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)
71 * Most of our rbtree usage is for sorting with min extraction, so
72 * if we cache the leftmost node we don't have to walk down the tree
73 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
74 * move this into the elevator for the rq sorting as well.
81 #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, }
84 * Per process-grouping structure
89 /* various state flags, see below */
92 struct cfq_data
*cfqd
;
93 /* service_tree member */
94 struct rb_node rb_node
;
95 /* service_tree key */
97 /* prio tree member */
98 struct rb_node p_node
;
99 /* prio tree root we belong to, if any */
100 struct rb_root
*p_root
;
101 /* sorted list of pending requests */
102 struct rb_root sort_list
;
103 /* if fifo isn't expired, next request to serve */
104 struct request
*next_rq
;
105 /* requests queued in sort_list */
107 /* currently allocated requests */
109 /* fifo list of requests in sort_list */
110 struct list_head fifo
;
112 unsigned long slice_end
;
114 unsigned int slice_dispatch
;
116 /* pending metadata requests */
118 /* number of requests that are on the dispatch list or inside driver */
121 /* io prio of this group */
122 unsigned short ioprio
, org_ioprio
;
123 unsigned short ioprio_class
, org_ioprio_class
;
125 unsigned int seek_samples
;
128 sector_t last_request_pos
;
129 unsigned long seeky_start
;
133 struct cfq_rb_root
*service_tree
;
134 struct cfq_queue
*new_cfqq
;
135 struct cfq_group
*cfqg
;
139 * First index in the service_trees.
140 * IDLE is handled separately, so it has negative index
149 * Second index in the service_trees.
153 SYNC_NOIDLE_WORKLOAD
= 1,
157 /* This is per cgroup per device grouping structure */
160 * rr lists of queues with requests, onle rr for each priority class.
161 * Counts are embedded in the cfq_rb_root
163 struct cfq_rb_root service_trees
[2][3];
164 struct cfq_rb_root service_tree_idle
;
168 * Per block device queue structure
171 struct request_queue
*queue
;
172 struct cfq_group root_group
;
175 * The priority currently being served
177 enum wl_prio_t serving_prio
;
178 enum wl_type_t serving_type
;
179 unsigned long workload_expires
;
180 struct cfq_group
*serving_group
;
181 bool noidle_tree_requires_idle
;
184 * Each priority tree is sorted by next_request position. These
185 * trees are used when determining if two or more queues are
186 * interleaving requests (see cfq_close_cooperator).
188 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
190 unsigned int busy_queues
;
191 unsigned int busy_queues_avg
[2];
197 * queue-depth detection
203 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
204 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
207 int hw_tag_est_depth
;
208 unsigned int hw_tag_samples
;
211 * idle window management
213 struct timer_list idle_slice_timer
;
214 struct work_struct unplug_work
;
216 struct cfq_queue
*active_queue
;
217 struct cfq_io_context
*active_cic
;
220 * async queue for each priority case
222 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
223 struct cfq_queue
*async_idle_cfqq
;
225 sector_t last_position
;
228 * tunables, see top of file
230 unsigned int cfq_quantum
;
231 unsigned int cfq_fifo_expire
[2];
232 unsigned int cfq_back_penalty
;
233 unsigned int cfq_back_max
;
234 unsigned int cfq_slice
[2];
235 unsigned int cfq_slice_async_rq
;
236 unsigned int cfq_slice_idle
;
237 unsigned int cfq_latency
;
239 struct list_head cic_list
;
242 * Fallback dummy cfqq for extreme OOM conditions
244 struct cfq_queue oom_cfqq
;
246 unsigned long last_end_sync_rq
;
249 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
252 struct cfq_data
*cfqd
)
254 if (prio
== IDLE_WORKLOAD
)
255 return &cfqg
->service_tree_idle
;
257 return &cfqg
->service_trees
[prio
][type
];
260 enum cfqq_state_flags
{
261 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
262 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
263 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
264 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
265 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
266 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
267 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
268 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
269 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
270 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
271 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
274 #define CFQ_CFQQ_FNS(name) \
275 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
277 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
279 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
281 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
283 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
285 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
289 CFQ_CFQQ_FNS(wait_request
);
290 CFQ_CFQQ_FNS(must_dispatch
);
291 CFQ_CFQQ_FNS(must_alloc_slice
);
292 CFQ_CFQQ_FNS(fifo_expire
);
293 CFQ_CFQQ_FNS(idle_window
);
294 CFQ_CFQQ_FNS(prio_changed
);
295 CFQ_CFQQ_FNS(slice_new
);
301 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
302 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
303 #define cfq_log(cfqd, fmt, args...) \
304 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
306 /* Traverses through cfq group service trees */
307 #define for_each_cfqg_st(cfqg, i, j, st) \
308 for (i = 0; i <= IDLE_WORKLOAD; i++) \
309 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
310 : &cfqg->service_tree_idle; \
311 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
312 (i == IDLE_WORKLOAD && j == 0); \
313 j++, st = i < IDLE_WORKLOAD ? \
314 &cfqg->service_trees[i][j]: NULL) \
317 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
319 if (cfq_class_idle(cfqq
))
320 return IDLE_WORKLOAD
;
321 if (cfq_class_rt(cfqq
))
327 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
329 if (!cfq_cfqq_sync(cfqq
))
330 return ASYNC_WORKLOAD
;
331 if (!cfq_cfqq_idle_window(cfqq
))
332 return SYNC_NOIDLE_WORKLOAD
;
333 return SYNC_WORKLOAD
;
336 static inline int cfq_busy_queues_wl(enum wl_prio_t wl
, struct cfq_data
*cfqd
)
338 struct cfq_group
*cfqg
= &cfqd
->root_group
;
340 if (wl
== IDLE_WORKLOAD
)
341 return cfqg
->service_tree_idle
.count
;
343 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
344 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
345 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
348 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
349 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
350 struct io_context
*, gfp_t
);
351 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
352 struct io_context
*);
354 static inline int rq_in_driver(struct cfq_data
*cfqd
)
356 return cfqd
->rq_in_driver
[0] + cfqd
->rq_in_driver
[1];
359 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
362 return cic
->cfqq
[is_sync
];
365 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
366 struct cfq_queue
*cfqq
, bool is_sync
)
368 cic
->cfqq
[is_sync
] = cfqq
;
372 * We regard a request as SYNC, if it's either a read or has the SYNC bit
373 * set (in which case it could also be direct WRITE).
375 static inline bool cfq_bio_sync(struct bio
*bio
)
377 return bio_data_dir(bio
) == READ
|| bio_rw_flagged(bio
, BIO_RW_SYNCIO
);
381 * scheduler run of queue, if there are requests pending and no one in the
382 * driver that will restart queueing
384 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
386 if (cfqd
->busy_queues
) {
387 cfq_log(cfqd
, "schedule dispatch");
388 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
392 static int cfq_queue_empty(struct request_queue
*q
)
394 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
396 return !cfqd
->rq_queued
;
400 * Scale schedule slice based on io priority. Use the sync time slice only
401 * if a queue is marked sync and has sync io queued. A sync queue with async
402 * io only, should not get full sync slice length.
404 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
407 const int base_slice
= cfqd
->cfq_slice
[sync
];
409 WARN_ON(prio
>= IOPRIO_BE_NR
);
411 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
415 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
417 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
421 * get averaged number of queues of RT/BE priority.
422 * average is updated, with a formula that gives more weight to higher numbers,
423 * to quickly follows sudden increases and decrease slowly
426 static inline unsigned cfq_get_avg_queues(struct cfq_data
*cfqd
, bool rt
)
428 unsigned min_q
, max_q
;
429 unsigned mult
= cfq_hist_divisor
- 1;
430 unsigned round
= cfq_hist_divisor
/ 2;
431 unsigned busy
= cfq_busy_queues_wl(rt
, cfqd
);
433 min_q
= min(cfqd
->busy_queues_avg
[rt
], busy
);
434 max_q
= max(cfqd
->busy_queues_avg
[rt
], busy
);
435 cfqd
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
437 return cfqd
->busy_queues_avg
[rt
];
441 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
443 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
444 if (cfqd
->cfq_latency
) {
445 /* interested queues (we consider only the ones with the same
447 unsigned iq
= cfq_get_avg_queues(cfqd
, cfq_class_rt(cfqq
));
448 unsigned sync_slice
= cfqd
->cfq_slice
[1];
449 unsigned expect_latency
= sync_slice
* iq
;
450 if (expect_latency
> cfq_target_latency
) {
451 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
452 /* scale low_slice according to IO priority
453 * and sync vs async */
455 min(slice
, base_low_slice
* slice
/ sync_slice
);
456 /* the adapted slice value is scaled to fit all iqs
457 * into the target latency */
458 slice
= max(slice
* cfq_target_latency
/ expect_latency
,
462 cfqq
->slice_end
= jiffies
+ slice
;
463 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
467 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
468 * isn't valid until the first request from the dispatch is activated
469 * and the slice time set.
471 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
473 if (cfq_cfqq_slice_new(cfqq
))
475 if (time_before(jiffies
, cfqq
->slice_end
))
482 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
483 * We choose the request that is closest to the head right now. Distance
484 * behind the head is penalized and only allowed to a certain extent.
486 static struct request
*
487 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
489 sector_t s1
, s2
, d1
= 0, d2
= 0;
490 unsigned long back_max
;
491 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
492 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
493 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
495 if (rq1
== NULL
|| rq1
== rq2
)
500 if (rq_is_sync(rq1
) && !rq_is_sync(rq2
))
502 else if (rq_is_sync(rq2
) && !rq_is_sync(rq1
))
504 if (rq_is_meta(rq1
) && !rq_is_meta(rq2
))
506 else if (rq_is_meta(rq2
) && !rq_is_meta(rq1
))
509 s1
= blk_rq_pos(rq1
);
510 s2
= blk_rq_pos(rq2
);
513 * by definition, 1KiB is 2 sectors
515 back_max
= cfqd
->cfq_back_max
* 2;
518 * Strict one way elevator _except_ in the case where we allow
519 * short backward seeks which are biased as twice the cost of a
520 * similar forward seek.
524 else if (s1
+ back_max
>= last
)
525 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
527 wrap
|= CFQ_RQ1_WRAP
;
531 else if (s2
+ back_max
>= last
)
532 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
534 wrap
|= CFQ_RQ2_WRAP
;
536 /* Found required data */
539 * By doing switch() on the bit mask "wrap" we avoid having to
540 * check two variables for all permutations: --> faster!
543 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
559 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
562 * Since both rqs are wrapped,
563 * start with the one that's further behind head
564 * (--> only *one* back seek required),
565 * since back seek takes more time than forward.
575 * The below is leftmost cache rbtree addon
577 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
579 /* Service tree is empty */
584 root
->left
= rb_first(&root
->rb
);
587 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
592 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
598 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
602 rb_erase_init(n
, &root
->rb
);
607 * would be nice to take fifo expire time into account as well
609 static struct request
*
610 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
611 struct request
*last
)
613 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
614 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
615 struct request
*next
= NULL
, *prev
= NULL
;
617 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
620 prev
= rb_entry_rq(rbprev
);
623 next
= rb_entry_rq(rbnext
);
625 rbnext
= rb_first(&cfqq
->sort_list
);
626 if (rbnext
&& rbnext
!= &last
->rb_node
)
627 next
= rb_entry_rq(rbnext
);
630 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
633 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
634 struct cfq_queue
*cfqq
)
637 * just an approximation, should be ok.
639 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
640 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
644 * The cfqd->service_trees holds all pending cfq_queue's that have
645 * requests waiting to be processed. It is sorted in the order that
646 * we will service the queues.
648 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
651 struct rb_node
**p
, *parent
;
652 struct cfq_queue
*__cfqq
;
653 unsigned long rb_key
;
654 struct cfq_rb_root
*service_tree
;
657 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
658 cfqq_type(cfqq
), cfqd
);
659 if (cfq_class_idle(cfqq
)) {
660 rb_key
= CFQ_IDLE_DELAY
;
661 parent
= rb_last(&service_tree
->rb
);
662 if (parent
&& parent
!= &cfqq
->rb_node
) {
663 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
664 rb_key
+= __cfqq
->rb_key
;
667 } else if (!add_front
) {
669 * Get our rb key offset. Subtract any residual slice
670 * value carried from last service. A negative resid
671 * count indicates slice overrun, and this should position
672 * the next service time further away in the tree.
674 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
675 rb_key
-= cfqq
->slice_resid
;
676 cfqq
->slice_resid
= 0;
679 __cfqq
= cfq_rb_first(service_tree
);
680 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
683 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
685 * same position, nothing more to do
687 if (rb_key
== cfqq
->rb_key
&&
688 cfqq
->service_tree
== service_tree
)
691 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
692 cfqq
->service_tree
= NULL
;
697 cfqq
->service_tree
= service_tree
;
698 p
= &service_tree
->rb
.rb_node
;
703 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
706 * sort by key, that represents service time.
708 if (time_before(rb_key
, __cfqq
->rb_key
))
719 service_tree
->left
= &cfqq
->rb_node
;
721 cfqq
->rb_key
= rb_key
;
722 rb_link_node(&cfqq
->rb_node
, parent
, p
);
723 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
724 service_tree
->count
++;
727 static struct cfq_queue
*
728 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
729 sector_t sector
, struct rb_node
**ret_parent
,
730 struct rb_node
***rb_link
)
732 struct rb_node
**p
, *parent
;
733 struct cfq_queue
*cfqq
= NULL
;
741 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
744 * Sort strictly based on sector. Smallest to the left,
745 * largest to the right.
747 if (sector
> blk_rq_pos(cfqq
->next_rq
))
749 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
757 *ret_parent
= parent
;
763 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
765 struct rb_node
**p
, *parent
;
766 struct cfq_queue
*__cfqq
;
769 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
773 if (cfq_class_idle(cfqq
))
778 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
779 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
780 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
782 rb_link_node(&cfqq
->p_node
, parent
, p
);
783 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
789 * Update cfqq's position in the service tree.
791 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
794 * Resorting requires the cfqq to be on the RR list already.
796 if (cfq_cfqq_on_rr(cfqq
)) {
797 cfq_service_tree_add(cfqd
, cfqq
, 0);
798 cfq_prio_tree_add(cfqd
, cfqq
);
803 * add to busy list of queues for service, trying to be fair in ordering
804 * the pending list according to last request service
806 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
808 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
809 BUG_ON(cfq_cfqq_on_rr(cfqq
));
810 cfq_mark_cfqq_on_rr(cfqq
);
813 cfq_resort_rr_list(cfqd
, cfqq
);
817 * Called when the cfqq no longer has requests pending, remove it from
820 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
822 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
823 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
824 cfq_clear_cfqq_on_rr(cfqq
);
826 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
827 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
828 cfqq
->service_tree
= NULL
;
831 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
835 BUG_ON(!cfqd
->busy_queues
);
840 * rb tree support functions
842 static void cfq_del_rq_rb(struct request
*rq
)
844 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
845 const int sync
= rq_is_sync(rq
);
847 BUG_ON(!cfqq
->queued
[sync
]);
848 cfqq
->queued
[sync
]--;
850 elv_rb_del(&cfqq
->sort_list
, rq
);
852 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
854 * Queue will be deleted from service tree when we actually
855 * expire it later. Right now just remove it from prio tree
859 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
865 static void cfq_add_rq_rb(struct request
*rq
)
867 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
868 struct cfq_data
*cfqd
= cfqq
->cfqd
;
869 struct request
*__alias
, *prev
;
871 cfqq
->queued
[rq_is_sync(rq
)]++;
874 * looks a little odd, but the first insert might return an alias.
875 * if that happens, put the alias on the dispatch list
877 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
878 cfq_dispatch_insert(cfqd
->queue
, __alias
);
880 if (!cfq_cfqq_on_rr(cfqq
))
881 cfq_add_cfqq_rr(cfqd
, cfqq
);
884 * check if this request is a better next-serve candidate
886 prev
= cfqq
->next_rq
;
887 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
890 * adjust priority tree position, if ->next_rq changes
892 if (prev
!= cfqq
->next_rq
)
893 cfq_prio_tree_add(cfqd
, cfqq
);
895 BUG_ON(!cfqq
->next_rq
);
898 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
900 elv_rb_del(&cfqq
->sort_list
, rq
);
901 cfqq
->queued
[rq_is_sync(rq
)]--;
905 static struct request
*
906 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
908 struct task_struct
*tsk
= current
;
909 struct cfq_io_context
*cic
;
910 struct cfq_queue
*cfqq
;
912 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
916 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
918 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
920 return elv_rb_find(&cfqq
->sort_list
, sector
);
926 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
928 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
930 cfqd
->rq_in_driver
[rq_is_sync(rq
)]++;
931 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
934 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
937 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
939 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
940 const int sync
= rq_is_sync(rq
);
942 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
943 cfqd
->rq_in_driver
[sync
]--;
944 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
948 static void cfq_remove_request(struct request
*rq
)
950 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
952 if (cfqq
->next_rq
== rq
)
953 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
955 list_del_init(&rq
->queuelist
);
958 cfqq
->cfqd
->rq_queued
--;
959 if (rq_is_meta(rq
)) {
960 WARN_ON(!cfqq
->meta_pending
);
961 cfqq
->meta_pending
--;
965 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
968 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
969 struct request
*__rq
;
971 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
972 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
974 return ELEVATOR_FRONT_MERGE
;
977 return ELEVATOR_NO_MERGE
;
980 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
983 if (type
== ELEVATOR_FRONT_MERGE
) {
984 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
986 cfq_reposition_rq_rb(cfqq
, req
);
991 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
992 struct request
*next
)
994 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
996 * reposition in fifo if next is older than rq
998 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
999 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1000 list_move(&rq
->queuelist
, &next
->queuelist
);
1001 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1004 if (cfqq
->next_rq
== next
)
1006 cfq_remove_request(next
);
1009 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1012 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1013 struct cfq_io_context
*cic
;
1014 struct cfq_queue
*cfqq
;
1017 * Disallow merge of a sync bio into an async request.
1019 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1023 * Lookup the cfqq that this bio will be queued with. Allow
1024 * merge only if rq is queued there.
1026 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1030 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1031 return cfqq
== RQ_CFQQ(rq
);
1034 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1035 struct cfq_queue
*cfqq
)
1038 cfq_log_cfqq(cfqd
, cfqq
, "set_active");
1039 cfqq
->slice_end
= 0;
1040 cfqq
->slice_dispatch
= 0;
1042 cfq_clear_cfqq_wait_request(cfqq
);
1043 cfq_clear_cfqq_must_dispatch(cfqq
);
1044 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1045 cfq_clear_cfqq_fifo_expire(cfqq
);
1046 cfq_mark_cfqq_slice_new(cfqq
);
1048 del_timer(&cfqd
->idle_slice_timer
);
1051 cfqd
->active_queue
= cfqq
;
1055 * current cfqq expired its slice (or was too idle), select new one
1058 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1061 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1063 if (cfq_cfqq_wait_request(cfqq
))
1064 del_timer(&cfqd
->idle_slice_timer
);
1066 cfq_clear_cfqq_wait_request(cfqq
);
1069 * store what was left of this slice, if the queue idled/timed out
1071 if (timed_out
&& !cfq_cfqq_slice_new(cfqq
)) {
1072 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1073 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1076 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1077 cfq_del_cfqq_rr(cfqd
, cfqq
);
1079 cfq_resort_rr_list(cfqd
, cfqq
);
1081 if (cfqq
== cfqd
->active_queue
)
1082 cfqd
->active_queue
= NULL
;
1084 if (cfqd
->active_cic
) {
1085 put_io_context(cfqd
->active_cic
->ioc
);
1086 cfqd
->active_cic
= NULL
;
1090 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1092 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1095 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1099 * Get next queue for service. Unless we have a queue preemption,
1100 * we'll simply select the first cfqq in the service tree.
1102 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1104 struct cfq_rb_root
*service_tree
=
1105 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1106 cfqd
->serving_type
, cfqd
);
1108 if (!cfqd
->rq_queued
)
1111 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1113 return cfq_rb_first(service_tree
);
1116 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1118 struct cfq_group
*cfqg
= &cfqd
->root_group
;
1119 struct cfq_queue
*cfqq
;
1121 struct cfq_rb_root
*st
;
1123 if (!cfqd
->rq_queued
)
1126 for_each_cfqg_st(cfqg
, i
, j
, st
)
1127 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1133 * Get and set a new active queue for service.
1135 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1136 struct cfq_queue
*cfqq
)
1139 cfqq
= cfq_get_next_queue(cfqd
);
1141 __cfq_set_active_queue(cfqd
, cfqq
);
1145 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1148 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1149 return blk_rq_pos(rq
) - cfqd
->last_position
;
1151 return cfqd
->last_position
- blk_rq_pos(rq
);
1154 #define CFQQ_SEEK_THR 8 * 1024
1155 #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
1157 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1160 sector_t sdist
= cfqq
->seek_mean
;
1162 if (!sample_valid(cfqq
->seek_samples
))
1163 sdist
= CFQQ_SEEK_THR
;
1165 return cfq_dist_from_last(cfqd
, rq
) <= sdist
;
1168 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1169 struct cfq_queue
*cur_cfqq
)
1171 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1172 struct rb_node
*parent
, *node
;
1173 struct cfq_queue
*__cfqq
;
1174 sector_t sector
= cfqd
->last_position
;
1176 if (RB_EMPTY_ROOT(root
))
1180 * First, if we find a request starting at the end of the last
1181 * request, choose it.
1183 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1188 * If the exact sector wasn't found, the parent of the NULL leaf
1189 * will contain the closest sector.
1191 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1192 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1195 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1196 node
= rb_next(&__cfqq
->p_node
);
1198 node
= rb_prev(&__cfqq
->p_node
);
1202 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1203 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1211 * cur_cfqq - passed in so that we don't decide that the current queue is
1212 * closely cooperating with itself.
1214 * So, basically we're assuming that that cur_cfqq has dispatched at least
1215 * one request, and that cfqd->last_position reflects a position on the disk
1216 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1219 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1220 struct cfq_queue
*cur_cfqq
)
1222 struct cfq_queue
*cfqq
;
1224 if (!cfq_cfqq_sync(cur_cfqq
))
1226 if (CFQQ_SEEKY(cur_cfqq
))
1230 * We should notice if some of the queues are cooperating, eg
1231 * working closely on the same area of the disk. In that case,
1232 * we can group them together and don't waste time idling.
1234 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1239 * It only makes sense to merge sync queues.
1241 if (!cfq_cfqq_sync(cfqq
))
1243 if (CFQQ_SEEKY(cfqq
))
1247 * Do not merge queues of different priority classes
1249 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1256 * Determine whether we should enforce idle window for this queue.
1259 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1261 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1262 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1264 BUG_ON(!service_tree
);
1265 BUG_ON(!service_tree
->count
);
1267 /* We never do for idle class queues. */
1268 if (prio
== IDLE_WORKLOAD
)
1271 /* We do for queues that were marked with idle window flag. */
1272 if (cfq_cfqq_idle_window(cfqq
))
1276 * Otherwise, we do only if they are the last ones
1277 * in their service tree.
1279 return service_tree
->count
== 1;
1282 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1284 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1285 struct cfq_io_context
*cic
;
1289 * SSD device without seek penalty, disable idling. But only do so
1290 * for devices that support queuing, otherwise we still have a problem
1291 * with sync vs async workloads.
1293 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1296 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1297 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1300 * idle is disabled, either manually or by past process history
1302 if (!cfqd
->cfq_slice_idle
|| !cfq_should_idle(cfqd
, cfqq
))
1306 * still active requests from this queue, don't idle
1308 if (cfqq
->dispatched
)
1312 * task has exited, don't wait
1314 cic
= cfqd
->active_cic
;
1315 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1319 * If our average think time is larger than the remaining time
1320 * slice, then don't idle. This avoids overrunning the allotted
1323 if (sample_valid(cic
->ttime_samples
) &&
1324 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
1327 cfq_mark_cfqq_wait_request(cfqq
);
1329 sl
= cfqd
->cfq_slice_idle
;
1331 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1332 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu", sl
);
1336 * Move request from internal lists to the request queue dispatch list.
1338 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1340 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1341 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1343 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1345 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1346 cfq_remove_request(rq
);
1348 elv_dispatch_sort(q
, rq
);
1350 if (cfq_cfqq_sync(cfqq
))
1351 cfqd
->sync_flight
++;
1355 * return expired entry, or NULL to just start from scratch in rbtree
1357 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1359 struct request
*rq
= NULL
;
1361 if (cfq_cfqq_fifo_expire(cfqq
))
1364 cfq_mark_cfqq_fifo_expire(cfqq
);
1366 if (list_empty(&cfqq
->fifo
))
1369 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
1370 if (time_before(jiffies
, rq_fifo_time(rq
)))
1373 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
1378 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1380 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1382 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1384 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1388 * Must be called with the queue_lock held.
1390 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
1392 int process_refs
, io_refs
;
1394 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
1395 process_refs
= atomic_read(&cfqq
->ref
) - io_refs
;
1396 BUG_ON(process_refs
< 0);
1397 return process_refs
;
1400 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
1402 int process_refs
, new_process_refs
;
1403 struct cfq_queue
*__cfqq
;
1405 /* Avoid a circular list and skip interim queue merges */
1406 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
1412 process_refs
= cfqq_process_refs(cfqq
);
1414 * If the process for the cfqq has gone away, there is no
1415 * sense in merging the queues.
1417 if (process_refs
== 0)
1421 * Merge in the direction of the lesser amount of work.
1423 new_process_refs
= cfqq_process_refs(new_cfqq
);
1424 if (new_process_refs
>= process_refs
) {
1425 cfqq
->new_cfqq
= new_cfqq
;
1426 atomic_add(process_refs
, &new_cfqq
->ref
);
1428 new_cfqq
->new_cfqq
= cfqq
;
1429 atomic_add(new_process_refs
, &cfqq
->ref
);
1433 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
1434 struct cfq_group
*cfqg
, enum wl_prio_t prio
,
1437 struct cfq_queue
*queue
;
1439 bool key_valid
= false;
1440 unsigned long lowest_key
= 0;
1441 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
1445 * When priorities switched, we prefer starting
1446 * from SYNC_NOIDLE (first choice), or just SYNC
1449 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1451 cur_best
= SYNC_WORKLOAD
;
1452 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1455 return ASYNC_WORKLOAD
;
1458 for (i
= 0; i
< 3; ++i
) {
1459 /* otherwise, select the one with lowest rb_key */
1460 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
, cfqd
));
1462 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
1463 lowest_key
= queue
->rb_key
;
1472 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1474 enum wl_prio_t previous_prio
= cfqd
->serving_prio
;
1478 struct cfq_rb_root
*st
;
1480 /* Choose next priority. RT > BE > IDLE */
1481 if (cfq_busy_queues_wl(RT_WORKLOAD
, cfqd
))
1482 cfqd
->serving_prio
= RT_WORKLOAD
;
1483 else if (cfq_busy_queues_wl(BE_WORKLOAD
, cfqd
))
1484 cfqd
->serving_prio
= BE_WORKLOAD
;
1486 cfqd
->serving_prio
= IDLE_WORKLOAD
;
1487 cfqd
->workload_expires
= jiffies
+ 1;
1492 * For RT and BE, we have to choose also the type
1493 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
1496 prio_changed
= (cfqd
->serving_prio
!= previous_prio
);
1497 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
1502 * If priority didn't change, check workload expiration,
1503 * and that we still have other queues ready
1505 if (!prio_changed
&& count
&&
1506 !time_after(jiffies
, cfqd
->workload_expires
))
1509 /* otherwise select new workload type */
1510 cfqd
->serving_type
=
1511 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
, prio_changed
);
1512 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
1517 * the workload slice is computed as a fraction of target latency
1518 * proportional to the number of queues in that workload, over
1519 * all the queues in the same priority class
1521 slice
= cfq_target_latency
* count
/
1522 max_t(unsigned, cfqd
->busy_queues_avg
[cfqd
->serving_prio
],
1523 cfq_busy_queues_wl(cfqd
->serving_prio
, cfqd
));
1525 if (cfqd
->serving_type
== ASYNC_WORKLOAD
)
1526 /* async workload slice is scaled down according to
1527 * the sync/async slice ratio. */
1528 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
1530 /* sync workload slice is at least 2 * cfq_slice_idle */
1531 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
1533 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
1534 cfqd
->workload_expires
= jiffies
+ slice
;
1535 cfqd
->noidle_tree_requires_idle
= false;
1538 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
1540 cfqd
->serving_group
= &cfqd
->root_group
;
1541 choose_service_tree(cfqd
, &cfqd
->root_group
);
1545 * Select a queue for service. If we have a current active queue,
1546 * check whether to continue servicing it, or retrieve and set a new one.
1548 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
1550 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1552 cfqq
= cfqd
->active_queue
;
1556 if (!cfqd
->rq_queued
)
1559 * The active queue has run out of time, expire it and select new.
1561 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
))
1565 * The active queue has requests and isn't expired, allow it to
1568 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
1572 * If another queue has a request waiting within our mean seek
1573 * distance, let it run. The expire code will check for close
1574 * cooperators and put the close queue at the front of the service
1575 * tree. If possible, merge the expiring queue with the new cfqq.
1577 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
1579 if (!cfqq
->new_cfqq
)
1580 cfq_setup_merge(cfqq
, new_cfqq
);
1585 * No requests pending. If the active queue still has requests in
1586 * flight or is idling for a new request, allow either of these
1587 * conditions to happen (or time out) before selecting a new queue.
1589 if (timer_pending(&cfqd
->idle_slice_timer
) ||
1590 (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
))) {
1596 cfq_slice_expired(cfqd
, 0);
1599 * Current queue expired. Check if we have to switch to a new
1603 cfq_choose_cfqg(cfqd
);
1605 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
1610 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
1614 while (cfqq
->next_rq
) {
1615 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
1619 BUG_ON(!list_empty(&cfqq
->fifo
));
1621 /* By default cfqq is not expired if it is empty. Do it explicitly */
1622 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
1627 * Drain our current requests. Used for barriers and when switching
1628 * io schedulers on-the-fly.
1630 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
1632 struct cfq_queue
*cfqq
;
1635 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
)
1636 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
1638 cfq_slice_expired(cfqd
, 0);
1639 BUG_ON(cfqd
->busy_queues
);
1641 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
1645 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1647 unsigned int max_dispatch
;
1650 * Drain async requests before we start sync IO
1652 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_driver
[BLK_RW_ASYNC
])
1656 * If this is an async queue and we have sync IO in flight, let it wait
1658 if (cfqd
->sync_flight
&& !cfq_cfqq_sync(cfqq
))
1661 max_dispatch
= cfqd
->cfq_quantum
;
1662 if (cfq_class_idle(cfqq
))
1666 * Does this cfqq already have too much IO in flight?
1668 if (cfqq
->dispatched
>= max_dispatch
) {
1670 * idle queue must always only have a single IO in flight
1672 if (cfq_class_idle(cfqq
))
1676 * We have other queues, don't allow more IO from this one
1678 if (cfqd
->busy_queues
> 1)
1682 * Sole queue user, no limit
1688 * Async queues must wait a bit before being allowed dispatch.
1689 * We also ramp up the dispatch depth gradually for async IO,
1690 * based on the last sync IO we serviced
1692 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
1693 unsigned long last_sync
= jiffies
- cfqd
->last_end_sync_rq
;
1696 depth
= last_sync
/ cfqd
->cfq_slice
[1];
1697 if (!depth
&& !cfqq
->dispatched
)
1699 if (depth
< max_dispatch
)
1700 max_dispatch
= depth
;
1704 * If we're below the current max, allow a dispatch
1706 return cfqq
->dispatched
< max_dispatch
;
1710 * Dispatch a request from cfqq, moving them to the request queue
1713 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1717 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
1719 if (!cfq_may_dispatch(cfqd
, cfqq
))
1723 * follow expired path, else get first next available
1725 rq
= cfq_check_fifo(cfqq
);
1730 * insert request into driver dispatch list
1732 cfq_dispatch_insert(cfqd
->queue
, rq
);
1734 if (!cfqd
->active_cic
) {
1735 struct cfq_io_context
*cic
= RQ_CIC(rq
);
1737 atomic_long_inc(&cic
->ioc
->refcount
);
1738 cfqd
->active_cic
= cic
;
1745 * Find the cfqq that we need to service and move a request from that to the
1748 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
1750 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1751 struct cfq_queue
*cfqq
;
1753 if (!cfqd
->busy_queues
)
1756 if (unlikely(force
))
1757 return cfq_forced_dispatch(cfqd
);
1759 cfqq
= cfq_select_queue(cfqd
);
1764 * Dispatch a request from this cfqq, if it is allowed
1766 if (!cfq_dispatch_request(cfqd
, cfqq
))
1769 cfqq
->slice_dispatch
++;
1770 cfq_clear_cfqq_must_dispatch(cfqq
);
1773 * expire an async queue immediately if it has used up its slice. idle
1774 * queue always expire after 1 dispatch round.
1776 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
1777 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1778 cfq_class_idle(cfqq
))) {
1779 cfqq
->slice_end
= jiffies
+ 1;
1780 cfq_slice_expired(cfqd
, 0);
1783 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
1788 * task holds one reference to the queue, dropped when task exits. each rq
1789 * in-flight on this queue also holds a reference, dropped when rq is freed.
1791 * queue lock must be held here.
1793 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1795 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1797 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1799 if (!atomic_dec_and_test(&cfqq
->ref
))
1802 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
1803 BUG_ON(rb_first(&cfqq
->sort_list
));
1804 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1806 if (unlikely(cfqd
->active_queue
== cfqq
)) {
1807 __cfq_slice_expired(cfqd
, cfqq
, 0);
1808 cfq_schedule_dispatch(cfqd
);
1811 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1812 kmem_cache_free(cfq_pool
, cfqq
);
1816 * Must always be called with the rcu_read_lock() held
1819 __call_for_each_cic(struct io_context
*ioc
,
1820 void (*func
)(struct io_context
*, struct cfq_io_context
*))
1822 struct cfq_io_context
*cic
;
1823 struct hlist_node
*n
;
1825 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
1830 * Call func for each cic attached to this ioc.
1833 call_for_each_cic(struct io_context
*ioc
,
1834 void (*func
)(struct io_context
*, struct cfq_io_context
*))
1837 __call_for_each_cic(ioc
, func
);
1841 static void cfq_cic_free_rcu(struct rcu_head
*head
)
1843 struct cfq_io_context
*cic
;
1845 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
1847 kmem_cache_free(cfq_ioc_pool
, cic
);
1848 elv_ioc_count_dec(cfq_ioc_count
);
1852 * CFQ scheduler is exiting, grab exit lock and check
1853 * the pending io context count. If it hits zero,
1854 * complete ioc_gone and set it back to NULL
1856 spin_lock(&ioc_gone_lock
);
1857 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
1861 spin_unlock(&ioc_gone_lock
);
1865 static void cfq_cic_free(struct cfq_io_context
*cic
)
1867 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
1870 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
1872 unsigned long flags
;
1874 BUG_ON(!cic
->dead_key
);
1876 spin_lock_irqsave(&ioc
->lock
, flags
);
1877 radix_tree_delete(&ioc
->radix_root
, cic
->dead_key
);
1878 hlist_del_rcu(&cic
->cic_list
);
1879 spin_unlock_irqrestore(&ioc
->lock
, flags
);
1885 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1886 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1887 * and ->trim() which is called with the task lock held
1889 static void cfq_free_io_context(struct io_context
*ioc
)
1892 * ioc->refcount is zero here, or we are called from elv_unregister(),
1893 * so no more cic's are allowed to be linked into this ioc. So it
1894 * should be ok to iterate over the known list, we will see all cic's
1895 * since no new ones are added.
1897 __call_for_each_cic(ioc
, cic_free_func
);
1900 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1902 struct cfq_queue
*__cfqq
, *next
;
1904 if (unlikely(cfqq
== cfqd
->active_queue
)) {
1905 __cfq_slice_expired(cfqd
, cfqq
, 0);
1906 cfq_schedule_dispatch(cfqd
);
1910 * If this queue was scheduled to merge with another queue, be
1911 * sure to drop the reference taken on that queue (and others in
1912 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
1914 __cfqq
= cfqq
->new_cfqq
;
1916 if (__cfqq
== cfqq
) {
1917 WARN(1, "cfqq->new_cfqq loop detected\n");
1920 next
= __cfqq
->new_cfqq
;
1921 cfq_put_queue(__cfqq
);
1925 cfq_put_queue(cfqq
);
1928 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
1929 struct cfq_io_context
*cic
)
1931 struct io_context
*ioc
= cic
->ioc
;
1933 list_del_init(&cic
->queue_list
);
1936 * Make sure key == NULL is seen for dead queues
1939 cic
->dead_key
= (unsigned long) cic
->key
;
1942 if (ioc
->ioc_data
== cic
)
1943 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
1945 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
1946 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
1947 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
1950 if (cic
->cfqq
[BLK_RW_SYNC
]) {
1951 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
1952 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
1956 static void cfq_exit_single_io_context(struct io_context
*ioc
,
1957 struct cfq_io_context
*cic
)
1959 struct cfq_data
*cfqd
= cic
->key
;
1962 struct request_queue
*q
= cfqd
->queue
;
1963 unsigned long flags
;
1965 spin_lock_irqsave(q
->queue_lock
, flags
);
1968 * Ensure we get a fresh copy of the ->key to prevent
1969 * race between exiting task and queue
1971 smp_read_barrier_depends();
1973 __cfq_exit_single_io_context(cfqd
, cic
);
1975 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1980 * The process that ioc belongs to has exited, we need to clean up
1981 * and put the internal structures we have that belongs to that process.
1983 static void cfq_exit_io_context(struct io_context
*ioc
)
1985 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
1988 static struct cfq_io_context
*
1989 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1991 struct cfq_io_context
*cic
;
1993 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
1996 cic
->last_end_request
= jiffies
;
1997 INIT_LIST_HEAD(&cic
->queue_list
);
1998 INIT_HLIST_NODE(&cic
->cic_list
);
1999 cic
->dtor
= cfq_free_io_context
;
2000 cic
->exit
= cfq_exit_io_context
;
2001 elv_ioc_count_inc(cfq_ioc_count
);
2007 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2009 struct task_struct
*tsk
= current
;
2012 if (!cfq_cfqq_prio_changed(cfqq
))
2015 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2016 switch (ioprio_class
) {
2018 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2019 case IOPRIO_CLASS_NONE
:
2021 * no prio set, inherit CPU scheduling settings
2023 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2024 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2026 case IOPRIO_CLASS_RT
:
2027 cfqq
->ioprio
= task_ioprio(ioc
);
2028 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2030 case IOPRIO_CLASS_BE
:
2031 cfqq
->ioprio
= task_ioprio(ioc
);
2032 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2034 case IOPRIO_CLASS_IDLE
:
2035 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2037 cfq_clear_cfqq_idle_window(cfqq
);
2042 * keep track of original prio settings in case we have to temporarily
2043 * elevate the priority of this queue
2045 cfqq
->org_ioprio
= cfqq
->ioprio
;
2046 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2047 cfq_clear_cfqq_prio_changed(cfqq
);
2050 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2052 struct cfq_data
*cfqd
= cic
->key
;
2053 struct cfq_queue
*cfqq
;
2054 unsigned long flags
;
2056 if (unlikely(!cfqd
))
2059 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2061 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2063 struct cfq_queue
*new_cfqq
;
2064 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2067 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2068 cfq_put_queue(cfqq
);
2072 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2074 cfq_mark_cfqq_prio_changed(cfqq
);
2076 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2079 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2081 call_for_each_cic(ioc
, changed_ioprio
);
2082 ioc
->ioprio_changed
= 0;
2085 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2086 pid_t pid
, bool is_sync
)
2088 RB_CLEAR_NODE(&cfqq
->rb_node
);
2089 RB_CLEAR_NODE(&cfqq
->p_node
);
2090 INIT_LIST_HEAD(&cfqq
->fifo
);
2092 atomic_set(&cfqq
->ref
, 0);
2095 cfq_mark_cfqq_prio_changed(cfqq
);
2098 if (!cfq_class_idle(cfqq
))
2099 cfq_mark_cfqq_idle_window(cfqq
);
2100 cfq_mark_cfqq_sync(cfqq
);
2105 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
2110 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
2112 return &cfqd
->root_group
;
2115 static struct cfq_queue
*
2116 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2117 struct io_context
*ioc
, gfp_t gfp_mask
)
2119 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2120 struct cfq_io_context
*cic
;
2121 struct cfq_group
*cfqg
;
2124 cfqg
= cfq_get_cfqg(cfqd
, 1);
2125 cic
= cfq_cic_lookup(cfqd
, ioc
);
2126 /* cic always exists here */
2127 cfqq
= cic_to_cfqq(cic
, is_sync
);
2130 * Always try a new alloc if we fell back to the OOM cfqq
2131 * originally, since it should just be a temporary situation.
2133 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2138 } else if (gfp_mask
& __GFP_WAIT
) {
2139 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2140 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2141 gfp_mask
| __GFP_ZERO
,
2143 spin_lock_irq(cfqd
->queue
->queue_lock
);
2147 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2148 gfp_mask
| __GFP_ZERO
,
2153 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2154 cfq_init_prio_data(cfqq
, ioc
);
2155 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2156 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2158 cfqq
= &cfqd
->oom_cfqq
;
2162 kmem_cache_free(cfq_pool
, new_cfqq
);
2167 static struct cfq_queue
**
2168 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2170 switch (ioprio_class
) {
2171 case IOPRIO_CLASS_RT
:
2172 return &cfqd
->async_cfqq
[0][ioprio
];
2173 case IOPRIO_CLASS_BE
:
2174 return &cfqd
->async_cfqq
[1][ioprio
];
2175 case IOPRIO_CLASS_IDLE
:
2176 return &cfqd
->async_idle_cfqq
;
2182 static struct cfq_queue
*
2183 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2186 const int ioprio
= task_ioprio(ioc
);
2187 const int ioprio_class
= task_ioprio_class(ioc
);
2188 struct cfq_queue
**async_cfqq
= NULL
;
2189 struct cfq_queue
*cfqq
= NULL
;
2192 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2197 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2200 * pin the queue now that it's allocated, scheduler exit will prune it
2202 if (!is_sync
&& !(*async_cfqq
)) {
2203 atomic_inc(&cfqq
->ref
);
2207 atomic_inc(&cfqq
->ref
);
2212 * We drop cfq io contexts lazily, so we may find a dead one.
2215 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2216 struct cfq_io_context
*cic
)
2218 unsigned long flags
;
2220 WARN_ON(!list_empty(&cic
->queue_list
));
2222 spin_lock_irqsave(&ioc
->lock
, flags
);
2224 BUG_ON(ioc
->ioc_data
== cic
);
2226 radix_tree_delete(&ioc
->radix_root
, (unsigned long) cfqd
);
2227 hlist_del_rcu(&cic
->cic_list
);
2228 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2233 static struct cfq_io_context
*
2234 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
2236 struct cfq_io_context
*cic
;
2237 unsigned long flags
;
2246 * we maintain a last-hit cache, to avoid browsing over the tree
2248 cic
= rcu_dereference(ioc
->ioc_data
);
2249 if (cic
&& cic
->key
== cfqd
) {
2255 cic
= radix_tree_lookup(&ioc
->radix_root
, (unsigned long) cfqd
);
2259 /* ->key must be copied to avoid race with cfq_exit_queue() */
2262 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
2267 spin_lock_irqsave(&ioc
->lock
, flags
);
2268 rcu_assign_pointer(ioc
->ioc_data
, cic
);
2269 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2277 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2278 * the process specific cfq io context when entered from the block layer.
2279 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2281 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2282 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
2284 unsigned long flags
;
2287 ret
= radix_tree_preload(gfp_mask
);
2292 spin_lock_irqsave(&ioc
->lock
, flags
);
2293 ret
= radix_tree_insert(&ioc
->radix_root
,
2294 (unsigned long) cfqd
, cic
);
2296 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
2297 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2299 radix_tree_preload_end();
2302 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2303 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
2304 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2309 printk(KERN_ERR
"cfq: cic link failed!\n");
2315 * Setup general io context and cfq io context. There can be several cfq
2316 * io contexts per general io context, if this process is doing io to more
2317 * than one device managed by cfq.
2319 static struct cfq_io_context
*
2320 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2322 struct io_context
*ioc
= NULL
;
2323 struct cfq_io_context
*cic
;
2325 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2327 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
2331 cic
= cfq_cic_lookup(cfqd
, ioc
);
2335 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
2339 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
2343 smp_read_barrier_depends();
2344 if (unlikely(ioc
->ioprio_changed
))
2345 cfq_ioc_set_ioprio(ioc
);
2351 put_io_context(ioc
);
2356 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
2358 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
2359 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
2361 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
2362 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
2363 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
2367 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2373 if (!cfqq
->last_request_pos
)
2375 else if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
2376 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
2378 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
2381 * Don't allow the seek distance to get too large from the
2382 * odd fragment, pagein, etc
2384 if (cfqq
->seek_samples
<= 60) /* second&third seek */
2385 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*1024);
2387 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*64);
2389 cfqq
->seek_samples
= (7*cfqq
->seek_samples
+ 256) / 8;
2390 cfqq
->seek_total
= (7*cfqq
->seek_total
+ (u64
)256*sdist
) / 8;
2391 total
= cfqq
->seek_total
+ (cfqq
->seek_samples
/2);
2392 do_div(total
, cfqq
->seek_samples
);
2393 cfqq
->seek_mean
= (sector_t
)total
;
2396 * If this cfqq is shared between multiple processes, check to
2397 * make sure that those processes are still issuing I/Os within
2398 * the mean seek distance. If not, it may be time to break the
2399 * queues apart again.
2401 if (cfq_cfqq_coop(cfqq
)) {
2402 if (CFQQ_SEEKY(cfqq
) && !cfqq
->seeky_start
)
2403 cfqq
->seeky_start
= jiffies
;
2404 else if (!CFQQ_SEEKY(cfqq
))
2405 cfqq
->seeky_start
= 0;
2410 * Disable idle window if the process thinks too long or seeks so much that
2414 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2415 struct cfq_io_context
*cic
)
2417 int old_idle
, enable_idle
;
2420 * Don't idle for async or idle io prio class
2422 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
2425 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
2427 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
2428 cfq_mark_cfqq_deep(cfqq
);
2430 if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
2431 (!cfq_cfqq_deep(cfqq
) && sample_valid(cfqq
->seek_samples
)
2432 && CFQQ_SEEKY(cfqq
)))
2434 else if (sample_valid(cic
->ttime_samples
)) {
2435 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
2441 if (old_idle
!= enable_idle
) {
2442 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
2444 cfq_mark_cfqq_idle_window(cfqq
);
2446 cfq_clear_cfqq_idle_window(cfqq
);
2451 * Check if new_cfqq should preempt the currently active queue. Return 0 for
2452 * no or if we aren't sure, a 1 will cause a preempt.
2455 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
2458 struct cfq_queue
*cfqq
;
2460 cfqq
= cfqd
->active_queue
;
2464 if (cfq_slice_used(cfqq
))
2467 if (cfq_class_idle(new_cfqq
))
2470 if (cfq_class_idle(cfqq
))
2473 /* Allow preemption only if we are idling on sync-noidle tree */
2474 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
2475 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
2476 new_cfqq
->service_tree
->count
== 2 &&
2477 RB_EMPTY_ROOT(&cfqq
->sort_list
))
2481 * if the new request is sync, but the currently running queue is
2482 * not, let the sync request have priority.
2484 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
2488 * So both queues are sync. Let the new request get disk time if
2489 * it's a metadata request and the current queue is doing regular IO.
2491 if (rq_is_meta(rq
) && !cfqq
->meta_pending
)
2495 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2497 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
2500 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
2504 * if this request is as-good as one we would expect from the
2505 * current cfqq, let it preempt
2507 if (cfq_rq_close(cfqd
, cfqq
, rq
))
2514 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2515 * let it have half of its nominal slice.
2517 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2519 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
2520 cfq_slice_expired(cfqd
, 1);
2523 * Put the new queue at the front of the of the current list,
2524 * so we know that it will be selected next.
2526 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
2528 cfq_service_tree_add(cfqd
, cfqq
, 1);
2530 cfqq
->slice_end
= 0;
2531 cfq_mark_cfqq_slice_new(cfqq
);
2535 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2536 * something we should do about it
2539 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2542 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2546 cfqq
->meta_pending
++;
2548 cfq_update_io_thinktime(cfqd
, cic
);
2549 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
2550 cfq_update_idle_window(cfqd
, cfqq
, cic
);
2552 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
2554 if (cfqq
== cfqd
->active_queue
) {
2556 * Remember that we saw a request from this process, but
2557 * don't start queuing just yet. Otherwise we risk seeing lots
2558 * of tiny requests, because we disrupt the normal plugging
2559 * and merging. If the request is already larger than a single
2560 * page, let it rip immediately. For that case we assume that
2561 * merging is already done. Ditto for a busy system that
2562 * has other work pending, don't risk delaying until the
2563 * idle timer unplug to continue working.
2565 if (cfq_cfqq_wait_request(cfqq
)) {
2566 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
2567 cfqd
->busy_queues
> 1) {
2568 del_timer(&cfqd
->idle_slice_timer
);
2569 __blk_run_queue(cfqd
->queue
);
2571 cfq_mark_cfqq_must_dispatch(cfqq
);
2573 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
2575 * not the active queue - expire current slice if it is
2576 * idle and has expired it's mean thinktime or this new queue
2577 * has some old slice time left and is of higher priority or
2578 * this new queue is RT and the current one is BE
2580 cfq_preempt_queue(cfqd
, cfqq
);
2581 __blk_run_queue(cfqd
->queue
);
2585 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
2587 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2588 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2590 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
2591 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
2593 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
2594 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
2597 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
2601 * Update hw_tag based on peak queue depth over 50 samples under
2604 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
2606 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2608 if (rq_in_driver(cfqd
) > cfqd
->hw_tag_est_depth
)
2609 cfqd
->hw_tag_est_depth
= rq_in_driver(cfqd
);
2611 if (cfqd
->hw_tag
== 1)
2614 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
2615 rq_in_driver(cfqd
) <= CFQ_HW_QUEUE_MIN
)
2619 * If active queue hasn't enough requests and can idle, cfq might not
2620 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
2623 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
2624 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
2625 CFQ_HW_QUEUE_MIN
&& rq_in_driver(cfqd
) < CFQ_HW_QUEUE_MIN
)
2628 if (cfqd
->hw_tag_samples
++ < 50)
2631 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
2637 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
2639 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2640 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2641 const int sync
= rq_is_sync(rq
);
2645 cfq_log_cfqq(cfqd
, cfqq
, "complete");
2647 cfq_update_hw_tag(cfqd
);
2649 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
2650 WARN_ON(!cfqq
->dispatched
);
2651 cfqd
->rq_in_driver
[sync
]--;
2654 if (cfq_cfqq_sync(cfqq
))
2655 cfqd
->sync_flight
--;
2658 RQ_CIC(rq
)->last_end_request
= now
;
2659 cfqd
->last_end_sync_rq
= now
;
2663 * If this is the active queue, check if it needs to be expired,
2664 * or if we want to idle in case it has no pending requests.
2666 if (cfqd
->active_queue
== cfqq
) {
2667 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
2669 if (cfq_cfqq_slice_new(cfqq
)) {
2670 cfq_set_prio_slice(cfqd
, cfqq
);
2671 cfq_clear_cfqq_slice_new(cfqq
);
2674 * Idling is not enabled on:
2676 * - idle-priority queues
2678 * - queues with still some requests queued
2679 * - when there is a close cooperator
2681 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
2682 cfq_slice_expired(cfqd
, 1);
2683 else if (sync
&& cfqq_empty
&&
2684 !cfq_close_cooperator(cfqd
, cfqq
)) {
2685 cfqd
->noidle_tree_requires_idle
|= !rq_noidle(rq
);
2687 * Idling is enabled for SYNC_WORKLOAD.
2688 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
2689 * only if we processed at least one !rq_noidle request
2691 if (cfqd
->serving_type
== SYNC_WORKLOAD
2692 || cfqd
->noidle_tree_requires_idle
)
2693 cfq_arm_slice_timer(cfqd
);
2697 if (!rq_in_driver(cfqd
))
2698 cfq_schedule_dispatch(cfqd
);
2702 * we temporarily boost lower priority queues if they are holding fs exclusive
2703 * resources. they are boosted to normal prio (CLASS_BE/4)
2705 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
2707 if (has_fs_excl()) {
2709 * boost idle prio on transactions that would lock out other
2710 * users of the filesystem
2712 if (cfq_class_idle(cfqq
))
2713 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2714 if (cfqq
->ioprio
> IOPRIO_NORM
)
2715 cfqq
->ioprio
= IOPRIO_NORM
;
2718 * unboost the queue (if needed)
2720 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
2721 cfqq
->ioprio
= cfqq
->org_ioprio
;
2725 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
2727 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
2728 cfq_mark_cfqq_must_alloc_slice(cfqq
);
2729 return ELV_MQUEUE_MUST
;
2732 return ELV_MQUEUE_MAY
;
2735 static int cfq_may_queue(struct request_queue
*q
, int rw
)
2737 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2738 struct task_struct
*tsk
= current
;
2739 struct cfq_io_context
*cic
;
2740 struct cfq_queue
*cfqq
;
2743 * don't force setup of a queue from here, as a call to may_queue
2744 * does not necessarily imply that a request actually will be queued.
2745 * so just lookup a possibly existing queue, or return 'may queue'
2748 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
2750 return ELV_MQUEUE_MAY
;
2752 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
2754 cfq_init_prio_data(cfqq
, cic
->ioc
);
2755 cfq_prio_boost(cfqq
);
2757 return __cfq_may_queue(cfqq
);
2760 return ELV_MQUEUE_MAY
;
2764 * queue lock held here
2766 static void cfq_put_request(struct request
*rq
)
2768 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2771 const int rw
= rq_data_dir(rq
);
2773 BUG_ON(!cfqq
->allocated
[rw
]);
2774 cfqq
->allocated
[rw
]--;
2776 put_io_context(RQ_CIC(rq
)->ioc
);
2778 rq
->elevator_private
= NULL
;
2779 rq
->elevator_private2
= NULL
;
2781 cfq_put_queue(cfqq
);
2785 static struct cfq_queue
*
2786 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
2787 struct cfq_queue
*cfqq
)
2789 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
2790 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
2791 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
2792 cfq_put_queue(cfqq
);
2793 return cic_to_cfqq(cic
, 1);
2796 static int should_split_cfqq(struct cfq_queue
*cfqq
)
2798 if (cfqq
->seeky_start
&&
2799 time_after(jiffies
, cfqq
->seeky_start
+ CFQQ_COOP_TOUT
))
2805 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
2806 * was the last process referring to said cfqq.
2808 static struct cfq_queue
*
2809 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
2811 if (cfqq_process_refs(cfqq
) == 1) {
2812 cfqq
->seeky_start
= 0;
2813 cfqq
->pid
= current
->pid
;
2814 cfq_clear_cfqq_coop(cfqq
);
2818 cic_set_cfqq(cic
, NULL
, 1);
2819 cfq_put_queue(cfqq
);
2823 * Allocate cfq data structures associated with this request.
2826 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
2828 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2829 struct cfq_io_context
*cic
;
2830 const int rw
= rq_data_dir(rq
);
2831 const bool is_sync
= rq_is_sync(rq
);
2832 struct cfq_queue
*cfqq
;
2833 unsigned long flags
;
2835 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2837 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
2839 spin_lock_irqsave(q
->queue_lock
, flags
);
2845 cfqq
= cic_to_cfqq(cic
, is_sync
);
2846 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2847 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
2848 cic_set_cfqq(cic
, cfqq
, is_sync
);
2851 * If the queue was seeky for too long, break it apart.
2853 if (cfq_cfqq_coop(cfqq
) && should_split_cfqq(cfqq
)) {
2854 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
2855 cfqq
= split_cfqq(cic
, cfqq
);
2861 * Check to see if this queue is scheduled to merge with
2862 * another, closely cooperating queue. The merging of
2863 * queues happens here as it must be done in process context.
2864 * The reference on new_cfqq was taken in merge_cfqqs.
2867 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
2870 cfqq
->allocated
[rw
]++;
2871 atomic_inc(&cfqq
->ref
);
2873 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2875 rq
->elevator_private
= cic
;
2876 rq
->elevator_private2
= cfqq
;
2881 put_io_context(cic
->ioc
);
2883 cfq_schedule_dispatch(cfqd
);
2884 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2885 cfq_log(cfqd
, "set_request fail");
2889 static void cfq_kick_queue(struct work_struct
*work
)
2891 struct cfq_data
*cfqd
=
2892 container_of(work
, struct cfq_data
, unplug_work
);
2893 struct request_queue
*q
= cfqd
->queue
;
2895 spin_lock_irq(q
->queue_lock
);
2896 __blk_run_queue(cfqd
->queue
);
2897 spin_unlock_irq(q
->queue_lock
);
2901 * Timer running if the active_queue is currently idling inside its time slice
2903 static void cfq_idle_slice_timer(unsigned long data
)
2905 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2906 struct cfq_queue
*cfqq
;
2907 unsigned long flags
;
2910 cfq_log(cfqd
, "idle timer fired");
2912 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2914 cfqq
= cfqd
->active_queue
;
2919 * We saw a request before the queue expired, let it through
2921 if (cfq_cfqq_must_dispatch(cfqq
))
2927 if (cfq_slice_used(cfqq
))
2931 * only expire and reinvoke request handler, if there are
2932 * other queues with pending requests
2934 if (!cfqd
->busy_queues
)
2938 * not expired and it has a request pending, let it dispatch
2940 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2944 * Queue depth flag is reset only when the idle didn't succeed
2946 cfq_clear_cfqq_deep(cfqq
);
2949 cfq_slice_expired(cfqd
, timed_out
);
2951 cfq_schedule_dispatch(cfqd
);
2953 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2956 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
2958 del_timer_sync(&cfqd
->idle_slice_timer
);
2959 cancel_work_sync(&cfqd
->unplug_work
);
2962 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
2966 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
2967 if (cfqd
->async_cfqq
[0][i
])
2968 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
2969 if (cfqd
->async_cfqq
[1][i
])
2970 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
2973 if (cfqd
->async_idle_cfqq
)
2974 cfq_put_queue(cfqd
->async_idle_cfqq
);
2977 static void cfq_exit_queue(struct elevator_queue
*e
)
2979 struct cfq_data
*cfqd
= e
->elevator_data
;
2980 struct request_queue
*q
= cfqd
->queue
;
2982 cfq_shutdown_timer_wq(cfqd
);
2984 spin_lock_irq(q
->queue_lock
);
2986 if (cfqd
->active_queue
)
2987 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
2989 while (!list_empty(&cfqd
->cic_list
)) {
2990 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
2991 struct cfq_io_context
,
2994 __cfq_exit_single_io_context(cfqd
, cic
);
2997 cfq_put_async_queues(cfqd
);
2999 spin_unlock_irq(q
->queue_lock
);
3001 cfq_shutdown_timer_wq(cfqd
);
3006 static void *cfq_init_queue(struct request_queue
*q
)
3008 struct cfq_data
*cfqd
;
3010 struct cfq_group
*cfqg
;
3011 struct cfq_rb_root
*st
;
3013 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3017 /* Init root group */
3018 cfqg
= &cfqd
->root_group
;
3019 for_each_cfqg_st(cfqg
, i
, j
, st
)
3023 * Not strictly needed (since RB_ROOT just clears the node and we
3024 * zeroed cfqd on alloc), but better be safe in case someone decides
3025 * to add magic to the rb code
3027 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3028 cfqd
->prio_trees
[i
] = RB_ROOT
;
3031 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3032 * Grab a permanent reference to it, so that the normal code flow
3033 * will not attempt to free it.
3035 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3036 atomic_inc(&cfqd
->oom_cfqq
.ref
);
3037 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3039 INIT_LIST_HEAD(&cfqd
->cic_list
);
3043 init_timer(&cfqd
->idle_slice_timer
);
3044 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3045 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3047 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3049 cfqd
->cfq_quantum
= cfq_quantum
;
3050 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3051 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3052 cfqd
->cfq_back_max
= cfq_back_max
;
3053 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3054 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3055 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3056 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3057 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3058 cfqd
->cfq_latency
= 1;
3060 cfqd
->last_end_sync_rq
= jiffies
;
3064 static void cfq_slab_kill(void)
3067 * Caller already ensured that pending RCU callbacks are completed,
3068 * so we should have no busy allocations at this point.
3071 kmem_cache_destroy(cfq_pool
);
3073 kmem_cache_destroy(cfq_ioc_pool
);
3076 static int __init
cfq_slab_setup(void)
3078 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3082 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3093 * sysfs parts below -->
3096 cfq_var_show(unsigned int var
, char *page
)
3098 return sprintf(page
, "%d\n", var
);
3102 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3104 char *p
= (char *) page
;
3106 *var
= simple_strtoul(p
, &p
, 10);
3110 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3111 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3113 struct cfq_data *cfqd = e->elevator_data; \
3114 unsigned int __data = __VAR; \
3116 __data = jiffies_to_msecs(__data); \
3117 return cfq_var_show(__data, (page)); \
3119 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3120 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3121 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3122 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3123 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3124 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3125 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
3126 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
3127 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
3128 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
3129 #undef SHOW_FUNCTION
3131 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3132 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3134 struct cfq_data *cfqd = e->elevator_data; \
3135 unsigned int __data; \
3136 int ret = cfq_var_store(&__data, (page), count); \
3137 if (__data < (MIN)) \
3139 else if (__data > (MAX)) \
3142 *(__PTR) = msecs_to_jiffies(__data); \
3144 *(__PTR) = __data; \
3147 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
3148 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
3150 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
3152 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
3153 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
3155 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
3156 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
3157 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
3158 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
3160 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
3161 #undef STORE_FUNCTION
3163 #define CFQ_ATTR(name) \
3164 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3166 static struct elv_fs_entry cfq_attrs
[] = {
3168 CFQ_ATTR(fifo_expire_sync
),
3169 CFQ_ATTR(fifo_expire_async
),
3170 CFQ_ATTR(back_seek_max
),
3171 CFQ_ATTR(back_seek_penalty
),
3172 CFQ_ATTR(slice_sync
),
3173 CFQ_ATTR(slice_async
),
3174 CFQ_ATTR(slice_async_rq
),
3175 CFQ_ATTR(slice_idle
),
3176 CFQ_ATTR(low_latency
),
3180 static struct elevator_type iosched_cfq
= {
3182 .elevator_merge_fn
= cfq_merge
,
3183 .elevator_merged_fn
= cfq_merged_request
,
3184 .elevator_merge_req_fn
= cfq_merged_requests
,
3185 .elevator_allow_merge_fn
= cfq_allow_merge
,
3186 .elevator_dispatch_fn
= cfq_dispatch_requests
,
3187 .elevator_add_req_fn
= cfq_insert_request
,
3188 .elevator_activate_req_fn
= cfq_activate_request
,
3189 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
3190 .elevator_queue_empty_fn
= cfq_queue_empty
,
3191 .elevator_completed_req_fn
= cfq_completed_request
,
3192 .elevator_former_req_fn
= elv_rb_former_request
,
3193 .elevator_latter_req_fn
= elv_rb_latter_request
,
3194 .elevator_set_req_fn
= cfq_set_request
,
3195 .elevator_put_req_fn
= cfq_put_request
,
3196 .elevator_may_queue_fn
= cfq_may_queue
,
3197 .elevator_init_fn
= cfq_init_queue
,
3198 .elevator_exit_fn
= cfq_exit_queue
,
3199 .trim
= cfq_free_io_context
,
3201 .elevator_attrs
= cfq_attrs
,
3202 .elevator_name
= "cfq",
3203 .elevator_owner
= THIS_MODULE
,
3206 static int __init
cfq_init(void)
3209 * could be 0 on HZ < 1000 setups
3211 if (!cfq_slice_async
)
3212 cfq_slice_async
= 1;
3213 if (!cfq_slice_idle
)
3216 if (cfq_slab_setup())
3219 elv_register(&iosched_cfq
);
3224 static void __exit
cfq_exit(void)
3226 DECLARE_COMPLETION_ONSTACK(all_gone
);
3227 elv_unregister(&iosched_cfq
);
3228 ioc_gone
= &all_gone
;
3229 /* ioc_gone's update must be visible before reading ioc_count */
3233 * this also protects us from entering cfq_slab_kill() with
3234 * pending RCU callbacks
3236 if (elv_ioc_count_read(cfq_ioc_count
))
3237 wait_for_completion(&all_gone
);
3241 module_init(cfq_init
);
3242 module_exit(cfq_exit
);
3244 MODULE_AUTHOR("Jens Axboe");
3245 MODULE_LICENSE("GPL");
3246 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");