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
;
211 /* Number of active cfq groups on group service tree */
215 * The priority currently being served
217 enum wl_prio_t serving_prio
;
218 enum wl_type_t serving_type
;
219 unsigned long workload_expires
;
220 struct cfq_group
*serving_group
;
221 bool noidle_tree_requires_idle
;
224 * Each priority tree is sorted by next_request position. These
225 * trees are used when determining if two or more queues are
226 * interleaving requests (see cfq_close_cooperator).
228 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
230 unsigned int busy_queues
;
236 * queue-depth detection
242 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
243 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
246 int hw_tag_est_depth
;
247 unsigned int hw_tag_samples
;
250 * idle window management
252 struct timer_list idle_slice_timer
;
253 struct work_struct unplug_work
;
255 struct cfq_queue
*active_queue
;
256 struct cfq_io_context
*active_cic
;
259 * async queue for each priority case
261 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
262 struct cfq_queue
*async_idle_cfqq
;
264 sector_t last_position
;
267 * tunables, see top of file
269 unsigned int cfq_quantum
;
270 unsigned int cfq_fifo_expire
[2];
271 unsigned int cfq_back_penalty
;
272 unsigned int cfq_back_max
;
273 unsigned int cfq_slice
[2];
274 unsigned int cfq_slice_async_rq
;
275 unsigned int cfq_slice_idle
;
276 unsigned int cfq_latency
;
277 unsigned int cfq_group_isolation
;
279 struct list_head cic_list
;
282 * Fallback dummy cfqq for extreme OOM conditions
284 struct cfq_queue oom_cfqq
;
286 unsigned long last_end_sync_rq
;
288 /* List of cfq groups being managed on this device*/
289 struct hlist_head cfqg_list
;
292 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
294 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
297 struct cfq_data
*cfqd
)
302 if (prio
== IDLE_WORKLOAD
)
303 return &cfqg
->service_tree_idle
;
305 return &cfqg
->service_trees
[prio
][type
];
308 enum cfqq_state_flags
{
309 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
310 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
311 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
312 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
313 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
314 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
315 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
316 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
317 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
318 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
319 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
320 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
321 CFQ_CFQQ_FLAG_wait_busy_done
, /* Got new request. Expire the queue */
324 #define CFQ_CFQQ_FNS(name) \
325 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
327 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
329 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
331 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
333 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
335 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
339 CFQ_CFQQ_FNS(wait_request
);
340 CFQ_CFQQ_FNS(must_dispatch
);
341 CFQ_CFQQ_FNS(must_alloc_slice
);
342 CFQ_CFQQ_FNS(fifo_expire
);
343 CFQ_CFQQ_FNS(idle_window
);
344 CFQ_CFQQ_FNS(prio_changed
);
345 CFQ_CFQQ_FNS(slice_new
);
349 CFQ_CFQQ_FNS(wait_busy
);
350 CFQ_CFQQ_FNS(wait_busy_done
);
353 #ifdef CONFIG_DEBUG_CFQ_IOSCHED
354 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
355 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
356 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
357 blkg_path(&(cfqq)->cfqg->blkg), ##args);
359 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
360 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
361 blkg_path(&(cfqg)->blkg), ##args); \
364 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
365 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
366 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
368 #define cfq_log(cfqd, fmt, args...) \
369 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
371 /* Traverses through cfq group service trees */
372 #define for_each_cfqg_st(cfqg, i, j, st) \
373 for (i = 0; i <= IDLE_WORKLOAD; i++) \
374 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
375 : &cfqg->service_tree_idle; \
376 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
377 (i == IDLE_WORKLOAD && j == 0); \
378 j++, st = i < IDLE_WORKLOAD ? \
379 &cfqg->service_trees[i][j]: NULL) \
382 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
384 if (cfq_class_idle(cfqq
))
385 return IDLE_WORKLOAD
;
386 if (cfq_class_rt(cfqq
))
392 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
394 if (!cfq_cfqq_sync(cfqq
))
395 return ASYNC_WORKLOAD
;
396 if (!cfq_cfqq_idle_window(cfqq
))
397 return SYNC_NOIDLE_WORKLOAD
;
398 return SYNC_WORKLOAD
;
401 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
402 struct cfq_data
*cfqd
,
403 struct cfq_group
*cfqg
)
405 if (wl
== IDLE_WORKLOAD
)
406 return cfqg
->service_tree_idle
.count
;
408 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
409 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
410 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
413 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
414 struct cfq_group
*cfqg
)
416 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
417 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
420 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
421 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
422 struct io_context
*, gfp_t
);
423 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
424 struct io_context
*);
426 static inline int rq_in_driver(struct cfq_data
*cfqd
)
428 return cfqd
->rq_in_driver
[0] + cfqd
->rq_in_driver
[1];
431 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
434 return cic
->cfqq
[is_sync
];
437 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
438 struct cfq_queue
*cfqq
, bool is_sync
)
440 cic
->cfqq
[is_sync
] = cfqq
;
444 * We regard a request as SYNC, if it's either a read or has the SYNC bit
445 * set (in which case it could also be direct WRITE).
447 static inline bool cfq_bio_sync(struct bio
*bio
)
449 return bio_data_dir(bio
) == READ
|| bio_rw_flagged(bio
, BIO_RW_SYNCIO
);
453 * scheduler run of queue, if there are requests pending and no one in the
454 * driver that will restart queueing
456 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
458 if (cfqd
->busy_queues
) {
459 cfq_log(cfqd
, "schedule dispatch");
460 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
464 static int cfq_queue_empty(struct request_queue
*q
)
466 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
468 return !cfqd
->rq_queued
;
472 * Scale schedule slice based on io priority. Use the sync time slice only
473 * if a queue is marked sync and has sync io queued. A sync queue with async
474 * io only, should not get full sync slice length.
476 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
479 const int base_slice
= cfqd
->cfq_slice
[sync
];
481 WARN_ON(prio
>= IOPRIO_BE_NR
);
483 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
487 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
489 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
492 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
494 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
496 d
= d
* BLKIO_WEIGHT_DEFAULT
;
497 do_div(d
, cfqg
->weight
);
501 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
503 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
505 min_vdisktime
= vdisktime
;
507 return min_vdisktime
;
510 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
512 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
514 min_vdisktime
= vdisktime
;
516 return min_vdisktime
;
519 static void update_min_vdisktime(struct cfq_rb_root
*st
)
521 u64 vdisktime
= st
->min_vdisktime
;
522 struct cfq_group
*cfqg
;
525 cfqg
= rb_entry_cfqg(st
->active
);
526 vdisktime
= cfqg
->vdisktime
;
530 cfqg
= rb_entry_cfqg(st
->left
);
531 vdisktime
= min_vdisktime(vdisktime
, cfqg
->vdisktime
);
534 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
, vdisktime
);
538 * get averaged number of queues of RT/BE priority.
539 * average is updated, with a formula that gives more weight to higher numbers,
540 * to quickly follows sudden increases and decrease slowly
543 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
544 struct cfq_group
*cfqg
, bool rt
)
546 unsigned min_q
, max_q
;
547 unsigned mult
= cfq_hist_divisor
- 1;
548 unsigned round
= cfq_hist_divisor
/ 2;
549 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
551 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
552 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
553 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
555 return cfqg
->busy_queues_avg
[rt
];
558 static inline unsigned
559 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
561 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
563 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
567 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
569 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
570 if (cfqd
->cfq_latency
) {
572 * interested queues (we consider only the ones with the same
573 * priority class in the cfq group)
575 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
577 unsigned sync_slice
= cfqd
->cfq_slice
[1];
578 unsigned expect_latency
= sync_slice
* iq
;
579 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
581 if (expect_latency
> group_slice
) {
582 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
583 /* scale low_slice according to IO priority
584 * and sync vs async */
586 min(slice
, base_low_slice
* slice
/ sync_slice
);
587 /* the adapted slice value is scaled to fit all iqs
588 * into the target latency */
589 slice
= max(slice
* group_slice
/ expect_latency
,
593 cfqq
->slice_start
= jiffies
;
594 cfqq
->slice_end
= jiffies
+ slice
;
595 cfqq
->allocated_slice
= slice
;
596 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
600 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
601 * isn't valid until the first request from the dispatch is activated
602 * and the slice time set.
604 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
606 if (cfq_cfqq_slice_new(cfqq
))
608 if (time_before(jiffies
, cfqq
->slice_end
))
615 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
616 * We choose the request that is closest to the head right now. Distance
617 * behind the head is penalized and only allowed to a certain extent.
619 static struct request
*
620 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
622 sector_t s1
, s2
, d1
= 0, d2
= 0;
623 unsigned long back_max
;
624 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
625 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
626 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
628 if (rq1
== NULL
|| rq1
== rq2
)
633 if (rq_is_sync(rq1
) && !rq_is_sync(rq2
))
635 else if (rq_is_sync(rq2
) && !rq_is_sync(rq1
))
637 if (rq_is_meta(rq1
) && !rq_is_meta(rq2
))
639 else if (rq_is_meta(rq2
) && !rq_is_meta(rq1
))
642 s1
= blk_rq_pos(rq1
);
643 s2
= blk_rq_pos(rq2
);
646 * by definition, 1KiB is 2 sectors
648 back_max
= cfqd
->cfq_back_max
* 2;
651 * Strict one way elevator _except_ in the case where we allow
652 * short backward seeks which are biased as twice the cost of a
653 * similar forward seek.
657 else if (s1
+ back_max
>= last
)
658 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
660 wrap
|= CFQ_RQ1_WRAP
;
664 else if (s2
+ back_max
>= last
)
665 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
667 wrap
|= CFQ_RQ2_WRAP
;
669 /* Found required data */
672 * By doing switch() on the bit mask "wrap" we avoid having to
673 * check two variables for all permutations: --> faster!
676 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
692 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
695 * Since both rqs are wrapped,
696 * start with the one that's further behind head
697 * (--> only *one* back seek required),
698 * since back seek takes more time than forward.
708 * The below is leftmost cache rbtree addon
710 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
712 /* Service tree is empty */
717 root
->left
= rb_first(&root
->rb
);
720 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
725 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
728 root
->left
= rb_first(&root
->rb
);
731 return rb_entry_cfqg(root
->left
);
736 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
742 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
746 rb_erase_init(n
, &root
->rb
);
751 * would be nice to take fifo expire time into account as well
753 static struct request
*
754 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
755 struct request
*last
)
757 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
758 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
759 struct request
*next
= NULL
, *prev
= NULL
;
761 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
764 prev
= rb_entry_rq(rbprev
);
767 next
= rb_entry_rq(rbnext
);
769 rbnext
= rb_first(&cfqq
->sort_list
);
770 if (rbnext
&& rbnext
!= &last
->rb_node
)
771 next
= rb_entry_rq(rbnext
);
774 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
777 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
778 struct cfq_queue
*cfqq
)
781 * just an approximation, should be ok.
783 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
784 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
788 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
790 return cfqg
->vdisktime
- st
->min_vdisktime
;
794 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
796 struct rb_node
**node
= &st
->rb
.rb_node
;
797 struct rb_node
*parent
= NULL
;
798 struct cfq_group
*__cfqg
;
799 s64 key
= cfqg_key(st
, cfqg
);
802 while (*node
!= NULL
) {
804 __cfqg
= rb_entry_cfqg(parent
);
806 if (key
< cfqg_key(st
, __cfqg
))
807 node
= &parent
->rb_left
;
809 node
= &parent
->rb_right
;
815 st
->left
= &cfqg
->rb_node
;
817 rb_link_node(&cfqg
->rb_node
, parent
, node
);
818 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
822 cfq_group_service_tree_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
824 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
825 struct cfq_group
*__cfqg
;
833 * Currently put the group at the end. Later implement something
834 * so that groups get lesser vtime based on their weights, so that
835 * if group does not loose all if it was not continously backlogged.
837 n
= rb_last(&st
->rb
);
839 __cfqg
= rb_entry_cfqg(n
);
840 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
842 cfqg
->vdisktime
= st
->min_vdisktime
;
844 __cfq_group_service_tree_add(st
, cfqg
);
847 st
->total_weight
+= cfqg
->weight
;
851 cfq_group_service_tree_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
853 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
855 if (st
->active
== &cfqg
->rb_node
)
858 BUG_ON(cfqg
->nr_cfqq
< 1);
861 /* If there are other cfq queues under this group, don't delete it */
865 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
868 st
->total_weight
-= cfqg
->weight
;
869 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
870 cfq_rb_erase(&cfqg
->rb_node
, st
);
871 cfqg
->saved_workload_slice
= 0;
872 blkiocg_update_blkio_group_dequeue_stats(&cfqg
->blkg
, 1);
875 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
)
877 unsigned int slice_used
;
880 * Queue got expired before even a single request completed or
881 * got expired immediately after first request completion.
883 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
885 * Also charge the seek time incurred to the group, otherwise
886 * if there are mutiple queues in the group, each can dispatch
887 * a single request on seeky media and cause lots of seek time
888 * and group will never know it.
890 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
893 slice_used
= jiffies
- cfqq
->slice_start
;
894 if (slice_used
> cfqq
->allocated_slice
)
895 slice_used
= cfqq
->allocated_slice
;
898 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "sl_used=%u sect=%lu", slice_used
,
903 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
904 struct cfq_queue
*cfqq
)
906 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
907 unsigned int used_sl
, charge_sl
;
908 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
909 - cfqg
->service_tree_idle
.count
;
912 used_sl
= charge_sl
= cfq_cfqq_slice_usage(cfqq
);
914 if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
915 charge_sl
= cfqq
->allocated_slice
;
917 /* Can't update vdisktime while group is on service tree */
918 cfq_rb_erase(&cfqg
->rb_node
, st
);
919 cfqg
->vdisktime
+= cfq_scale_slice(charge_sl
, cfqg
);
920 __cfq_group_service_tree_add(st
, cfqg
);
922 /* This group is being expired. Save the context */
923 if (time_after(cfqd
->workload_expires
, jiffies
)) {
924 cfqg
->saved_workload_slice
= cfqd
->workload_expires
926 cfqg
->saved_workload
= cfqd
->serving_type
;
927 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
929 cfqg
->saved_workload_slice
= 0;
931 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
933 blkiocg_update_blkio_group_stats(&cfqg
->blkg
, used_sl
,
937 #ifdef CONFIG_CFQ_GROUP_IOSCHED
938 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
941 return container_of(blkg
, struct cfq_group
, blkg
);
946 cfq_update_blkio_group_weight(struct blkio_group
*blkg
, unsigned int weight
)
948 cfqg_of_blkg(blkg
)->weight
= weight
;
951 static struct cfq_group
*
952 cfq_find_alloc_cfqg(struct cfq_data
*cfqd
, struct cgroup
*cgroup
, int create
)
954 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgroup
);
955 struct cfq_group
*cfqg
= NULL
;
958 struct cfq_rb_root
*st
;
959 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
960 unsigned int major
, minor
;
962 /* Do we need to take this reference */
963 if (!css_tryget(&blkcg
->css
))
966 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
970 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
974 cfqg
->weight
= blkcg
->weight
;
975 for_each_cfqg_st(cfqg
, i
, j
, st
)
977 RB_CLEAR_NODE(&cfqg
->rb_node
);
980 * Take the initial reference that will be released on destroy
981 * This can be thought of a joint reference by cgroup and
982 * elevator which will be dropped by either elevator exit
983 * or cgroup deletion path depending on who is exiting first.
985 atomic_set(&cfqg
->ref
, 1);
987 /* Add group onto cgroup list */
988 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
989 blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
, (void *)cfqd
,
990 MKDEV(major
, minor
));
992 /* Add group on cfqd list */
993 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
996 css_put(&blkcg
->css
);
1001 * Search for the cfq group current task belongs to. If create = 1, then also
1002 * create the cfq group if it does not exist. request_queue lock must be held.
1004 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1006 struct cgroup
*cgroup
;
1007 struct cfq_group
*cfqg
= NULL
;
1010 cgroup
= task_cgroup(current
, blkio_subsys_id
);
1011 cfqg
= cfq_find_alloc_cfqg(cfqd
, cgroup
, create
);
1012 if (!cfqg
&& create
)
1013 cfqg
= &cfqd
->root_group
;
1018 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1020 /* Currently, all async queues are mapped to root group */
1021 if (!cfq_cfqq_sync(cfqq
))
1022 cfqg
= &cfqq
->cfqd
->root_group
;
1025 /* cfqq reference on cfqg */
1026 atomic_inc(&cfqq
->cfqg
->ref
);
1029 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1031 struct cfq_rb_root
*st
;
1034 BUG_ON(atomic_read(&cfqg
->ref
) <= 0);
1035 if (!atomic_dec_and_test(&cfqg
->ref
))
1037 for_each_cfqg_st(cfqg
, i
, j
, st
)
1038 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
) || st
->active
!= NULL
);
1042 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1044 /* Something wrong if we are trying to remove same group twice */
1045 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1047 hlist_del_init(&cfqg
->cfqd_node
);
1050 * Put the reference taken at the time of creation so that when all
1051 * queues are gone, group can be destroyed.
1056 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1058 struct hlist_node
*pos
, *n
;
1059 struct cfq_group
*cfqg
;
1061 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1063 * If cgroup removal path got to blk_group first and removed
1064 * it from cgroup list, then it will take care of destroying
1067 if (!blkiocg_del_blkio_group(&cfqg
->blkg
))
1068 cfq_destroy_cfqg(cfqd
, cfqg
);
1073 * Blk cgroup controller notification saying that blkio_group object is being
1074 * delinked as associated cgroup object is going away. That also means that
1075 * no new IO will come in this group. So get rid of this group as soon as
1076 * any pending IO in the group is finished.
1078 * This function is called under rcu_read_lock(). key is the rcu protected
1079 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1082 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1083 * it should not be NULL as even if elevator was exiting, cgroup deltion
1084 * path got to it first.
1086 void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1088 unsigned long flags
;
1089 struct cfq_data
*cfqd
= key
;
1091 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1092 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1093 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1096 #else /* GROUP_IOSCHED */
1097 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1099 return &cfqd
->root_group
;
1102 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1106 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1107 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1109 #endif /* GROUP_IOSCHED */
1112 * The cfqd->service_trees holds all pending cfq_queue's that have
1113 * requests waiting to be processed. It is sorted in the order that
1114 * we will service the queues.
1116 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1119 struct rb_node
**p
, *parent
;
1120 struct cfq_queue
*__cfqq
;
1121 unsigned long rb_key
;
1122 struct cfq_rb_root
*service_tree
;
1125 int group_changed
= 0;
1127 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1128 if (!cfqd
->cfq_group_isolation
1129 && cfqq_type(cfqq
) == SYNC_NOIDLE_WORKLOAD
1130 && cfqq
->cfqg
&& cfqq
->cfqg
!= &cfqd
->root_group
) {
1131 /* Move this cfq to root group */
1132 cfq_log_cfqq(cfqd
, cfqq
, "moving to root group");
1133 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1134 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1135 cfqq
->orig_cfqg
= cfqq
->cfqg
;
1136 cfqq
->cfqg
= &cfqd
->root_group
;
1137 atomic_inc(&cfqd
->root_group
.ref
);
1139 } else if (!cfqd
->cfq_group_isolation
1140 && cfqq_type(cfqq
) == SYNC_WORKLOAD
&& cfqq
->orig_cfqg
) {
1141 /* cfqq is sequential now needs to go to its original group */
1142 BUG_ON(cfqq
->cfqg
!= &cfqd
->root_group
);
1143 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1144 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1145 cfq_put_cfqg(cfqq
->cfqg
);
1146 cfqq
->cfqg
= cfqq
->orig_cfqg
;
1147 cfqq
->orig_cfqg
= NULL
;
1149 cfq_log_cfqq(cfqd
, cfqq
, "moved to origin group");
1153 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1154 cfqq_type(cfqq
), cfqd
);
1155 if (cfq_class_idle(cfqq
)) {
1156 rb_key
= CFQ_IDLE_DELAY
;
1157 parent
= rb_last(&service_tree
->rb
);
1158 if (parent
&& parent
!= &cfqq
->rb_node
) {
1159 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1160 rb_key
+= __cfqq
->rb_key
;
1163 } else if (!add_front
) {
1165 * Get our rb key offset. Subtract any residual slice
1166 * value carried from last service. A negative resid
1167 * count indicates slice overrun, and this should position
1168 * the next service time further away in the tree.
1170 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1171 rb_key
-= cfqq
->slice_resid
;
1172 cfqq
->slice_resid
= 0;
1175 __cfqq
= cfq_rb_first(service_tree
);
1176 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1179 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1182 * same position, nothing more to do
1184 if (rb_key
== cfqq
->rb_key
&&
1185 cfqq
->service_tree
== service_tree
)
1188 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1189 cfqq
->service_tree
= NULL
;
1194 cfqq
->service_tree
= service_tree
;
1195 p
= &service_tree
->rb
.rb_node
;
1200 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1203 * sort by key, that represents service time.
1205 if (time_before(rb_key
, __cfqq
->rb_key
))
1208 n
= &(*p
)->rb_right
;
1216 service_tree
->left
= &cfqq
->rb_node
;
1218 cfqq
->rb_key
= rb_key
;
1219 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1220 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1221 service_tree
->count
++;
1222 if ((add_front
|| !new_cfqq
) && !group_changed
)
1224 cfq_group_service_tree_add(cfqd
, cfqq
->cfqg
);
1227 static struct cfq_queue
*
1228 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1229 sector_t sector
, struct rb_node
**ret_parent
,
1230 struct rb_node
***rb_link
)
1232 struct rb_node
**p
, *parent
;
1233 struct cfq_queue
*cfqq
= NULL
;
1241 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1244 * Sort strictly based on sector. Smallest to the left,
1245 * largest to the right.
1247 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1248 n
= &(*p
)->rb_right
;
1249 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1257 *ret_parent
= parent
;
1263 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1265 struct rb_node
**p
, *parent
;
1266 struct cfq_queue
*__cfqq
;
1269 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1270 cfqq
->p_root
= NULL
;
1273 if (cfq_class_idle(cfqq
))
1278 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1279 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1280 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1282 rb_link_node(&cfqq
->p_node
, parent
, p
);
1283 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1285 cfqq
->p_root
= NULL
;
1289 * Update cfqq's position in the service tree.
1291 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1294 * Resorting requires the cfqq to be on the RR list already.
1296 if (cfq_cfqq_on_rr(cfqq
)) {
1297 cfq_service_tree_add(cfqd
, cfqq
, 0);
1298 cfq_prio_tree_add(cfqd
, cfqq
);
1303 * add to busy list of queues for service, trying to be fair in ordering
1304 * the pending list according to last request service
1306 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1308 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1309 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1310 cfq_mark_cfqq_on_rr(cfqq
);
1311 cfqd
->busy_queues
++;
1313 cfq_resort_rr_list(cfqd
, cfqq
);
1317 * Called when the cfqq no longer has requests pending, remove it from
1320 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1322 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1323 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1324 cfq_clear_cfqq_on_rr(cfqq
);
1326 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1327 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1328 cfqq
->service_tree
= NULL
;
1331 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1332 cfqq
->p_root
= NULL
;
1335 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1336 BUG_ON(!cfqd
->busy_queues
);
1337 cfqd
->busy_queues
--;
1341 * rb tree support functions
1343 static void cfq_del_rq_rb(struct request
*rq
)
1345 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1346 const int sync
= rq_is_sync(rq
);
1348 BUG_ON(!cfqq
->queued
[sync
]);
1349 cfqq
->queued
[sync
]--;
1351 elv_rb_del(&cfqq
->sort_list
, rq
);
1353 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1355 * Queue will be deleted from service tree when we actually
1356 * expire it later. Right now just remove it from prio tree
1360 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1361 cfqq
->p_root
= NULL
;
1366 static void cfq_add_rq_rb(struct request
*rq
)
1368 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1369 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1370 struct request
*__alias
, *prev
;
1372 cfqq
->queued
[rq_is_sync(rq
)]++;
1375 * looks a little odd, but the first insert might return an alias.
1376 * if that happens, put the alias on the dispatch list
1378 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
1379 cfq_dispatch_insert(cfqd
->queue
, __alias
);
1381 if (!cfq_cfqq_on_rr(cfqq
))
1382 cfq_add_cfqq_rr(cfqd
, cfqq
);
1385 * check if this request is a better next-serve candidate
1387 prev
= cfqq
->next_rq
;
1388 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1391 * adjust priority tree position, if ->next_rq changes
1393 if (prev
!= cfqq
->next_rq
)
1394 cfq_prio_tree_add(cfqd
, cfqq
);
1396 BUG_ON(!cfqq
->next_rq
);
1399 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1401 elv_rb_del(&cfqq
->sort_list
, rq
);
1402 cfqq
->queued
[rq_is_sync(rq
)]--;
1406 static struct request
*
1407 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1409 struct task_struct
*tsk
= current
;
1410 struct cfq_io_context
*cic
;
1411 struct cfq_queue
*cfqq
;
1413 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1417 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1419 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1421 return elv_rb_find(&cfqq
->sort_list
, sector
);
1427 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1429 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1431 cfqd
->rq_in_driver
[rq_is_sync(rq
)]++;
1432 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1433 rq_in_driver(cfqd
));
1435 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1438 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1440 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1441 const int sync
= rq_is_sync(rq
);
1443 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
1444 cfqd
->rq_in_driver
[sync
]--;
1445 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1446 rq_in_driver(cfqd
));
1449 static void cfq_remove_request(struct request
*rq
)
1451 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1453 if (cfqq
->next_rq
== rq
)
1454 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1456 list_del_init(&rq
->queuelist
);
1459 cfqq
->cfqd
->rq_queued
--;
1460 if (rq_is_meta(rq
)) {
1461 WARN_ON(!cfqq
->meta_pending
);
1462 cfqq
->meta_pending
--;
1466 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1469 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1470 struct request
*__rq
;
1472 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1473 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1475 return ELEVATOR_FRONT_MERGE
;
1478 return ELEVATOR_NO_MERGE
;
1481 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1484 if (type
== ELEVATOR_FRONT_MERGE
) {
1485 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1487 cfq_reposition_rq_rb(cfqq
, req
);
1492 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1493 struct request
*next
)
1495 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1497 * reposition in fifo if next is older than rq
1499 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1500 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1501 list_move(&rq
->queuelist
, &next
->queuelist
);
1502 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1505 if (cfqq
->next_rq
== next
)
1507 cfq_remove_request(next
);
1510 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1513 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1514 struct cfq_io_context
*cic
;
1515 struct cfq_queue
*cfqq
;
1517 /* Deny merge if bio and rq don't belong to same cfq group */
1518 if ((RQ_CFQQ(rq
))->cfqg
!= cfq_get_cfqg(cfqd
, 0))
1521 * Disallow merge of a sync bio into an async request.
1523 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1527 * Lookup the cfqq that this bio will be queued with. Allow
1528 * merge only if rq is queued there.
1530 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1534 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1535 return cfqq
== RQ_CFQQ(rq
);
1538 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1539 struct cfq_queue
*cfqq
)
1542 cfq_log_cfqq(cfqd
, cfqq
, "set_active");
1543 cfqq
->slice_start
= 0;
1544 cfqq
->dispatch_start
= jiffies
;
1545 cfqq
->allocated_slice
= 0;
1546 cfqq
->slice_end
= 0;
1547 cfqq
->slice_dispatch
= 0;
1548 cfqq
->nr_sectors
= 0;
1550 cfq_clear_cfqq_wait_request(cfqq
);
1551 cfq_clear_cfqq_must_dispatch(cfqq
);
1552 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1553 cfq_clear_cfqq_fifo_expire(cfqq
);
1554 cfq_mark_cfqq_slice_new(cfqq
);
1556 del_timer(&cfqd
->idle_slice_timer
);
1559 cfqd
->active_queue
= cfqq
;
1563 * current cfqq expired its slice (or was too idle), select new one
1566 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1569 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1571 if (cfq_cfqq_wait_request(cfqq
))
1572 del_timer(&cfqd
->idle_slice_timer
);
1574 cfq_clear_cfqq_wait_request(cfqq
);
1575 cfq_clear_cfqq_wait_busy(cfqq
);
1576 cfq_clear_cfqq_wait_busy_done(cfqq
);
1579 * store what was left of this slice, if the queue idled/timed out
1581 if (timed_out
&& !cfq_cfqq_slice_new(cfqq
)) {
1582 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1583 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1586 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1588 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1589 cfq_del_cfqq_rr(cfqd
, cfqq
);
1591 cfq_resort_rr_list(cfqd
, cfqq
);
1593 if (cfqq
== cfqd
->active_queue
)
1594 cfqd
->active_queue
= NULL
;
1596 if (&cfqq
->cfqg
->rb_node
== cfqd
->grp_service_tree
.active
)
1597 cfqd
->grp_service_tree
.active
= NULL
;
1599 if (cfqd
->active_cic
) {
1600 put_io_context(cfqd
->active_cic
->ioc
);
1601 cfqd
->active_cic
= NULL
;
1605 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1607 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1610 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1614 * Get next queue for service. Unless we have a queue preemption,
1615 * we'll simply select the first cfqq in the service tree.
1617 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1619 struct cfq_rb_root
*service_tree
=
1620 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1621 cfqd
->serving_type
, cfqd
);
1623 if (!cfqd
->rq_queued
)
1626 /* There is nothing to dispatch */
1629 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1631 return cfq_rb_first(service_tree
);
1634 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1636 struct cfq_group
*cfqg
;
1637 struct cfq_queue
*cfqq
;
1639 struct cfq_rb_root
*st
;
1641 if (!cfqd
->rq_queued
)
1644 cfqg
= cfq_get_next_cfqg(cfqd
);
1648 for_each_cfqg_st(cfqg
, i
, j
, st
)
1649 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1655 * Get and set a new active queue for service.
1657 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1658 struct cfq_queue
*cfqq
)
1661 cfqq
= cfq_get_next_queue(cfqd
);
1663 __cfq_set_active_queue(cfqd
, cfqq
);
1667 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1670 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1671 return blk_rq_pos(rq
) - cfqd
->last_position
;
1673 return cfqd
->last_position
- blk_rq_pos(rq
);
1676 #define CFQQ_SEEK_THR 8 * 1024
1677 #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
1679 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1682 sector_t sdist
= cfqq
->seek_mean
;
1684 if (!sample_valid(cfqq
->seek_samples
))
1685 sdist
= CFQQ_SEEK_THR
;
1687 return cfq_dist_from_last(cfqd
, rq
) <= sdist
;
1690 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1691 struct cfq_queue
*cur_cfqq
)
1693 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1694 struct rb_node
*parent
, *node
;
1695 struct cfq_queue
*__cfqq
;
1696 sector_t sector
= cfqd
->last_position
;
1698 if (RB_EMPTY_ROOT(root
))
1702 * First, if we find a request starting at the end of the last
1703 * request, choose it.
1705 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1710 * If the exact sector wasn't found, the parent of the NULL leaf
1711 * will contain the closest sector.
1713 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1714 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1717 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1718 node
= rb_next(&__cfqq
->p_node
);
1720 node
= rb_prev(&__cfqq
->p_node
);
1724 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1725 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1733 * cur_cfqq - passed in so that we don't decide that the current queue is
1734 * closely cooperating with itself.
1736 * So, basically we're assuming that that cur_cfqq has dispatched at least
1737 * one request, and that cfqd->last_position reflects a position on the disk
1738 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1741 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1742 struct cfq_queue
*cur_cfqq
)
1744 struct cfq_queue
*cfqq
;
1746 if (!cfq_cfqq_sync(cur_cfqq
))
1748 if (CFQQ_SEEKY(cur_cfqq
))
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
))
1802 * Otherwise, we do only if they are the last ones
1803 * in their service tree.
1805 return service_tree
->count
== 1;
1808 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1810 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1811 struct cfq_io_context
*cic
;
1815 * SSD device without seek penalty, disable idling. But only do so
1816 * for devices that support queuing, otherwise we still have a problem
1817 * with sync vs async workloads.
1819 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1822 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1823 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1826 * idle is disabled, either manually or by past process history
1828 if (!cfqd
->cfq_slice_idle
|| !cfq_should_idle(cfqd
, cfqq
))
1832 * still active requests from this queue, don't idle
1834 if (cfqq
->dispatched
)
1838 * task has exited, don't wait
1840 cic
= cfqd
->active_cic
;
1841 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1845 * If our average think time is larger than the remaining time
1846 * slice, then don't idle. This avoids overrunning the allotted
1849 if (sample_valid(cic
->ttime_samples
) &&
1850 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
1853 cfq_mark_cfqq_wait_request(cfqq
);
1855 sl
= cfqd
->cfq_slice_idle
;
1857 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1858 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu", sl
);
1862 * Move request from internal lists to the request queue dispatch list.
1864 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1866 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1867 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1869 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1871 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1872 cfq_remove_request(rq
);
1874 elv_dispatch_sort(q
, rq
);
1876 if (cfq_cfqq_sync(cfqq
))
1877 cfqd
->sync_flight
++;
1878 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
1882 * return expired entry, or NULL to just start from scratch in rbtree
1884 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1886 struct request
*rq
= NULL
;
1888 if (cfq_cfqq_fifo_expire(cfqq
))
1891 cfq_mark_cfqq_fifo_expire(cfqq
);
1893 if (list_empty(&cfqq
->fifo
))
1896 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
1897 if (time_before(jiffies
, rq_fifo_time(rq
)))
1900 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
1905 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1907 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1909 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1911 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1915 * Must be called with the queue_lock held.
1917 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
1919 int process_refs
, io_refs
;
1921 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
1922 process_refs
= atomic_read(&cfqq
->ref
) - io_refs
;
1923 BUG_ON(process_refs
< 0);
1924 return process_refs
;
1927 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
1929 int process_refs
, new_process_refs
;
1930 struct cfq_queue
*__cfqq
;
1932 /* Avoid a circular list and skip interim queue merges */
1933 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
1939 process_refs
= cfqq_process_refs(cfqq
);
1941 * If the process for the cfqq has gone away, there is no
1942 * sense in merging the queues.
1944 if (process_refs
== 0)
1948 * Merge in the direction of the lesser amount of work.
1950 new_process_refs
= cfqq_process_refs(new_cfqq
);
1951 if (new_process_refs
>= process_refs
) {
1952 cfqq
->new_cfqq
= new_cfqq
;
1953 atomic_add(process_refs
, &new_cfqq
->ref
);
1955 new_cfqq
->new_cfqq
= cfqq
;
1956 atomic_add(new_process_refs
, &cfqq
->ref
);
1960 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
1961 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
;
1972 * When priorities switched, we prefer starting
1973 * from SYNC_NOIDLE (first choice), or just SYNC
1976 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1978 cur_best
= SYNC_WORKLOAD
;
1979 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1982 return ASYNC_WORKLOAD
;
1985 for (i
= 0; i
< 3; ++i
) {
1986 /* otherwise, select the one with lowest rb_key */
1987 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
, cfqd
));
1989 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
1990 lowest_key
= queue
->rb_key
;
1999 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2001 enum wl_prio_t previous_prio
= cfqd
->serving_prio
;
2005 struct cfq_rb_root
*st
;
2006 unsigned group_slice
;
2009 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2010 cfqd
->workload_expires
= jiffies
+ 1;
2014 /* Choose next priority. RT > BE > IDLE */
2015 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2016 cfqd
->serving_prio
= RT_WORKLOAD
;
2017 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2018 cfqd
->serving_prio
= BE_WORKLOAD
;
2020 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2021 cfqd
->workload_expires
= jiffies
+ 1;
2026 * For RT and BE, we have to choose also the type
2027 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2030 prio_changed
= (cfqd
->serving_prio
!= previous_prio
);
2031 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
2036 * If priority didn't change, check workload expiration,
2037 * and that we still have other queues ready
2039 if (!prio_changed
&& count
&&
2040 !time_after(jiffies
, cfqd
->workload_expires
))
2043 /* otherwise select new workload type */
2044 cfqd
->serving_type
=
2045 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
, prio_changed
);
2046 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
2051 * the workload slice is computed as a fraction of target latency
2052 * proportional to the number of queues in that workload, over
2053 * all the queues in the same priority class
2055 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2057 slice
= group_slice
* count
/
2058 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2059 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2061 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2065 * Async queues are currently system wide. Just taking
2066 * proportion of queues with-in same group will lead to higher
2067 * async ratio system wide as generally root group is going
2068 * to have higher weight. A more accurate thing would be to
2069 * calculate system wide asnc/sync ratio.
2071 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2072 tmp
= tmp
/cfqd
->busy_queues
;
2073 slice
= min_t(unsigned, slice
, tmp
);
2075 /* async workload slice is scaled down according to
2076 * the sync/async slice ratio. */
2077 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2079 /* sync workload slice is at least 2 * cfq_slice_idle */
2080 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2082 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2083 cfqd
->workload_expires
= jiffies
+ slice
;
2084 cfqd
->noidle_tree_requires_idle
= false;
2087 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2089 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2090 struct cfq_group
*cfqg
;
2092 if (RB_EMPTY_ROOT(&st
->rb
))
2094 cfqg
= cfq_rb_first_group(st
);
2095 st
->active
= &cfqg
->rb_node
;
2096 update_min_vdisktime(st
);
2100 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2102 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2104 cfqd
->serving_group
= cfqg
;
2106 /* Restore the workload type data */
2107 if (cfqg
->saved_workload_slice
) {
2108 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2109 cfqd
->serving_type
= cfqg
->saved_workload
;
2110 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2112 choose_service_tree(cfqd
, cfqg
);
2116 * Select a queue for service. If we have a current active queue,
2117 * check whether to continue servicing it, or retrieve and set a new one.
2119 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2121 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2123 cfqq
= cfqd
->active_queue
;
2127 if (!cfqd
->rq_queued
)
2130 * The active queue has run out of time, expire it and select new.
2132 if ((cfq_slice_used(cfqq
) || cfq_cfqq_wait_busy_done(cfqq
))
2133 && !cfq_cfqq_must_dispatch(cfqq
))
2137 * The active queue has requests and isn't expired, allow it to
2140 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2144 * If another queue has a request waiting within our mean seek
2145 * distance, let it run. The expire code will check for close
2146 * cooperators and put the close queue at the front of the service
2147 * tree. If possible, merge the expiring queue with the new cfqq.
2149 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2151 if (!cfqq
->new_cfqq
)
2152 cfq_setup_merge(cfqq
, new_cfqq
);
2157 * No requests pending. If the active queue still has requests in
2158 * flight or is idling for a new request, allow either of these
2159 * conditions to happen (or time out) before selecting a new queue.
2161 if (timer_pending(&cfqd
->idle_slice_timer
) ||
2162 (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
))) {
2168 cfq_slice_expired(cfqd
, 0);
2171 * Current queue expired. Check if we have to switch to a new
2175 cfq_choose_cfqg(cfqd
);
2177 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2182 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2186 while (cfqq
->next_rq
) {
2187 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2191 BUG_ON(!list_empty(&cfqq
->fifo
));
2193 /* By default cfqq is not expired if it is empty. Do it explicitly */
2194 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2199 * Drain our current requests. Used for barriers and when switching
2200 * io schedulers on-the-fly.
2202 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2204 struct cfq_queue
*cfqq
;
2207 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
)
2208 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2210 cfq_slice_expired(cfqd
, 0);
2211 BUG_ON(cfqd
->busy_queues
);
2213 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2217 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2219 unsigned int max_dispatch
;
2222 * Drain async requests before we start sync IO
2224 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_driver
[BLK_RW_ASYNC
])
2228 * If this is an async queue and we have sync IO in flight, let it wait
2230 if (cfqd
->sync_flight
&& !cfq_cfqq_sync(cfqq
))
2233 max_dispatch
= cfqd
->cfq_quantum
;
2234 if (cfq_class_idle(cfqq
))
2238 * Does this cfqq already have too much IO in flight?
2240 if (cfqq
->dispatched
>= max_dispatch
) {
2242 * idle queue must always only have a single IO in flight
2244 if (cfq_class_idle(cfqq
))
2248 * We have other queues, don't allow more IO from this one
2250 if (cfqd
->busy_queues
> 1)
2254 * Sole queue user, no limit
2260 * Async queues must wait a bit before being allowed dispatch.
2261 * We also ramp up the dispatch depth gradually for async IO,
2262 * based on the last sync IO we serviced
2264 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2265 unsigned long last_sync
= jiffies
- cfqd
->last_end_sync_rq
;
2268 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2269 if (!depth
&& !cfqq
->dispatched
)
2271 if (depth
< max_dispatch
)
2272 max_dispatch
= depth
;
2276 * If we're below the current max, allow a dispatch
2278 return cfqq
->dispatched
< max_dispatch
;
2282 * Dispatch a request from cfqq, moving them to the request queue
2285 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2289 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2291 if (!cfq_may_dispatch(cfqd
, cfqq
))
2295 * follow expired path, else get first next available
2297 rq
= cfq_check_fifo(cfqq
);
2302 * insert request into driver dispatch list
2304 cfq_dispatch_insert(cfqd
->queue
, rq
);
2306 if (!cfqd
->active_cic
) {
2307 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2309 atomic_long_inc(&cic
->ioc
->refcount
);
2310 cfqd
->active_cic
= cic
;
2317 * Find the cfqq that we need to service and move a request from that to the
2320 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2322 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2323 struct cfq_queue
*cfqq
;
2325 if (!cfqd
->busy_queues
)
2328 if (unlikely(force
))
2329 return cfq_forced_dispatch(cfqd
);
2331 cfqq
= cfq_select_queue(cfqd
);
2336 * Dispatch a request from this cfqq, if it is allowed
2338 if (!cfq_dispatch_request(cfqd
, cfqq
))
2341 cfqq
->slice_dispatch
++;
2342 cfq_clear_cfqq_must_dispatch(cfqq
);
2345 * expire an async queue immediately if it has used up its slice. idle
2346 * queue always expire after 1 dispatch round.
2348 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2349 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2350 cfq_class_idle(cfqq
))) {
2351 cfqq
->slice_end
= jiffies
+ 1;
2352 cfq_slice_expired(cfqd
, 0);
2355 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2360 * task holds one reference to the queue, dropped when task exits. each rq
2361 * in-flight on this queue also holds a reference, dropped when rq is freed.
2363 * Each cfq queue took a reference on the parent group. Drop it now.
2364 * queue lock must be held here.
2366 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2368 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2369 struct cfq_group
*cfqg
;
2371 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
2373 if (!atomic_dec_and_test(&cfqq
->ref
))
2376 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2377 BUG_ON(rb_first(&cfqq
->sort_list
));
2378 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2381 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2382 __cfq_slice_expired(cfqd
, cfqq
, 0);
2383 cfq_schedule_dispatch(cfqd
);
2386 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2387 kmem_cache_free(cfq_pool
, cfqq
);
2389 if (cfqq
->orig_cfqg
)
2390 cfq_put_cfqg(cfqq
->orig_cfqg
);
2394 * Must always be called with the rcu_read_lock() held
2397 __call_for_each_cic(struct io_context
*ioc
,
2398 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2400 struct cfq_io_context
*cic
;
2401 struct hlist_node
*n
;
2403 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
2408 * Call func for each cic attached to this ioc.
2411 call_for_each_cic(struct io_context
*ioc
,
2412 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2415 __call_for_each_cic(ioc
, func
);
2419 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2421 struct cfq_io_context
*cic
;
2423 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
2425 kmem_cache_free(cfq_ioc_pool
, cic
);
2426 elv_ioc_count_dec(cfq_ioc_count
);
2430 * CFQ scheduler is exiting, grab exit lock and check
2431 * the pending io context count. If it hits zero,
2432 * complete ioc_gone and set it back to NULL
2434 spin_lock(&ioc_gone_lock
);
2435 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
2439 spin_unlock(&ioc_gone_lock
);
2443 static void cfq_cic_free(struct cfq_io_context
*cic
)
2445 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2448 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2450 unsigned long flags
;
2452 BUG_ON(!cic
->dead_key
);
2454 spin_lock_irqsave(&ioc
->lock
, flags
);
2455 radix_tree_delete(&ioc
->radix_root
, cic
->dead_key
);
2456 hlist_del_rcu(&cic
->cic_list
);
2457 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2463 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2464 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2465 * and ->trim() which is called with the task lock held
2467 static void cfq_free_io_context(struct io_context
*ioc
)
2470 * ioc->refcount is zero here, or we are called from elv_unregister(),
2471 * so no more cic's are allowed to be linked into this ioc. So it
2472 * should be ok to iterate over the known list, we will see all cic's
2473 * since no new ones are added.
2475 __call_for_each_cic(ioc
, cic_free_func
);
2478 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2480 struct cfq_queue
*__cfqq
, *next
;
2482 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2483 __cfq_slice_expired(cfqd
, cfqq
, 0);
2484 cfq_schedule_dispatch(cfqd
);
2488 * If this queue was scheduled to merge with another queue, be
2489 * sure to drop the reference taken on that queue (and others in
2490 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2492 __cfqq
= cfqq
->new_cfqq
;
2494 if (__cfqq
== cfqq
) {
2495 WARN(1, "cfqq->new_cfqq loop detected\n");
2498 next
= __cfqq
->new_cfqq
;
2499 cfq_put_queue(__cfqq
);
2503 cfq_put_queue(cfqq
);
2506 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
2507 struct cfq_io_context
*cic
)
2509 struct io_context
*ioc
= cic
->ioc
;
2511 list_del_init(&cic
->queue_list
);
2514 * Make sure key == NULL is seen for dead queues
2517 cic
->dead_key
= (unsigned long) cic
->key
;
2520 if (ioc
->ioc_data
== cic
)
2521 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2523 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2524 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2525 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2528 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2529 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2530 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2534 static void cfq_exit_single_io_context(struct io_context
*ioc
,
2535 struct cfq_io_context
*cic
)
2537 struct cfq_data
*cfqd
= cic
->key
;
2540 struct request_queue
*q
= cfqd
->queue
;
2541 unsigned long flags
;
2543 spin_lock_irqsave(q
->queue_lock
, flags
);
2546 * Ensure we get a fresh copy of the ->key to prevent
2547 * race between exiting task and queue
2549 smp_read_barrier_depends();
2551 __cfq_exit_single_io_context(cfqd
, cic
);
2553 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2558 * The process that ioc belongs to has exited, we need to clean up
2559 * and put the internal structures we have that belongs to that process.
2561 static void cfq_exit_io_context(struct io_context
*ioc
)
2563 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
2566 static struct cfq_io_context
*
2567 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2569 struct cfq_io_context
*cic
;
2571 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2574 cic
->last_end_request
= jiffies
;
2575 INIT_LIST_HEAD(&cic
->queue_list
);
2576 INIT_HLIST_NODE(&cic
->cic_list
);
2577 cic
->dtor
= cfq_free_io_context
;
2578 cic
->exit
= cfq_exit_io_context
;
2579 elv_ioc_count_inc(cfq_ioc_count
);
2585 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2587 struct task_struct
*tsk
= current
;
2590 if (!cfq_cfqq_prio_changed(cfqq
))
2593 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2594 switch (ioprio_class
) {
2596 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2597 case IOPRIO_CLASS_NONE
:
2599 * no prio set, inherit CPU scheduling settings
2601 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2602 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2604 case IOPRIO_CLASS_RT
:
2605 cfqq
->ioprio
= task_ioprio(ioc
);
2606 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2608 case IOPRIO_CLASS_BE
:
2609 cfqq
->ioprio
= task_ioprio(ioc
);
2610 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2612 case IOPRIO_CLASS_IDLE
:
2613 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2615 cfq_clear_cfqq_idle_window(cfqq
);
2620 * keep track of original prio settings in case we have to temporarily
2621 * elevate the priority of this queue
2623 cfqq
->org_ioprio
= cfqq
->ioprio
;
2624 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2625 cfq_clear_cfqq_prio_changed(cfqq
);
2628 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2630 struct cfq_data
*cfqd
= cic
->key
;
2631 struct cfq_queue
*cfqq
;
2632 unsigned long flags
;
2634 if (unlikely(!cfqd
))
2637 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2639 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2641 struct cfq_queue
*new_cfqq
;
2642 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2645 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2646 cfq_put_queue(cfqq
);
2650 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2652 cfq_mark_cfqq_prio_changed(cfqq
);
2654 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2657 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2659 call_for_each_cic(ioc
, changed_ioprio
);
2660 ioc
->ioprio_changed
= 0;
2663 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2664 pid_t pid
, bool is_sync
)
2666 RB_CLEAR_NODE(&cfqq
->rb_node
);
2667 RB_CLEAR_NODE(&cfqq
->p_node
);
2668 INIT_LIST_HEAD(&cfqq
->fifo
);
2670 atomic_set(&cfqq
->ref
, 0);
2673 cfq_mark_cfqq_prio_changed(cfqq
);
2676 if (!cfq_class_idle(cfqq
))
2677 cfq_mark_cfqq_idle_window(cfqq
);
2678 cfq_mark_cfqq_sync(cfqq
);
2683 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2684 static void changed_cgroup(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2686 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2687 struct cfq_data
*cfqd
= cic
->key
;
2688 unsigned long flags
;
2689 struct request_queue
*q
;
2691 if (unlikely(!cfqd
))
2696 spin_lock_irqsave(q
->queue_lock
, flags
);
2700 * Drop reference to sync queue. A new sync queue will be
2701 * assigned in new group upon arrival of a fresh request.
2703 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2704 cic_set_cfqq(cic
, NULL
, 1);
2705 cfq_put_queue(sync_cfqq
);
2708 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2711 static void cfq_ioc_set_cgroup(struct io_context
*ioc
)
2713 call_for_each_cic(ioc
, changed_cgroup
);
2714 ioc
->cgroup_changed
= 0;
2716 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2718 static struct cfq_queue
*
2719 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2720 struct io_context
*ioc
, gfp_t gfp_mask
)
2722 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2723 struct cfq_io_context
*cic
;
2724 struct cfq_group
*cfqg
;
2727 cfqg
= cfq_get_cfqg(cfqd
, 1);
2728 cic
= cfq_cic_lookup(cfqd
, ioc
);
2729 /* cic always exists here */
2730 cfqq
= cic_to_cfqq(cic
, is_sync
);
2733 * Always try a new alloc if we fell back to the OOM cfqq
2734 * originally, since it should just be a temporary situation.
2736 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2741 } else if (gfp_mask
& __GFP_WAIT
) {
2742 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2743 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2744 gfp_mask
| __GFP_ZERO
,
2746 spin_lock_irq(cfqd
->queue
->queue_lock
);
2750 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2751 gfp_mask
| __GFP_ZERO
,
2756 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2757 cfq_init_prio_data(cfqq
, ioc
);
2758 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2759 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2761 cfqq
= &cfqd
->oom_cfqq
;
2765 kmem_cache_free(cfq_pool
, new_cfqq
);
2770 static struct cfq_queue
**
2771 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2773 switch (ioprio_class
) {
2774 case IOPRIO_CLASS_RT
:
2775 return &cfqd
->async_cfqq
[0][ioprio
];
2776 case IOPRIO_CLASS_BE
:
2777 return &cfqd
->async_cfqq
[1][ioprio
];
2778 case IOPRIO_CLASS_IDLE
:
2779 return &cfqd
->async_idle_cfqq
;
2785 static struct cfq_queue
*
2786 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2789 const int ioprio
= task_ioprio(ioc
);
2790 const int ioprio_class
= task_ioprio_class(ioc
);
2791 struct cfq_queue
**async_cfqq
= NULL
;
2792 struct cfq_queue
*cfqq
= NULL
;
2795 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2800 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2803 * pin the queue now that it's allocated, scheduler exit will prune it
2805 if (!is_sync
&& !(*async_cfqq
)) {
2806 atomic_inc(&cfqq
->ref
);
2810 atomic_inc(&cfqq
->ref
);
2815 * We drop cfq io contexts lazily, so we may find a dead one.
2818 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2819 struct cfq_io_context
*cic
)
2821 unsigned long flags
;
2823 WARN_ON(!list_empty(&cic
->queue_list
));
2825 spin_lock_irqsave(&ioc
->lock
, flags
);
2827 BUG_ON(ioc
->ioc_data
== cic
);
2829 radix_tree_delete(&ioc
->radix_root
, (unsigned long) cfqd
);
2830 hlist_del_rcu(&cic
->cic_list
);
2831 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2836 static struct cfq_io_context
*
2837 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
2839 struct cfq_io_context
*cic
;
2840 unsigned long flags
;
2849 * we maintain a last-hit cache, to avoid browsing over the tree
2851 cic
= rcu_dereference(ioc
->ioc_data
);
2852 if (cic
&& cic
->key
== cfqd
) {
2858 cic
= radix_tree_lookup(&ioc
->radix_root
, (unsigned long) cfqd
);
2862 /* ->key must be copied to avoid race with cfq_exit_queue() */
2865 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
2870 spin_lock_irqsave(&ioc
->lock
, flags
);
2871 rcu_assign_pointer(ioc
->ioc_data
, cic
);
2872 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2880 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2881 * the process specific cfq io context when entered from the block layer.
2882 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2884 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2885 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
2887 unsigned long flags
;
2890 ret
= radix_tree_preload(gfp_mask
);
2895 spin_lock_irqsave(&ioc
->lock
, flags
);
2896 ret
= radix_tree_insert(&ioc
->radix_root
,
2897 (unsigned long) cfqd
, cic
);
2899 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
2900 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2902 radix_tree_preload_end();
2905 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2906 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
2907 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2912 printk(KERN_ERR
"cfq: cic link failed!\n");
2918 * Setup general io context and cfq io context. There can be several cfq
2919 * io contexts per general io context, if this process is doing io to more
2920 * than one device managed by cfq.
2922 static struct cfq_io_context
*
2923 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2925 struct io_context
*ioc
= NULL
;
2926 struct cfq_io_context
*cic
;
2928 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2930 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
2934 cic
= cfq_cic_lookup(cfqd
, ioc
);
2938 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
2942 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
2946 smp_read_barrier_depends();
2947 if (unlikely(ioc
->ioprio_changed
))
2948 cfq_ioc_set_ioprio(ioc
);
2950 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2951 if (unlikely(ioc
->cgroup_changed
))
2952 cfq_ioc_set_cgroup(ioc
);
2958 put_io_context(ioc
);
2963 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
2965 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
2966 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
2968 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
2969 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
2970 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
2974 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2980 if (!cfqq
->last_request_pos
)
2982 else if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
2983 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
2985 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
2988 * Don't allow the seek distance to get too large from the
2989 * odd fragment, pagein, etc
2991 if (cfqq
->seek_samples
<= 60) /* second&third seek */
2992 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*1024);
2994 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*64);
2996 cfqq
->seek_samples
= (7*cfqq
->seek_samples
+ 256) / 8;
2997 cfqq
->seek_total
= (7*cfqq
->seek_total
+ (u64
)256*sdist
) / 8;
2998 total
= cfqq
->seek_total
+ (cfqq
->seek_samples
/2);
2999 do_div(total
, cfqq
->seek_samples
);
3000 cfqq
->seek_mean
= (sector_t
)total
;
3003 * If this cfqq is shared between multiple processes, check to
3004 * make sure that those processes are still issuing I/Os within
3005 * the mean seek distance. If not, it may be time to break the
3006 * queues apart again.
3008 if (cfq_cfqq_coop(cfqq
)) {
3009 if (CFQQ_SEEKY(cfqq
) && !cfqq
->seeky_start
)
3010 cfqq
->seeky_start
= jiffies
;
3011 else if (!CFQQ_SEEKY(cfqq
))
3012 cfqq
->seeky_start
= 0;
3017 * Disable idle window if the process thinks too long or seeks so much that
3021 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3022 struct cfq_io_context
*cic
)
3024 int old_idle
, enable_idle
;
3027 * Don't idle for async or idle io prio class
3029 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3032 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3034 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3035 cfq_mark_cfqq_deep(cfqq
);
3037 if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3038 (!cfq_cfqq_deep(cfqq
) && sample_valid(cfqq
->seek_samples
)
3039 && CFQQ_SEEKY(cfqq
)))
3041 else if (sample_valid(cic
->ttime_samples
)) {
3042 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
3048 if (old_idle
!= enable_idle
) {
3049 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3051 cfq_mark_cfqq_idle_window(cfqq
);
3053 cfq_clear_cfqq_idle_window(cfqq
);
3058 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3059 * no or if we aren't sure, a 1 will cause a preempt.
3062 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3065 struct cfq_queue
*cfqq
;
3067 cfqq
= cfqd
->active_queue
;
3071 if (cfq_class_idle(new_cfqq
))
3074 if (cfq_class_idle(cfqq
))
3078 * if the new request is sync, but the currently running queue is
3079 * not, let the sync request have priority.
3081 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3084 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3087 if (cfq_slice_used(cfqq
))
3090 /* Allow preemption only if we are idling on sync-noidle tree */
3091 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3092 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3093 new_cfqq
->service_tree
->count
== 2 &&
3094 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3098 * So both queues are sync. Let the new request get disk time if
3099 * it's a metadata request and the current queue is doing regular IO.
3101 if (rq_is_meta(rq
) && !cfqq
->meta_pending
)
3105 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3107 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3110 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3114 * if this request is as-good as one we would expect from the
3115 * current cfqq, let it preempt
3117 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3124 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3125 * let it have half of its nominal slice.
3127 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3129 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3130 cfq_slice_expired(cfqd
, 1);
3133 * Put the new queue at the front of the of the current list,
3134 * so we know that it will be selected next.
3136 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3138 cfq_service_tree_add(cfqd
, cfqq
, 1);
3140 cfqq
->slice_end
= 0;
3141 cfq_mark_cfqq_slice_new(cfqq
);
3145 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3146 * something we should do about it
3149 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3152 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3156 cfqq
->meta_pending
++;
3158 cfq_update_io_thinktime(cfqd
, cic
);
3159 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3160 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3162 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3164 if (cfqq
== cfqd
->active_queue
) {
3165 if (cfq_cfqq_wait_busy(cfqq
)) {
3166 cfq_clear_cfqq_wait_busy(cfqq
);
3167 cfq_mark_cfqq_wait_busy_done(cfqq
);
3170 * Remember that we saw a request from this process, but
3171 * don't start queuing just yet. Otherwise we risk seeing lots
3172 * of tiny requests, because we disrupt the normal plugging
3173 * and merging. If the request is already larger than a single
3174 * page, let it rip immediately. For that case we assume that
3175 * merging is already done. Ditto for a busy system that
3176 * has other work pending, don't risk delaying until the
3177 * idle timer unplug to continue working.
3179 if (cfq_cfqq_wait_request(cfqq
)) {
3180 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3181 cfqd
->busy_queues
> 1) {
3182 del_timer(&cfqd
->idle_slice_timer
);
3183 __blk_run_queue(cfqd
->queue
);
3185 cfq_mark_cfqq_must_dispatch(cfqq
);
3187 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3189 * not the active queue - expire current slice if it is
3190 * idle and has expired it's mean thinktime or this new queue
3191 * has some old slice time left and is of higher priority or
3192 * this new queue is RT and the current one is BE
3194 cfq_preempt_queue(cfqd
, cfqq
);
3195 __blk_run_queue(cfqd
->queue
);
3199 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3201 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3202 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3204 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3205 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3207 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3208 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3211 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3215 * Update hw_tag based on peak queue depth over 50 samples under
3218 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3220 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3222 if (rq_in_driver(cfqd
) > cfqd
->hw_tag_est_depth
)
3223 cfqd
->hw_tag_est_depth
= rq_in_driver(cfqd
);
3225 if (cfqd
->hw_tag
== 1)
3228 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3229 rq_in_driver(cfqd
) <= CFQ_HW_QUEUE_MIN
)
3233 * If active queue hasn't enough requests and can idle, cfq might not
3234 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3237 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3238 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3239 CFQ_HW_QUEUE_MIN
&& rq_in_driver(cfqd
) < CFQ_HW_QUEUE_MIN
)
3242 if (cfqd
->hw_tag_samples
++ < 50)
3245 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3251 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3253 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3254 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3255 const int sync
= rq_is_sync(rq
);
3259 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d", !!rq_noidle(rq
));
3261 cfq_update_hw_tag(cfqd
);
3263 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
3264 WARN_ON(!cfqq
->dispatched
);
3265 cfqd
->rq_in_driver
[sync
]--;
3268 if (cfq_cfqq_sync(cfqq
))
3269 cfqd
->sync_flight
--;
3272 RQ_CIC(rq
)->last_end_request
= now
;
3273 cfqd
->last_end_sync_rq
= now
;
3277 * If this is the active queue, check if it needs to be expired,
3278 * or if we want to idle in case it has no pending requests.
3280 if (cfqd
->active_queue
== cfqq
) {
3281 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3283 if (cfq_cfqq_slice_new(cfqq
)) {
3284 cfq_set_prio_slice(cfqd
, cfqq
);
3285 cfq_clear_cfqq_slice_new(cfqq
);
3289 * If this queue consumed its slice and this is last queue
3290 * in the group, wait for next request before we expire
3293 if (cfq_slice_used(cfqq
) && cfqq
->cfqg
->nr_cfqq
== 1) {
3294 cfqq
->slice_end
= jiffies
+ cfqd
->cfq_slice_idle
;
3295 cfq_mark_cfqq_wait_busy(cfqq
);
3299 * Idling is not enabled on:
3301 * - idle-priority queues
3303 * - queues with still some requests queued
3304 * - when there is a close cooperator
3306 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3307 cfq_slice_expired(cfqd
, 1);
3308 else if (sync
&& cfqq_empty
&&
3309 !cfq_close_cooperator(cfqd
, cfqq
)) {
3310 cfqd
->noidle_tree_requires_idle
|= !rq_noidle(rq
);
3312 * Idling is enabled for SYNC_WORKLOAD.
3313 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
3314 * only if we processed at least one !rq_noidle request
3316 if (cfqd
->serving_type
== SYNC_WORKLOAD
3317 || cfqd
->noidle_tree_requires_idle
3318 || cfqq
->cfqg
->nr_cfqq
== 1)
3319 cfq_arm_slice_timer(cfqd
);
3323 if (!rq_in_driver(cfqd
))
3324 cfq_schedule_dispatch(cfqd
);
3328 * we temporarily boost lower priority queues if they are holding fs exclusive
3329 * resources. they are boosted to normal prio (CLASS_BE/4)
3331 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
3333 if (has_fs_excl()) {
3335 * boost idle prio on transactions that would lock out other
3336 * users of the filesystem
3338 if (cfq_class_idle(cfqq
))
3339 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3340 if (cfqq
->ioprio
> IOPRIO_NORM
)
3341 cfqq
->ioprio
= IOPRIO_NORM
;
3344 * unboost the queue (if needed)
3346 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
3347 cfqq
->ioprio
= cfqq
->org_ioprio
;
3351 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3353 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3354 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3355 return ELV_MQUEUE_MUST
;
3358 return ELV_MQUEUE_MAY
;
3361 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3363 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3364 struct task_struct
*tsk
= current
;
3365 struct cfq_io_context
*cic
;
3366 struct cfq_queue
*cfqq
;
3369 * don't force setup of a queue from here, as a call to may_queue
3370 * does not necessarily imply that a request actually will be queued.
3371 * so just lookup a possibly existing queue, or return 'may queue'
3374 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3376 return ELV_MQUEUE_MAY
;
3378 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3380 cfq_init_prio_data(cfqq
, cic
->ioc
);
3381 cfq_prio_boost(cfqq
);
3383 return __cfq_may_queue(cfqq
);
3386 return ELV_MQUEUE_MAY
;
3390 * queue lock held here
3392 static void cfq_put_request(struct request
*rq
)
3394 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3397 const int rw
= rq_data_dir(rq
);
3399 BUG_ON(!cfqq
->allocated
[rw
]);
3400 cfqq
->allocated
[rw
]--;
3402 put_io_context(RQ_CIC(rq
)->ioc
);
3404 rq
->elevator_private
= NULL
;
3405 rq
->elevator_private2
= NULL
;
3407 cfq_put_queue(cfqq
);
3411 static struct cfq_queue
*
3412 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3413 struct cfq_queue
*cfqq
)
3415 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3416 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3417 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3418 cfq_put_queue(cfqq
);
3419 return cic_to_cfqq(cic
, 1);
3422 static int should_split_cfqq(struct cfq_queue
*cfqq
)
3424 if (cfqq
->seeky_start
&&
3425 time_after(jiffies
, cfqq
->seeky_start
+ CFQQ_COOP_TOUT
))
3431 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3432 * was the last process referring to said cfqq.
3434 static struct cfq_queue
*
3435 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3437 if (cfqq_process_refs(cfqq
) == 1) {
3438 cfqq
->seeky_start
= 0;
3439 cfqq
->pid
= current
->pid
;
3440 cfq_clear_cfqq_coop(cfqq
);
3444 cic_set_cfqq(cic
, NULL
, 1);
3445 cfq_put_queue(cfqq
);
3449 * Allocate cfq data structures associated with this request.
3452 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3454 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3455 struct cfq_io_context
*cic
;
3456 const int rw
= rq_data_dir(rq
);
3457 const bool is_sync
= rq_is_sync(rq
);
3458 struct cfq_queue
*cfqq
;
3459 unsigned long flags
;
3461 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3463 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3465 spin_lock_irqsave(q
->queue_lock
, flags
);
3471 cfqq
= cic_to_cfqq(cic
, is_sync
);
3472 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3473 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3474 cic_set_cfqq(cic
, cfqq
, is_sync
);
3477 * If the queue was seeky for too long, break it apart.
3479 if (cfq_cfqq_coop(cfqq
) && should_split_cfqq(cfqq
)) {
3480 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3481 cfqq
= split_cfqq(cic
, cfqq
);
3487 * Check to see if this queue is scheduled to merge with
3488 * another, closely cooperating queue. The merging of
3489 * queues happens here as it must be done in process context.
3490 * The reference on new_cfqq was taken in merge_cfqqs.
3493 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3496 cfqq
->allocated
[rw
]++;
3497 atomic_inc(&cfqq
->ref
);
3499 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3501 rq
->elevator_private
= cic
;
3502 rq
->elevator_private2
= cfqq
;
3507 put_io_context(cic
->ioc
);
3509 cfq_schedule_dispatch(cfqd
);
3510 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3511 cfq_log(cfqd
, "set_request fail");
3515 static void cfq_kick_queue(struct work_struct
*work
)
3517 struct cfq_data
*cfqd
=
3518 container_of(work
, struct cfq_data
, unplug_work
);
3519 struct request_queue
*q
= cfqd
->queue
;
3521 spin_lock_irq(q
->queue_lock
);
3522 __blk_run_queue(cfqd
->queue
);
3523 spin_unlock_irq(q
->queue_lock
);
3527 * Timer running if the active_queue is currently idling inside its time slice
3529 static void cfq_idle_slice_timer(unsigned long data
)
3531 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3532 struct cfq_queue
*cfqq
;
3533 unsigned long flags
;
3536 cfq_log(cfqd
, "idle timer fired");
3538 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3540 cfqq
= cfqd
->active_queue
;
3545 * We saw a request before the queue expired, let it through
3547 if (cfq_cfqq_must_dispatch(cfqq
))
3553 if (cfq_slice_used(cfqq
))
3557 * only expire and reinvoke request handler, if there are
3558 * other queues with pending requests
3560 if (!cfqd
->busy_queues
)
3564 * not expired and it has a request pending, let it dispatch
3566 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3570 * Queue depth flag is reset only when the idle didn't succeed
3572 cfq_clear_cfqq_deep(cfqq
);
3575 cfq_slice_expired(cfqd
, timed_out
);
3577 cfq_schedule_dispatch(cfqd
);
3579 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3582 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3584 del_timer_sync(&cfqd
->idle_slice_timer
);
3585 cancel_work_sync(&cfqd
->unplug_work
);
3588 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3592 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3593 if (cfqd
->async_cfqq
[0][i
])
3594 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3595 if (cfqd
->async_cfqq
[1][i
])
3596 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3599 if (cfqd
->async_idle_cfqq
)
3600 cfq_put_queue(cfqd
->async_idle_cfqq
);
3603 static void cfq_exit_queue(struct elevator_queue
*e
)
3605 struct cfq_data
*cfqd
= e
->elevator_data
;
3606 struct request_queue
*q
= cfqd
->queue
;
3608 cfq_shutdown_timer_wq(cfqd
);
3610 spin_lock_irq(q
->queue_lock
);
3612 if (cfqd
->active_queue
)
3613 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3615 while (!list_empty(&cfqd
->cic_list
)) {
3616 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3617 struct cfq_io_context
,
3620 __cfq_exit_single_io_context(cfqd
, cic
);
3623 cfq_put_async_queues(cfqd
);
3624 cfq_release_cfq_groups(cfqd
);
3625 blkiocg_del_blkio_group(&cfqd
->root_group
.blkg
);
3627 spin_unlock_irq(q
->queue_lock
);
3629 cfq_shutdown_timer_wq(cfqd
);
3631 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3636 static void *cfq_init_queue(struct request_queue
*q
)
3638 struct cfq_data
*cfqd
;
3640 struct cfq_group
*cfqg
;
3641 struct cfq_rb_root
*st
;
3643 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3647 /* Init root service tree */
3648 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3650 /* Init root group */
3651 cfqg
= &cfqd
->root_group
;
3652 for_each_cfqg_st(cfqg
, i
, j
, st
)
3654 RB_CLEAR_NODE(&cfqg
->rb_node
);
3656 /* Give preference to root group over other groups */
3657 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3659 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3661 * Take a reference to root group which we never drop. This is just
3662 * to make sure that cfq_put_cfqg() does not try to kfree root group
3664 atomic_set(&cfqg
->ref
, 1);
3665 blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
, (void *)cfqd
,
3669 * Not strictly needed (since RB_ROOT just clears the node and we
3670 * zeroed cfqd on alloc), but better be safe in case someone decides
3671 * to add magic to the rb code
3673 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3674 cfqd
->prio_trees
[i
] = RB_ROOT
;
3677 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3678 * Grab a permanent reference to it, so that the normal code flow
3679 * will not attempt to free it.
3681 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3682 atomic_inc(&cfqd
->oom_cfqq
.ref
);
3683 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3685 INIT_LIST_HEAD(&cfqd
->cic_list
);
3689 init_timer(&cfqd
->idle_slice_timer
);
3690 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3691 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3693 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3695 cfqd
->cfq_quantum
= cfq_quantum
;
3696 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3697 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3698 cfqd
->cfq_back_max
= cfq_back_max
;
3699 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3700 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3701 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3702 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3703 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3704 cfqd
->cfq_latency
= 1;
3705 cfqd
->cfq_group_isolation
= 0;
3707 cfqd
->last_end_sync_rq
= jiffies
;
3711 static void cfq_slab_kill(void)
3714 * Caller already ensured that pending RCU callbacks are completed,
3715 * so we should have no busy allocations at this point.
3718 kmem_cache_destroy(cfq_pool
);
3720 kmem_cache_destroy(cfq_ioc_pool
);
3723 static int __init
cfq_slab_setup(void)
3725 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3729 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3740 * sysfs parts below -->
3743 cfq_var_show(unsigned int var
, char *page
)
3745 return sprintf(page
, "%d\n", var
);
3749 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3751 char *p
= (char *) page
;
3753 *var
= simple_strtoul(p
, &p
, 10);
3757 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3758 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3760 struct cfq_data *cfqd = e->elevator_data; \
3761 unsigned int __data = __VAR; \
3763 __data = jiffies_to_msecs(__data); \
3764 return cfq_var_show(__data, (page)); \
3766 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3767 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3768 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3769 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3770 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3771 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3772 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
3773 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
3774 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
3775 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
3776 SHOW_FUNCTION(cfq_group_isolation_show
, cfqd
->cfq_group_isolation
, 0);
3777 #undef SHOW_FUNCTION
3779 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3780 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3782 struct cfq_data *cfqd = e->elevator_data; \
3783 unsigned int __data; \
3784 int ret = cfq_var_store(&__data, (page), count); \
3785 if (__data < (MIN)) \
3787 else if (__data > (MAX)) \
3790 *(__PTR) = msecs_to_jiffies(__data); \
3792 *(__PTR) = __data; \
3795 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
3796 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
3798 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
3800 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
3801 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
3803 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
3804 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
3805 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
3806 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
3808 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
3809 STORE_FUNCTION(cfq_group_isolation_store
, &cfqd
->cfq_group_isolation
, 0, 1, 0);
3810 #undef STORE_FUNCTION
3812 #define CFQ_ATTR(name) \
3813 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3815 static struct elv_fs_entry cfq_attrs
[] = {
3817 CFQ_ATTR(fifo_expire_sync
),
3818 CFQ_ATTR(fifo_expire_async
),
3819 CFQ_ATTR(back_seek_max
),
3820 CFQ_ATTR(back_seek_penalty
),
3821 CFQ_ATTR(slice_sync
),
3822 CFQ_ATTR(slice_async
),
3823 CFQ_ATTR(slice_async_rq
),
3824 CFQ_ATTR(slice_idle
),
3825 CFQ_ATTR(low_latency
),
3826 CFQ_ATTR(group_isolation
),
3830 static struct elevator_type iosched_cfq
= {
3832 .elevator_merge_fn
= cfq_merge
,
3833 .elevator_merged_fn
= cfq_merged_request
,
3834 .elevator_merge_req_fn
= cfq_merged_requests
,
3835 .elevator_allow_merge_fn
= cfq_allow_merge
,
3836 .elevator_dispatch_fn
= cfq_dispatch_requests
,
3837 .elevator_add_req_fn
= cfq_insert_request
,
3838 .elevator_activate_req_fn
= cfq_activate_request
,
3839 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
3840 .elevator_queue_empty_fn
= cfq_queue_empty
,
3841 .elevator_completed_req_fn
= cfq_completed_request
,
3842 .elevator_former_req_fn
= elv_rb_former_request
,
3843 .elevator_latter_req_fn
= elv_rb_latter_request
,
3844 .elevator_set_req_fn
= cfq_set_request
,
3845 .elevator_put_req_fn
= cfq_put_request
,
3846 .elevator_may_queue_fn
= cfq_may_queue
,
3847 .elevator_init_fn
= cfq_init_queue
,
3848 .elevator_exit_fn
= cfq_exit_queue
,
3849 .trim
= cfq_free_io_context
,
3851 .elevator_attrs
= cfq_attrs
,
3852 .elevator_name
= "cfq",
3853 .elevator_owner
= THIS_MODULE
,
3856 static int __init
cfq_init(void)
3859 * could be 0 on HZ < 1000 setups
3861 if (!cfq_slice_async
)
3862 cfq_slice_async
= 1;
3863 if (!cfq_slice_idle
)
3866 if (cfq_slab_setup())
3869 elv_register(&iosched_cfq
);
3874 static void __exit
cfq_exit(void)
3876 DECLARE_COMPLETION_ONSTACK(all_gone
);
3877 elv_unregister(&iosched_cfq
);
3878 ioc_gone
= &all_gone
;
3879 /* ioc_gone's update must be visible before reading ioc_count */
3883 * this also protects us from entering cfq_slab_kill() with
3884 * pending RCU callbacks
3886 if (elv_ioc_count_read(cfq_ioc_count
))
3887 wait_for_completion(&all_gone
);
3891 module_init(cfq_init
);
3892 module_exit(cfq_exit
);
3894 MODULE_AUTHOR("Jens Axboe");
3895 MODULE_LICENSE("GPL");
3896 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");