struct io_context
*ioc
,
2537 struct cfq_io_context
*cic
)
2539 struct cfq_data
*cfqd
= cic
->key
;
2542 struct request_queue
*q
= cfqd
->queue
;
2543 unsigned long flags
;
2545 spin_lock_irqsave(q
->queue_lock
, flags
);
2548 * Ensure we get a fresh copy of the ->key to prevent
2549 * race between exiting task and queue
2551 smp_read_barrier_depends();
2553 __cfq_exit_single_io_context(cfqd
, cic
);
2555 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2560 * The process that ioc belongs to has exited, we need to clean up
2561 * and put the internal structures we have that belongs to that process.
2563 static void cfq_exit_io_context(struct io_context
*ioc
)
2565 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
2568 static struct cfq_io_context
*
2569 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2571 struct cfq_io_context
*cic
;
2573 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2576 cic
->last_end_request
= jiffies
;
2577 INIT_LIST_HEAD(&cic
->queue_list
);
2578 INIT_HLIST_NODE(&cic
->cic_list
);
2579 cic
->dtor
= cfq_free_io_context
;
2580 cic
->exit
= cfq_exit_io_context
;
2581 elv_ioc_count_inc(cfq_ioc_count
);
2587 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2589 struct task_struct
*tsk
= current
;
2592 if (!cfq_cfqq_prio_changed(cfqq
))
2595 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2596 switch (ioprio_class
) {
2598 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2599 case IOPRIO_CLASS_NONE
:
2601 * no prio set, inherit CPU scheduling settings
2603 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2604 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2606 case IOPRIO_CLASS_RT
:
2607 cfqq
->ioprio
= task_ioprio(ioc
);
2608 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2610 case IOPRIO_CLASS_BE
:
2611 cfqq
->ioprio
= task_ioprio(ioc
);
2612 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2614 case IOPRIO_CLASS_IDLE
:
2615 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2617 cfq_clear_cfqq_idle_window(cfqq
);
2622 * keep track of original prio settings in case we have to temporarily
2623 * elevate the priority of this queue
2625 cfqq
->org_ioprio
= cfqq
->ioprio
;
2626 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2627 cfq_clear_cfqq_prio_changed(cfqq
);
2630 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2632 struct cfq_data
*cfqd
= cic
->key
;
2633 struct cfq_queue
*cfqq
;
2634 unsigned long flags
;
2636 if (unlikely(!cfqd
))
2639 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2641 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2643 struct cfq_queue
*new_cfqq
;
2644 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2647 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2648 cfq_put_queue(cfqq
);
2652 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2654 cfq_mark_cfqq_prio_changed(cfqq
);
2656 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2659 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2661 call_for_each_cic(ioc
, changed_ioprio
);
2662 ioc
->ioprio_changed
= 0;
2665 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2666 pid_t pid
, bool is_sync
)
2668 RB_CLEAR_NODE(&cfqq
->rb_node
);
2669 RB_CLEAR_NODE(&cfqq
->p_node
);
2670 INIT_LIST_HEAD(&cfqq
->fifo
);
2672 atomic_set(&cfqq
->ref
, 0);
2675 cfq_mark_cfqq_prio_changed(cfqq
);
2678 if (!cfq_class_idle(cfqq
))
2679 cfq_mark_cfqq_idle_window(cfqq
);
2680 cfq_mark_cfqq_sync(cfqq
);
2685 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2686 static void changed_cgroup(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2688 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2689 struct cfq_data
*cfqd
= cic
->key
;
2690 unsigned long flags
;
2691 struct request_queue
*q
;
2693 if (unlikely(!cfqd
))
2698 spin_lock_irqsave(q
->queue_lock
, flags
);
2702 * Drop reference to sync queue. A new sync queue will be
2703 * assigned in new group upon arrival of a fresh request.
2705 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2706 cic_set_cfqq(cic
, NULL
, 1);
2707 cfq_put_queue(sync_cfqq
);
2710 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2713 static void cfq_ioc_set_cgroup(struct io_context
*ioc
)
2715 call_for_each_cic(ioc
, changed_cgroup
);
2716 ioc
->cgroup_changed
= 0;
2718 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2720 static struct cfq_queue
*
2721 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2722 struct io_context
*ioc
, gfp_t gfp_mask
)
2724 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2725 struct cfq_io_context
*cic
;
2726 struct cfq_group
*cfqg
;
2729 cfqg
= cfq_get_cfqg(cfqd
, 1);
2730 cic
= cfq_cic_lookup(cfqd
, ioc
);
2731 /* cic always exists here */
2732 cfqq
= cic_to_cfqq(cic
, is_sync
);
2735 * Always try a new alloc if we fell back to the OOM cfqq
2736 * originally, since it should just be a temporary situation.
2738 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2743 } else if (gfp_mask
& __GFP_WAIT
) {
2744 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2745 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2746 gfp_mask
| __GFP_ZERO
,
2748 spin_lock_irq(cfqd
->queue
->queue_lock
);
2752 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2753 gfp_mask
| __GFP_ZERO
,
2758 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2759 cfq_init_prio_data(cfqq
, ioc
);
2760 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2761 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2763 cfqq
= &cfqd
->oom_cfqq
;
2767 kmem_cache_free(cfq_pool
, new_cfqq
);
2772 static struct cfq_queue
**
2773 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2775 switch (ioprio_class
) {
2776 case IOPRIO_CLASS_RT
:
2777 return &cfqd
->async_cfqq
[0][ioprio
];
2778 case IOPRIO_CLASS_BE
:
2779 return &cfqd
->async_cfqq
[1][ioprio
];
2780 case IOPRIO_CLASS_IDLE
:
2781 return &cfqd
->async_idle_cfqq
;
2787 static struct cfq_queue
*
2788 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2791 const int ioprio
= task_ioprio(ioc
);
2792 const int ioprio_class
= task_ioprio_class(ioc
);
2793 struct cfq_queue
**async_cfqq
= NULL
;
2794 struct cfq_queue
*cfqq
= NULL
;
2797 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2802 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2805 * pin the queue now that it's allocated, scheduler exit will prune it
2807 if (!is_sync
&& !(*async_cfqq
)) {
2808 atomic_inc(&cfqq
->ref
);
2812 atomic_inc(&cfqq
->ref
);
2817 * We drop cfq io contexts lazily, so we may find a dead one.
2820 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2821 struct cfq_io_context
*cic
)
2823 unsigned long flags
;
2825 WARN_ON(!list_empty(&cic
->queue_list
));
2827 spin_lock_irqsave(&ioc
->lock
, flags
);
2829 BUG_ON(ioc
->ioc_data
== cic
);
2831 radix_tree_delete(&ioc
->radix_root
, (unsigned long) cfqd
);
2832 hlist_del_rcu(&cic
->cic_list
);
2833 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2838 static struct cfq_io_context
*
2839 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
2841 struct cfq_io_context
*cic
;
2842 unsigned long flags
;
2851 * we maintain a last-hit cache, to avoid browsing over the tree
2853 cic
= rcu_dereference(ioc
->ioc_data
);
2854 if (cic
&& cic
->key
== cfqd
) {
2860 cic
= radix_tree_lookup(&ioc
->radix_root
, (unsigned long) cfqd
);
2864 /* ->key must be copied to avoid race with cfq_exit_queue() */
2867 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
2872 spin_lock_irqsave(&ioc
->lock
, flags
);
2873 rcu_assign_pointer(ioc
->ioc_data
, cic
);
2874 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2882 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2883 * the process specific cfq io context when entered from the block layer.
2884 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2886 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2887 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
2889 unsigned long flags
;
2892 ret
= radix_tree_preload(gfp_mask
);
2897 spin_lock_irqsave(&ioc
->lock
, flags
);
2898 ret
= radix_tree_insert(&ioc
->radix_root
,
2899 (unsigned long) cfqd
, cic
);
2901 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
2902 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2904 radix_tree_preload_end();
2907 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2908 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
2909 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2914 printk(KERN_ERR
"cfq: cic link failed!\n");
2920 * Setup general io context and cfq io context. There can be several cfq
2921 * io contexts per general io context, if this process is doing io to more
2922 * than one device managed by cfq.
2924 static struct cfq_io_context
*
2925 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2927 struct io_context
*ioc
= NULL
;
2928 struct cfq_io_context
*cic
;
2930 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2932 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
2936 cic
= cfq_cic_lookup(cfqd
, ioc
);
2940 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
2944 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
2948 smp_read_barrier_depends();
2949 if (unlikely(ioc
->ioprio_changed
))
2950 cfq_ioc_set_ioprio(ioc
);
2952 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2953 if (unlikely(ioc
->cgroup_changed
))
2954 cfq_ioc_set_cgroup(ioc
);
2960 put_io_context(ioc
);
2965 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
2967 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
2968 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
2970 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
2971 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
2972 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
2976 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2982 if (!cfqq
->last_request_pos
)
2984 else if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
2985 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
2987 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
2990 * Don't allow the seek distance to get too large from the
2991 * odd fragment, pagein, etc
2993 if (cfqq
->seek_samples
<= 60) /* second&third seek */
2994 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*1024);
2996 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*64);
2998 cfqq
->seek_samples
= (7*cfqq
->seek_samples
+ 256) / 8;
2999 cfqq
->seek_total
= (7*cfqq
->seek_total
+ (u64
)256*sdist
) / 8;
3000 total
= cfqq
->seek_total
+ (cfqq
->seek_samples
/2);
3001 do_div(total
, cfqq
->seek_samples
);
3002 cfqq
->seek_mean
= (sector_t
)total
;
3005 * If this cfqq is shared between multiple processes, check to
3006 * make sure that those processes are still issuing I/Os within
3007 * the mean seek distance. If not, it may be time to break the
3008 * queues apart again.
3010 if (cfq_cfqq_coop(cfqq
)) {
3011 if (CFQQ_SEEKY(cfqq
) && !cfqq
->seeky_start
)
3012 cfqq
->seeky_start
= jiffies
;
3013 else if (!CFQQ_SEEKY(cfqq
))
3014 cfqq
->seeky_start
= 0;
3019 * Disable idle window if the process thinks too long or seeks so much that
3023 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3024 struct cfq_io_context
*cic
)
3026 int old_idle
, enable_idle
;
3029 * Don't idle for async or idle io prio class
3031 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3034 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3036 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3037 cfq_mark_cfqq_deep(cfqq
);
3039 if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3040 (!cfq_cfqq_deep(cfqq
) && sample_valid(cfqq
->seek_samples
)
3041 && CFQQ_SEEKY(cfqq
)))
3043 else if (sample_valid(cic
->ttime_samples
)) {
3044 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
3050 if (old_idle
!= enable_idle
) {
3051 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3053 cfq_mark_cfqq_idle_window(cfqq
);
3055 cfq_clear_cfqq_idle_window(cfqq
);
3060 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3061 * no or if we aren't sure, a 1 will cause a preempt.
3064 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3067 struct cfq_queue
*cfqq
;
3069 cfqq
= cfqd
->active_queue
;
3073 if (cfq_class_idle(new_cfqq
))
3076 if (cfq_class_idle(cfqq
))
3080 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3082 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3086 * if the new request is sync, but the currently running queue is
3087 * not, let the sync request have priority.
3089 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3092 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3095 if (cfq_slice_used(cfqq
))
3098 /* Allow preemption only if we are idling on sync-noidle tree */
3099 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3100 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3101 new_cfqq
->service_tree
->count
== 2 &&
3102 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3106 * So both queues are sync. Let the new request get disk time if
3107 * it's a metadata request and the current queue is doing regular IO.
3109 if (rq_is_meta(rq
) && !cfqq
->meta_pending
)
3113 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3115 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3118 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3122 * if this request is as-good as one we would expect from the
3123 * current cfqq, let it preempt
3125 if (cfq_rq_close(cfqd
, cfqq
, rq
, true))
3132 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3133 * let it have half of its nominal slice.
3135 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3137 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3138 cfq_slice_expired(cfqd
, 1);
3141 * Put the new queue at the front of the of the current list,
3142 * so we know that it will be selected next.
3144 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3146 cfq_service_tree_add(cfqd
, cfqq
, 1);
3148 cfqq
->slice_end
= 0;
3149 cfq_mark_cfqq_slice_new(cfqq
);
3153 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3154 * something we should do about it
3157 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3160 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3164 cfqq
->meta_pending
++;
3166 cfq_update_io_thinktime(cfqd
, cic
);
3167 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3168 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3170 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3172 if (cfqq
== cfqd
->active_queue
) {
3174 * Remember that we saw a request from this process, but
3175 * don't start queuing just yet. Otherwise we risk seeing lots
3176 * of tiny requests, because we disrupt the normal plugging
3177 * and merging. If the request is already larger than a single
3178 * page, let it rip immediately. For that case we assume that
3179 * merging is already done. Ditto for a busy system that
3180 * has other work pending, don't risk delaying until the
3181 * idle timer unplug to continue working.
3183 if (cfq_cfqq_wait_request(cfqq
)) {
3184 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3185 cfqd
->busy_queues
> 1) {
3186 del_timer(&cfqd
->idle_slice_timer
);
3187 cfq_clear_cfqq_wait_request(cfqq
);
3188 __blk_run_queue(cfqd
->queue
);
3190 cfq_mark_cfqq_must_dispatch(cfqq
);
3192 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3194 * not the active queue - expire current slice if it is
3195 * idle and has expired it's mean thinktime or this new queue
3196 * has some old slice time left and is of higher priority or
3197 * this new queue is RT and the current one is BE
3199 cfq_preempt_queue(cfqd
, cfqq
);
3200 __blk_run_queue(cfqd
->queue
);
3204 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3206 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3207 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3209 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3210 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3212 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3213 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3216 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3220 * Update hw_tag based on peak queue depth over 50 samples under
3223 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3225 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3227 if (rq_in_driver(cfqd
) > cfqd
->hw_tag_est_depth
)
3228 cfqd
->hw_tag_est_depth
= rq_in_driver(cfqd
);
3230 if (cfqd
->hw_tag
== 1)
3233 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3234 rq_in_driver(cfqd
) <= CFQ_HW_QUEUE_MIN
)
3238 * If active queue hasn't enough requests and can idle, cfq might not
3239 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3242 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3243 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3244 CFQ_HW_QUEUE_MIN
&& rq_in_driver(cfqd
) < CFQ_HW_QUEUE_MIN
)
3247 if (cfqd
->hw_tag_samples
++ < 50)
3250 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3256 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3258 struct cfq_io_context
*cic
= cfqd
->active_cic
;
3260 /* If there are other queues in the group, don't wait */
3261 if (cfqq
->cfqg
->nr_cfqq
> 1)
3264 if (cfq_slice_used(cfqq
))
3267 /* if slice left is less than think time, wait busy */
3268 if (cic
&& sample_valid(cic
->ttime_samples
)
3269 && (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
3273 * If think times is less than a jiffy than ttime_mean=0 and above
3274 * will not be true. It might happen that slice has not expired yet
3275 * but will expire soon (4-5 ns) during select_queue(). To cover the
3276 * case where think time is less than a jiffy, mark the queue wait
3277 * busy if only 1 jiffy is left in the slice.
3279 if (cfqq
->slice_end
- jiffies
== 1)
3285 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3287 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3288 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3289 const int sync
= rq_is_sync(rq
);
3293 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d", !!rq_noidle(rq
));
3295 cfq_update_hw_tag(cfqd
);
3297 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
3298 WARN_ON(!cfqq
->dispatched
);
3299 cfqd
->rq_in_driver
[sync
]--;
3302 if (cfq_cfqq_sync(cfqq
))
3303 cfqd
->sync_flight
--;
3306 RQ_CIC(rq
)->last_end_request
= now
;
3307 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3308 cfqd
->last_delayed_sync
= now
;
3312 * If this is the active queue, check if it needs to be expired,
3313 * or if we want to idle in case it has no pending requests.
3315 if (cfqd
->active_queue
== cfqq
) {
3316 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3318 if (cfq_cfqq_slice_new(cfqq
)) {
3319 cfq_set_prio_slice(cfqd
, cfqq
);
3320 cfq_clear_cfqq_slice_new(cfqq
);
3324 * Should we wait for next request to come in before we expire
3327 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3328 cfqq
->slice_end
= jiffies
+ cfqd
->cfq_slice_idle
;
3329 cfq_mark_cfqq_wait_busy(cfqq
);
3333 * Idling is not enabled on:
3335 * - idle-priority queues
3337 * - queues with still some requests queued
3338 * - when there is a close cooperator
3340 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3341 cfq_slice_expired(cfqd
, 1);
3342 else if (sync
&& cfqq_empty
&&
3343 !cfq_close_cooperator(cfqd
, cfqq
)) {
3344 cfqd
->noidle_tree_requires_idle
|= !rq_noidle(rq
);
3346 * Idling is enabled for SYNC_WORKLOAD.
3347 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
3348 * only if we processed at least one !rq_noidle request
3350 if (cfqd
->serving_type
== SYNC_WORKLOAD
3351 || cfqd
->noidle_tree_requires_idle
3352 || cfqq
->cfqg
->nr_cfqq
== 1)
3353 cfq_arm_slice_timer(cfqd
);
3357 if (!rq_in_driver(cfqd
))
3358 cfq_schedule_dispatch(cfqd
);
3362 * we temporarily boost lower priority queues if they are holding fs exclusive
3363 * resources. they are boosted to normal prio (CLASS_BE/4)
3365 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
3367 if (has_fs_excl()) {
3369 * boost idle prio on transactions that would lock out other
3370 * users of the filesystem
3372 if (cfq_class_idle(cfqq
))
3373 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3374 if (cfqq
->ioprio
> IOPRIO_NORM
)
3375 cfqq
->ioprio
= IOPRIO_NORM
;
3378 * unboost the queue (if needed)
3380 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
3381 cfqq
->ioprio
= cfqq
->org_ioprio
;
3385 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3387 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3388 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3389 return ELV_MQUEUE_MUST
;
3392 return ELV_MQUEUE_MAY
;
3395 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3397 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3398 struct task_struct
*tsk
= current
;
3399 struct cfq_io_context
*cic
;
3400 struct cfq_queue
*cfqq
;
3403 * don't force setup of a queue from here, as a call to may_queue
3404 * does not necessarily imply that a request actually will be queued.
3405 * so just lookup a possibly existing queue, or return 'may queue'
3408 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3410 return ELV_MQUEUE_MAY
;
3412 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3414 cfq_init_prio_data(cfqq
, cic
->ioc
);
3415 cfq_prio_boost(cfqq
);
3417 return __cfq_may_queue(cfqq
);
3420 return ELV_MQUEUE_MAY
;
3424 * queue lock held here
3426 static void cfq_put_request(struct request
*rq
)
3428 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3431 const int rw
= rq_data_dir(rq
);
3433 BUG_ON(!cfqq
->allocated
[rw
]);
3434 cfqq
->allocated
[rw
]--;
3436 put_io_context(RQ_CIC(rq
)->ioc
);
3438 rq
->elevator_private
= NULL
;
3439 rq
->elevator_private2
= NULL
;
3441 cfq_put_queue(cfqq
);
3445 static struct cfq_queue
*
3446 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3447 struct cfq_queue
*cfqq
)
3449 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3450 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3451 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3452 cfq_put_queue(cfqq
);
3453 return cic_to_cfqq(cic
, 1);
3456 static int should_split_cfqq(struct cfq_queue
*cfqq
)
3458 if (cfqq
->seeky_start
&&
3459 time_after(jiffies
, cfqq
->seeky_start
+ CFQQ_COOP_TOUT
))
3465 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3466 * was the last process referring to said cfqq.
3468 static struct cfq_queue
*
3469 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3471 if (cfqq_process_refs(cfqq
) == 1) {
3472 cfqq
->seeky_start
= 0;
3473 cfqq
->pid
= current
->pid
;
3474 cfq_clear_cfqq_coop(cfqq
);
3478 cic_set_cfqq(cic
, NULL
, 1);
3479 cfq_put_queue(cfqq
);
3483 * Allocate cfq data structures associated with this request.
3486 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3488 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3489 struct cfq_io_context
*cic
;
3490 const int rw
= rq_data_dir(rq
);
3491 const bool is_sync
= rq_is_sync(rq
);
3492 struct cfq_queue
*cfqq
;
3493 unsigned long flags
;
3495 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3497 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3499 spin_lock_irqsave(q
->queue_lock
, flags
);
3505 cfqq
= cic_to_cfqq(cic
, is_sync
);
3506 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3507 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3508 cic_set_cfqq(cic
, cfqq
, is_sync
);
3511 * If the queue was seeky for too long, break it apart.
3513 if (cfq_cfqq_coop(cfqq
) && should_split_cfqq(cfqq
)) {
3514 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3515 cfqq
= split_cfqq(cic
, cfqq
);
3521 * Check to see if this queue is scheduled to merge with
3522 * another, closely cooperating queue. The merging of
3523 * queues happens here as it must be done in process context.
3524 * The reference on new_cfqq was taken in merge_cfqqs.
3527 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3530 cfqq
->allocated
[rw
]++;
3531 atomic_inc(&cfqq
->ref
);
3533 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3535 rq
->elevator_private
= cic
;
3536 rq
->elevator_private2
= cfqq
;
3541 put_io_context(cic
->ioc
);
3543 cfq_schedule_dispatch(cfqd
);
3544 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3545 cfq_log(cfqd
, "set_request fail");
3549 static void cfq_kick_queue(struct work_struct
*work
)
3551 struct cfq_data
*cfqd
=
3552 container_of(work
, struct cfq_data
, unplug_work
);
3553 struct request_queue
*q
= cfqd
->queue
;
3555 spin_lock_irq(q
->queue_lock
);
3556 __blk_run_queue(cfqd
->queue
);
3557 spin_unlock_irq(q
->queue_lock
);
3561 * Timer running if the active_queue is currently idling inside its time slice
3563 static void cfq_idle_slice_timer(unsigned long data
)
3565 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3566 struct cfq_queue
*cfqq
;
3567 unsigned long flags
;
3570 cfq_log(cfqd
, "idle timer fired");
3572 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3574 cfqq
= cfqd
->active_queue
;
3579 * We saw a request before the queue expired, let it through
3581 if (cfq_cfqq_must_dispatch(cfqq
))
3587 if (cfq_slice_used(cfqq
))
3591 * only expire and reinvoke request handler, if there are
3592 * other queues with pending requests
3594 if (!cfqd
->busy_queues
)
3598 * not expired and it has a request pending, let it dispatch
3600 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3604 * Queue depth flag is reset only when the idle didn't succeed
3606 cfq_clear_cfqq_deep(cfqq
);
3609 cfq_slice_expired(cfqd
, timed_out
);
3611 cfq_schedule_dispatch(cfqd
);
3613 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3616 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3618 del_timer_sync(&cfqd
->idle_slice_timer
);
3619 cancel_work_sync(&cfqd
->unplug_work
);
3622 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3626 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3627 if (cfqd
->async_cfqq
[0][i
])
3628 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3629 if (cfqd
->async_cfqq
[1][i
])
3630 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3633 if (cfqd
->async_idle_cfqq
)
3634 cfq_put_queue(cfqd
->async_idle_cfqq
);
3637 static void cfq_cfqd_free(struct rcu_head
*head
)
3639 kfree(container_of(head
, struct cfq_data
, rcu
));
3642 static void cfq_exit_queue(struct elevator_queue
*e
)
3644 struct cfq_data
*cfqd
= e
->elevator_data
;
3645 struct request_queue
*q
= cfqd
->queue
;
3647 cfq_shutdown_timer_wq(cfqd
);
3649 spin_lock_irq(q
->queue_lock
);
3651 if (cfqd
->active_queue
)
3652 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3654 while (!list_empty(&cfqd
->cic_list
)) {
3655 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3656 struct cfq_io_context
,
3659 __cfq_exit_single_io_context(cfqd
, cic
);
3662 cfq_put_async_queues(cfqd
);
3663 cfq_release_cfq_groups(cfqd
);
3664 blkiocg_del_blkio_group(&cfqd
->root_group
.blkg
);
3666 spin_unlock_irq(q
->queue_lock
);
3668 cfq_shutdown_timer_wq(cfqd
);
3670 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3671 call_rcu(&cfqd
->rcu
, cfq_cfqd_free
);
3674 static void *cfq_init_queue(struct request_queue
*q
)
3676 struct cfq_data
*cfqd
;
3678 struct cfq_group
*cfqg
;
3679 struct cfq_rb_root
*st
;
3681 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3685 /* Init root service tree */
3686 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3688 /* Init root group */
3689 cfqg
= &cfqd
->root_group
;
3690 for_each_cfqg_st(cfqg
, i
, j
, st
)
3692 RB_CLEAR_NODE(&cfqg
->rb_node
);
3694 /* Give preference to root group over other groups */
3695 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3697 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3699 * Take a reference to root group which we never drop. This is just
3700 * to make sure that cfq_put_cfqg() does not try to kfree root group
3702 atomic_set(&cfqg
->ref
, 1);
3703 blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
, (void *)cfqd
,
3707 * Not strictly needed (since RB_ROOT just clears the node and we
3708 * zeroed cfqd on alloc), but better be safe in case someone decides
3709 * to add magic to the rb code
3711 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3712 cfqd
->prio_trees
[i
] = RB_ROOT
;
3715 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3716 * Grab a permanent reference to it, so that the normal code flow
3717 * will not attempt to free it.
3719 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3720 atomic_inc(&cfqd
->oom_cfqq
.ref
);
3721 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3723 INIT_LIST_HEAD(&cfqd
->cic_list
);
3727 init_timer(&cfqd
->idle_slice_timer
);
3728 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3729 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3731 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3733 cfqd
->cfq_quantum
= cfq_quantum
;
3734 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3735 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3736 cfqd
->cfq_back_max
= cfq_back_max
;
3737 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3738 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3739 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3740 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3741 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3742 cfqd
->cfq_latency
= 1;
3743 cfqd
->cfq_group_isolation
= 0;
3746 * we optimistically start assuming sync ops weren't delayed in last
3747 * second, in order to have larger depth for async operations.
3749 cfqd
->last_delayed_sync
= jiffies
- HZ
;
3750 INIT_RCU_HEAD(&cfqd
->rcu
);
3754 static void cfq_slab_kill(void)
3757 * Caller already ensured that pending RCU callbacks are completed,
3758 * so we should have no busy allocations at this point.
3761 kmem_cache_destroy(cfq_pool
);
3763 kmem_cache_destroy(cfq_ioc_pool
);
3766 static int __init
cfq_slab_setup(void)
3768 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3772 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3783 * sysfs parts below -->
3786 cfq_var_show(unsigned int var
, char *page
)
3788 return sprintf(page
, "%d\n", var
);
3792 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3794 char *p
= (char *) page
;
3796 *var
= simple_strtoul(p
, &p
, 10);
3800 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3801 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3803 struct cfq_data *cfqd = e->elevator_data; \
3804 unsigned int __data = __VAR; \
3806 __data = jiffies_to_msecs(__data); \
3807 return cfq_var_show(__data, (page)); \
3809 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3810 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3811 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3812 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3813 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3814 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3815 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
3816 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
3817 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
3818 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
3819 SHOW_FUNCTION(cfq_group_isolation_show
, cfqd
->cfq_group_isolation
, 0);
3820 #undef SHOW_FUNCTION
3822 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3823 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3825 struct cfq_data *cfqd = e->elevator_data; \
3826 unsigned int __data; \
3827 int ret = cfq_var_store(&__data, (page), count); \
3828 if (__data < (MIN)) \
3830 else if (__data > (MAX)) \
3833 *(__PTR) = msecs_to_jiffies(__data); \
3835 *(__PTR) = __data; \
3838 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
3839 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
3841 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
3843 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
3844 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
3846 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
3847 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
3848 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
3849 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
3851 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
3852 STORE_FUNCTION(cfq_group_isolation_store
, &cfqd
->cfq_group_isolation
, 0, 1, 0);
3853 #undef STORE_FUNCTION
3855 #define CFQ_ATTR(name) \
3856 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3858 static struct elv_fs_entry cfq_attrs
[] = {
3860 CFQ_ATTR(fifo_expire_sync
),
3861 CFQ_ATTR(fifo_expire_async
),
3862 CFQ_ATTR(back_seek_max
),
3863 CFQ_ATTR(back_seek_penalty
),
3864 CFQ_ATTR(slice_sync
),
3865 CFQ_ATTR(slice_async
),
3866 CFQ_ATTR(slice_async_rq
),
3867 CFQ_ATTR(slice_idle
),
3868 CFQ_ATTR(low_latency
),
3869 CFQ_ATTR(group_isolation
),
3873 static struct elevator_type iosched_cfq
= {
3875 .elevator_merge_fn
= cfq_merge
,
3876 .elevator_merged_fn
= cfq_merged_request
,
3877 .elevator_merge_req_fn
= cfq_merged_requests
,
3878 .elevator_allow_merge_fn
= cfq_allow_merge
,
3879 .elevator_dispatch_fn
= cfq_dispatch_requests
,
3880 .elevator_add_req_fn
= cfq_insert_request
,
3881 .elevator_activate_req_fn
= cfq_activate_request
,
3882 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
3883 .elevator_queue_empty_fn
= cfq_queue_empty
,
3884 .elevator_completed_req_fn
= cfq_completed_request
,
3885 .elevator_former_req_fn
= elv_rb_former_request
,
3886 .elevator_latter_req_fn
= elv_rb_latter_request
,
3887 .elevator_set_req_fn
= cfq_set_request
,
3888 .elevator_put_req_fn
= cfq_put_request
,
3889 .elevator_may_queue_fn
= cfq_may_queue
,
3890 .elevator_init_fn
= cfq_init_queue
,
3891 .elevator_exit_fn
= cfq_exit_queue
,
3892 .trim
= cfq_free_io_context
,
3894 .elevator_attrs
= cfq_attrs
,
3895 .elevator_name
= "cfq",
3896 .elevator_owner
= THIS_MODULE
,
3899 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3900 static struct blkio_policy_type blkio_policy_cfq
= {
3902 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
3903 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
3907 static struct blkio_policy_type blkio_policy_cfq
;
3910 static int __init
cfq_init(void)
3913 * could be 0 on HZ < 1000 setups
3915 if (!cfq_slice_async
)
3916 cfq_slice_async
= 1;
3917 if (!cfq_slice_idle
)
3920 if (cfq_slab_setup())
3923 elv_register(&iosched_cfq
);
3924 blkio_policy_register(&blkio_policy_cfq
);
3929 static void __exit
cfq_exit(void)
3931 DECLARE_COMPLETION_ONSTACK(all_gone
);
3932 blkio_policy_unregister(&blkio_policy_cfq
);
3933 elv_unregister(&iosched_cfq
);
3934 ioc_gone
= &all_gone
;
3935 /* ioc_gone's update must be visible before reading ioc_count */
3939 * this also protects us from entering cfq_slab_kill() with
3940 * pending RCU callbacks
3942 if (elv_ioc_count_read(cfq_ioc_count
))
3943 wait_for_completion(&all_gone
);
3947 module_init(cfq_init
);
3948 module_exit(cfq_exit
);
3950 MODULE_AUTHOR("Jens Axboe");
3951 MODULE_LICENSE("GPL");
3952 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");