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>
20 /* max queue in one round of service */
21 static const int cfq_quantum
= 4;
22 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
23 /* maximum backwards seek, in KiB */
24 static const int cfq_back_max
= 16 * 1024;
25 /* penalty of a backwards seek */
26 static const int cfq_back_penalty
= 2;
27 static const int cfq_slice_sync
= HZ
/ 10;
28 static int cfq_slice_async
= HZ
/ 25;
29 static const int cfq_slice_async_rq
= 2;
30 static int cfq_slice_idle
= HZ
/ 125;
31 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
32 static const int cfq_hist_divisor
= 4;
35 * offset from end of service tree
37 #define CFQ_IDLE_DELAY (HZ / 5)
40 * below this threshold, we consider thinktime immediate
42 #define CFQ_MIN_TT (2)
45 * Allow merged cfqqs to perform this amount of seeky I/O before
46 * deciding to break the queues up again.
48 #define CFQQ_COOP_TOUT (HZ)
50 #define CFQ_SLICE_SCALE (5)
51 #define CFQ_HW_QUEUE_MIN (5)
54 ((struct cfq_io_context *) (rq)->elevator_private)
55 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
57 static struct kmem_cache
*cfq_pool
;
58 static struct kmem_cache
*cfq_ioc_pool
;
60 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count
);
61 static struct completion
*ioc_gone
;
62 static DEFINE_SPINLOCK(ioc_gone_lock
);
64 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
65 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
66 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
68 #define sample_valid(samples) ((samples) > 80)
69 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
72 * Most of our rbtree usage is for sorting with min extraction, so
73 * if we cache the leftmost node we don't have to walk down the tree
74 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
75 * move this into the elevator for the rq sorting as well.
83 #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
86 * Per process-grouping structure
91 /* various state flags, see below */
94 struct cfq_data
*cfqd
;
95 /* service_tree member */
96 struct rb_node rb_node
;
97 /* service_tree key */
99 /* prio tree member */
100 struct rb_node p_node
;
101 /* prio tree root we belong to, if any */
102 struct rb_root
*p_root
;
103 /* sorted list of pending requests */
104 struct rb_root sort_list
;
105 /* if fifo isn't expired, next request to serve */
106 struct request
*next_rq
;
107 /* requests queued in sort_list */
109 /* currently allocated requests */
111 /* fifo list of requests in sort_list */
112 struct list_head fifo
;
114 unsigned long slice_end
;
116 unsigned int slice_dispatch
;
118 /* pending metadata requests */
120 /* number of requests that are on the dispatch list or inside driver */
123 /* io prio of this group */
124 unsigned short ioprio
, org_ioprio
;
125 unsigned short ioprio_class
, org_ioprio_class
;
127 unsigned int seek_samples
;
130 sector_t last_request_pos
;
131 unsigned long seeky_start
;
135 struct cfq_rb_root
*service_tree
;
136 struct cfq_queue
*new_cfqq
;
137 struct cfq_group
*cfqg
;
141 * First index in the service_trees.
142 * IDLE is handled separately, so it has negative index
151 * Second index in the service_trees.
155 SYNC_NOIDLE_WORKLOAD
= 1,
159 /* This is per cgroup per device grouping structure */
161 /* group service_tree member */
162 struct rb_node rb_node
;
164 /* group service_tree key */
168 /* number of cfqq currently on this group */
172 * rr lists of queues with requests, onle rr for each priority class.
173 * Counts are embedded in the cfq_rb_root
175 struct cfq_rb_root service_trees
[2][3];
176 struct cfq_rb_root service_tree_idle
;
180 * Per block device queue structure
183 struct request_queue
*queue
;
184 /* Root service tree for cfq_groups */
185 struct cfq_rb_root grp_service_tree
;
186 struct cfq_group root_group
;
189 * The priority currently being served
191 enum wl_prio_t serving_prio
;
192 enum wl_type_t serving_type
;
193 unsigned long workload_expires
;
194 struct cfq_group
*serving_group
;
195 bool noidle_tree_requires_idle
;
198 * Each priority tree is sorted by next_request position. These
199 * trees are used when determining if two or more queues are
200 * interleaving requests (see cfq_close_cooperator).
202 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
204 unsigned int busy_queues
;
205 unsigned int busy_queues_avg
[2];
211 * queue-depth detection
217 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
218 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
221 int hw_tag_est_depth
;
222 unsigned int hw_tag_samples
;
225 * idle window management
227 struct timer_list idle_slice_timer
;
228 struct work_struct unplug_work
;
230 struct cfq_queue
*active_queue
;
231 struct cfq_io_context
*active_cic
;
234 * async queue for each priority case
236 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
237 struct cfq_queue
*async_idle_cfqq
;
239 sector_t last_position
;
242 * tunables, see top of file
244 unsigned int cfq_quantum
;
245 unsigned int cfq_fifo_expire
[2];
246 unsigned int cfq_back_penalty
;
247 unsigned int cfq_back_max
;
248 unsigned int cfq_slice
[2];
249 unsigned int cfq_slice_async_rq
;
250 unsigned int cfq_slice_idle
;
251 unsigned int cfq_latency
;
253 struct list_head cic_list
;
256 * Fallback dummy cfqq for extreme OOM conditions
258 struct cfq_queue oom_cfqq
;
260 unsigned long last_end_sync_rq
;
263 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
266 struct cfq_data
*cfqd
)
271 if (prio
== IDLE_WORKLOAD
)
272 return &cfqg
->service_tree_idle
;
274 return &cfqg
->service_trees
[prio
][type
];
277 enum cfqq_state_flags
{
278 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
279 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
280 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
281 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
282 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
283 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
284 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
285 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
286 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
287 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
288 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
291 #define CFQ_CFQQ_FNS(name) \
292 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
294 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
296 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
298 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
300 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
302 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
306 CFQ_CFQQ_FNS(wait_request
);
307 CFQ_CFQQ_FNS(must_dispatch
);
308 CFQ_CFQQ_FNS(must_alloc_slice
);
309 CFQ_CFQQ_FNS(fifo_expire
);
310 CFQ_CFQQ_FNS(idle_window
);
311 CFQ_CFQQ_FNS(prio_changed
);
312 CFQ_CFQQ_FNS(slice_new
);
318 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
319 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
320 #define cfq_log(cfqd, fmt, args...) \
321 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
323 /* Traverses through cfq group service trees */
324 #define for_each_cfqg_st(cfqg, i, j, st) \
325 for (i = 0; i <= IDLE_WORKLOAD; i++) \
326 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
327 : &cfqg->service_tree_idle; \
328 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
329 (i == IDLE_WORKLOAD && j == 0); \
330 j++, st = i < IDLE_WORKLOAD ? \
331 &cfqg->service_trees[i][j]: NULL) \
334 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
336 if (cfq_class_idle(cfqq
))
337 return IDLE_WORKLOAD
;
338 if (cfq_class_rt(cfqq
))
344 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
346 if (!cfq_cfqq_sync(cfqq
))
347 return ASYNC_WORKLOAD
;
348 if (!cfq_cfqq_idle_window(cfqq
))
349 return SYNC_NOIDLE_WORKLOAD
;
350 return SYNC_WORKLOAD
;
353 static inline int cfq_busy_queues_wl(enum wl_prio_t wl
, struct cfq_data
*cfqd
)
355 struct cfq_group
*cfqg
= &cfqd
->root_group
;
357 if (wl
== IDLE_WORKLOAD
)
358 return cfqg
->service_tree_idle
.count
;
360 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
361 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
362 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
365 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
366 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
367 struct io_context
*, gfp_t
);
368 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
369 struct io_context
*);
371 static inline int rq_in_driver(struct cfq_data
*cfqd
)
373 return cfqd
->rq_in_driver
[0] + cfqd
->rq_in_driver
[1];
376 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
379 return cic
->cfqq
[is_sync
];
382 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
383 struct cfq_queue
*cfqq
, bool is_sync
)
385 cic
->cfqq
[is_sync
] = cfqq
;
389 * We regard a request as SYNC, if it's either a read or has the SYNC bit
390 * set (in which case it could also be direct WRITE).
392 static inline bool cfq_bio_sync(struct bio
*bio
)
394 return bio_data_dir(bio
) == READ
|| bio_rw_flagged(bio
, BIO_RW_SYNCIO
);
398 * scheduler run of queue, if there are requests pending and no one in the
399 * driver that will restart queueing
401 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
403 if (cfqd
->busy_queues
) {
404 cfq_log(cfqd
, "schedule dispatch");
405 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
409 static int cfq_queue_empty(struct request_queue
*q
)
411 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
413 return !cfqd
->rq_queued
;
417 * Scale schedule slice based on io priority. Use the sync time slice only
418 * if a queue is marked sync and has sync io queued. A sync queue with async
419 * io only, should not get full sync slice length.
421 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
424 const int base_slice
= cfqd
->cfq_slice
[sync
];
426 WARN_ON(prio
>= IOPRIO_BE_NR
);
428 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
432 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
434 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
438 * get averaged number of queues of RT/BE priority.
439 * average is updated, with a formula that gives more weight to higher numbers,
440 * to quickly follows sudden increases and decrease slowly
443 static inline unsigned cfq_get_avg_queues(struct cfq_data
*cfqd
, bool rt
)
445 unsigned min_q
, max_q
;
446 unsigned mult
= cfq_hist_divisor
- 1;
447 unsigned round
= cfq_hist_divisor
/ 2;
448 unsigned busy
= cfq_busy_queues_wl(rt
, cfqd
);
450 min_q
= min(cfqd
->busy_queues_avg
[rt
], busy
);
451 max_q
= max(cfqd
->busy_queues_avg
[rt
], busy
);
452 cfqd
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
454 return cfqd
->busy_queues_avg
[rt
];
458 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
460 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
461 if (cfqd
->cfq_latency
) {
462 /* interested queues (we consider only the ones with the same
464 unsigned iq
= cfq_get_avg_queues(cfqd
, cfq_class_rt(cfqq
));
465 unsigned sync_slice
= cfqd
->cfq_slice
[1];
466 unsigned expect_latency
= sync_slice
* iq
;
467 if (expect_latency
> cfq_target_latency
) {
468 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
469 /* scale low_slice according to IO priority
470 * and sync vs async */
472 min(slice
, base_low_slice
* slice
/ sync_slice
);
473 /* the adapted slice value is scaled to fit all iqs
474 * into the target latency */
475 slice
= max(slice
* cfq_target_latency
/ expect_latency
,
479 cfqq
->slice_end
= jiffies
+ slice
;
480 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
484 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
485 * isn't valid until the first request from the dispatch is activated
486 * and the slice time set.
488 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
490 if (cfq_cfqq_slice_new(cfqq
))
492 if (time_before(jiffies
, cfqq
->slice_end
))
499 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
500 * We choose the request that is closest to the head right now. Distance
501 * behind the head is penalized and only allowed to a certain extent.
503 static struct request
*
504 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
506 sector_t s1
, s2
, d1
= 0, d2
= 0;
507 unsigned long back_max
;
508 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
509 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
510 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
512 if (rq1
== NULL
|| rq1
== rq2
)
517 if (rq_is_sync(rq1
) && !rq_is_sync(rq2
))
519 else if (rq_is_sync(rq2
) && !rq_is_sync(rq1
))
521 if (rq_is_meta(rq1
) && !rq_is_meta(rq2
))
523 else if (rq_is_meta(rq2
) && !rq_is_meta(rq1
))
526 s1
= blk_rq_pos(rq1
);
527 s2
= blk_rq_pos(rq2
);
530 * by definition, 1KiB is 2 sectors
532 back_max
= cfqd
->cfq_back_max
* 2;
535 * Strict one way elevator _except_ in the case where we allow
536 * short backward seeks which are biased as twice the cost of a
537 * similar forward seek.
541 else if (s1
+ back_max
>= last
)
542 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
544 wrap
|= CFQ_RQ1_WRAP
;
548 else if (s2
+ back_max
>= last
)
549 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
551 wrap
|= CFQ_RQ2_WRAP
;
553 /* Found required data */
556 * By doing switch() on the bit mask "wrap" we avoid having to
557 * check two variables for all permutations: --> faster!
560 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
576 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
579 * Since both rqs are wrapped,
580 * start with the one that's further behind head
581 * (--> only *one* back seek required),
582 * since back seek takes more time than forward.
592 * The below is leftmost cache rbtree addon
594 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
596 /* Service tree is empty */
601 root
->left
= rb_first(&root
->rb
);
604 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
609 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
612 root
->left
= rb_first(&root
->rb
);
615 return rb_entry_cfqg(root
->left
);
620 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
626 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
630 rb_erase_init(n
, &root
->rb
);
635 * would be nice to take fifo expire time into account as well
637 static struct request
*
638 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
639 struct request
*last
)
641 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
642 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
643 struct request
*next
= NULL
, *prev
= NULL
;
645 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
648 prev
= rb_entry_rq(rbprev
);
651 next
= rb_entry_rq(rbnext
);
653 rbnext
= rb_first(&cfqq
->sort_list
);
654 if (rbnext
&& rbnext
!= &last
->rb_node
)
655 next
= rb_entry_rq(rbnext
);
658 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
661 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
662 struct cfq_queue
*cfqq
)
665 * just an approximation, should be ok.
667 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
668 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
672 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
674 return cfqg
->vdisktime
- st
->min_vdisktime
;
678 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
680 struct rb_node
**node
= &st
->rb
.rb_node
;
681 struct rb_node
*parent
= NULL
;
682 struct cfq_group
*__cfqg
;
683 s64 key
= cfqg_key(st
, cfqg
);
686 while (*node
!= NULL
) {
688 __cfqg
= rb_entry_cfqg(parent
);
690 if (key
< cfqg_key(st
, __cfqg
))
691 node
= &parent
->rb_left
;
693 node
= &parent
->rb_right
;
699 st
->left
= &cfqg
->rb_node
;
701 rb_link_node(&cfqg
->rb_node
, parent
, node
);
702 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
706 cfq_group_service_tree_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
708 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
709 struct cfq_group
*__cfqg
;
717 * Currently put the group at the end. Later implement something
718 * so that groups get lesser vtime based on their weights, so that
719 * if group does not loose all if it was not continously backlogged.
721 n
= rb_last(&st
->rb
);
723 __cfqg
= rb_entry_cfqg(n
);
724 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
726 cfqg
->vdisktime
= st
->min_vdisktime
;
728 __cfq_group_service_tree_add(st
, cfqg
);
733 cfq_group_service_tree_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
735 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
737 BUG_ON(cfqg
->nr_cfqq
< 1);
739 /* If there are other cfq queues under this group, don't delete it */
744 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
745 cfq_rb_erase(&cfqg
->rb_node
, st
);
749 * The cfqd->service_trees holds all pending cfq_queue's that have
750 * requests waiting to be processed. It is sorted in the order that
751 * we will service the queues.
753 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
756 struct rb_node
**p
, *parent
;
757 struct cfq_queue
*__cfqq
;
758 unsigned long rb_key
;
759 struct cfq_rb_root
*service_tree
;
762 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
763 cfqq_type(cfqq
), cfqd
);
764 if (cfq_class_idle(cfqq
)) {
765 rb_key
= CFQ_IDLE_DELAY
;
766 parent
= rb_last(&service_tree
->rb
);
767 if (parent
&& parent
!= &cfqq
->rb_node
) {
768 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
769 rb_key
+= __cfqq
->rb_key
;
772 } else if (!add_front
) {
774 * Get our rb key offset. Subtract any residual slice
775 * value carried from last service. A negative resid
776 * count indicates slice overrun, and this should position
777 * the next service time further away in the tree.
779 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
780 rb_key
-= cfqq
->slice_resid
;
781 cfqq
->slice_resid
= 0;
784 __cfqq
= cfq_rb_first(service_tree
);
785 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
788 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
790 * same position, nothing more to do
792 if (rb_key
== cfqq
->rb_key
&&
793 cfqq
->service_tree
== service_tree
)
796 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
797 cfqq
->service_tree
= NULL
;
802 cfqq
->service_tree
= service_tree
;
803 p
= &service_tree
->rb
.rb_node
;
808 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
811 * sort by key, that represents service time.
813 if (time_before(rb_key
, __cfqq
->rb_key
))
824 service_tree
->left
= &cfqq
->rb_node
;
826 cfqq
->rb_key
= rb_key
;
827 rb_link_node(&cfqq
->rb_node
, parent
, p
);
828 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
829 service_tree
->count
++;
830 cfq_group_service_tree_add(cfqd
, cfqq
->cfqg
);
833 static struct cfq_queue
*
834 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
835 sector_t sector
, struct rb_node
**ret_parent
,
836 struct rb_node
***rb_link
)
838 struct rb_node
**p
, *parent
;
839 struct cfq_queue
*cfqq
= NULL
;
847 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
850 * Sort strictly based on sector. Smallest to the left,
851 * largest to the right.
853 if (sector
> blk_rq_pos(cfqq
->next_rq
))
855 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
863 *ret_parent
= parent
;
869 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
871 struct rb_node
**p
, *parent
;
872 struct cfq_queue
*__cfqq
;
875 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
879 if (cfq_class_idle(cfqq
))
884 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
885 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
886 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
888 rb_link_node(&cfqq
->p_node
, parent
, p
);
889 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
895 * Update cfqq's position in the service tree.
897 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
900 * Resorting requires the cfqq to be on the RR list already.
902 if (cfq_cfqq_on_rr(cfqq
)) {
903 cfq_service_tree_add(cfqd
, cfqq
, 0);
904 cfq_prio_tree_add(cfqd
, cfqq
);
909 * add to busy list of queues for service, trying to be fair in ordering
910 * the pending list according to last request service
912 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
914 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
915 BUG_ON(cfq_cfqq_on_rr(cfqq
));
916 cfq_mark_cfqq_on_rr(cfqq
);
919 cfq_resort_rr_list(cfqd
, cfqq
);
923 * Called when the cfqq no longer has requests pending, remove it from
926 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
928 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
929 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
930 cfq_clear_cfqq_on_rr(cfqq
);
932 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
933 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
934 cfqq
->service_tree
= NULL
;
937 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
941 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
942 BUG_ON(!cfqd
->busy_queues
);
947 * rb tree support functions
949 static void cfq_del_rq_rb(struct request
*rq
)
951 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
952 const int sync
= rq_is_sync(rq
);
954 BUG_ON(!cfqq
->queued
[sync
]);
955 cfqq
->queued
[sync
]--;
957 elv_rb_del(&cfqq
->sort_list
, rq
);
959 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
961 * Queue will be deleted from service tree when we actually
962 * expire it later. Right now just remove it from prio tree
966 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
972 static void cfq_add_rq_rb(struct request
*rq
)
974 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
975 struct cfq_data
*cfqd
= cfqq
->cfqd
;
976 struct request
*__alias
, *prev
;
978 cfqq
->queued
[rq_is_sync(rq
)]++;
981 * looks a little odd, but the first insert might return an alias.
982 * if that happens, put the alias on the dispatch list
984 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
985 cfq_dispatch_insert(cfqd
->queue
, __alias
);
987 if (!cfq_cfqq_on_rr(cfqq
))
988 cfq_add_cfqq_rr(cfqd
, cfqq
);
991 * check if this request is a better next-serve candidate
993 prev
= cfqq
->next_rq
;
994 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
997 * adjust priority tree position, if ->next_rq changes
999 if (prev
!= cfqq
->next_rq
)
1000 cfq_prio_tree_add(cfqd
, cfqq
);
1002 BUG_ON(!cfqq
->next_rq
);
1005 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1007 elv_rb_del(&cfqq
->sort_list
, rq
);
1008 cfqq
->queued
[rq_is_sync(rq
)]--;
1012 static struct request
*
1013 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1015 struct task_struct
*tsk
= current
;
1016 struct cfq_io_context
*cic
;
1017 struct cfq_queue
*cfqq
;
1019 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1023 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1025 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1027 return elv_rb_find(&cfqq
->sort_list
, sector
);
1033 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1035 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1037 cfqd
->rq_in_driver
[rq_is_sync(rq
)]++;
1038 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1039 rq_in_driver(cfqd
));
1041 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1044 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1046 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1047 const int sync
= rq_is_sync(rq
);
1049 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
1050 cfqd
->rq_in_driver
[sync
]--;
1051 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1052 rq_in_driver(cfqd
));
1055 static void cfq_remove_request(struct request
*rq
)
1057 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1059 if (cfqq
->next_rq
== rq
)
1060 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1062 list_del_init(&rq
->queuelist
);
1065 cfqq
->cfqd
->rq_queued
--;
1066 if (rq_is_meta(rq
)) {
1067 WARN_ON(!cfqq
->meta_pending
);
1068 cfqq
->meta_pending
--;
1072 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1075 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1076 struct request
*__rq
;
1078 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1079 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1081 return ELEVATOR_FRONT_MERGE
;
1084 return ELEVATOR_NO_MERGE
;
1087 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1090 if (type
== ELEVATOR_FRONT_MERGE
) {
1091 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1093 cfq_reposition_rq_rb(cfqq
, req
);
1098 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1099 struct request
*next
)
1101 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1103 * reposition in fifo if next is older than rq
1105 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1106 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1107 list_move(&rq
->queuelist
, &next
->queuelist
);
1108 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1111 if (cfqq
->next_rq
== next
)
1113 cfq_remove_request(next
);
1116 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1119 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1120 struct cfq_io_context
*cic
;
1121 struct cfq_queue
*cfqq
;
1124 * Disallow merge of a sync bio into an async request.
1126 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1130 * Lookup the cfqq that this bio will be queued with. Allow
1131 * merge only if rq is queued there.
1133 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1137 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1138 return cfqq
== RQ_CFQQ(rq
);
1141 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1142 struct cfq_queue
*cfqq
)
1145 cfq_log_cfqq(cfqd
, cfqq
, "set_active");
1146 cfqq
->slice_end
= 0;
1147 cfqq
->slice_dispatch
= 0;
1149 cfq_clear_cfqq_wait_request(cfqq
);
1150 cfq_clear_cfqq_must_dispatch(cfqq
);
1151 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1152 cfq_clear_cfqq_fifo_expire(cfqq
);
1153 cfq_mark_cfqq_slice_new(cfqq
);
1155 del_timer(&cfqd
->idle_slice_timer
);
1158 cfqd
->active_queue
= cfqq
;
1162 * current cfqq expired its slice (or was too idle), select new one
1165 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1168 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1170 if (cfq_cfqq_wait_request(cfqq
))
1171 del_timer(&cfqd
->idle_slice_timer
);
1173 cfq_clear_cfqq_wait_request(cfqq
);
1176 * store what was left of this slice, if the queue idled/timed out
1178 if (timed_out
&& !cfq_cfqq_slice_new(cfqq
)) {
1179 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1180 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1183 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1184 cfq_del_cfqq_rr(cfqd
, cfqq
);
1186 cfq_resort_rr_list(cfqd
, cfqq
);
1188 if (cfqq
== cfqd
->active_queue
)
1189 cfqd
->active_queue
= NULL
;
1191 if (cfqd
->active_cic
) {
1192 put_io_context(cfqd
->active_cic
->ioc
);
1193 cfqd
->active_cic
= NULL
;
1197 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1199 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1202 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1206 * Get next queue for service. Unless we have a queue preemption,
1207 * we'll simply select the first cfqq in the service tree.
1209 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1211 struct cfq_rb_root
*service_tree
=
1212 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1213 cfqd
->serving_type
, cfqd
);
1215 if (!cfqd
->rq_queued
)
1218 /* There is nothing to dispatch */
1221 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1223 return cfq_rb_first(service_tree
);
1226 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1228 struct cfq_group
*cfqg
= &cfqd
->root_group
;
1229 struct cfq_queue
*cfqq
;
1231 struct cfq_rb_root
*st
;
1233 if (!cfqd
->rq_queued
)
1236 for_each_cfqg_st(cfqg
, i
, j
, st
)
1237 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1243 * Get and set a new active queue for service.
1245 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1246 struct cfq_queue
*cfqq
)
1249 cfqq
= cfq_get_next_queue(cfqd
);
1251 __cfq_set_active_queue(cfqd
, cfqq
);
1255 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1258 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1259 return blk_rq_pos(rq
) - cfqd
->last_position
;
1261 return cfqd
->last_position
- blk_rq_pos(rq
);
1264 #define CFQQ_SEEK_THR 8 * 1024
1265 #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
1267 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1270 sector_t sdist
= cfqq
->seek_mean
;
1272 if (!sample_valid(cfqq
->seek_samples
))
1273 sdist
= CFQQ_SEEK_THR
;
1275 return cfq_dist_from_last(cfqd
, rq
) <= sdist
;
1278 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1279 struct cfq_queue
*cur_cfqq
)
1281 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1282 struct rb_node
*parent
, *node
;
1283 struct cfq_queue
*__cfqq
;
1284 sector_t sector
= cfqd
->last_position
;
1286 if (RB_EMPTY_ROOT(root
))
1290 * First, if we find a request starting at the end of the last
1291 * request, choose it.
1293 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1298 * If the exact sector wasn't found, the parent of the NULL leaf
1299 * will contain the closest sector.
1301 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1302 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1305 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1306 node
= rb_next(&__cfqq
->p_node
);
1308 node
= rb_prev(&__cfqq
->p_node
);
1312 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1313 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1321 * cur_cfqq - passed in so that we don't decide that the current queue is
1322 * closely cooperating with itself.
1324 * So, basically we're assuming that that cur_cfqq has dispatched at least
1325 * one request, and that cfqd->last_position reflects a position on the disk
1326 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1329 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1330 struct cfq_queue
*cur_cfqq
)
1332 struct cfq_queue
*cfqq
;
1334 if (!cfq_cfqq_sync(cur_cfqq
))
1336 if (CFQQ_SEEKY(cur_cfqq
))
1340 * We should notice if some of the queues are cooperating, eg
1341 * working closely on the same area of the disk. In that case,
1342 * we can group them together and don't waste time idling.
1344 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1349 * It only makes sense to merge sync queues.
1351 if (!cfq_cfqq_sync(cfqq
))
1353 if (CFQQ_SEEKY(cfqq
))
1357 * Do not merge queues of different priority classes
1359 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1366 * Determine whether we should enforce idle window for this queue.
1369 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1371 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1372 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1374 BUG_ON(!service_tree
);
1375 BUG_ON(!service_tree
->count
);
1377 /* We never do for idle class queues. */
1378 if (prio
== IDLE_WORKLOAD
)
1381 /* We do for queues that were marked with idle window flag. */
1382 if (cfq_cfqq_idle_window(cfqq
))
1386 * Otherwise, we do only if they are the last ones
1387 * in their service tree.
1389 return service_tree
->count
== 1;
1392 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1394 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1395 struct cfq_io_context
*cic
;
1399 * SSD device without seek penalty, disable idling. But only do so
1400 * for devices that support queuing, otherwise we still have a problem
1401 * with sync vs async workloads.
1403 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1406 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1407 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1410 * idle is disabled, either manually or by past process history
1412 if (!cfqd
->cfq_slice_idle
|| !cfq_should_idle(cfqd
, cfqq
))
1416 * still active requests from this queue, don't idle
1418 if (cfqq
->dispatched
)
1422 * task has exited, don't wait
1424 cic
= cfqd
->active_cic
;
1425 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1429 * If our average think time is larger than the remaining time
1430 * slice, then don't idle. This avoids overrunning the allotted
1433 if (sample_valid(cic
->ttime_samples
) &&
1434 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
1437 cfq_mark_cfqq_wait_request(cfqq
);
1439 sl
= cfqd
->cfq_slice_idle
;
1441 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1442 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu", sl
);
1446 * Move request from internal lists to the request queue dispatch list.
1448 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1450 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1451 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1453 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1455 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1456 cfq_remove_request(rq
);
1458 elv_dispatch_sort(q
, rq
);
1460 if (cfq_cfqq_sync(cfqq
))
1461 cfqd
->sync_flight
++;
1465 * return expired entry, or NULL to just start from scratch in rbtree
1467 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1469 struct request
*rq
= NULL
;
1471 if (cfq_cfqq_fifo_expire(cfqq
))
1474 cfq_mark_cfqq_fifo_expire(cfqq
);
1476 if (list_empty(&cfqq
->fifo
))
1479 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
1480 if (time_before(jiffies
, rq_fifo_time(rq
)))
1483 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
1488 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1490 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1492 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1494 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1498 * Must be called with the queue_lock held.
1500 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
1502 int process_refs
, io_refs
;
1504 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
1505 process_refs
= atomic_read(&cfqq
->ref
) - io_refs
;
1506 BUG_ON(process_refs
< 0);
1507 return process_refs
;
1510 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
1512 int process_refs
, new_process_refs
;
1513 struct cfq_queue
*__cfqq
;
1515 /* Avoid a circular list and skip interim queue merges */
1516 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
1522 process_refs
= cfqq_process_refs(cfqq
);
1524 * If the process for the cfqq has gone away, there is no
1525 * sense in merging the queues.
1527 if (process_refs
== 0)
1531 * Merge in the direction of the lesser amount of work.
1533 new_process_refs
= cfqq_process_refs(new_cfqq
);
1534 if (new_process_refs
>= process_refs
) {
1535 cfqq
->new_cfqq
= new_cfqq
;
1536 atomic_add(process_refs
, &new_cfqq
->ref
);
1538 new_cfqq
->new_cfqq
= cfqq
;
1539 atomic_add(new_process_refs
, &cfqq
->ref
);
1543 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
1544 struct cfq_group
*cfqg
, enum wl_prio_t prio
,
1547 struct cfq_queue
*queue
;
1549 bool key_valid
= false;
1550 unsigned long lowest_key
= 0;
1551 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
1555 * When priorities switched, we prefer starting
1556 * from SYNC_NOIDLE (first choice), or just SYNC
1559 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1561 cur_best
= SYNC_WORKLOAD
;
1562 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1565 return ASYNC_WORKLOAD
;
1568 for (i
= 0; i
< 3; ++i
) {
1569 /* otherwise, select the one with lowest rb_key */
1570 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
, cfqd
));
1572 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
1573 lowest_key
= queue
->rb_key
;
1582 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1584 enum wl_prio_t previous_prio
= cfqd
->serving_prio
;
1588 struct cfq_rb_root
*st
;
1591 cfqd
->serving_prio
= IDLE_WORKLOAD
;
1592 cfqd
->workload_expires
= jiffies
+ 1;
1596 /* Choose next priority. RT > BE > IDLE */
1597 if (cfq_busy_queues_wl(RT_WORKLOAD
, cfqd
))
1598 cfqd
->serving_prio
= RT_WORKLOAD
;
1599 else if (cfq_busy_queues_wl(BE_WORKLOAD
, cfqd
))
1600 cfqd
->serving_prio
= BE_WORKLOAD
;
1602 cfqd
->serving_prio
= IDLE_WORKLOAD
;
1603 cfqd
->workload_expires
= jiffies
+ 1;
1608 * For RT and BE, we have to choose also the type
1609 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
1612 prio_changed
= (cfqd
->serving_prio
!= previous_prio
);
1613 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
1618 * If priority didn't change, check workload expiration,
1619 * and that we still have other queues ready
1621 if (!prio_changed
&& count
&&
1622 !time_after(jiffies
, cfqd
->workload_expires
))
1625 /* otherwise select new workload type */
1626 cfqd
->serving_type
=
1627 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
, prio_changed
);
1628 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
1633 * the workload slice is computed as a fraction of target latency
1634 * proportional to the number of queues in that workload, over
1635 * all the queues in the same priority class
1637 slice
= cfq_target_latency
* count
/
1638 max_t(unsigned, cfqd
->busy_queues_avg
[cfqd
->serving_prio
],
1639 cfq_busy_queues_wl(cfqd
->serving_prio
, cfqd
));
1641 if (cfqd
->serving_type
== ASYNC_WORKLOAD
)
1642 /* async workload slice is scaled down according to
1643 * the sync/async slice ratio. */
1644 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
1646 /* sync workload slice is at least 2 * cfq_slice_idle */
1647 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
1649 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
1650 cfqd
->workload_expires
= jiffies
+ slice
;
1651 cfqd
->noidle_tree_requires_idle
= false;
1654 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
1656 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
1658 if (RB_EMPTY_ROOT(&st
->rb
))
1660 return cfq_rb_first_group(st
);
1663 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
1665 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
1667 cfqd
->serving_group
= cfqg
;
1668 choose_service_tree(cfqd
, cfqg
);
1672 * Select a queue for service. If we have a current active queue,
1673 * check whether to continue servicing it, or retrieve and set a new one.
1675 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
1677 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1679 cfqq
= cfqd
->active_queue
;
1683 if (!cfqd
->rq_queued
)
1686 * The active queue has run out of time, expire it and select new.
1688 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
))
1692 * The active queue has requests and isn't expired, allow it to
1695 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
1699 * If another queue has a request waiting within our mean seek
1700 * distance, let it run. The expire code will check for close
1701 * cooperators and put the close queue at the front of the service
1702 * tree. If possible, merge the expiring queue with the new cfqq.
1704 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
1706 if (!cfqq
->new_cfqq
)
1707 cfq_setup_merge(cfqq
, new_cfqq
);
1712 * No requests pending. If the active queue still has requests in
1713 * flight or is idling for a new request, allow either of these
1714 * conditions to happen (or time out) before selecting a new queue.
1716 if (timer_pending(&cfqd
->idle_slice_timer
) ||
1717 (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
))) {
1723 cfq_slice_expired(cfqd
, 0);
1726 * Current queue expired. Check if we have to switch to a new
1730 cfq_choose_cfqg(cfqd
);
1732 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
1737 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
1741 while (cfqq
->next_rq
) {
1742 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
1746 BUG_ON(!list_empty(&cfqq
->fifo
));
1748 /* By default cfqq is not expired if it is empty. Do it explicitly */
1749 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
1754 * Drain our current requests. Used for barriers and when switching
1755 * io schedulers on-the-fly.
1757 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
1759 struct cfq_queue
*cfqq
;
1762 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
)
1763 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
1765 cfq_slice_expired(cfqd
, 0);
1766 BUG_ON(cfqd
->busy_queues
);
1768 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
1772 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1774 unsigned int max_dispatch
;
1777 * Drain async requests before we start sync IO
1779 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_driver
[BLK_RW_ASYNC
])
1783 * If this is an async queue and we have sync IO in flight, let it wait
1785 if (cfqd
->sync_flight
&& !cfq_cfqq_sync(cfqq
))
1788 max_dispatch
= cfqd
->cfq_quantum
;
1789 if (cfq_class_idle(cfqq
))
1793 * Does this cfqq already have too much IO in flight?
1795 if (cfqq
->dispatched
>= max_dispatch
) {
1797 * idle queue must always only have a single IO in flight
1799 if (cfq_class_idle(cfqq
))
1803 * We have other queues, don't allow more IO from this one
1805 if (cfqd
->busy_queues
> 1)
1809 * Sole queue user, no limit
1815 * Async queues must wait a bit before being allowed dispatch.
1816 * We also ramp up the dispatch depth gradually for async IO,
1817 * based on the last sync IO we serviced
1819 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
1820 unsigned long last_sync
= jiffies
- cfqd
->last_end_sync_rq
;
1823 depth
= last_sync
/ cfqd
->cfq_slice
[1];
1824 if (!depth
&& !cfqq
->dispatched
)
1826 if (depth
< max_dispatch
)
1827 max_dispatch
= depth
;
1831 * If we're below the current max, allow a dispatch
1833 return cfqq
->dispatched
< max_dispatch
;
1837 * Dispatch a request from cfqq, moving them to the request queue
1840 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1844 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
1846 if (!cfq_may_dispatch(cfqd
, cfqq
))
1850 * follow expired path, else get first next available
1852 rq
= cfq_check_fifo(cfqq
);
1857 * insert request into driver dispatch list
1859 cfq_dispatch_insert(cfqd
->queue
, rq
);
1861 if (!cfqd
->active_cic
) {
1862 struct cfq_io_context
*cic
= RQ_CIC(rq
);
1864 atomic_long_inc(&cic
->ioc
->refcount
);
1865 cfqd
->active_cic
= cic
;
1872 * Find the cfqq that we need to service and move a request from that to the
1875 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
1877 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1878 struct cfq_queue
*cfqq
;
1880 if (!cfqd
->busy_queues
)
1883 if (unlikely(force
))
1884 return cfq_forced_dispatch(cfqd
);
1886 cfqq
= cfq_select_queue(cfqd
);
1891 * Dispatch a request from this cfqq, if it is allowed
1893 if (!cfq_dispatch_request(cfqd
, cfqq
))
1896 cfqq
->slice_dispatch
++;
1897 cfq_clear_cfqq_must_dispatch(cfqq
);
1900 * expire an async queue immediately if it has used up its slice. idle
1901 * queue always expire after 1 dispatch round.
1903 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
1904 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1905 cfq_class_idle(cfqq
))) {
1906 cfqq
->slice_end
= jiffies
+ 1;
1907 cfq_slice_expired(cfqd
, 0);
1910 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
1915 * task holds one reference to the queue, dropped when task exits. each rq
1916 * in-flight on this queue also holds a reference, dropped when rq is freed.
1918 * queue lock must be held here.
1920 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1922 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1924 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1926 if (!atomic_dec_and_test(&cfqq
->ref
))
1929 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
1930 BUG_ON(rb_first(&cfqq
->sort_list
));
1931 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1933 if (unlikely(cfqd
->active_queue
== cfqq
)) {
1934 __cfq_slice_expired(cfqd
, cfqq
, 0);
1935 cfq_schedule_dispatch(cfqd
);
1938 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1939 kmem_cache_free(cfq_pool
, cfqq
);
1943 * Must always be called with the rcu_read_lock() held
1946 __call_for_each_cic(struct io_context
*ioc
,
1947 void (*func
)(struct io_context
*, struct cfq_io_context
*))
1949 struct cfq_io_context
*cic
;
1950 struct hlist_node
*n
;
1952 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
1957 * Call func for each cic attached to this ioc.
1960 call_for_each_cic(struct io_context
*ioc
,
1961 void (*func
)(struct io_context
*, struct cfq_io_context
*))
1964 __call_for_each_cic(ioc
, func
);
1968 static void cfq_cic_free_rcu(struct rcu_head
*head
)
1970 struct cfq_io_context
*cic
;
1972 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
1974 kmem_cache_free(cfq_ioc_pool
, cic
);
1975 elv_ioc_count_dec(cfq_ioc_count
);
1979 * CFQ scheduler is exiting, grab exit lock and check
1980 * the pending io context count. If it hits zero,
1981 * complete ioc_gone and set it back to NULL
1983 spin_lock(&ioc_gone_lock
);
1984 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
1988 spin_unlock(&ioc_gone_lock
);
1992 static void cfq_cic_free(struct cfq_io_context
*cic
)
1994 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
1997 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
1999 unsigned long flags
;
2001 BUG_ON(!cic
->dead_key
);
2003 spin_lock_irqsave(&ioc
->lock
, flags
);
2004 radix_tree_delete(&ioc
->radix_root
, cic
->dead_key
);
2005 hlist_del_rcu(&cic
->cic_list
);
2006 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2012 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2013 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2014 * and ->trim() which is called with the task lock held
2016 static void cfq_free_io_context(struct io_context
*ioc
)
2019 * ioc->refcount is zero here, or we are called from elv_unregister(),
2020 * so no more cic's are allowed to be linked into this ioc. So it
2021 * should be ok to iterate over the known list, we will see all cic's
2022 * since no new ones are added.
2024 __call_for_each_cic(ioc
, cic_free_func
);
2027 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2029 struct cfq_queue
*__cfqq
, *next
;
2031 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2032 __cfq_slice_expired(cfqd
, cfqq
, 0);
2033 cfq_schedule_dispatch(cfqd
);
2037 * If this queue was scheduled to merge with another queue, be
2038 * sure to drop the reference taken on that queue (and others in
2039 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2041 __cfqq
= cfqq
->new_cfqq
;
2043 if (__cfqq
== cfqq
) {
2044 WARN(1, "cfqq->new_cfqq loop detected\n");
2047 next
= __cfqq
->new_cfqq
;
2048 cfq_put_queue(__cfqq
);
2052 cfq_put_queue(cfqq
);
2055 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
2056 struct cfq_io_context
*cic
)
2058 struct io_context
*ioc
= cic
->ioc
;
2060 list_del_init(&cic
->queue_list
);
2063 * Make sure key == NULL is seen for dead queues
2066 cic
->dead_key
= (unsigned long) cic
->key
;
2069 if (ioc
->ioc_data
== cic
)
2070 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2072 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2073 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2074 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2077 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2078 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2079 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2083 static void cfq_exit_single_io_context(struct io_context
*ioc
,
2084 struct cfq_io_context
*cic
)
2086 struct cfq_data
*cfqd
= cic
->key
;
2089 struct request_queue
*q
= cfqd
->queue
;
2090 unsigned long flags
;
2092 spin_lock_irqsave(q
->queue_lock
, flags
);
2095 * Ensure we get a fresh copy of the ->key to prevent
2096 * race between exiting task and queue
2098 smp_read_barrier_depends();
2100 __cfq_exit_single_io_context(cfqd
, cic
);
2102 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2107 * The process that ioc belongs to has exited, we need to clean up
2108 * and put the internal structures we have that belongs to that process.
2110 static void cfq_exit_io_context(struct io_context
*ioc
)
2112 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
2115 static struct cfq_io_context
*
2116 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2118 struct cfq_io_context
*cic
;
2120 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2123 cic
->last_end_request
= jiffies
;
2124 INIT_LIST_HEAD(&cic
->queue_list
);
2125 INIT_HLIST_NODE(&cic
->cic_list
);
2126 cic
->dtor
= cfq_free_io_context
;
2127 cic
->exit
= cfq_exit_io_context
;
2128 elv_ioc_count_inc(cfq_ioc_count
);
2134 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2136 struct task_struct
*tsk
= current
;
2139 if (!cfq_cfqq_prio_changed(cfqq
))
2142 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2143 switch (ioprio_class
) {
2145 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2146 case IOPRIO_CLASS_NONE
:
2148 * no prio set, inherit CPU scheduling settings
2150 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2151 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2153 case IOPRIO_CLASS_RT
:
2154 cfqq
->ioprio
= task_ioprio(ioc
);
2155 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2157 case IOPRIO_CLASS_BE
:
2158 cfqq
->ioprio
= task_ioprio(ioc
);
2159 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2161 case IOPRIO_CLASS_IDLE
:
2162 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2164 cfq_clear_cfqq_idle_window(cfqq
);
2169 * keep track of original prio settings in case we have to temporarily
2170 * elevate the priority of this queue
2172 cfqq
->org_ioprio
= cfqq
->ioprio
;
2173 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2174 cfq_clear_cfqq_prio_changed(cfqq
);
2177 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2179 struct cfq_data
*cfqd
= cic
->key
;
2180 struct cfq_queue
*cfqq
;
2181 unsigned long flags
;
2183 if (unlikely(!cfqd
))
2186 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2188 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2190 struct cfq_queue
*new_cfqq
;
2191 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2194 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2195 cfq_put_queue(cfqq
);
2199 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2201 cfq_mark_cfqq_prio_changed(cfqq
);
2203 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2206 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2208 call_for_each_cic(ioc
, changed_ioprio
);
2209 ioc
->ioprio_changed
= 0;
2212 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2213 pid_t pid
, bool is_sync
)
2215 RB_CLEAR_NODE(&cfqq
->rb_node
);
2216 RB_CLEAR_NODE(&cfqq
->p_node
);
2217 INIT_LIST_HEAD(&cfqq
->fifo
);
2219 atomic_set(&cfqq
->ref
, 0);
2222 cfq_mark_cfqq_prio_changed(cfqq
);
2225 if (!cfq_class_idle(cfqq
))
2226 cfq_mark_cfqq_idle_window(cfqq
);
2227 cfq_mark_cfqq_sync(cfqq
);
2232 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
2237 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
2239 return &cfqd
->root_group
;
2242 static struct cfq_queue
*
2243 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2244 struct io_context
*ioc
, gfp_t gfp_mask
)
2246 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2247 struct cfq_io_context
*cic
;
2248 struct cfq_group
*cfqg
;
2251 cfqg
= cfq_get_cfqg(cfqd
, 1);
2252 cic
= cfq_cic_lookup(cfqd
, ioc
);
2253 /* cic always exists here */
2254 cfqq
= cic_to_cfqq(cic
, is_sync
);
2257 * Always try a new alloc if we fell back to the OOM cfqq
2258 * originally, since it should just be a temporary situation.
2260 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2265 } else if (gfp_mask
& __GFP_WAIT
) {
2266 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2267 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2268 gfp_mask
| __GFP_ZERO
,
2270 spin_lock_irq(cfqd
->queue
->queue_lock
);
2274 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2275 gfp_mask
| __GFP_ZERO
,
2280 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2281 cfq_init_prio_data(cfqq
, ioc
);
2282 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2283 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2285 cfqq
= &cfqd
->oom_cfqq
;
2289 kmem_cache_free(cfq_pool
, new_cfqq
);
2294 static struct cfq_queue
**
2295 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2297 switch (ioprio_class
) {
2298 case IOPRIO_CLASS_RT
:
2299 return &cfqd
->async_cfqq
[0][ioprio
];
2300 case IOPRIO_CLASS_BE
:
2301 return &cfqd
->async_cfqq
[1][ioprio
];
2302 case IOPRIO_CLASS_IDLE
:
2303 return &cfqd
->async_idle_cfqq
;
2309 static struct cfq_queue
*
2310 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2313 const int ioprio
= task_ioprio(ioc
);
2314 const int ioprio_class
= task_ioprio_class(ioc
);
2315 struct cfq_queue
**async_cfqq
= NULL
;
2316 struct cfq_queue
*cfqq
= NULL
;
2319 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2324 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2327 * pin the queue now that it's allocated, scheduler exit will prune it
2329 if (!is_sync
&& !(*async_cfqq
)) {
2330 atomic_inc(&cfqq
->ref
);
2334 atomic_inc(&cfqq
->ref
);
2339 * We drop cfq io contexts lazily, so we may find a dead one.
2342 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2343 struct cfq_io_context
*cic
)
2345 unsigned long flags
;
2347 WARN_ON(!list_empty(&cic
->queue_list
));
2349 spin_lock_irqsave(&ioc
->lock
, flags
);
2351 BUG_ON(ioc
->ioc_data
== cic
);
2353 radix_tree_delete(&ioc
->radix_root
, (unsigned long) cfqd
);
2354 hlist_del_rcu(&cic
->cic_list
);
2355 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2360 static struct cfq_io_context
*
2361 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
2363 struct cfq_io_context
*cic
;
2364 unsigned long flags
;
2373 * we maintain a last-hit cache, to avoid browsing over the tree
2375 cic
= rcu_dereference(ioc
->ioc_data
);
2376 if (cic
&& cic
->key
== cfqd
) {
2382 cic
= radix_tree_lookup(&ioc
->radix_root
, (unsigned long) cfqd
);
2386 /* ->key must be copied to avoid race with cfq_exit_queue() */
2389 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
2394 spin_lock_irqsave(&ioc
->lock
, flags
);
2395 rcu_assign_pointer(ioc
->ioc_data
, cic
);
2396 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2404 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2405 * the process specific cfq io context when entered from the block layer.
2406 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2408 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2409 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
2411 unsigned long flags
;
2414 ret
= radix_tree_preload(gfp_mask
);
2419 spin_lock_irqsave(&ioc
->lock
, flags
);
2420 ret
= radix_tree_insert(&ioc
->radix_root
,
2421 (unsigned long) cfqd
, cic
);
2423 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
2424 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2426 radix_tree_preload_end();
2429 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2430 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
2431 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2436 printk(KERN_ERR
"cfq: cic link failed!\n");
2442 * Setup general io context and cfq io context. There can be several cfq
2443 * io contexts per general io context, if this process is doing io to more
2444 * than one device managed by cfq.
2446 static struct cfq_io_context
*
2447 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2449 struct io_context
*ioc
= NULL
;
2450 struct cfq_io_context
*cic
;
2452 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2454 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
2458 cic
= cfq_cic_lookup(cfqd
, ioc
);
2462 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
2466 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
2470 smp_read_barrier_depends();
2471 if (unlikely(ioc
->ioprio_changed
))
2472 cfq_ioc_set_ioprio(ioc
);
2478 put_io_context(ioc
);
2483 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
2485 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
2486 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
2488 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
2489 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
2490 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
2494 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2500 if (!cfqq
->last_request_pos
)
2502 else if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
2503 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
2505 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
2508 * Don't allow the seek distance to get too large from the
2509 * odd fragment, pagein, etc
2511 if (cfqq
->seek_samples
<= 60) /* second&third seek */
2512 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*1024);
2514 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*64);
2516 cfqq
->seek_samples
= (7*cfqq
->seek_samples
+ 256) / 8;
2517 cfqq
->seek_total
= (7*cfqq
->seek_total
+ (u64
)256*sdist
) / 8;
2518 total
= cfqq
->seek_total
+ (cfqq
->seek_samples
/2);
2519 do_div(total
, cfqq
->seek_samples
);
2520 cfqq
->seek_mean
= (sector_t
)total
;
2523 * If this cfqq is shared between multiple processes, check to
2524 * make sure that those processes are still issuing I/Os within
2525 * the mean seek distance. If not, it may be time to break the
2526 * queues apart again.
2528 if (cfq_cfqq_coop(cfqq
)) {
2529 if (CFQQ_SEEKY(cfqq
) && !cfqq
->seeky_start
)
2530 cfqq
->seeky_start
= jiffies
;
2531 else if (!CFQQ_SEEKY(cfqq
))
2532 cfqq
->seeky_start
= 0;
2537 * Disable idle window if the process thinks too long or seeks so much that
2541 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2542 struct cfq_io_context
*cic
)
2544 int old_idle
, enable_idle
;
2547 * Don't idle for async or idle io prio class
2549 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
2552 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
2554 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
2555 cfq_mark_cfqq_deep(cfqq
);
2557 if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
2558 (!cfq_cfqq_deep(cfqq
) && sample_valid(cfqq
->seek_samples
)
2559 && CFQQ_SEEKY(cfqq
)))
2561 else if (sample_valid(cic
->ttime_samples
)) {
2562 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
2568 if (old_idle
!= enable_idle
) {
2569 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
2571 cfq_mark_cfqq_idle_window(cfqq
);
2573 cfq_clear_cfqq_idle_window(cfqq
);
2578 * Check if new_cfqq should preempt the currently active queue. Return 0 for
2579 * no or if we aren't sure, a 1 will cause a preempt.
2582 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
2585 struct cfq_queue
*cfqq
;
2587 cfqq
= cfqd
->active_queue
;
2591 if (cfq_slice_used(cfqq
))
2594 if (cfq_class_idle(new_cfqq
))
2597 if (cfq_class_idle(cfqq
))
2600 /* Allow preemption only if we are idling on sync-noidle tree */
2601 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
2602 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
2603 new_cfqq
->service_tree
->count
== 2 &&
2604 RB_EMPTY_ROOT(&cfqq
->sort_list
))
2608 * if the new request is sync, but the currently running queue is
2609 * not, let the sync request have priority.
2611 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
2615 * So both queues are sync. Let the new request get disk time if
2616 * it's a metadata request and the current queue is doing regular IO.
2618 if (rq_is_meta(rq
) && !cfqq
->meta_pending
)
2622 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2624 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
2627 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
2631 * if this request is as-good as one we would expect from the
2632 * current cfqq, let it preempt
2634 if (cfq_rq_close(cfqd
, cfqq
, rq
))
2641 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2642 * let it have half of its nominal slice.
2644 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2646 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
2647 cfq_slice_expired(cfqd
, 1);
2650 * Put the new queue at the front of the of the current list,
2651 * so we know that it will be selected next.
2653 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
2655 cfq_service_tree_add(cfqd
, cfqq
, 1);
2657 cfqq
->slice_end
= 0;
2658 cfq_mark_cfqq_slice_new(cfqq
);
2662 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2663 * something we should do about it
2666 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2669 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2673 cfqq
->meta_pending
++;
2675 cfq_update_io_thinktime(cfqd
, cic
);
2676 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
2677 cfq_update_idle_window(cfqd
, cfqq
, cic
);
2679 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
2681 if (cfqq
== cfqd
->active_queue
) {
2683 * Remember that we saw a request from this process, but
2684 * don't start queuing just yet. Otherwise we risk seeing lots
2685 * of tiny requests, because we disrupt the normal plugging
2686 * and merging. If the request is already larger than a single
2687 * page, let it rip immediately. For that case we assume that
2688 * merging is already done. Ditto for a busy system that
2689 * has other work pending, don't risk delaying until the
2690 * idle timer unplug to continue working.
2692 if (cfq_cfqq_wait_request(cfqq
)) {
2693 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
2694 cfqd
->busy_queues
> 1) {
2695 del_timer(&cfqd
->idle_slice_timer
);
2696 __blk_run_queue(cfqd
->queue
);
2698 cfq_mark_cfqq_must_dispatch(cfqq
);
2700 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
2702 * not the active queue - expire current slice if it is
2703 * idle and has expired it's mean thinktime or this new queue
2704 * has some old slice time left and is of higher priority or
2705 * this new queue is RT and the current one is BE
2707 cfq_preempt_queue(cfqd
, cfqq
);
2708 __blk_run_queue(cfqd
->queue
);
2712 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
2714 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2715 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2717 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
2718 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
2720 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
2721 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
2724 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
2728 * Update hw_tag based on peak queue depth over 50 samples under
2731 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
2733 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2735 if (rq_in_driver(cfqd
) > cfqd
->hw_tag_est_depth
)
2736 cfqd
->hw_tag_est_depth
= rq_in_driver(cfqd
);
2738 if (cfqd
->hw_tag
== 1)
2741 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
2742 rq_in_driver(cfqd
) <= CFQ_HW_QUEUE_MIN
)
2746 * If active queue hasn't enough requests and can idle, cfq might not
2747 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
2750 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
2751 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
2752 CFQ_HW_QUEUE_MIN
&& rq_in_driver(cfqd
) < CFQ_HW_QUEUE_MIN
)
2755 if (cfqd
->hw_tag_samples
++ < 50)
2758 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
2764 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
2766 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2767 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2768 const int sync
= rq_is_sync(rq
);
2772 cfq_log_cfqq(cfqd
, cfqq
, "complete");
2774 cfq_update_hw_tag(cfqd
);
2776 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
2777 WARN_ON(!cfqq
->dispatched
);
2778 cfqd
->rq_in_driver
[sync
]--;
2781 if (cfq_cfqq_sync(cfqq
))
2782 cfqd
->sync_flight
--;
2785 RQ_CIC(rq
)->last_end_request
= now
;
2786 cfqd
->last_end_sync_rq
= now
;
2790 * If this is the active queue, check if it needs to be expired,
2791 * or if we want to idle in case it has no pending requests.
2793 if (cfqd
->active_queue
== cfqq
) {
2794 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
2796 if (cfq_cfqq_slice_new(cfqq
)) {
2797 cfq_set_prio_slice(cfqd
, cfqq
);
2798 cfq_clear_cfqq_slice_new(cfqq
);
2801 * Idling is not enabled on:
2803 * - idle-priority queues
2805 * - queues with still some requests queued
2806 * - when there is a close cooperator
2808 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
2809 cfq_slice_expired(cfqd
, 1);
2810 else if (sync
&& cfqq_empty
&&
2811 !cfq_close_cooperator(cfqd
, cfqq
)) {
2812 cfqd
->noidle_tree_requires_idle
|= !rq_noidle(rq
);
2814 * Idling is enabled for SYNC_WORKLOAD.
2815 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
2816 * only if we processed at least one !rq_noidle request
2818 if (cfqd
->serving_type
== SYNC_WORKLOAD
2819 || cfqd
->noidle_tree_requires_idle
)
2820 cfq_arm_slice_timer(cfqd
);
2824 if (!rq_in_driver(cfqd
))
2825 cfq_schedule_dispatch(cfqd
);
2829 * we temporarily boost lower priority queues if they are holding fs exclusive
2830 * resources. they are boosted to normal prio (CLASS_BE/4)
2832 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
2834 if (has_fs_excl()) {
2836 * boost idle prio on transactions that would lock out other
2837 * users of the filesystem
2839 if (cfq_class_idle(cfqq
))
2840 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2841 if (cfqq
->ioprio
> IOPRIO_NORM
)
2842 cfqq
->ioprio
= IOPRIO_NORM
;
2845 * unboost the queue (if needed)
2847 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
2848 cfqq
->ioprio
= cfqq
->org_ioprio
;
2852 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
2854 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
2855 cfq_mark_cfqq_must_alloc_slice(cfqq
);
2856 return ELV_MQUEUE_MUST
;
2859 return ELV_MQUEUE_MAY
;
2862 static int cfq_may_queue(struct request_queue
*q
, int rw
)
2864 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2865 struct task_struct
*tsk
= current
;
2866 struct cfq_io_context
*cic
;
2867 struct cfq_queue
*cfqq
;
2870 * don't force setup of a queue from here, as a call to may_queue
2871 * does not necessarily imply that a request actually will be queued.
2872 * so just lookup a possibly existing queue, or return 'may queue'
2875 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
2877 return ELV_MQUEUE_MAY
;
2879 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
2881 cfq_init_prio_data(cfqq
, cic
->ioc
);
2882 cfq_prio_boost(cfqq
);
2884 return __cfq_may_queue(cfqq
);
2887 return ELV_MQUEUE_MAY
;
2891 * queue lock held here
2893 static void cfq_put_request(struct request
*rq
)
2895 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2898 const int rw
= rq_data_dir(rq
);
2900 BUG_ON(!cfqq
->allocated
[rw
]);
2901 cfqq
->allocated
[rw
]--;
2903 put_io_context(RQ_CIC(rq
)->ioc
);
2905 rq
->elevator_private
= NULL
;
2906 rq
->elevator_private2
= NULL
;
2908 cfq_put_queue(cfqq
);
2912 static struct cfq_queue
*
2913 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
2914 struct cfq_queue
*cfqq
)
2916 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
2917 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
2918 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
2919 cfq_put_queue(cfqq
);
2920 return cic_to_cfqq(cic
, 1);
2923 static int should_split_cfqq(struct cfq_queue
*cfqq
)
2925 if (cfqq
->seeky_start
&&
2926 time_after(jiffies
, cfqq
->seeky_start
+ CFQQ_COOP_TOUT
))
2932 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
2933 * was the last process referring to said cfqq.
2935 static struct cfq_queue
*
2936 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
2938 if (cfqq_process_refs(cfqq
) == 1) {
2939 cfqq
->seeky_start
= 0;
2940 cfqq
->pid
= current
->pid
;
2941 cfq_clear_cfqq_coop(cfqq
);
2945 cic_set_cfqq(cic
, NULL
, 1);
2946 cfq_put_queue(cfqq
);
2950 * Allocate cfq data structures associated with this request.
2953 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
2955 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2956 struct cfq_io_context
*cic
;
2957 const int rw
= rq_data_dir(rq
);
2958 const bool is_sync
= rq_is_sync(rq
);
2959 struct cfq_queue
*cfqq
;
2960 unsigned long flags
;
2962 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2964 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
2966 spin_lock_irqsave(q
->queue_lock
, flags
);
2972 cfqq
= cic_to_cfqq(cic
, is_sync
);
2973 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2974 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
2975 cic_set_cfqq(cic
, cfqq
, is_sync
);
2978 * If the queue was seeky for too long, break it apart.
2980 if (cfq_cfqq_coop(cfqq
) && should_split_cfqq(cfqq
)) {
2981 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
2982 cfqq
= split_cfqq(cic
, cfqq
);
2988 * Check to see if this queue is scheduled to merge with
2989 * another, closely cooperating queue. The merging of
2990 * queues happens here as it must be done in process context.
2991 * The reference on new_cfqq was taken in merge_cfqqs.
2994 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
2997 cfqq
->allocated
[rw
]++;
2998 atomic_inc(&cfqq
->ref
);
3000 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3002 rq
->elevator_private
= cic
;
3003 rq
->elevator_private2
= cfqq
;
3008 put_io_context(cic
->ioc
);
3010 cfq_schedule_dispatch(cfqd
);
3011 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3012 cfq_log(cfqd
, "set_request fail");
3016 static void cfq_kick_queue(struct work_struct
*work
)
3018 struct cfq_data
*cfqd
=
3019 container_of(work
, struct cfq_data
, unplug_work
);
3020 struct request_queue
*q
= cfqd
->queue
;
3022 spin_lock_irq(q
->queue_lock
);
3023 __blk_run_queue(cfqd
->queue
);
3024 spin_unlock_irq(q
->queue_lock
);
3028 * Timer running if the active_queue is currently idling inside its time slice
3030 static void cfq_idle_slice_timer(unsigned long data
)
3032 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3033 struct cfq_queue
*cfqq
;
3034 unsigned long flags
;
3037 cfq_log(cfqd
, "idle timer fired");
3039 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3041 cfqq
= cfqd
->active_queue
;
3046 * We saw a request before the queue expired, let it through
3048 if (cfq_cfqq_must_dispatch(cfqq
))
3054 if (cfq_slice_used(cfqq
))
3058 * only expire and reinvoke request handler, if there are
3059 * other queues with pending requests
3061 if (!cfqd
->busy_queues
)
3065 * not expired and it has a request pending, let it dispatch
3067 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3071 * Queue depth flag is reset only when the idle didn't succeed
3073 cfq_clear_cfqq_deep(cfqq
);
3076 cfq_slice_expired(cfqd
, timed_out
);
3078 cfq_schedule_dispatch(cfqd
);
3080 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3083 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3085 del_timer_sync(&cfqd
->idle_slice_timer
);
3086 cancel_work_sync(&cfqd
->unplug_work
);
3089 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3093 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3094 if (cfqd
->async_cfqq
[0][i
])
3095 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3096 if (cfqd
->async_cfqq
[1][i
])
3097 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3100 if (cfqd
->async_idle_cfqq
)
3101 cfq_put_queue(cfqd
->async_idle_cfqq
);
3104 static void cfq_exit_queue(struct elevator_queue
*e
)
3106 struct cfq_data
*cfqd
= e
->elevator_data
;
3107 struct request_queue
*q
= cfqd
->queue
;
3109 cfq_shutdown_timer_wq(cfqd
);
3111 spin_lock_irq(q
->queue_lock
);
3113 if (cfqd
->active_queue
)
3114 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3116 while (!list_empty(&cfqd
->cic_list
)) {
3117 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3118 struct cfq_io_context
,
3121 __cfq_exit_single_io_context(cfqd
, cic
);
3124 cfq_put_async_queues(cfqd
);
3126 spin_unlock_irq(q
->queue_lock
);
3128 cfq_shutdown_timer_wq(cfqd
);
3133 static void *cfq_init_queue(struct request_queue
*q
)
3135 struct cfq_data
*cfqd
;
3137 struct cfq_group
*cfqg
;
3138 struct cfq_rb_root
*st
;
3140 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3144 /* Init root service tree */
3145 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3147 /* Init root group */
3148 cfqg
= &cfqd
->root_group
;
3149 for_each_cfqg_st(cfqg
, i
, j
, st
)
3151 RB_CLEAR_NODE(&cfqg
->rb_node
);
3154 * Not strictly needed (since RB_ROOT just clears the node and we
3155 * zeroed cfqd on alloc), but better be safe in case someone decides
3156 * to add magic to the rb code
3158 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3159 cfqd
->prio_trees
[i
] = RB_ROOT
;
3162 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3163 * Grab a permanent reference to it, so that the normal code flow
3164 * will not attempt to free it.
3166 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3167 atomic_inc(&cfqd
->oom_cfqq
.ref
);
3168 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3170 INIT_LIST_HEAD(&cfqd
->cic_list
);
3174 init_timer(&cfqd
->idle_slice_timer
);
3175 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3176 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3178 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3180 cfqd
->cfq_quantum
= cfq_quantum
;
3181 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3182 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3183 cfqd
->cfq_back_max
= cfq_back_max
;
3184 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3185 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3186 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3187 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3188 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3189 cfqd
->cfq_latency
= 1;
3191 cfqd
->last_end_sync_rq
= jiffies
;
3195 static void cfq_slab_kill(void)
3198 * Caller already ensured that pending RCU callbacks are completed,
3199 * so we should have no busy allocations at this point.
3202 kmem_cache_destroy(cfq_pool
);
3204 kmem_cache_destroy(cfq_ioc_pool
);
3207 static int __init
cfq_slab_setup(void)
3209 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3213 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3224 * sysfs parts below -->
3227 cfq_var_show(unsigned int var
, char *page
)
3229 return sprintf(page
, "%d\n", var
);
3233 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3235 char *p
= (char *) page
;
3237 *var
= simple_strtoul(p
, &p
, 10);
3241 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3242 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3244 struct cfq_data *cfqd = e->elevator_data; \
3245 unsigned int __data = __VAR; \
3247 __data = jiffies_to_msecs(__data); \
3248 return cfq_var_show(__data, (page)); \
3250 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3251 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3252 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3253 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3254 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3255 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3256 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
3257 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
3258 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
3259 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
3260 #undef SHOW_FUNCTION
3262 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3263 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3265 struct cfq_data *cfqd = e->elevator_data; \
3266 unsigned int __data; \
3267 int ret = cfq_var_store(&__data, (page), count); \
3268 if (__data < (MIN)) \
3270 else if (__data > (MAX)) \
3273 *(__PTR) = msecs_to_jiffies(__data); \
3275 *(__PTR) = __data; \
3278 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
3279 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
3281 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
3283 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
3284 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
3286 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
3287 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
3288 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
3289 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
3291 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
3292 #undef STORE_FUNCTION
3294 #define CFQ_ATTR(name) \
3295 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3297 static struct elv_fs_entry cfq_attrs
[] = {
3299 CFQ_ATTR(fifo_expire_sync
),
3300 CFQ_ATTR(fifo_expire_async
),
3301 CFQ_ATTR(back_seek_max
),
3302 CFQ_ATTR(back_seek_penalty
),
3303 CFQ_ATTR(slice_sync
),
3304 CFQ_ATTR(slice_async
),
3305 CFQ_ATTR(slice_async_rq
),
3306 CFQ_ATTR(slice_idle
),
3307 CFQ_ATTR(low_latency
),
3311 static struct elevator_type iosched_cfq
= {
3313 .elevator_merge_fn
= cfq_merge
,
3314 .elevator_merged_fn
= cfq_merged_request
,
3315 .elevator_merge_req_fn
= cfq_merged_requests
,
3316 .elevator_allow_merge_fn
= cfq_allow_merge
,
3317 .elevator_dispatch_fn
= cfq_dispatch_requests
,
3318 .elevator_add_req_fn
= cfq_insert_request
,
3319 .elevator_activate_req_fn
= cfq_activate_request
,
3320 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
3321 .elevator_queue_empty_fn
= cfq_queue_empty
,
3322 .elevator_completed_req_fn
= cfq_completed_request
,
3323 .elevator_former_req_fn
= elv_rb_former_request
,
3324 .elevator_latter_req_fn
= elv_rb_latter_request
,
3325 .elevator_set_req_fn
= cfq_set_request
,
3326 .elevator_put_req_fn
= cfq_put_request
,
3327 .elevator_may_queue_fn
= cfq_may_queue
,
3328 .elevator_init_fn
= cfq_init_queue
,
3329 .elevator_exit_fn
= cfq_exit_queue
,
3330 .trim
= cfq_free_io_context
,
3332 .elevator_attrs
= cfq_attrs
,
3333 .elevator_name
= "cfq",
3334 .elevator_owner
= THIS_MODULE
,
3337 static int __init
cfq_init(void)
3340 * could be 0 on HZ < 1000 setups
3342 if (!cfq_slice_async
)
3343 cfq_slice_async
= 1;
3344 if (!cfq_slice_idle
)
3347 if (cfq_slab_setup())
3350 elv_register(&iosched_cfq
);
3355 static void __exit
cfq_exit(void)
3357 DECLARE_COMPLETION_ONSTACK(all_gone
);
3358 elv_unregister(&iosched_cfq
);
3359 ioc_gone
= &all_gone
;
3360 /* ioc_gone's update must be visible before reading ioc_count */
3364 * this also protects us from entering cfq_slab_kill() with
3365 * pending RCU callbacks
3367 if (elv_ioc_count_read(cfq_ioc_count
))
3368 wait_for_completion(&all_gone
);
3372 module_init(cfq_init
);
3373 module_exit(cfq_exit
);
3375 MODULE_AUTHOR("Jens Axboe");
3376 MODULE_LICENSE("GPL");
3377 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");