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 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
308 if (cfq_class_idle(cfqq
))
309 return IDLE_WORKLOAD
;
310 if (cfq_class_rt(cfqq
))
316 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
318 if (!cfq_cfqq_sync(cfqq
))
319 return ASYNC_WORKLOAD
;
320 if (!cfq_cfqq_idle_window(cfqq
))
321 return SYNC_NOIDLE_WORKLOAD
;
322 return SYNC_WORKLOAD
;
325 static inline int cfq_busy_queues_wl(enum wl_prio_t wl
, struct cfq_data
*cfqd
)
327 struct cfq_group
*cfqg
= &cfqd
->root_group
;
329 if (wl
== IDLE_WORKLOAD
)
330 return cfqg
->service_tree_idle
.count
;
332 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
333 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
334 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
337 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
338 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
339 struct io_context
*, gfp_t
);
340 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
341 struct io_context
*);
343 static inline int rq_in_driver(struct cfq_data
*cfqd
)
345 return cfqd
->rq_in_driver
[0] + cfqd
->rq_in_driver
[1];
348 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
351 return cic
->cfqq
[is_sync
];
354 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
355 struct cfq_queue
*cfqq
, bool is_sync
)
357 cic
->cfqq
[is_sync
] = cfqq
;
361 * We regard a request as SYNC, if it's either a read or has the SYNC bit
362 * set (in which case it could also be direct WRITE).
364 static inline bool cfq_bio_sync(struct bio
*bio
)
366 return bio_data_dir(bio
) == READ
|| bio_rw_flagged(bio
, BIO_RW_SYNCIO
);
370 * scheduler run of queue, if there are requests pending and no one in the
371 * driver that will restart queueing
373 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
375 if (cfqd
->busy_queues
) {
376 cfq_log(cfqd
, "schedule dispatch");
377 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
381 static int cfq_queue_empty(struct request_queue
*q
)
383 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
385 return !cfqd
->busy_queues
;
389 * Scale schedule slice based on io priority. Use the sync time slice only
390 * if a queue is marked sync and has sync io queued. A sync queue with async
391 * io only, should not get full sync slice length.
393 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
396 const int base_slice
= cfqd
->cfq_slice
[sync
];
398 WARN_ON(prio
>= IOPRIO_BE_NR
);
400 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
404 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
406 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
410 * get averaged number of queues of RT/BE priority.
411 * average is updated, with a formula that gives more weight to higher numbers,
412 * to quickly follows sudden increases and decrease slowly
415 static inline unsigned cfq_get_avg_queues(struct cfq_data
*cfqd
, bool rt
)
417 unsigned min_q
, max_q
;
418 unsigned mult
= cfq_hist_divisor
- 1;
419 unsigned round
= cfq_hist_divisor
/ 2;
420 unsigned busy
= cfq_busy_queues_wl(rt
, cfqd
);
422 min_q
= min(cfqd
->busy_queues_avg
[rt
], busy
);
423 max_q
= max(cfqd
->busy_queues_avg
[rt
], busy
);
424 cfqd
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
426 return cfqd
->busy_queues_avg
[rt
];
430 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
432 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
433 if (cfqd
->cfq_latency
) {
434 /* interested queues (we consider only the ones with the same
436 unsigned iq
= cfq_get_avg_queues(cfqd
, cfq_class_rt(cfqq
));
437 unsigned sync_slice
= cfqd
->cfq_slice
[1];
438 unsigned expect_latency
= sync_slice
* iq
;
439 if (expect_latency
> cfq_target_latency
) {
440 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
441 /* scale low_slice according to IO priority
442 * and sync vs async */
444 min(slice
, base_low_slice
* slice
/ sync_slice
);
445 /* the adapted slice value is scaled to fit all iqs
446 * into the target latency */
447 slice
= max(slice
* cfq_target_latency
/ expect_latency
,
451 cfqq
->slice_end
= jiffies
+ slice
;
452 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
456 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
457 * isn't valid until the first request from the dispatch is activated
458 * and the slice time set.
460 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
462 if (cfq_cfqq_slice_new(cfqq
))
464 if (time_before(jiffies
, cfqq
->slice_end
))
471 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
472 * We choose the request that is closest to the head right now. Distance
473 * behind the head is penalized and only allowed to a certain extent.
475 static struct request
*
476 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
478 sector_t s1
, s2
, d1
= 0, d2
= 0;
479 unsigned long back_max
;
480 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
481 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
482 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
484 if (rq1
== NULL
|| rq1
== rq2
)
489 if (rq_is_sync(rq1
) && !rq_is_sync(rq2
))
491 else if (rq_is_sync(rq2
) && !rq_is_sync(rq1
))
493 if (rq_is_meta(rq1
) && !rq_is_meta(rq2
))
495 else if (rq_is_meta(rq2
) && !rq_is_meta(rq1
))
498 s1
= blk_rq_pos(rq1
);
499 s2
= blk_rq_pos(rq2
);
502 * by definition, 1KiB is 2 sectors
504 back_max
= cfqd
->cfq_back_max
* 2;
507 * Strict one way elevator _except_ in the case where we allow
508 * short backward seeks which are biased as twice the cost of a
509 * similar forward seek.
513 else if (s1
+ back_max
>= last
)
514 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
516 wrap
|= CFQ_RQ1_WRAP
;
520 else if (s2
+ back_max
>= last
)
521 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
523 wrap
|= CFQ_RQ2_WRAP
;
525 /* Found required data */
528 * By doing switch() on the bit mask "wrap" we avoid having to
529 * check two variables for all permutations: --> faster!
532 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
548 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
551 * Since both rqs are wrapped,
552 * start with the one that's further behind head
553 * (--> only *one* back seek required),
554 * since back seek takes more time than forward.
564 * The below is leftmost cache rbtree addon
566 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
569 root
->left
= rb_first(&root
->rb
);
572 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
577 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
583 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
587 rb_erase_init(n
, &root
->rb
);
592 * would be nice to take fifo expire time into account as well
594 static struct request
*
595 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
596 struct request
*last
)
598 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
599 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
600 struct request
*next
= NULL
, *prev
= NULL
;
602 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
605 prev
= rb_entry_rq(rbprev
);
608 next
= rb_entry_rq(rbnext
);
610 rbnext
= rb_first(&cfqq
->sort_list
);
611 if (rbnext
&& rbnext
!= &last
->rb_node
)
612 next
= rb_entry_rq(rbnext
);
615 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
618 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
619 struct cfq_queue
*cfqq
)
622 * just an approximation, should be ok.
624 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
625 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
629 * The cfqd->service_trees holds all pending cfq_queue's that have
630 * requests waiting to be processed. It is sorted in the order that
631 * we will service the queues.
633 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
636 struct rb_node
**p
, *parent
;
637 struct cfq_queue
*__cfqq
;
638 unsigned long rb_key
;
639 struct cfq_rb_root
*service_tree
;
642 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
643 cfqq_type(cfqq
), cfqd
);
644 if (cfq_class_idle(cfqq
)) {
645 rb_key
= CFQ_IDLE_DELAY
;
646 parent
= rb_last(&service_tree
->rb
);
647 if (parent
&& parent
!= &cfqq
->rb_node
) {
648 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
649 rb_key
+= __cfqq
->rb_key
;
652 } else if (!add_front
) {
654 * Get our rb key offset. Subtract any residual slice
655 * value carried from last service. A negative resid
656 * count indicates slice overrun, and this should position
657 * the next service time further away in the tree.
659 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
660 rb_key
-= cfqq
->slice_resid
;
661 cfqq
->slice_resid
= 0;
664 __cfqq
= cfq_rb_first(service_tree
);
665 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
668 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
670 * same position, nothing more to do
672 if (rb_key
== cfqq
->rb_key
&&
673 cfqq
->service_tree
== service_tree
)
676 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
677 cfqq
->service_tree
= NULL
;
682 cfqq
->service_tree
= service_tree
;
683 p
= &service_tree
->rb
.rb_node
;
688 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
691 * sort by key, that represents service time.
693 if (time_before(rb_key
, __cfqq
->rb_key
))
704 service_tree
->left
= &cfqq
->rb_node
;
706 cfqq
->rb_key
= rb_key
;
707 rb_link_node(&cfqq
->rb_node
, parent
, p
);
708 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
709 service_tree
->count
++;
712 static struct cfq_queue
*
713 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
714 sector_t sector
, struct rb_node
**ret_parent
,
715 struct rb_node
***rb_link
)
717 struct rb_node
**p
, *parent
;
718 struct cfq_queue
*cfqq
= NULL
;
726 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
729 * Sort strictly based on sector. Smallest to the left,
730 * largest to the right.
732 if (sector
> blk_rq_pos(cfqq
->next_rq
))
734 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
742 *ret_parent
= parent
;
748 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
750 struct rb_node
**p
, *parent
;
751 struct cfq_queue
*__cfqq
;
754 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
758 if (cfq_class_idle(cfqq
))
763 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
764 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
765 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
767 rb_link_node(&cfqq
->p_node
, parent
, p
);
768 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
774 * Update cfqq's position in the service tree.
776 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
779 * Resorting requires the cfqq to be on the RR list already.
781 if (cfq_cfqq_on_rr(cfqq
)) {
782 cfq_service_tree_add(cfqd
, cfqq
, 0);
783 cfq_prio_tree_add(cfqd
, cfqq
);
788 * add to busy list of queues for service, trying to be fair in ordering
789 * the pending list according to last request service
791 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
793 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
794 BUG_ON(cfq_cfqq_on_rr(cfqq
));
795 cfq_mark_cfqq_on_rr(cfqq
);
798 cfq_resort_rr_list(cfqd
, cfqq
);
802 * Called when the cfqq no longer has requests pending, remove it from
805 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
807 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
808 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
809 cfq_clear_cfqq_on_rr(cfqq
);
811 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
812 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
813 cfqq
->service_tree
= NULL
;
816 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
820 BUG_ON(!cfqd
->busy_queues
);
825 * rb tree support functions
827 static void cfq_del_rq_rb(struct request
*rq
)
829 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
830 struct cfq_data
*cfqd
= cfqq
->cfqd
;
831 const int sync
= rq_is_sync(rq
);
833 BUG_ON(!cfqq
->queued
[sync
]);
834 cfqq
->queued
[sync
]--;
836 elv_rb_del(&cfqq
->sort_list
, rq
);
838 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
839 cfq_del_cfqq_rr(cfqd
, cfqq
);
842 static void cfq_add_rq_rb(struct request
*rq
)
844 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
845 struct cfq_data
*cfqd
= cfqq
->cfqd
;
846 struct request
*__alias
, *prev
;
848 cfqq
->queued
[rq_is_sync(rq
)]++;
851 * looks a little odd, but the first insert might return an alias.
852 * if that happens, put the alias on the dispatch list
854 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
855 cfq_dispatch_insert(cfqd
->queue
, __alias
);
857 if (!cfq_cfqq_on_rr(cfqq
))
858 cfq_add_cfqq_rr(cfqd
, cfqq
);
861 * check if this request is a better next-serve candidate
863 prev
= cfqq
->next_rq
;
864 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
867 * adjust priority tree position, if ->next_rq changes
869 if (prev
!= cfqq
->next_rq
)
870 cfq_prio_tree_add(cfqd
, cfqq
);
872 BUG_ON(!cfqq
->next_rq
);
875 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
877 elv_rb_del(&cfqq
->sort_list
, rq
);
878 cfqq
->queued
[rq_is_sync(rq
)]--;
882 static struct request
*
883 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
885 struct task_struct
*tsk
= current
;
886 struct cfq_io_context
*cic
;
887 struct cfq_queue
*cfqq
;
889 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
893 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
895 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
897 return elv_rb_find(&cfqq
->sort_list
, sector
);
903 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
905 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
907 cfqd
->rq_in_driver
[rq_is_sync(rq
)]++;
908 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
911 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
914 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
916 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
917 const int sync
= rq_is_sync(rq
);
919 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
920 cfqd
->rq_in_driver
[sync
]--;
921 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
925 static void cfq_remove_request(struct request
*rq
)
927 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
929 if (cfqq
->next_rq
== rq
)
930 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
932 list_del_init(&rq
->queuelist
);
935 cfqq
->cfqd
->rq_queued
--;
936 if (rq_is_meta(rq
)) {
937 WARN_ON(!cfqq
->meta_pending
);
938 cfqq
->meta_pending
--;
942 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
945 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
946 struct request
*__rq
;
948 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
949 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
951 return ELEVATOR_FRONT_MERGE
;
954 return ELEVATOR_NO_MERGE
;
957 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
960 if (type
== ELEVATOR_FRONT_MERGE
) {
961 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
963 cfq_reposition_rq_rb(cfqq
, req
);
968 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
969 struct request
*next
)
971 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
973 * reposition in fifo if next is older than rq
975 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
976 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
977 list_move(&rq
->queuelist
, &next
->queuelist
);
978 rq_set_fifo_time(rq
, rq_fifo_time(next
));
981 if (cfqq
->next_rq
== next
)
983 cfq_remove_request(next
);
986 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
989 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
990 struct cfq_io_context
*cic
;
991 struct cfq_queue
*cfqq
;
994 * Disallow merge of a sync bio into an async request.
996 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1000 * Lookup the cfqq that this bio will be queued with. Allow
1001 * merge only if rq is queued there.
1003 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1007 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1008 return cfqq
== RQ_CFQQ(rq
);
1011 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1012 struct cfq_queue
*cfqq
)
1015 cfq_log_cfqq(cfqd
, cfqq
, "set_active");
1016 cfqq
->slice_end
= 0;
1017 cfqq
->slice_dispatch
= 0;
1019 cfq_clear_cfqq_wait_request(cfqq
);
1020 cfq_clear_cfqq_must_dispatch(cfqq
);
1021 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1022 cfq_clear_cfqq_fifo_expire(cfqq
);
1023 cfq_mark_cfqq_slice_new(cfqq
);
1025 del_timer(&cfqd
->idle_slice_timer
);
1028 cfqd
->active_queue
= cfqq
;
1032 * current cfqq expired its slice (or was too idle), select new one
1035 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1038 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1040 if (cfq_cfqq_wait_request(cfqq
))
1041 del_timer(&cfqd
->idle_slice_timer
);
1043 cfq_clear_cfqq_wait_request(cfqq
);
1046 * store what was left of this slice, if the queue idled/timed out
1048 if (timed_out
&& !cfq_cfqq_slice_new(cfqq
)) {
1049 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1050 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1053 cfq_resort_rr_list(cfqd
, cfqq
);
1055 if (cfqq
== cfqd
->active_queue
)
1056 cfqd
->active_queue
= NULL
;
1058 if (cfqd
->active_cic
) {
1059 put_io_context(cfqd
->active_cic
->ioc
);
1060 cfqd
->active_cic
= NULL
;
1064 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1066 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1069 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1073 * Get next queue for service. Unless we have a queue preemption,
1074 * we'll simply select the first cfqq in the service tree.
1076 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1078 struct cfq_rb_root
*service_tree
=
1079 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1080 cfqd
->serving_type
, cfqd
);
1082 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1084 return cfq_rb_first(service_tree
);
1088 * Get and set a new active queue for service.
1090 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1091 struct cfq_queue
*cfqq
)
1094 cfqq
= cfq_get_next_queue(cfqd
);
1096 __cfq_set_active_queue(cfqd
, cfqq
);
1100 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1103 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1104 return blk_rq_pos(rq
) - cfqd
->last_position
;
1106 return cfqd
->last_position
- blk_rq_pos(rq
);
1109 #define CFQQ_SEEK_THR 8 * 1024
1110 #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
1112 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1115 sector_t sdist
= cfqq
->seek_mean
;
1117 if (!sample_valid(cfqq
->seek_samples
))
1118 sdist
= CFQQ_SEEK_THR
;
1120 return cfq_dist_from_last(cfqd
, rq
) <= sdist
;
1123 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1124 struct cfq_queue
*cur_cfqq
)
1126 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1127 struct rb_node
*parent
, *node
;
1128 struct cfq_queue
*__cfqq
;
1129 sector_t sector
= cfqd
->last_position
;
1131 if (RB_EMPTY_ROOT(root
))
1135 * First, if we find a request starting at the end of the last
1136 * request, choose it.
1138 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1143 * If the exact sector wasn't found, the parent of the NULL leaf
1144 * will contain the closest sector.
1146 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1147 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1150 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1151 node
= rb_next(&__cfqq
->p_node
);
1153 node
= rb_prev(&__cfqq
->p_node
);
1157 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1158 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1166 * cur_cfqq - passed in so that we don't decide that the current queue is
1167 * closely cooperating with itself.
1169 * So, basically we're assuming that that cur_cfqq has dispatched at least
1170 * one request, and that cfqd->last_position reflects a position on the disk
1171 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1174 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1175 struct cfq_queue
*cur_cfqq
)
1177 struct cfq_queue
*cfqq
;
1179 if (!cfq_cfqq_sync(cur_cfqq
))
1181 if (CFQQ_SEEKY(cur_cfqq
))
1185 * We should notice if some of the queues are cooperating, eg
1186 * working closely on the same area of the disk. In that case,
1187 * we can group them together and don't waste time idling.
1189 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1194 * It only makes sense to merge sync queues.
1196 if (!cfq_cfqq_sync(cfqq
))
1198 if (CFQQ_SEEKY(cfqq
))
1202 * Do not merge queues of different priority classes
1204 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1211 * Determine whether we should enforce idle window for this queue.
1214 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1216 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1217 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1219 /* We never do for idle class queues. */
1220 if (prio
== IDLE_WORKLOAD
)
1223 /* We do for queues that were marked with idle window flag. */
1224 if (cfq_cfqq_idle_window(cfqq
))
1228 * Otherwise, we do only if they are the last ones
1229 * in their service tree.
1232 service_tree
= service_tree_for(cfqq
->cfqg
, prio
,
1233 cfqq_type(cfqq
), cfqd
);
1235 if (service_tree
->count
== 0)
1238 return (service_tree
->count
== 1 && cfq_rb_first(service_tree
) == cfqq
);
1241 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1243 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1244 struct cfq_io_context
*cic
;
1248 * SSD device without seek penalty, disable idling. But only do so
1249 * for devices that support queuing, otherwise we still have a problem
1250 * with sync vs async workloads.
1252 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1255 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1256 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1259 * idle is disabled, either manually or by past process history
1261 if (!cfqd
->cfq_slice_idle
|| !cfq_should_idle(cfqd
, cfqq
))
1265 * still active requests from this queue, don't idle
1267 if (cfqq
->dispatched
)
1271 * task has exited, don't wait
1273 cic
= cfqd
->active_cic
;
1274 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1278 * If our average think time is larger than the remaining time
1279 * slice, then don't idle. This avoids overrunning the allotted
1282 if (sample_valid(cic
->ttime_samples
) &&
1283 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
1286 cfq_mark_cfqq_wait_request(cfqq
);
1288 sl
= cfqd
->cfq_slice_idle
;
1290 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1291 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu", sl
);
1295 * Move request from internal lists to the request queue dispatch list.
1297 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1299 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1300 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1302 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1304 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1305 cfq_remove_request(rq
);
1307 elv_dispatch_sort(q
, rq
);
1309 if (cfq_cfqq_sync(cfqq
))
1310 cfqd
->sync_flight
++;
1314 * return expired entry, or NULL to just start from scratch in rbtree
1316 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1318 struct request
*rq
= NULL
;
1320 if (cfq_cfqq_fifo_expire(cfqq
))
1323 cfq_mark_cfqq_fifo_expire(cfqq
);
1325 if (list_empty(&cfqq
->fifo
))
1328 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
1329 if (time_before(jiffies
, rq_fifo_time(rq
)))
1332 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
1337 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1339 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1341 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
1343 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
1347 * Must be called with the queue_lock held.
1349 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
1351 int process_refs
, io_refs
;
1353 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
1354 process_refs
= atomic_read(&cfqq
->ref
) - io_refs
;
1355 BUG_ON(process_refs
< 0);
1356 return process_refs
;
1359 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
1361 int process_refs
, new_process_refs
;
1362 struct cfq_queue
*__cfqq
;
1364 /* Avoid a circular list and skip interim queue merges */
1365 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
1371 process_refs
= cfqq_process_refs(cfqq
);
1373 * If the process for the cfqq has gone away, there is no
1374 * sense in merging the queues.
1376 if (process_refs
== 0)
1380 * Merge in the direction of the lesser amount of work.
1382 new_process_refs
= cfqq_process_refs(new_cfqq
);
1383 if (new_process_refs
>= process_refs
) {
1384 cfqq
->new_cfqq
= new_cfqq
;
1385 atomic_add(process_refs
, &new_cfqq
->ref
);
1387 new_cfqq
->new_cfqq
= cfqq
;
1388 atomic_add(new_process_refs
, &cfqq
->ref
);
1392 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
1393 struct cfq_group
*cfqg
, enum wl_prio_t prio
,
1396 struct cfq_queue
*queue
;
1398 bool key_valid
= false;
1399 unsigned long lowest_key
= 0;
1400 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
1404 * When priorities switched, we prefer starting
1405 * from SYNC_NOIDLE (first choice), or just SYNC
1408 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1410 cur_best
= SYNC_WORKLOAD
;
1411 if (service_tree_for(cfqg
, prio
, cur_best
, cfqd
)->count
)
1414 return ASYNC_WORKLOAD
;
1417 for (i
= 0; i
< 3; ++i
) {
1418 /* otherwise, select the one with lowest rb_key */
1419 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
, cfqd
));
1421 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
1422 lowest_key
= queue
->rb_key
;
1431 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1433 enum wl_prio_t previous_prio
= cfqd
->serving_prio
;
1437 struct cfq_rb_root
*st
;
1439 /* Choose next priority. RT > BE > IDLE */
1440 if (cfq_busy_queues_wl(RT_WORKLOAD
, cfqd
))
1441 cfqd
->serving_prio
= RT_WORKLOAD
;
1442 else if (cfq_busy_queues_wl(BE_WORKLOAD
, cfqd
))
1443 cfqd
->serving_prio
= BE_WORKLOAD
;
1445 cfqd
->serving_prio
= IDLE_WORKLOAD
;
1446 cfqd
->workload_expires
= jiffies
+ 1;
1451 * For RT and BE, we have to choose also the type
1452 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
1455 prio_changed
= (cfqd
->serving_prio
!= previous_prio
);
1456 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
1461 * If priority didn't change, check workload expiration,
1462 * and that we still have other queues ready
1464 if (!prio_changed
&& count
&&
1465 !time_after(jiffies
, cfqd
->workload_expires
))
1468 /* otherwise select new workload type */
1469 cfqd
->serving_type
=
1470 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
, prio_changed
);
1471 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
,
1476 * the workload slice is computed as a fraction of target latency
1477 * proportional to the number of queues in that workload, over
1478 * all the queues in the same priority class
1480 slice
= cfq_target_latency
* count
/
1481 max_t(unsigned, cfqd
->busy_queues_avg
[cfqd
->serving_prio
],
1482 cfq_busy_queues_wl(cfqd
->serving_prio
, cfqd
));
1484 if (cfqd
->serving_type
== ASYNC_WORKLOAD
)
1485 /* async workload slice is scaled down according to
1486 * the sync/async slice ratio. */
1487 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
1489 /* sync workload slice is at least 2 * cfq_slice_idle */
1490 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
1492 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
1493 cfqd
->workload_expires
= jiffies
+ slice
;
1494 cfqd
->noidle_tree_requires_idle
= false;
1497 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
1499 cfqd
->serving_group
= &cfqd
->root_group
;
1500 choose_service_tree(cfqd
, &cfqd
->root_group
);
1504 * Select a queue for service. If we have a current active queue,
1505 * check whether to continue servicing it, or retrieve and set a new one.
1507 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
1509 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
1511 cfqq
= cfqd
->active_queue
;
1516 * The active queue has run out of time, expire it and select new.
1518 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
))
1522 * The active queue has requests and isn't expired, allow it to
1525 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
1529 * If another queue has a request waiting within our mean seek
1530 * distance, let it run. The expire code will check for close
1531 * cooperators and put the close queue at the front of the service
1532 * tree. If possible, merge the expiring queue with the new cfqq.
1534 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
1536 if (!cfqq
->new_cfqq
)
1537 cfq_setup_merge(cfqq
, new_cfqq
);
1542 * No requests pending. If the active queue still has requests in
1543 * flight or is idling for a new request, allow either of these
1544 * conditions to happen (or time out) before selecting a new queue.
1546 if (timer_pending(&cfqd
->idle_slice_timer
) ||
1547 (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
))) {
1553 cfq_slice_expired(cfqd
, 0);
1556 * Current queue expired. Check if we have to switch to a new
1560 cfq_choose_cfqg(cfqd
);
1562 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
1567 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
1571 while (cfqq
->next_rq
) {
1572 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
1576 BUG_ON(!list_empty(&cfqq
->fifo
));
1581 * Drain our current requests. Used for barriers and when switching
1582 * io schedulers on-the-fly.
1584 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
1586 struct cfq_queue
*cfqq
;
1589 struct cfq_group
*cfqg
= &cfqd
->root_group
;
1591 for (i
= 0; i
< 2; ++i
)
1592 for (j
= 0; j
< 3; ++j
)
1593 while ((cfqq
= cfq_rb_first(&cfqg
->service_trees
[i
][j
]))
1595 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
1597 while ((cfqq
= cfq_rb_first(&cfqg
->service_tree_idle
)) != NULL
)
1598 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
1600 cfq_slice_expired(cfqd
, 0);
1602 BUG_ON(cfqd
->busy_queues
);
1604 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
1608 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1610 unsigned int max_dispatch
;
1613 * Drain async requests before we start sync IO
1615 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_driver
[BLK_RW_ASYNC
])
1619 * If this is an async queue and we have sync IO in flight, let it wait
1621 if (cfqd
->sync_flight
&& !cfq_cfqq_sync(cfqq
))
1624 max_dispatch
= cfqd
->cfq_quantum
;
1625 if (cfq_class_idle(cfqq
))
1629 * Does this cfqq already have too much IO in flight?
1631 if (cfqq
->dispatched
>= max_dispatch
) {
1633 * idle queue must always only have a single IO in flight
1635 if (cfq_class_idle(cfqq
))
1639 * We have other queues, don't allow more IO from this one
1641 if (cfqd
->busy_queues
> 1)
1645 * Sole queue user, no limit
1651 * Async queues must wait a bit before being allowed dispatch.
1652 * We also ramp up the dispatch depth gradually for async IO,
1653 * based on the last sync IO we serviced
1655 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
1656 unsigned long last_sync
= jiffies
- cfqd
->last_end_sync_rq
;
1659 depth
= last_sync
/ cfqd
->cfq_slice
[1];
1660 if (!depth
&& !cfqq
->dispatched
)
1662 if (depth
< max_dispatch
)
1663 max_dispatch
= depth
;
1667 * If we're below the current max, allow a dispatch
1669 return cfqq
->dispatched
< max_dispatch
;
1673 * Dispatch a request from cfqq, moving them to the request queue
1676 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1680 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
1682 if (!cfq_may_dispatch(cfqd
, cfqq
))
1686 * follow expired path, else get first next available
1688 rq
= cfq_check_fifo(cfqq
);
1693 * insert request into driver dispatch list
1695 cfq_dispatch_insert(cfqd
->queue
, rq
);
1697 if (!cfqd
->active_cic
) {
1698 struct cfq_io_context
*cic
= RQ_CIC(rq
);
1700 atomic_long_inc(&cic
->ioc
->refcount
);
1701 cfqd
->active_cic
= cic
;
1708 * Find the cfqq that we need to service and move a request from that to the
1711 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
1713 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1714 struct cfq_queue
*cfqq
;
1716 if (!cfqd
->busy_queues
)
1719 if (unlikely(force
))
1720 return cfq_forced_dispatch(cfqd
);
1722 cfqq
= cfq_select_queue(cfqd
);
1727 * Dispatch a request from this cfqq, if it is allowed
1729 if (!cfq_dispatch_request(cfqd
, cfqq
))
1732 cfqq
->slice_dispatch
++;
1733 cfq_clear_cfqq_must_dispatch(cfqq
);
1736 * expire an async queue immediately if it has used up its slice. idle
1737 * queue always expire after 1 dispatch round.
1739 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
1740 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
1741 cfq_class_idle(cfqq
))) {
1742 cfqq
->slice_end
= jiffies
+ 1;
1743 cfq_slice_expired(cfqd
, 0);
1746 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
1751 * task holds one reference to the queue, dropped when task exits. each rq
1752 * in-flight on this queue also holds a reference, dropped when rq is freed.
1754 * queue lock must be held here.
1756 static void cfq_put_queue(struct cfq_queue
*cfqq
)
1758 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1760 BUG_ON(atomic_read(&cfqq
->ref
) <= 0);
1762 if (!atomic_dec_and_test(&cfqq
->ref
))
1765 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
1766 BUG_ON(rb_first(&cfqq
->sort_list
));
1767 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
1768 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1770 if (unlikely(cfqd
->active_queue
== cfqq
)) {
1771 __cfq_slice_expired(cfqd
, cfqq
, 0);
1772 cfq_schedule_dispatch(cfqd
);
1775 kmem_cache_free(cfq_pool
, cfqq
);
1779 * Must always be called with the rcu_read_lock() held
1782 __call_for_each_cic(struct io_context
*ioc
,
1783 void (*func
)(struct io_context
*, struct cfq_io_context
*))
1785 struct cfq_io_context
*cic
;
1786 struct hlist_node
*n
;
1788 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
1793 * Call func for each cic attached to this ioc.
1796 call_for_each_cic(struct io_context
*ioc
,
1797 void (*func
)(struct io_context
*, struct cfq_io_context
*))
1800 __call_for_each_cic(ioc
, func
);
1804 static void cfq_cic_free_rcu(struct rcu_head
*head
)
1806 struct cfq_io_context
*cic
;
1808 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
1810 kmem_cache_free(cfq_ioc_pool
, cic
);
1811 elv_ioc_count_dec(cfq_ioc_count
);
1815 * CFQ scheduler is exiting, grab exit lock and check
1816 * the pending io context count. If it hits zero,
1817 * complete ioc_gone and set it back to NULL
1819 spin_lock(&ioc_gone_lock
);
1820 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
1824 spin_unlock(&ioc_gone_lock
);
1828 static void cfq_cic_free(struct cfq_io_context
*cic
)
1830 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
1833 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
1835 unsigned long flags
;
1837 BUG_ON(!cic
->dead_key
);
1839 spin_lock_irqsave(&ioc
->lock
, flags
);
1840 radix_tree_delete(&ioc
->radix_root
, cic
->dead_key
);
1841 hlist_del_rcu(&cic
->cic_list
);
1842 spin_unlock_irqrestore(&ioc
->lock
, flags
);
1848 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1849 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1850 * and ->trim() which is called with the task lock held
1852 static void cfq_free_io_context(struct io_context
*ioc
)
1855 * ioc->refcount is zero here, or we are called from elv_unregister(),
1856 * so no more cic's are allowed to be linked into this ioc. So it
1857 * should be ok to iterate over the known list, we will see all cic's
1858 * since no new ones are added.
1860 __call_for_each_cic(ioc
, cic_free_func
);
1863 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1865 struct cfq_queue
*__cfqq
, *next
;
1867 if (unlikely(cfqq
== cfqd
->active_queue
)) {
1868 __cfq_slice_expired(cfqd
, cfqq
, 0);
1869 cfq_schedule_dispatch(cfqd
);
1873 * If this queue was scheduled to merge with another queue, be
1874 * sure to drop the reference taken on that queue (and others in
1875 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
1877 __cfqq
= cfqq
->new_cfqq
;
1879 if (__cfqq
== cfqq
) {
1880 WARN(1, "cfqq->new_cfqq loop detected\n");
1883 next
= __cfqq
->new_cfqq
;
1884 cfq_put_queue(__cfqq
);
1888 cfq_put_queue(cfqq
);
1891 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
1892 struct cfq_io_context
*cic
)
1894 struct io_context
*ioc
= cic
->ioc
;
1896 list_del_init(&cic
->queue_list
);
1899 * Make sure key == NULL is seen for dead queues
1902 cic
->dead_key
= (unsigned long) cic
->key
;
1905 if (ioc
->ioc_data
== cic
)
1906 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
1908 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
1909 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
1910 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
1913 if (cic
->cfqq
[BLK_RW_SYNC
]) {
1914 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
1915 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
1919 static void cfq_exit_single_io_context(struct io_context
*ioc
,
1920 struct cfq_io_context
*cic
)
1922 struct cfq_data
*cfqd
= cic
->key
;
1925 struct request_queue
*q
= cfqd
->queue
;
1926 unsigned long flags
;
1928 spin_lock_irqsave(q
->queue_lock
, flags
);
1931 * Ensure we get a fresh copy of the ->key to prevent
1932 * race between exiting task and queue
1934 smp_read_barrier_depends();
1936 __cfq_exit_single_io_context(cfqd
, cic
);
1938 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1943 * The process that ioc belongs to has exited, we need to clean up
1944 * and put the internal structures we have that belongs to that process.
1946 static void cfq_exit_io_context(struct io_context
*ioc
)
1948 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
1951 static struct cfq_io_context
*
1952 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
1954 struct cfq_io_context
*cic
;
1956 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
1959 cic
->last_end_request
= jiffies
;
1960 INIT_LIST_HEAD(&cic
->queue_list
);
1961 INIT_HLIST_NODE(&cic
->cic_list
);
1962 cic
->dtor
= cfq_free_io_context
;
1963 cic
->exit
= cfq_exit_io_context
;
1964 elv_ioc_count_inc(cfq_ioc_count
);
1970 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
1972 struct task_struct
*tsk
= current
;
1975 if (!cfq_cfqq_prio_changed(cfqq
))
1978 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
1979 switch (ioprio_class
) {
1981 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
1982 case IOPRIO_CLASS_NONE
:
1984 * no prio set, inherit CPU scheduling settings
1986 cfqq
->ioprio
= task_nice_ioprio(tsk
);
1987 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
1989 case IOPRIO_CLASS_RT
:
1990 cfqq
->ioprio
= task_ioprio(ioc
);
1991 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
1993 case IOPRIO_CLASS_BE
:
1994 cfqq
->ioprio
= task_ioprio(ioc
);
1995 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
1997 case IOPRIO_CLASS_IDLE
:
1998 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2000 cfq_clear_cfqq_idle_window(cfqq
);
2005 * keep track of original prio settings in case we have to temporarily
2006 * elevate the priority of this queue
2008 cfqq
->org_ioprio
= cfqq
->ioprio
;
2009 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2010 cfq_clear_cfqq_prio_changed(cfqq
);
2013 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2015 struct cfq_data
*cfqd
= cic
->key
;
2016 struct cfq_queue
*cfqq
;
2017 unsigned long flags
;
2019 if (unlikely(!cfqd
))
2022 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2024 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2026 struct cfq_queue
*new_cfqq
;
2027 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2030 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2031 cfq_put_queue(cfqq
);
2035 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2037 cfq_mark_cfqq_prio_changed(cfqq
);
2039 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2042 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2044 call_for_each_cic(ioc
, changed_ioprio
);
2045 ioc
->ioprio_changed
= 0;
2048 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2049 pid_t pid
, bool is_sync
)
2051 RB_CLEAR_NODE(&cfqq
->rb_node
);
2052 RB_CLEAR_NODE(&cfqq
->p_node
);
2053 INIT_LIST_HEAD(&cfqq
->fifo
);
2055 atomic_set(&cfqq
->ref
, 0);
2058 cfq_mark_cfqq_prio_changed(cfqq
);
2061 if (!cfq_class_idle(cfqq
))
2062 cfq_mark_cfqq_idle_window(cfqq
);
2063 cfq_mark_cfqq_sync(cfqq
);
2068 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
2073 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
2075 return &cfqd
->root_group
;
2078 static struct cfq_queue
*
2079 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2080 struct io_context
*ioc
, gfp_t gfp_mask
)
2082 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2083 struct cfq_io_context
*cic
;
2084 struct cfq_group
*cfqg
;
2087 cfqg
= cfq_get_cfqg(cfqd
, 1);
2088 cic
= cfq_cic_lookup(cfqd
, ioc
);
2089 /* cic always exists here */
2090 cfqq
= cic_to_cfqq(cic
, is_sync
);
2093 * Always try a new alloc if we fell back to the OOM cfqq
2094 * originally, since it should just be a temporary situation.
2096 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2101 } else if (gfp_mask
& __GFP_WAIT
) {
2102 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2103 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2104 gfp_mask
| __GFP_ZERO
,
2106 spin_lock_irq(cfqd
->queue
->queue_lock
);
2110 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2111 gfp_mask
| __GFP_ZERO
,
2116 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2117 cfq_init_prio_data(cfqq
, ioc
);
2118 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2119 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2121 cfqq
= &cfqd
->oom_cfqq
;
2125 kmem_cache_free(cfq_pool
, new_cfqq
);
2130 static struct cfq_queue
**
2131 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2133 switch (ioprio_class
) {
2134 case IOPRIO_CLASS_RT
:
2135 return &cfqd
->async_cfqq
[0][ioprio
];
2136 case IOPRIO_CLASS_BE
:
2137 return &cfqd
->async_cfqq
[1][ioprio
];
2138 case IOPRIO_CLASS_IDLE
:
2139 return &cfqd
->async_idle_cfqq
;
2145 static struct cfq_queue
*
2146 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2149 const int ioprio
= task_ioprio(ioc
);
2150 const int ioprio_class
= task_ioprio_class(ioc
);
2151 struct cfq_queue
**async_cfqq
= NULL
;
2152 struct cfq_queue
*cfqq
= NULL
;
2155 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2160 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2163 * pin the queue now that it's allocated, scheduler exit will prune it
2165 if (!is_sync
&& !(*async_cfqq
)) {
2166 atomic_inc(&cfqq
->ref
);
2170 atomic_inc(&cfqq
->ref
);
2175 * We drop cfq io contexts lazily, so we may find a dead one.
2178 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2179 struct cfq_io_context
*cic
)
2181 unsigned long flags
;
2183 WARN_ON(!list_empty(&cic
->queue_list
));
2185 spin_lock_irqsave(&ioc
->lock
, flags
);
2187 BUG_ON(ioc
->ioc_data
== cic
);
2189 radix_tree_delete(&ioc
->radix_root
, (unsigned long) cfqd
);
2190 hlist_del_rcu(&cic
->cic_list
);
2191 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2196 static struct cfq_io_context
*
2197 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
2199 struct cfq_io_context
*cic
;
2200 unsigned long flags
;
2209 * we maintain a last-hit cache, to avoid browsing over the tree
2211 cic
= rcu_dereference(ioc
->ioc_data
);
2212 if (cic
&& cic
->key
== cfqd
) {
2218 cic
= radix_tree_lookup(&ioc
->radix_root
, (unsigned long) cfqd
);
2222 /* ->key must be copied to avoid race with cfq_exit_queue() */
2225 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
2230 spin_lock_irqsave(&ioc
->lock
, flags
);
2231 rcu_assign_pointer(ioc
->ioc_data
, cic
);
2232 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2240 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2241 * the process specific cfq io context when entered from the block layer.
2242 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2244 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2245 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
2247 unsigned long flags
;
2250 ret
= radix_tree_preload(gfp_mask
);
2255 spin_lock_irqsave(&ioc
->lock
, flags
);
2256 ret
= radix_tree_insert(&ioc
->radix_root
,
2257 (unsigned long) cfqd
, cic
);
2259 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
2260 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2262 radix_tree_preload_end();
2265 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2266 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
2267 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2272 printk(KERN_ERR
"cfq: cic link failed!\n");
2278 * Setup general io context and cfq io context. There can be several cfq
2279 * io contexts per general io context, if this process is doing io to more
2280 * than one device managed by cfq.
2282 static struct cfq_io_context
*
2283 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2285 struct io_context
*ioc
= NULL
;
2286 struct cfq_io_context
*cic
;
2288 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2290 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
2294 cic
= cfq_cic_lookup(cfqd
, ioc
);
2298 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
2302 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
2306 smp_read_barrier_depends();
2307 if (unlikely(ioc
->ioprio_changed
))
2308 cfq_ioc_set_ioprio(ioc
);
2314 put_io_context(ioc
);
2319 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
2321 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
2322 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
2324 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
2325 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
2326 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
2330 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2336 if (!cfqq
->last_request_pos
)
2338 else if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
2339 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
2341 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
2344 * Don't allow the seek distance to get too large from the
2345 * odd fragment, pagein, etc
2347 if (cfqq
->seek_samples
<= 60) /* second&third seek */
2348 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*1024);
2350 sdist
= min(sdist
, (cfqq
->seek_mean
* 4) + 2*1024*64);
2352 cfqq
->seek_samples
= (7*cfqq
->seek_samples
+ 256) / 8;
2353 cfqq
->seek_total
= (7*cfqq
->seek_total
+ (u64
)256*sdist
) / 8;
2354 total
= cfqq
->seek_total
+ (cfqq
->seek_samples
/2);
2355 do_div(total
, cfqq
->seek_samples
);
2356 cfqq
->seek_mean
= (sector_t
)total
;
2359 * If this cfqq is shared between multiple processes, check to
2360 * make sure that those processes are still issuing I/Os within
2361 * the mean seek distance. If not, it may be time to break the
2362 * queues apart again.
2364 if (cfq_cfqq_coop(cfqq
)) {
2365 if (CFQQ_SEEKY(cfqq
) && !cfqq
->seeky_start
)
2366 cfqq
->seeky_start
= jiffies
;
2367 else if (!CFQQ_SEEKY(cfqq
))
2368 cfqq
->seeky_start
= 0;
2373 * Disable idle window if the process thinks too long or seeks so much that
2377 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2378 struct cfq_io_context
*cic
)
2380 int old_idle
, enable_idle
;
2383 * Don't idle for async or idle io prio class
2385 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
2388 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
2390 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
2391 cfq_mark_cfqq_deep(cfqq
);
2393 if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
2394 (!cfq_cfqq_deep(cfqq
) && sample_valid(cfqq
->seek_samples
)
2395 && CFQQ_SEEKY(cfqq
)))
2397 else if (sample_valid(cic
->ttime_samples
)) {
2398 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
2404 if (old_idle
!= enable_idle
) {
2405 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
2407 cfq_mark_cfqq_idle_window(cfqq
);
2409 cfq_clear_cfqq_idle_window(cfqq
);
2414 * Check if new_cfqq should preempt the currently active queue. Return 0 for
2415 * no or if we aren't sure, a 1 will cause a preempt.
2418 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
2421 struct cfq_queue
*cfqq
;
2423 cfqq
= cfqd
->active_queue
;
2427 if (cfq_slice_used(cfqq
))
2430 if (cfq_class_idle(new_cfqq
))
2433 if (cfq_class_idle(cfqq
))
2436 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
2437 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
2438 new_cfqq
->service_tree
->count
== 1)
2442 * if the new request is sync, but the currently running queue is
2443 * not, let the sync request have priority.
2445 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
2449 * So both queues are sync. Let the new request get disk time if
2450 * it's a metadata request and the current queue is doing regular IO.
2452 if (rq_is_meta(rq
) && !cfqq
->meta_pending
)
2456 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2458 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
2461 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
2465 * if this request is as-good as one we would expect from the
2466 * current cfqq, let it preempt
2468 if (cfq_rq_close(cfqd
, cfqq
, rq
))
2475 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2476 * let it have half of its nominal slice.
2478 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2480 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
2481 cfq_slice_expired(cfqd
, 1);
2484 * Put the new queue at the front of the of the current list,
2485 * so we know that it will be selected next.
2487 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
2489 cfq_service_tree_add(cfqd
, cfqq
, 1);
2491 cfqq
->slice_end
= 0;
2492 cfq_mark_cfqq_slice_new(cfqq
);
2496 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2497 * something we should do about it
2500 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2503 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2507 cfqq
->meta_pending
++;
2509 cfq_update_io_thinktime(cfqd
, cic
);
2510 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
2511 cfq_update_idle_window(cfqd
, cfqq
, cic
);
2513 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
2515 if (cfqq
== cfqd
->active_queue
) {
2517 * Remember that we saw a request from this process, but
2518 * don't start queuing just yet. Otherwise we risk seeing lots
2519 * of tiny requests, because we disrupt the normal plugging
2520 * and merging. If the request is already larger than a single
2521 * page, let it rip immediately. For that case we assume that
2522 * merging is already done. Ditto for a busy system that
2523 * has other work pending, don't risk delaying until the
2524 * idle timer unplug to continue working.
2526 if (cfq_cfqq_wait_request(cfqq
)) {
2527 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
2528 cfqd
->busy_queues
> 1) {
2529 del_timer(&cfqd
->idle_slice_timer
);
2530 __blk_run_queue(cfqd
->queue
);
2532 cfq_mark_cfqq_must_dispatch(cfqq
);
2534 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
2536 * not the active queue - expire current slice if it is
2537 * idle and has expired it's mean thinktime or this new queue
2538 * has some old slice time left and is of higher priority or
2539 * this new queue is RT and the current one is BE
2541 cfq_preempt_queue(cfqd
, cfqq
);
2542 __blk_run_queue(cfqd
->queue
);
2546 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
2548 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2549 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2551 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
2552 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
2554 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
2555 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
2558 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
2562 * Update hw_tag based on peak queue depth over 50 samples under
2565 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
2567 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2569 if (rq_in_driver(cfqd
) > cfqd
->hw_tag_est_depth
)
2570 cfqd
->hw_tag_est_depth
= rq_in_driver(cfqd
);
2572 if (cfqd
->hw_tag
== 1)
2575 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
2576 rq_in_driver(cfqd
) <= CFQ_HW_QUEUE_MIN
)
2580 * If active queue hasn't enough requests and can idle, cfq might not
2581 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
2584 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
2585 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
2586 CFQ_HW_QUEUE_MIN
&& rq_in_driver(cfqd
) < CFQ_HW_QUEUE_MIN
)
2589 if (cfqd
->hw_tag_samples
++ < 50)
2592 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
2598 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
2600 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2601 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2602 const int sync
= rq_is_sync(rq
);
2606 cfq_log_cfqq(cfqd
, cfqq
, "complete");
2608 cfq_update_hw_tag(cfqd
);
2610 WARN_ON(!cfqd
->rq_in_driver
[sync
]);
2611 WARN_ON(!cfqq
->dispatched
);
2612 cfqd
->rq_in_driver
[sync
]--;
2615 if (cfq_cfqq_sync(cfqq
))
2616 cfqd
->sync_flight
--;
2619 RQ_CIC(rq
)->last_end_request
= now
;
2620 cfqd
->last_end_sync_rq
= now
;
2624 * If this is the active queue, check if it needs to be expired,
2625 * or if we want to idle in case it has no pending requests.
2627 if (cfqd
->active_queue
== cfqq
) {
2628 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
2630 if (cfq_cfqq_slice_new(cfqq
)) {
2631 cfq_set_prio_slice(cfqd
, cfqq
);
2632 cfq_clear_cfqq_slice_new(cfqq
);
2635 * Idling is not enabled on:
2637 * - idle-priority queues
2639 * - queues with still some requests queued
2640 * - when there is a close cooperator
2642 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
2643 cfq_slice_expired(cfqd
, 1);
2644 else if (sync
&& cfqq_empty
&&
2645 !cfq_close_cooperator(cfqd
, cfqq
)) {
2646 cfqd
->noidle_tree_requires_idle
|= !rq_noidle(rq
);
2648 * Idling is enabled for SYNC_WORKLOAD.
2649 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
2650 * only if we processed at least one !rq_noidle request
2652 if (cfqd
->serving_type
== SYNC_WORKLOAD
2653 || cfqd
->noidle_tree_requires_idle
)
2654 cfq_arm_slice_timer(cfqd
);
2658 if (!rq_in_driver(cfqd
))
2659 cfq_schedule_dispatch(cfqd
);
2663 * we temporarily boost lower priority queues if they are holding fs exclusive
2664 * resources. they are boosted to normal prio (CLASS_BE/4)
2666 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
2668 if (has_fs_excl()) {
2670 * boost idle prio on transactions that would lock out other
2671 * users of the filesystem
2673 if (cfq_class_idle(cfqq
))
2674 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2675 if (cfqq
->ioprio
> IOPRIO_NORM
)
2676 cfqq
->ioprio
= IOPRIO_NORM
;
2679 * unboost the queue (if needed)
2681 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
2682 cfqq
->ioprio
= cfqq
->org_ioprio
;
2686 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
2688 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
2689 cfq_mark_cfqq_must_alloc_slice(cfqq
);
2690 return ELV_MQUEUE_MUST
;
2693 return ELV_MQUEUE_MAY
;
2696 static int cfq_may_queue(struct request_queue
*q
, int rw
)
2698 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2699 struct task_struct
*tsk
= current
;
2700 struct cfq_io_context
*cic
;
2701 struct cfq_queue
*cfqq
;
2704 * don't force setup of a queue from here, as a call to may_queue
2705 * does not necessarily imply that a request actually will be queued.
2706 * so just lookup a possibly existing queue, or return 'may queue'
2709 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
2711 return ELV_MQUEUE_MAY
;
2713 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
2715 cfq_init_prio_data(cfqq
, cic
->ioc
);
2716 cfq_prio_boost(cfqq
);
2718 return __cfq_may_queue(cfqq
);
2721 return ELV_MQUEUE_MAY
;
2725 * queue lock held here
2727 static void cfq_put_request(struct request
*rq
)
2729 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2732 const int rw
= rq_data_dir(rq
);
2734 BUG_ON(!cfqq
->allocated
[rw
]);
2735 cfqq
->allocated
[rw
]--;
2737 put_io_context(RQ_CIC(rq
)->ioc
);
2739 rq
->elevator_private
= NULL
;
2740 rq
->elevator_private2
= NULL
;
2742 cfq_put_queue(cfqq
);
2746 static struct cfq_queue
*
2747 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
2748 struct cfq_queue
*cfqq
)
2750 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
2751 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
2752 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
2753 cfq_put_queue(cfqq
);
2754 return cic_to_cfqq(cic
, 1);
2757 static int should_split_cfqq(struct cfq_queue
*cfqq
)
2759 if (cfqq
->seeky_start
&&
2760 time_after(jiffies
, cfqq
->seeky_start
+ CFQQ_COOP_TOUT
))
2766 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
2767 * was the last process referring to said cfqq.
2769 static struct cfq_queue
*
2770 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
2772 if (cfqq_process_refs(cfqq
) == 1) {
2773 cfqq
->seeky_start
= 0;
2774 cfqq
->pid
= current
->pid
;
2775 cfq_clear_cfqq_coop(cfqq
);
2779 cic_set_cfqq(cic
, NULL
, 1);
2780 cfq_put_queue(cfqq
);
2784 * Allocate cfq data structures associated with this request.
2787 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
2789 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2790 struct cfq_io_context
*cic
;
2791 const int rw
= rq_data_dir(rq
);
2792 const bool is_sync
= rq_is_sync(rq
);
2793 struct cfq_queue
*cfqq
;
2794 unsigned long flags
;
2796 might_sleep_if(gfp_mask
& __GFP_WAIT
);
2798 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
2800 spin_lock_irqsave(q
->queue_lock
, flags
);
2806 cfqq
= cic_to_cfqq(cic
, is_sync
);
2807 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2808 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
2809 cic_set_cfqq(cic
, cfqq
, is_sync
);
2812 * If the queue was seeky for too long, break it apart.
2814 if (cfq_cfqq_coop(cfqq
) && should_split_cfqq(cfqq
)) {
2815 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
2816 cfqq
= split_cfqq(cic
, cfqq
);
2822 * Check to see if this queue is scheduled to merge with
2823 * another, closely cooperating queue. The merging of
2824 * queues happens here as it must be done in process context.
2825 * The reference on new_cfqq was taken in merge_cfqqs.
2828 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
2831 cfqq
->allocated
[rw
]++;
2832 atomic_inc(&cfqq
->ref
);
2834 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2836 rq
->elevator_private
= cic
;
2837 rq
->elevator_private2
= cfqq
;
2842 put_io_context(cic
->ioc
);
2844 cfq_schedule_dispatch(cfqd
);
2845 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2846 cfq_log(cfqd
, "set_request fail");
2850 static void cfq_kick_queue(struct work_struct
*work
)
2852 struct cfq_data
*cfqd
=
2853 container_of(work
, struct cfq_data
, unplug_work
);
2854 struct request_queue
*q
= cfqd
->queue
;
2856 spin_lock_irq(q
->queue_lock
);
2857 __blk_run_queue(cfqd
->queue
);
2858 spin_unlock_irq(q
->queue_lock
);
2862 * Timer running if the active_queue is currently idling inside its time slice
2864 static void cfq_idle_slice_timer(unsigned long data
)
2866 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
2867 struct cfq_queue
*cfqq
;
2868 unsigned long flags
;
2871 cfq_log(cfqd
, "idle timer fired");
2873 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2875 cfqq
= cfqd
->active_queue
;
2880 * We saw a request before the queue expired, let it through
2882 if (cfq_cfqq_must_dispatch(cfqq
))
2888 if (cfq_slice_used(cfqq
))
2892 * only expire and reinvoke request handler, if there are
2893 * other queues with pending requests
2895 if (!cfqd
->busy_queues
)
2899 * not expired and it has a request pending, let it dispatch
2901 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2905 * Queue depth flag is reset only when the idle didn't succeed
2907 cfq_clear_cfqq_deep(cfqq
);
2910 cfq_slice_expired(cfqd
, timed_out
);
2912 cfq_schedule_dispatch(cfqd
);
2914 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2917 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
2919 del_timer_sync(&cfqd
->idle_slice_timer
);
2920 cancel_work_sync(&cfqd
->unplug_work
);
2923 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
2927 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
2928 if (cfqd
->async_cfqq
[0][i
])
2929 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
2930 if (cfqd
->async_cfqq
[1][i
])
2931 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
2934 if (cfqd
->async_idle_cfqq
)
2935 cfq_put_queue(cfqd
->async_idle_cfqq
);
2938 static void cfq_exit_queue(struct elevator_queue
*e
)
2940 struct cfq_data
*cfqd
= e
->elevator_data
;
2941 struct request_queue
*q
= cfqd
->queue
;
2943 cfq_shutdown_timer_wq(cfqd
);
2945 spin_lock_irq(q
->queue_lock
);
2947 if (cfqd
->active_queue
)
2948 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
2950 while (!list_empty(&cfqd
->cic_list
)) {
2951 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
2952 struct cfq_io_context
,
2955 __cfq_exit_single_io_context(cfqd
, cic
);
2958 cfq_put_async_queues(cfqd
);
2960 spin_unlock_irq(q
->queue_lock
);
2962 cfq_shutdown_timer_wq(cfqd
);
2967 static void *cfq_init_queue(struct request_queue
*q
)
2969 struct cfq_data
*cfqd
;
2971 struct cfq_group
*cfqg
;
2973 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
2977 /* Init root group */
2978 cfqg
= &cfqd
->root_group
;
2980 for (i
= 0; i
< 2; ++i
)
2981 for (j
= 0; j
< 3; ++j
)
2982 cfqg
->service_trees
[i
][j
] = CFQ_RB_ROOT
;
2983 cfqg
->service_tree_idle
= CFQ_RB_ROOT
;
2986 * Not strictly needed (since RB_ROOT just clears the node and we
2987 * zeroed cfqd on alloc), but better be safe in case someone decides
2988 * to add magic to the rb code
2990 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
2991 cfqd
->prio_trees
[i
] = RB_ROOT
;
2994 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
2995 * Grab a permanent reference to it, so that the normal code flow
2996 * will not attempt to free it.
2998 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
2999 atomic_inc(&cfqd
->oom_cfqq
.ref
);
3000 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3002 INIT_LIST_HEAD(&cfqd
->cic_list
);
3006 init_timer(&cfqd
->idle_slice_timer
);
3007 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3008 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3010 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3012 cfqd
->cfq_quantum
= cfq_quantum
;
3013 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3014 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3015 cfqd
->cfq_back_max
= cfq_back_max
;
3016 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3017 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3018 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3019 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3020 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3021 cfqd
->cfq_latency
= 1;
3023 cfqd
->last_end_sync_rq
= jiffies
;
3027 static void cfq_slab_kill(void)
3030 * Caller already ensured that pending RCU callbacks are completed,
3031 * so we should have no busy allocations at this point.
3034 kmem_cache_destroy(cfq_pool
);
3036 kmem_cache_destroy(cfq_ioc_pool
);
3039 static int __init
cfq_slab_setup(void)
3041 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3045 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3056 * sysfs parts below -->
3059 cfq_var_show(unsigned int var
, char *page
)
3061 return sprintf(page
, "%d\n", var
);
3065 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3067 char *p
= (char *) page
;
3069 *var
= simple_strtoul(p
, &p
, 10);
3073 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3074 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3076 struct cfq_data *cfqd = e->elevator_data; \
3077 unsigned int __data = __VAR; \
3079 __data = jiffies_to_msecs(__data); \
3080 return cfq_var_show(__data, (page)); \
3082 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3083 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3084 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3085 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3086 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3087 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3088 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
3089 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
3090 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
3091 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
3092 #undef SHOW_FUNCTION
3094 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3095 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3097 struct cfq_data *cfqd = e->elevator_data; \
3098 unsigned int __data; \
3099 int ret = cfq_var_store(&__data, (page), count); \
3100 if (__data < (MIN)) \
3102 else if (__data > (MAX)) \
3105 *(__PTR) = msecs_to_jiffies(__data); \
3107 *(__PTR) = __data; \
3110 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
3111 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
3113 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
3115 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
3116 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
3118 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
3119 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
3120 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
3121 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
3123 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
3124 #undef STORE_FUNCTION
3126 #define CFQ_ATTR(name) \
3127 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3129 static struct elv_fs_entry cfq_attrs
[] = {
3131 CFQ_ATTR(fifo_expire_sync
),
3132 CFQ_ATTR(fifo_expire_async
),
3133 CFQ_ATTR(back_seek_max
),
3134 CFQ_ATTR(back_seek_penalty
),
3135 CFQ_ATTR(slice_sync
),
3136 CFQ_ATTR(slice_async
),
3137 CFQ_ATTR(slice_async_rq
),
3138 CFQ_ATTR(slice_idle
),
3139 CFQ_ATTR(low_latency
),
3143 static struct elevator_type iosched_cfq
= {
3145 .elevator_merge_fn
= cfq_merge
,
3146 .elevator_merged_fn
= cfq_merged_request
,
3147 .elevator_merge_req_fn
= cfq_merged_requests
,
3148 .elevator_allow_merge_fn
= cfq_allow_merge
,
3149 .elevator_dispatch_fn
= cfq_dispatch_requests
,
3150 .elevator_add_req_fn
= cfq_insert_request
,
3151 .elevator_activate_req_fn
= cfq_activate_request
,
3152 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
3153 .elevator_queue_empty_fn
= cfq_queue_empty
,
3154 .elevator_completed_req_fn
= cfq_completed_request
,
3155 .elevator_former_req_fn
= elv_rb_former_request
,
3156 .elevator_latter_req_fn
= elv_rb_latter_request
,
3157 .elevator_set_req_fn
= cfq_set_request
,
3158 .elevator_put_req_fn
= cfq_put_request
,
3159 .elevator_may_queue_fn
= cfq_may_queue
,
3160 .elevator_init_fn
= cfq_init_queue
,
3161 .elevator_exit_fn
= cfq_exit_queue
,
3162 .trim
= cfq_free_io_context
,
3164 .elevator_attrs
= cfq_attrs
,
3165 .elevator_name
= "cfq",
3166 .elevator_owner
= THIS_MODULE
,
3169 static int __init
cfq_init(void)
3172 * could be 0 on HZ < 1000 setups
3174 if (!cfq_slice_async
)
3175 cfq_slice_async
= 1;
3176 if (!cfq_slice_idle
)
3179 if (cfq_slab_setup())
3182 elv_register(&iosched_cfq
);
3187 static void __exit
cfq_exit(void)
3189 DECLARE_COMPLETION_ONSTACK(all_gone
);
3190 elv_unregister(&iosched_cfq
);
3191 ioc_gone
= &all_gone
;
3192 /* ioc_gone's update must be visible before reading ioc_count */
3196 * this also protects us from entering cfq_slab_kill() with
3197 * pending RCU callbacks
3199 if (elv_ioc_count_read(cfq_ioc_count
))
3200 wait_for_completion(&all_gone
);
3204 module_init(cfq_init
);
3205 module_exit(cfq_exit
);
3207 MODULE_AUTHOR("Jens Axboe");
3208 MODULE_LICENSE("GPL");
3209 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");