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/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
23 /* max queue in one round of service */
24 static const int cfq_quantum
= 8;
25 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
26 /* maximum backwards seek, in KiB */
27 static const int cfq_back_max
= 16 * 1024;
28 /* penalty of a backwards seek */
29 static const int cfq_back_penalty
= 2;
30 static const int cfq_slice_sync
= HZ
/ 10;
31 static int cfq_slice_async
= HZ
/ 25;
32 static const int cfq_slice_async_rq
= 2;
33 static int cfq_slice_idle
= HZ
/ 125;
34 static int cfq_group_idle
= HZ
/ 125;
35 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
36 static const int cfq_hist_divisor
= 4;
39 * offset from end of service tree
41 #define CFQ_IDLE_DELAY (HZ / 5)
44 * below this threshold, we consider thinktime immediate
46 #define CFQ_MIN_TT (2)
48 #define CFQ_SLICE_SCALE (5)
49 #define CFQ_HW_QUEUE_MIN (5)
50 #define CFQ_SERVICE_SHIFT 12
52 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
53 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
54 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
55 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
61 static struct kmem_cache
*cfq_pool
;
63 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
64 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
65 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
67 #define sample_valid(samples) ((samples) > 80)
68 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
71 unsigned long last_end_request
;
73 unsigned long ttime_total
;
74 unsigned long ttime_samples
;
75 unsigned long ttime_mean
;
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
88 unsigned total_weight
;
90 struct cfq_ttime ttime
;
92 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
93 .ttime = {.last_end_request = jiffies,},}
96 * Per process-grouping structure
101 /* various state flags, see below */
103 /* parent cfq_data */
104 struct cfq_data
*cfqd
;
105 /* service_tree member */
106 struct rb_node rb_node
;
107 /* service_tree key */
108 unsigned long rb_key
;
109 /* prio tree member */
110 struct rb_node p_node
;
111 /* prio tree root we belong to, if any */
112 struct rb_root
*p_root
;
113 /* sorted list of pending requests */
114 struct rb_root sort_list
;
115 /* if fifo isn't expired, next request to serve */
116 struct request
*next_rq
;
117 /* requests queued in sort_list */
119 /* currently allocated requests */
121 /* fifo list of requests in sort_list */
122 struct list_head fifo
;
124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start
;
126 unsigned int allocated_slice
;
127 unsigned int slice_dispatch
;
128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start
;
130 unsigned long slice_end
;
133 /* pending priority requests */
135 /* number of requests that are on the dispatch list or inside driver */
138 /* io prio of this group */
139 unsigned short ioprio
, org_ioprio
;
140 unsigned short ioprio_class
;
145 sector_t last_request_pos
;
147 struct cfq_rb_root
*service_tree
;
148 struct cfq_queue
*new_cfqq
;
149 struct cfq_group
*cfqg
;
150 /* Number of sectors dispatched from queue in single dispatch round */
151 unsigned long nr_sectors
;
155 * First index in the service_trees.
156 * IDLE is handled separately, so it has negative index
166 * Second index in the service_trees.
170 SYNC_NOIDLE_WORKLOAD
= 1,
174 /* This is per cgroup per device grouping structure */
176 /* group service_tree member */
177 struct rb_node rb_node
;
179 /* group service_tree key */
182 unsigned int new_weight
;
185 /* number of cfqq currently on this group */
189 * Per group busy queues average. Useful for workload slice calc. We
190 * create the array for each prio class but at run time it is used
191 * only for RT and BE class and slot for IDLE class remains unused.
192 * This is primarily done to avoid confusion and a gcc warning.
194 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
196 * rr lists of queues with requests. We maintain service trees for
197 * RT and BE classes. These trees are subdivided in subclasses
198 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
199 * class there is no subclassification and all the cfq queues go on
200 * a single tree service_tree_idle.
201 * Counts are embedded in the cfq_rb_root
203 struct cfq_rb_root service_trees
[2][3];
204 struct cfq_rb_root service_tree_idle
;
206 unsigned long saved_workload_slice
;
207 enum wl_type_t saved_workload
;
208 enum wl_prio_t saved_serving_prio
;
209 struct blkio_group blkg
;
210 #ifdef CONFIG_CFQ_GROUP_IOSCHED
211 struct hlist_node cfqd_node
;
214 /* number of requests that are on the dispatch list or inside driver */
216 struct cfq_ttime ttime
;
220 struct io_cq icq
; /* must be the first member */
221 struct cfq_queue
*cfqq
[2];
222 struct cfq_ttime ttime
;
226 * Per block device queue structure
229 struct request_queue
*queue
;
230 /* Root service tree for cfq_groups */
231 struct cfq_rb_root grp_service_tree
;
232 struct cfq_group root_group
;
235 * The priority currently being served
237 enum wl_prio_t serving_prio
;
238 enum wl_type_t serving_type
;
239 unsigned long workload_expires
;
240 struct cfq_group
*serving_group
;
243 * Each priority tree is sorted by next_request position. These
244 * trees are used when determining if two or more queues are
245 * interleaving requests (see cfq_close_cooperator).
247 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
249 unsigned int busy_queues
;
250 unsigned int busy_sync_queues
;
256 * queue-depth detection
262 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
263 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
266 int hw_tag_est_depth
;
267 unsigned int hw_tag_samples
;
270 * idle window management
272 struct timer_list idle_slice_timer
;
273 struct work_struct unplug_work
;
275 struct cfq_queue
*active_queue
;
276 struct cfq_io_cq
*active_cic
;
279 * async queue for each priority case
281 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
282 struct cfq_queue
*async_idle_cfqq
;
284 sector_t last_position
;
287 * tunables, see top of file
289 unsigned int cfq_quantum
;
290 unsigned int cfq_fifo_expire
[2];
291 unsigned int cfq_back_penalty
;
292 unsigned int cfq_back_max
;
293 unsigned int cfq_slice
[2];
294 unsigned int cfq_slice_async_rq
;
295 unsigned int cfq_slice_idle
;
296 unsigned int cfq_group_idle
;
297 unsigned int cfq_latency
;
300 * Fallback dummy cfqq for extreme OOM conditions
302 struct cfq_queue oom_cfqq
;
304 unsigned long last_delayed_sync
;
306 /* List of cfq groups being managed on this device*/
307 struct hlist_head cfqg_list
;
309 /* Number of groups which are on blkcg->blkg_list */
310 unsigned int nr_blkcg_linked_grps
;
313 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
315 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
322 if (prio
== IDLE_WORKLOAD
)
323 return &cfqg
->service_tree_idle
;
325 return &cfqg
->service_trees
[prio
][type
];
328 enum cfqq_state_flags
{
329 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
330 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
331 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
332 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
333 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
334 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
335 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
336 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
337 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
338 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
339 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
340 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
341 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
344 #define CFQ_CFQQ_FNS(name) \
345 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
347 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
349 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
351 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
353 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
355 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
359 CFQ_CFQQ_FNS(wait_request
);
360 CFQ_CFQQ_FNS(must_dispatch
);
361 CFQ_CFQQ_FNS(must_alloc_slice
);
362 CFQ_CFQQ_FNS(fifo_expire
);
363 CFQ_CFQQ_FNS(idle_window
);
364 CFQ_CFQQ_FNS(prio_changed
);
365 CFQ_CFQQ_FNS(slice_new
);
368 CFQ_CFQQ_FNS(split_coop
);
370 CFQ_CFQQ_FNS(wait_busy
);
373 #ifdef CONFIG_CFQ_GROUP_IOSCHED
374 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
375 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
376 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
377 blkg_path(&(cfqq)->cfqg->blkg), ##args)
379 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
380 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
381 blkg_path(&(cfqg)->blkg), ##args) \
384 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
385 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
386 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
388 #define cfq_log(cfqd, fmt, args...) \
389 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
391 /* Traverses through cfq group service trees */
392 #define for_each_cfqg_st(cfqg, i, j, st) \
393 for (i = 0; i <= IDLE_WORKLOAD; i++) \
394 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
395 : &cfqg->service_tree_idle; \
396 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
397 (i == IDLE_WORKLOAD && j == 0); \
398 j++, st = i < IDLE_WORKLOAD ? \
399 &cfqg->service_trees[i][j]: NULL) \
401 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
402 struct cfq_ttime
*ttime
, bool group_idle
)
405 if (!sample_valid(ttime
->ttime_samples
))
408 slice
= cfqd
->cfq_group_idle
;
410 slice
= cfqd
->cfq_slice_idle
;
411 return ttime
->ttime_mean
> slice
;
414 static inline bool iops_mode(struct cfq_data
*cfqd
)
417 * If we are not idling on queues and it is a NCQ drive, parallel
418 * execution of requests is on and measuring time is not possible
419 * in most of the cases until and unless we drive shallower queue
420 * depths and that becomes a performance bottleneck. In such cases
421 * switch to start providing fairness in terms of number of IOs.
423 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
429 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
431 if (cfq_class_idle(cfqq
))
432 return IDLE_WORKLOAD
;
433 if (cfq_class_rt(cfqq
))
439 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
441 if (!cfq_cfqq_sync(cfqq
))
442 return ASYNC_WORKLOAD
;
443 if (!cfq_cfqq_idle_window(cfqq
))
444 return SYNC_NOIDLE_WORKLOAD
;
445 return SYNC_WORKLOAD
;
448 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
449 struct cfq_data
*cfqd
,
450 struct cfq_group
*cfqg
)
452 if (wl
== IDLE_WORKLOAD
)
453 return cfqg
->service_tree_idle
.count
;
455 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
456 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
457 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
460 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
461 struct cfq_group
*cfqg
)
463 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
464 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
467 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
468 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
469 struct io_context
*, gfp_t
);
471 static inline struct cfq_io_cq
*icq_to_cic(struct io_cq
*icq
)
473 /* cic->icq is the first member, %NULL will convert to %NULL */
474 return container_of(icq
, struct cfq_io_cq
, icq
);
477 static inline struct cfq_io_cq
*cfq_cic_lookup(struct cfq_data
*cfqd
,
478 struct io_context
*ioc
)
481 return icq_to_cic(ioc_lookup_icq(ioc
, cfqd
->queue
));
485 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_cq
*cic
, bool is_sync
)
487 return cic
->cfqq
[is_sync
];
490 static inline void cic_set_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
,
493 cic
->cfqq
[is_sync
] = cfqq
;
496 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_cq
*cic
)
498 return cic
->icq
.q
->elevator
->elevator_data
;
502 * We regard a request as SYNC, if it's either a read or has the SYNC bit
503 * set (in which case it could also be direct WRITE).
505 static inline bool cfq_bio_sync(struct bio
*bio
)
507 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
511 * scheduler run of queue, if there are requests pending and no one in the
512 * driver that will restart queueing
514 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
516 if (cfqd
->busy_queues
) {
517 cfq_log(cfqd
, "schedule dispatch");
518 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
523 * Scale schedule slice based on io priority. Use the sync time slice only
524 * if a queue is marked sync and has sync io queued. A sync queue with async
525 * io only, should not get full sync slice length.
527 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
530 const int base_slice
= cfqd
->cfq_slice
[sync
];
532 WARN_ON(prio
>= IOPRIO_BE_NR
);
534 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
538 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
540 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
543 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
545 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
547 d
= d
* BLKIO_WEIGHT_DEFAULT
;
548 do_div(d
, cfqg
->weight
);
552 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
554 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
556 min_vdisktime
= vdisktime
;
558 return min_vdisktime
;
561 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
563 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
565 min_vdisktime
= vdisktime
;
567 return min_vdisktime
;
570 static void update_min_vdisktime(struct cfq_rb_root
*st
)
572 struct cfq_group
*cfqg
;
575 cfqg
= rb_entry_cfqg(st
->left
);
576 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
582 * get averaged number of queues of RT/BE priority.
583 * average is updated, with a formula that gives more weight to higher numbers,
584 * to quickly follows sudden increases and decrease slowly
587 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
588 struct cfq_group
*cfqg
, bool rt
)
590 unsigned min_q
, max_q
;
591 unsigned mult
= cfq_hist_divisor
- 1;
592 unsigned round
= cfq_hist_divisor
/ 2;
593 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
595 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
596 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
597 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
599 return cfqg
->busy_queues_avg
[rt
];
602 static inline unsigned
603 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
605 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
607 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
610 static inline unsigned
611 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
613 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
614 if (cfqd
->cfq_latency
) {
616 * interested queues (we consider only the ones with the same
617 * priority class in the cfq group)
619 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
621 unsigned sync_slice
= cfqd
->cfq_slice
[1];
622 unsigned expect_latency
= sync_slice
* iq
;
623 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
625 if (expect_latency
> group_slice
) {
626 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
627 /* scale low_slice according to IO priority
628 * and sync vs async */
630 min(slice
, base_low_slice
* slice
/ sync_slice
);
631 /* the adapted slice value is scaled to fit all iqs
632 * into the target latency */
633 slice
= max(slice
* group_slice
/ expect_latency
,
641 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
643 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
645 cfqq
->slice_start
= jiffies
;
646 cfqq
->slice_end
= jiffies
+ slice
;
647 cfqq
->allocated_slice
= slice
;
648 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
652 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
653 * isn't valid until the first request from the dispatch is activated
654 * and the slice time set.
656 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
658 if (cfq_cfqq_slice_new(cfqq
))
660 if (time_before(jiffies
, cfqq
->slice_end
))
667 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
668 * We choose the request that is closest to the head right now. Distance
669 * behind the head is penalized and only allowed to a certain extent.
671 static struct request
*
672 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
674 sector_t s1
, s2
, d1
= 0, d2
= 0;
675 unsigned long back_max
;
676 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
677 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
678 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
680 if (rq1
== NULL
|| rq1
== rq2
)
685 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
686 return rq_is_sync(rq1
) ? rq1
: rq2
;
688 if ((rq1
->cmd_flags
^ rq2
->cmd_flags
) & REQ_PRIO
)
689 return rq1
->cmd_flags
& REQ_PRIO
? rq1
: rq2
;
691 s1
= blk_rq_pos(rq1
);
692 s2
= blk_rq_pos(rq2
);
695 * by definition, 1KiB is 2 sectors
697 back_max
= cfqd
->cfq_back_max
* 2;
700 * Strict one way elevator _except_ in the case where we allow
701 * short backward seeks which are biased as twice the cost of a
702 * similar forward seek.
706 else if (s1
+ back_max
>= last
)
707 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
709 wrap
|= CFQ_RQ1_WRAP
;
713 else if (s2
+ back_max
>= last
)
714 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
716 wrap
|= CFQ_RQ2_WRAP
;
718 /* Found required data */
721 * By doing switch() on the bit mask "wrap" we avoid having to
722 * check two variables for all permutations: --> faster!
725 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
741 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
744 * Since both rqs are wrapped,
745 * start with the one that's further behind head
746 * (--> only *one* back seek required),
747 * since back seek takes more time than forward.
757 * The below is leftmost cache rbtree addon
759 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
761 /* Service tree is empty */
766 root
->left
= rb_first(&root
->rb
);
769 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
774 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
777 root
->left
= rb_first(&root
->rb
);
780 return rb_entry_cfqg(root
->left
);
785 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
791 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
795 rb_erase_init(n
, &root
->rb
);
800 * would be nice to take fifo expire time into account as well
802 static struct request
*
803 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
804 struct request
*last
)
806 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
807 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
808 struct request
*next
= NULL
, *prev
= NULL
;
810 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
813 prev
= rb_entry_rq(rbprev
);
816 next
= rb_entry_rq(rbnext
);
818 rbnext
= rb_first(&cfqq
->sort_list
);
819 if (rbnext
&& rbnext
!= &last
->rb_node
)
820 next
= rb_entry_rq(rbnext
);
823 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
826 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
827 struct cfq_queue
*cfqq
)
830 * just an approximation, should be ok.
832 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
833 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
837 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
839 return cfqg
->vdisktime
- st
->min_vdisktime
;
843 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
845 struct rb_node
**node
= &st
->rb
.rb_node
;
846 struct rb_node
*parent
= NULL
;
847 struct cfq_group
*__cfqg
;
848 s64 key
= cfqg_key(st
, cfqg
);
851 while (*node
!= NULL
) {
853 __cfqg
= rb_entry_cfqg(parent
);
855 if (key
< cfqg_key(st
, __cfqg
))
856 node
= &parent
->rb_left
;
858 node
= &parent
->rb_right
;
864 st
->left
= &cfqg
->rb_node
;
866 rb_link_node(&cfqg
->rb_node
, parent
, node
);
867 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
871 cfq_update_group_weight(struct cfq_group
*cfqg
)
873 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
874 if (cfqg
->needs_update
) {
875 cfqg
->weight
= cfqg
->new_weight
;
876 cfqg
->needs_update
= false;
881 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
883 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
885 cfq_update_group_weight(cfqg
);
886 __cfq_group_service_tree_add(st
, cfqg
);
887 st
->total_weight
+= cfqg
->weight
;
891 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
893 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
894 struct cfq_group
*__cfqg
;
898 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
902 * Currently put the group at the end. Later implement something
903 * so that groups get lesser vtime based on their weights, so that
904 * if group does not loose all if it was not continuously backlogged.
906 n
= rb_last(&st
->rb
);
908 __cfqg
= rb_entry_cfqg(n
);
909 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
911 cfqg
->vdisktime
= st
->min_vdisktime
;
912 cfq_group_service_tree_add(st
, cfqg
);
916 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
918 st
->total_weight
-= cfqg
->weight
;
919 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
920 cfq_rb_erase(&cfqg
->rb_node
, st
);
924 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
926 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
928 BUG_ON(cfqg
->nr_cfqq
< 1);
931 /* If there are other cfq queues under this group, don't delete it */
935 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
936 cfq_group_service_tree_del(st
, cfqg
);
937 cfqg
->saved_workload_slice
= 0;
938 cfq_blkiocg_update_dequeue_stats(&cfqg
->blkg
, 1);
941 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
942 unsigned int *unaccounted_time
)
944 unsigned int slice_used
;
947 * Queue got expired before even a single request completed or
948 * got expired immediately after first request completion.
950 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
952 * Also charge the seek time incurred to the group, otherwise
953 * if there are mutiple queues in the group, each can dispatch
954 * a single request on seeky media and cause lots of seek time
955 * and group will never know it.
957 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
960 slice_used
= jiffies
- cfqq
->slice_start
;
961 if (slice_used
> cfqq
->allocated_slice
) {
962 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
963 slice_used
= cfqq
->allocated_slice
;
965 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
966 *unaccounted_time
+= cfqq
->slice_start
-
967 cfqq
->dispatch_start
;
973 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
974 struct cfq_queue
*cfqq
)
976 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
977 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
978 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
979 - cfqg
->service_tree_idle
.count
;
982 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
985 charge
= cfqq
->slice_dispatch
;
986 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
987 charge
= cfqq
->allocated_slice
;
989 /* Can't update vdisktime while group is on service tree */
990 cfq_group_service_tree_del(st
, cfqg
);
991 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
992 /* If a new weight was requested, update now, off tree */
993 cfq_group_service_tree_add(st
, cfqg
);
995 /* This group is being expired. Save the context */
996 if (time_after(cfqd
->workload_expires
, jiffies
)) {
997 cfqg
->saved_workload_slice
= cfqd
->workload_expires
999 cfqg
->saved_workload
= cfqd
->serving_type
;
1000 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
1002 cfqg
->saved_workload_slice
= 0;
1004 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
1006 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
1007 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1008 used_sl
, cfqq
->slice_dispatch
, charge
,
1009 iops_mode(cfqd
), cfqq
->nr_sectors
);
1010 cfq_blkiocg_update_timeslice_used(&cfqg
->blkg
, used_sl
,
1012 cfq_blkiocg_set_start_empty_time(&cfqg
->blkg
);
1015 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1016 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
1019 return container_of(blkg
, struct cfq_group
, blkg
);
1023 static void cfq_update_blkio_group_weight(void *key
, struct blkio_group
*blkg
,
1024 unsigned int weight
)
1026 struct cfq_group
*cfqg
= cfqg_of_blkg(blkg
);
1027 cfqg
->new_weight
= weight
;
1028 cfqg
->needs_update
= true;
1031 static void cfq_init_add_cfqg_lists(struct cfq_data
*cfqd
,
1032 struct cfq_group
*cfqg
, struct blkio_cgroup
*blkcg
)
1034 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1035 unsigned int major
, minor
;
1038 * Add group onto cgroup list. It might happen that bdi->dev is
1039 * not initialized yet. Initialize this new group without major
1040 * and minor info and this info will be filled in once a new thread
1044 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1045 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1046 (void *)cfqd
, MKDEV(major
, minor
));
1048 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1051 cfqd
->nr_blkcg_linked_grps
++;
1052 cfqg
->weight
= blkcg_get_weight(blkcg
, cfqg
->blkg
.dev
);
1054 /* Add group on cfqd list */
1055 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
1059 * Should be called from sleepable context. No request queue lock as per
1060 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1061 * from sleepable context.
1063 static struct cfq_group
* cfq_alloc_cfqg(struct cfq_data
*cfqd
)
1065 struct cfq_group
*cfqg
= NULL
;
1067 struct cfq_rb_root
*st
;
1069 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
1073 for_each_cfqg_st(cfqg
, i
, j
, st
)
1075 RB_CLEAR_NODE(&cfqg
->rb_node
);
1077 cfqg
->ttime
.last_end_request
= jiffies
;
1080 * Take the initial reference that will be released on destroy
1081 * This can be thought of a joint reference by cgroup and
1082 * elevator which will be dropped by either elevator exit
1083 * or cgroup deletion path depending on who is exiting first.
1087 ret
= blkio_alloc_blkg_stats(&cfqg
->blkg
);
1096 static struct cfq_group
*
1097 cfq_find_cfqg(struct cfq_data
*cfqd
, struct blkio_cgroup
*blkcg
)
1099 struct cfq_group
*cfqg
= NULL
;
1101 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1102 unsigned int major
, minor
;
1105 * This is the common case when there are no blkio cgroups.
1106 * Avoid lookup in this case
1108 if (blkcg
== &blkio_root_cgroup
)
1109 cfqg
= &cfqd
->root_group
;
1111 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
1113 if (cfqg
&& !cfqg
->blkg
.dev
&& bdi
->dev
&& dev_name(bdi
->dev
)) {
1114 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1115 cfqg
->blkg
.dev
= MKDEV(major
, minor
);
1122 * Search for the cfq group current task belongs to. request_queue lock must
1125 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1127 struct blkio_cgroup
*blkcg
;
1128 struct cfq_group
*cfqg
= NULL
, *__cfqg
= NULL
;
1129 struct request_queue
*q
= cfqd
->queue
;
1132 blkcg
= task_blkio_cgroup(current
);
1133 cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1140 * Need to allocate a group. Allocation of group also needs allocation
1141 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1142 * we need to drop rcu lock and queue_lock before we call alloc.
1144 * Not taking any queue reference here and assuming that queue is
1145 * around by the time we return. CFQ queue allocation code does
1146 * the same. It might be racy though.
1150 spin_unlock_irq(q
->queue_lock
);
1152 cfqg
= cfq_alloc_cfqg(cfqd
);
1154 spin_lock_irq(q
->queue_lock
);
1157 blkcg
= task_blkio_cgroup(current
);
1160 * If some other thread already allocated the group while we were
1161 * not holding queue lock, free up the group
1163 __cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1172 cfqg
= &cfqd
->root_group
;
1174 cfq_init_add_cfqg_lists(cfqd
, cfqg
, blkcg
);
1179 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1185 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1187 /* Currently, all async queues are mapped to root group */
1188 if (!cfq_cfqq_sync(cfqq
))
1189 cfqg
= &cfqq
->cfqd
->root_group
;
1192 /* cfqq reference on cfqg */
1196 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1198 struct cfq_rb_root
*st
;
1201 BUG_ON(cfqg
->ref
<= 0);
1205 for_each_cfqg_st(cfqg
, i
, j
, st
)
1206 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
));
1207 free_percpu(cfqg
->blkg
.stats_cpu
);
1211 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1213 /* Something wrong if we are trying to remove same group twice */
1214 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1216 hlist_del_init(&cfqg
->cfqd_node
);
1218 BUG_ON(cfqd
->nr_blkcg_linked_grps
<= 0);
1219 cfqd
->nr_blkcg_linked_grps
--;
1222 * Put the reference taken at the time of creation so that when all
1223 * queues are gone, group can be destroyed.
1228 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1230 struct hlist_node
*pos
, *n
;
1231 struct cfq_group
*cfqg
;
1233 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1235 * If cgroup removal path got to blk_group first and removed
1236 * it from cgroup list, then it will take care of destroying
1239 if (!cfq_blkiocg_del_blkio_group(&cfqg
->blkg
))
1240 cfq_destroy_cfqg(cfqd
, cfqg
);
1245 * Blk cgroup controller notification saying that blkio_group object is being
1246 * delinked as associated cgroup object is going away. That also means that
1247 * no new IO will come in this group. So get rid of this group as soon as
1248 * any pending IO in the group is finished.
1250 * This function is called under rcu_read_lock(). key is the rcu protected
1251 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1254 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1255 * it should not be NULL as even if elevator was exiting, cgroup deltion
1256 * path got to it first.
1258 static void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1260 unsigned long flags
;
1261 struct cfq_data
*cfqd
= key
;
1263 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1264 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1265 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1268 #else /* GROUP_IOSCHED */
1269 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1271 return &cfqd
->root_group
;
1274 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1280 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1284 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1285 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1287 #endif /* GROUP_IOSCHED */
1290 * The cfqd->service_trees holds all pending cfq_queue's that have
1291 * requests waiting to be processed. It is sorted in the order that
1292 * we will service the queues.
1294 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1297 struct rb_node
**p
, *parent
;
1298 struct cfq_queue
*__cfqq
;
1299 unsigned long rb_key
;
1300 struct cfq_rb_root
*service_tree
;
1304 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1306 if (cfq_class_idle(cfqq
)) {
1307 rb_key
= CFQ_IDLE_DELAY
;
1308 parent
= rb_last(&service_tree
->rb
);
1309 if (parent
&& parent
!= &cfqq
->rb_node
) {
1310 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1311 rb_key
+= __cfqq
->rb_key
;
1314 } else if (!add_front
) {
1316 * Get our rb key offset. Subtract any residual slice
1317 * value carried from last service. A negative resid
1318 * count indicates slice overrun, and this should position
1319 * the next service time further away in the tree.
1321 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1322 rb_key
-= cfqq
->slice_resid
;
1323 cfqq
->slice_resid
= 0;
1326 __cfqq
= cfq_rb_first(service_tree
);
1327 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1330 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1333 * same position, nothing more to do
1335 if (rb_key
== cfqq
->rb_key
&&
1336 cfqq
->service_tree
== service_tree
)
1339 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1340 cfqq
->service_tree
= NULL
;
1345 cfqq
->service_tree
= service_tree
;
1346 p
= &service_tree
->rb
.rb_node
;
1351 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1354 * sort by key, that represents service time.
1356 if (time_before(rb_key
, __cfqq
->rb_key
))
1359 n
= &(*p
)->rb_right
;
1367 service_tree
->left
= &cfqq
->rb_node
;
1369 cfqq
->rb_key
= rb_key
;
1370 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1371 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1372 service_tree
->count
++;
1373 if (add_front
|| !new_cfqq
)
1375 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
1378 static struct cfq_queue
*
1379 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1380 sector_t sector
, struct rb_node
**ret_parent
,
1381 struct rb_node
***rb_link
)
1383 struct rb_node
**p
, *parent
;
1384 struct cfq_queue
*cfqq
= NULL
;
1392 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1395 * Sort strictly based on sector. Smallest to the left,
1396 * largest to the right.
1398 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1399 n
= &(*p
)->rb_right
;
1400 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1408 *ret_parent
= parent
;
1414 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1416 struct rb_node
**p
, *parent
;
1417 struct cfq_queue
*__cfqq
;
1420 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1421 cfqq
->p_root
= NULL
;
1424 if (cfq_class_idle(cfqq
))
1429 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1430 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1431 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1433 rb_link_node(&cfqq
->p_node
, parent
, p
);
1434 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1436 cfqq
->p_root
= NULL
;
1440 * Update cfqq's position in the service tree.
1442 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1445 * Resorting requires the cfqq to be on the RR list already.
1447 if (cfq_cfqq_on_rr(cfqq
)) {
1448 cfq_service_tree_add(cfqd
, cfqq
, 0);
1449 cfq_prio_tree_add(cfqd
, cfqq
);
1454 * add to busy list of queues for service, trying to be fair in ordering
1455 * the pending list according to last request service
1457 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1459 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1460 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1461 cfq_mark_cfqq_on_rr(cfqq
);
1462 cfqd
->busy_queues
++;
1463 if (cfq_cfqq_sync(cfqq
))
1464 cfqd
->busy_sync_queues
++;
1466 cfq_resort_rr_list(cfqd
, cfqq
);
1470 * Called when the cfqq no longer has requests pending, remove it from
1473 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1475 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1476 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1477 cfq_clear_cfqq_on_rr(cfqq
);
1479 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1480 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1481 cfqq
->service_tree
= NULL
;
1484 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1485 cfqq
->p_root
= NULL
;
1488 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
1489 BUG_ON(!cfqd
->busy_queues
);
1490 cfqd
->busy_queues
--;
1491 if (cfq_cfqq_sync(cfqq
))
1492 cfqd
->busy_sync_queues
--;
1496 * rb tree support functions
1498 static void cfq_del_rq_rb(struct request
*rq
)
1500 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1501 const int sync
= rq_is_sync(rq
);
1503 BUG_ON(!cfqq
->queued
[sync
]);
1504 cfqq
->queued
[sync
]--;
1506 elv_rb_del(&cfqq
->sort_list
, rq
);
1508 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1510 * Queue will be deleted from service tree when we actually
1511 * expire it later. Right now just remove it from prio tree
1515 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1516 cfqq
->p_root
= NULL
;
1521 static void cfq_add_rq_rb(struct request
*rq
)
1523 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1524 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1525 struct request
*prev
;
1527 cfqq
->queued
[rq_is_sync(rq
)]++;
1529 elv_rb_add(&cfqq
->sort_list
, rq
);
1531 if (!cfq_cfqq_on_rr(cfqq
))
1532 cfq_add_cfqq_rr(cfqd
, cfqq
);
1535 * check if this request is a better next-serve candidate
1537 prev
= cfqq
->next_rq
;
1538 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1541 * adjust priority tree position, if ->next_rq changes
1543 if (prev
!= cfqq
->next_rq
)
1544 cfq_prio_tree_add(cfqd
, cfqq
);
1546 BUG_ON(!cfqq
->next_rq
);
1549 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1551 elv_rb_del(&cfqq
->sort_list
, rq
);
1552 cfqq
->queued
[rq_is_sync(rq
)]--;
1553 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1554 rq_data_dir(rq
), rq_is_sync(rq
));
1556 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
1557 &cfqq
->cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
1561 static struct request
*
1562 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1564 struct task_struct
*tsk
= current
;
1565 struct cfq_io_cq
*cic
;
1566 struct cfq_queue
*cfqq
;
1568 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1572 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1574 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1576 return elv_rb_find(&cfqq
->sort_list
, sector
);
1582 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1584 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1586 cfqd
->rq_in_driver
++;
1587 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1588 cfqd
->rq_in_driver
);
1590 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1593 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1595 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1597 WARN_ON(!cfqd
->rq_in_driver
);
1598 cfqd
->rq_in_driver
--;
1599 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1600 cfqd
->rq_in_driver
);
1603 static void cfq_remove_request(struct request
*rq
)
1605 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1607 if (cfqq
->next_rq
== rq
)
1608 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1610 list_del_init(&rq
->queuelist
);
1613 cfqq
->cfqd
->rq_queued
--;
1614 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1615 rq_data_dir(rq
), rq_is_sync(rq
));
1616 if (rq
->cmd_flags
& REQ_PRIO
) {
1617 WARN_ON(!cfqq
->prio_pending
);
1618 cfqq
->prio_pending
--;
1622 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1625 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1626 struct request
*__rq
;
1628 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1629 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1631 return ELEVATOR_FRONT_MERGE
;
1634 return ELEVATOR_NO_MERGE
;
1637 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1640 if (type
== ELEVATOR_FRONT_MERGE
) {
1641 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1643 cfq_reposition_rq_rb(cfqq
, req
);
1647 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1650 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req
))->blkg
,
1651 bio_data_dir(bio
), cfq_bio_sync(bio
));
1655 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1656 struct request
*next
)
1658 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1659 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1662 * reposition in fifo if next is older than rq
1664 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1665 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1666 list_move(&rq
->queuelist
, &next
->queuelist
);
1667 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1670 if (cfqq
->next_rq
== next
)
1672 cfq_remove_request(next
);
1673 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq
))->blkg
,
1674 rq_data_dir(next
), rq_is_sync(next
));
1676 cfqq
= RQ_CFQQ(next
);
1678 * all requests of this queue are merged to other queues, delete it
1679 * from the service tree. If it's the active_queue,
1680 * cfq_dispatch_requests() will choose to expire it or do idle
1682 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
) &&
1683 cfqq
!= cfqd
->active_queue
)
1684 cfq_del_cfqq_rr(cfqd
, cfqq
);
1687 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1690 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1691 struct cfq_io_cq
*cic
;
1692 struct cfq_queue
*cfqq
;
1695 * Disallow merge of a sync bio into an async request.
1697 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1701 * Lookup the cfqq that this bio will be queued with and allow
1702 * merge only if rq is queued there.
1704 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1708 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1709 return cfqq
== RQ_CFQQ(rq
);
1712 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1714 del_timer(&cfqd
->idle_slice_timer
);
1715 cfq_blkiocg_update_idle_time_stats(&cfqq
->cfqg
->blkg
);
1718 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1719 struct cfq_queue
*cfqq
)
1722 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
1723 cfqd
->serving_prio
, cfqd
->serving_type
);
1724 cfq_blkiocg_update_avg_queue_size_stats(&cfqq
->cfqg
->blkg
);
1725 cfqq
->slice_start
= 0;
1726 cfqq
->dispatch_start
= jiffies
;
1727 cfqq
->allocated_slice
= 0;
1728 cfqq
->slice_end
= 0;
1729 cfqq
->slice_dispatch
= 0;
1730 cfqq
->nr_sectors
= 0;
1732 cfq_clear_cfqq_wait_request(cfqq
);
1733 cfq_clear_cfqq_must_dispatch(cfqq
);
1734 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1735 cfq_clear_cfqq_fifo_expire(cfqq
);
1736 cfq_mark_cfqq_slice_new(cfqq
);
1738 cfq_del_timer(cfqd
, cfqq
);
1741 cfqd
->active_queue
= cfqq
;
1745 * current cfqq expired its slice (or was too idle), select new one
1748 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1751 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1753 if (cfq_cfqq_wait_request(cfqq
))
1754 cfq_del_timer(cfqd
, cfqq
);
1756 cfq_clear_cfqq_wait_request(cfqq
);
1757 cfq_clear_cfqq_wait_busy(cfqq
);
1760 * If this cfqq is shared between multiple processes, check to
1761 * make sure that those processes are still issuing I/Os within
1762 * the mean seek distance. If not, it may be time to break the
1763 * queues apart again.
1765 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
1766 cfq_mark_cfqq_split_coop(cfqq
);
1769 * store what was left of this slice, if the queue idled/timed out
1772 if (cfq_cfqq_slice_new(cfqq
))
1773 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
1775 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1776 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1779 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1781 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1782 cfq_del_cfqq_rr(cfqd
, cfqq
);
1784 cfq_resort_rr_list(cfqd
, cfqq
);
1786 if (cfqq
== cfqd
->active_queue
)
1787 cfqd
->active_queue
= NULL
;
1789 if (cfqd
->active_cic
) {
1790 put_io_context(cfqd
->active_cic
->icq
.ioc
);
1791 cfqd
->active_cic
= NULL
;
1795 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1797 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1800 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1804 * Get next queue for service. Unless we have a queue preemption,
1805 * we'll simply select the first cfqq in the service tree.
1807 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1809 struct cfq_rb_root
*service_tree
=
1810 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1811 cfqd
->serving_type
);
1813 if (!cfqd
->rq_queued
)
1816 /* There is nothing to dispatch */
1819 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1821 return cfq_rb_first(service_tree
);
1824 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1826 struct cfq_group
*cfqg
;
1827 struct cfq_queue
*cfqq
;
1829 struct cfq_rb_root
*st
;
1831 if (!cfqd
->rq_queued
)
1834 cfqg
= cfq_get_next_cfqg(cfqd
);
1838 for_each_cfqg_st(cfqg
, i
, j
, st
)
1839 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1845 * Get and set a new active queue for service.
1847 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1848 struct cfq_queue
*cfqq
)
1851 cfqq
= cfq_get_next_queue(cfqd
);
1853 __cfq_set_active_queue(cfqd
, cfqq
);
1857 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1860 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1861 return blk_rq_pos(rq
) - cfqd
->last_position
;
1863 return cfqd
->last_position
- blk_rq_pos(rq
);
1866 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1869 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
1872 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1873 struct cfq_queue
*cur_cfqq
)
1875 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1876 struct rb_node
*parent
, *node
;
1877 struct cfq_queue
*__cfqq
;
1878 sector_t sector
= cfqd
->last_position
;
1880 if (RB_EMPTY_ROOT(root
))
1884 * First, if we find a request starting at the end of the last
1885 * request, choose it.
1887 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1892 * If the exact sector wasn't found, the parent of the NULL leaf
1893 * will contain the closest sector.
1895 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1896 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1899 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1900 node
= rb_next(&__cfqq
->p_node
);
1902 node
= rb_prev(&__cfqq
->p_node
);
1906 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1907 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1915 * cur_cfqq - passed in so that we don't decide that the current queue is
1916 * closely cooperating with itself.
1918 * So, basically we're assuming that that cur_cfqq has dispatched at least
1919 * one request, and that cfqd->last_position reflects a position on the disk
1920 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1923 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1924 struct cfq_queue
*cur_cfqq
)
1926 struct cfq_queue
*cfqq
;
1928 if (cfq_class_idle(cur_cfqq
))
1930 if (!cfq_cfqq_sync(cur_cfqq
))
1932 if (CFQQ_SEEKY(cur_cfqq
))
1936 * Don't search priority tree if it's the only queue in the group.
1938 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1942 * We should notice if some of the queues are cooperating, eg
1943 * working closely on the same area of the disk. In that case,
1944 * we can group them together and don't waste time idling.
1946 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1950 /* If new queue belongs to different cfq_group, don't choose it */
1951 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1955 * It only makes sense to merge sync queues.
1957 if (!cfq_cfqq_sync(cfqq
))
1959 if (CFQQ_SEEKY(cfqq
))
1963 * Do not merge queues of different priority classes
1965 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1972 * Determine whether we should enforce idle window for this queue.
1975 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1977 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1978 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1980 BUG_ON(!service_tree
);
1981 BUG_ON(!service_tree
->count
);
1983 if (!cfqd
->cfq_slice_idle
)
1986 /* We never do for idle class queues. */
1987 if (prio
== IDLE_WORKLOAD
)
1990 /* We do for queues that were marked with idle window flag. */
1991 if (cfq_cfqq_idle_window(cfqq
) &&
1992 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1996 * Otherwise, we do only if they are the last ones
1997 * in their service tree.
1999 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
2000 !cfq_io_thinktime_big(cfqd
, &service_tree
->ttime
, false))
2002 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
2003 service_tree
->count
);
2007 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
2009 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2010 struct cfq_io_cq
*cic
;
2011 unsigned long sl
, group_idle
= 0;
2014 * SSD device without seek penalty, disable idling. But only do so
2015 * for devices that support queuing, otherwise we still have a problem
2016 * with sync vs async workloads.
2018 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
2021 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
2022 WARN_ON(cfq_cfqq_slice_new(cfqq
));
2025 * idle is disabled, either manually or by past process history
2027 if (!cfq_should_idle(cfqd
, cfqq
)) {
2028 /* no queue idling. Check for group idling */
2029 if (cfqd
->cfq_group_idle
)
2030 group_idle
= cfqd
->cfq_group_idle
;
2036 * still active requests from this queue, don't idle
2038 if (cfqq
->dispatched
)
2042 * task has exited, don't wait
2044 cic
= cfqd
->active_cic
;
2045 if (!cic
|| !atomic_read(&cic
->icq
.ioc
->nr_tasks
))
2049 * If our average think time is larger than the remaining time
2050 * slice, then don't idle. This avoids overrunning the allotted
2053 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2054 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2055 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2056 cic
->ttime
.ttime_mean
);
2060 /* There are other queues in the group, don't do group idle */
2061 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2064 cfq_mark_cfqq_wait_request(cfqq
);
2067 sl
= cfqd
->cfq_group_idle
;
2069 sl
= cfqd
->cfq_slice_idle
;
2071 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2072 cfq_blkiocg_update_set_idle_time_stats(&cfqq
->cfqg
->blkg
);
2073 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2074 group_idle
? 1 : 0);
2078 * Move request from internal lists to the request queue dispatch list.
2080 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2082 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2083 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2085 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2087 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2088 cfq_remove_request(rq
);
2090 (RQ_CFQG(rq
))->dispatched
++;
2091 elv_dispatch_sort(q
, rq
);
2093 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2094 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2095 cfq_blkiocg_update_dispatch_stats(&cfqq
->cfqg
->blkg
, blk_rq_bytes(rq
),
2096 rq_data_dir(rq
), rq_is_sync(rq
));
2100 * return expired entry, or NULL to just start from scratch in rbtree
2102 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2104 struct request
*rq
= NULL
;
2106 if (cfq_cfqq_fifo_expire(cfqq
))
2109 cfq_mark_cfqq_fifo_expire(cfqq
);
2111 if (list_empty(&cfqq
->fifo
))
2114 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2115 if (time_before(jiffies
, rq_fifo_time(rq
)))
2118 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2123 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2125 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2127 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2129 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2133 * Must be called with the queue_lock held.
2135 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2137 int process_refs
, io_refs
;
2139 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2140 process_refs
= cfqq
->ref
- io_refs
;
2141 BUG_ON(process_refs
< 0);
2142 return process_refs
;
2145 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2147 int process_refs
, new_process_refs
;
2148 struct cfq_queue
*__cfqq
;
2151 * If there are no process references on the new_cfqq, then it is
2152 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2153 * chain may have dropped their last reference (not just their
2154 * last process reference).
2156 if (!cfqq_process_refs(new_cfqq
))
2159 /* Avoid a circular list and skip interim queue merges */
2160 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2166 process_refs
= cfqq_process_refs(cfqq
);
2167 new_process_refs
= cfqq_process_refs(new_cfqq
);
2169 * If the process for the cfqq has gone away, there is no
2170 * sense in merging the queues.
2172 if (process_refs
== 0 || new_process_refs
== 0)
2176 * Merge in the direction of the lesser amount of work.
2178 if (new_process_refs
>= process_refs
) {
2179 cfqq
->new_cfqq
= new_cfqq
;
2180 new_cfqq
->ref
+= process_refs
;
2182 new_cfqq
->new_cfqq
= cfqq
;
2183 cfqq
->ref
+= new_process_refs
;
2187 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2188 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2190 struct cfq_queue
*queue
;
2192 bool key_valid
= false;
2193 unsigned long lowest_key
= 0;
2194 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2196 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2197 /* select the one with lowest rb_key */
2198 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2200 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2201 lowest_key
= queue
->rb_key
;
2210 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2214 struct cfq_rb_root
*st
;
2215 unsigned group_slice
;
2216 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2218 /* Choose next priority. RT > BE > IDLE */
2219 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2220 cfqd
->serving_prio
= RT_WORKLOAD
;
2221 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2222 cfqd
->serving_prio
= BE_WORKLOAD
;
2224 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2225 cfqd
->workload_expires
= jiffies
+ 1;
2229 if (original_prio
!= cfqd
->serving_prio
)
2233 * For RT and BE, we have to choose also the type
2234 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2237 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2241 * check workload expiration, and that we still have other queues ready
2243 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2247 /* otherwise select new workload type */
2248 cfqd
->serving_type
=
2249 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2250 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2254 * the workload slice is computed as a fraction of target latency
2255 * proportional to the number of queues in that workload, over
2256 * all the queues in the same priority class
2258 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2260 slice
= group_slice
* count
/
2261 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2262 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2264 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2268 * Async queues are currently system wide. Just taking
2269 * proportion of queues with-in same group will lead to higher
2270 * async ratio system wide as generally root group is going
2271 * to have higher weight. A more accurate thing would be to
2272 * calculate system wide asnc/sync ratio.
2274 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2275 tmp
= tmp
/cfqd
->busy_queues
;
2276 slice
= min_t(unsigned, slice
, tmp
);
2278 /* async workload slice is scaled down according to
2279 * the sync/async slice ratio. */
2280 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2282 /* sync workload slice is at least 2 * cfq_slice_idle */
2283 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2285 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2286 cfq_log(cfqd
, "workload slice:%d", slice
);
2287 cfqd
->workload_expires
= jiffies
+ slice
;
2290 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2292 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2293 struct cfq_group
*cfqg
;
2295 if (RB_EMPTY_ROOT(&st
->rb
))
2297 cfqg
= cfq_rb_first_group(st
);
2298 update_min_vdisktime(st
);
2302 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2304 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2306 cfqd
->serving_group
= cfqg
;
2308 /* Restore the workload type data */
2309 if (cfqg
->saved_workload_slice
) {
2310 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2311 cfqd
->serving_type
= cfqg
->saved_workload
;
2312 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2314 cfqd
->workload_expires
= jiffies
- 1;
2316 choose_service_tree(cfqd
, cfqg
);
2320 * Select a queue for service. If we have a current active queue,
2321 * check whether to continue servicing it, or retrieve and set a new one.
2323 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2325 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2327 cfqq
= cfqd
->active_queue
;
2331 if (!cfqd
->rq_queued
)
2335 * We were waiting for group to get backlogged. Expire the queue
2337 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2341 * The active queue has run out of time, expire it and select new.
2343 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2345 * If slice had not expired at the completion of last request
2346 * we might not have turned on wait_busy flag. Don't expire
2347 * the queue yet. Allow the group to get backlogged.
2349 * The very fact that we have used the slice, that means we
2350 * have been idling all along on this queue and it should be
2351 * ok to wait for this request to complete.
2353 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2354 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2358 goto check_group_idle
;
2362 * The active queue has requests and isn't expired, allow it to
2365 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2369 * If another queue has a request waiting within our mean seek
2370 * distance, let it run. The expire code will check for close
2371 * cooperators and put the close queue at the front of the service
2372 * tree. If possible, merge the expiring queue with the new cfqq.
2374 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2376 if (!cfqq
->new_cfqq
)
2377 cfq_setup_merge(cfqq
, new_cfqq
);
2382 * No requests pending. If the active queue still has requests in
2383 * flight or is idling for a new request, allow either of these
2384 * conditions to happen (or time out) before selecting a new queue.
2386 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2392 * This is a deep seek queue, but the device is much faster than
2393 * the queue can deliver, don't idle
2395 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2396 (cfq_cfqq_slice_new(cfqq
) ||
2397 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2398 cfq_clear_cfqq_deep(cfqq
);
2399 cfq_clear_cfqq_idle_window(cfqq
);
2402 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2408 * If group idle is enabled and there are requests dispatched from
2409 * this group, wait for requests to complete.
2412 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
2413 cfqq
->cfqg
->dispatched
&&
2414 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
2420 cfq_slice_expired(cfqd
, 0);
2423 * Current queue expired. Check if we have to switch to a new
2427 cfq_choose_cfqg(cfqd
);
2429 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2434 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2438 while (cfqq
->next_rq
) {
2439 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2443 BUG_ON(!list_empty(&cfqq
->fifo
));
2445 /* By default cfqq is not expired if it is empty. Do it explicitly */
2446 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2451 * Drain our current requests. Used for barriers and when switching
2452 * io schedulers on-the-fly.
2454 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2456 struct cfq_queue
*cfqq
;
2459 /* Expire the timeslice of the current active queue first */
2460 cfq_slice_expired(cfqd
, 0);
2461 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2462 __cfq_set_active_queue(cfqd
, cfqq
);
2463 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2466 BUG_ON(cfqd
->busy_queues
);
2468 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2472 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2473 struct cfq_queue
*cfqq
)
2475 /* the queue hasn't finished any request, can't estimate */
2476 if (cfq_cfqq_slice_new(cfqq
))
2478 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2485 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2487 unsigned int max_dispatch
;
2490 * Drain async requests before we start sync IO
2492 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2496 * If this is an async queue and we have sync IO in flight, let it wait
2498 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2501 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2502 if (cfq_class_idle(cfqq
))
2506 * Does this cfqq already have too much IO in flight?
2508 if (cfqq
->dispatched
>= max_dispatch
) {
2509 bool promote_sync
= false;
2511 * idle queue must always only have a single IO in flight
2513 if (cfq_class_idle(cfqq
))
2517 * If there is only one sync queue
2518 * we can ignore async queue here and give the sync
2519 * queue no dispatch limit. The reason is a sync queue can
2520 * preempt async queue, limiting the sync queue doesn't make
2521 * sense. This is useful for aiostress test.
2523 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
2524 promote_sync
= true;
2527 * We have other queues, don't allow more IO from this one
2529 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
2534 * Sole queue user, no limit
2536 if (cfqd
->busy_queues
== 1 || promote_sync
)
2540 * Normally we start throttling cfqq when cfq_quantum/2
2541 * requests have been dispatched. But we can drive
2542 * deeper queue depths at the beginning of slice
2543 * subjected to upper limit of cfq_quantum.
2545 max_dispatch
= cfqd
->cfq_quantum
;
2549 * Async queues must wait a bit before being allowed dispatch.
2550 * We also ramp up the dispatch depth gradually for async IO,
2551 * based on the last sync IO we serviced
2553 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2554 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2557 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2558 if (!depth
&& !cfqq
->dispatched
)
2560 if (depth
< max_dispatch
)
2561 max_dispatch
= depth
;
2565 * If we're below the current max, allow a dispatch
2567 return cfqq
->dispatched
< max_dispatch
;
2571 * Dispatch a request from cfqq, moving them to the request queue
2574 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2578 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2580 if (!cfq_may_dispatch(cfqd
, cfqq
))
2584 * follow expired path, else get first next available
2586 rq
= cfq_check_fifo(cfqq
);
2591 * insert request into driver dispatch list
2593 cfq_dispatch_insert(cfqd
->queue
, rq
);
2595 if (!cfqd
->active_cic
) {
2596 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
2598 atomic_long_inc(&cic
->icq
.ioc
->refcount
);
2599 cfqd
->active_cic
= cic
;
2606 * Find the cfqq that we need to service and move a request from that to the
2609 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2611 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2612 struct cfq_queue
*cfqq
;
2614 if (!cfqd
->busy_queues
)
2617 if (unlikely(force
))
2618 return cfq_forced_dispatch(cfqd
);
2620 cfqq
= cfq_select_queue(cfqd
);
2625 * Dispatch a request from this cfqq, if it is allowed
2627 if (!cfq_dispatch_request(cfqd
, cfqq
))
2630 cfqq
->slice_dispatch
++;
2631 cfq_clear_cfqq_must_dispatch(cfqq
);
2634 * expire an async queue immediately if it has used up its slice. idle
2635 * queue always expire after 1 dispatch round.
2637 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2638 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2639 cfq_class_idle(cfqq
))) {
2640 cfqq
->slice_end
= jiffies
+ 1;
2641 cfq_slice_expired(cfqd
, 0);
2644 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2649 * task holds one reference to the queue, dropped when task exits. each rq
2650 * in-flight on this queue also holds a reference, dropped when rq is freed.
2652 * Each cfq queue took a reference on the parent group. Drop it now.
2653 * queue lock must be held here.
2655 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2657 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2658 struct cfq_group
*cfqg
;
2660 BUG_ON(cfqq
->ref
<= 0);
2666 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2667 BUG_ON(rb_first(&cfqq
->sort_list
));
2668 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2671 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2672 __cfq_slice_expired(cfqd
, cfqq
, 0);
2673 cfq_schedule_dispatch(cfqd
);
2676 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2677 kmem_cache_free(cfq_pool
, cfqq
);
2681 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2683 struct cfq_queue
*__cfqq
, *next
;
2686 * If this queue was scheduled to merge with another queue, be
2687 * sure to drop the reference taken on that queue (and others in
2688 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2690 __cfqq
= cfqq
->new_cfqq
;
2692 if (__cfqq
== cfqq
) {
2693 WARN(1, "cfqq->new_cfqq loop detected\n");
2696 next
= __cfqq
->new_cfqq
;
2697 cfq_put_queue(__cfqq
);
2702 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2704 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2705 __cfq_slice_expired(cfqd
, cfqq
, 0);
2706 cfq_schedule_dispatch(cfqd
);
2709 cfq_put_cooperator(cfqq
);
2711 cfq_put_queue(cfqq
);
2714 static void cfq_init_icq(struct io_cq
*icq
)
2716 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
2718 cic
->ttime
.last_end_request
= jiffies
;
2721 static void cfq_exit_icq(struct io_cq
*icq
)
2723 struct cfq_io_cq
*cic
= icq_to_cic(icq
);
2724 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2726 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2727 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2728 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2731 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2732 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2733 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2737 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2739 struct task_struct
*tsk
= current
;
2742 if (!cfq_cfqq_prio_changed(cfqq
))
2745 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2746 switch (ioprio_class
) {
2748 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2749 case IOPRIO_CLASS_NONE
:
2751 * no prio set, inherit CPU scheduling settings
2753 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2754 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2756 case IOPRIO_CLASS_RT
:
2757 cfqq
->ioprio
= task_ioprio(ioc
);
2758 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2760 case IOPRIO_CLASS_BE
:
2761 cfqq
->ioprio
= task_ioprio(ioc
);
2762 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2764 case IOPRIO_CLASS_IDLE
:
2765 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2767 cfq_clear_cfqq_idle_window(cfqq
);
2772 * keep track of original prio settings in case we have to temporarily
2773 * elevate the priority of this queue
2775 cfqq
->org_ioprio
= cfqq
->ioprio
;
2776 cfq_clear_cfqq_prio_changed(cfqq
);
2779 static void changed_ioprio(struct cfq_io_cq
*cic
)
2781 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2782 struct cfq_queue
*cfqq
;
2784 if (unlikely(!cfqd
))
2787 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2789 struct cfq_queue
*new_cfqq
;
2790 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->icq
.ioc
,
2793 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2794 cfq_put_queue(cfqq
);
2798 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2800 cfq_mark_cfqq_prio_changed(cfqq
);
2803 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2804 pid_t pid
, bool is_sync
)
2806 RB_CLEAR_NODE(&cfqq
->rb_node
);
2807 RB_CLEAR_NODE(&cfqq
->p_node
);
2808 INIT_LIST_HEAD(&cfqq
->fifo
);
2813 cfq_mark_cfqq_prio_changed(cfqq
);
2816 if (!cfq_class_idle(cfqq
))
2817 cfq_mark_cfqq_idle_window(cfqq
);
2818 cfq_mark_cfqq_sync(cfqq
);
2823 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2824 static void changed_cgroup(struct cfq_io_cq
*cic
)
2826 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2827 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2828 struct request_queue
*q
;
2830 if (unlikely(!cfqd
))
2837 * Drop reference to sync queue. A new sync queue will be
2838 * assigned in new group upon arrival of a fresh request.
2840 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2841 cic_set_cfqq(cic
, NULL
, 1);
2842 cfq_put_queue(sync_cfqq
);
2845 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2847 static struct cfq_queue
*
2848 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2849 struct io_context
*ioc
, gfp_t gfp_mask
)
2851 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2852 struct cfq_io_cq
*cic
;
2853 struct cfq_group
*cfqg
;
2856 cfqg
= cfq_get_cfqg(cfqd
);
2857 cic
= cfq_cic_lookup(cfqd
, ioc
);
2858 /* cic always exists here */
2859 cfqq
= cic_to_cfqq(cic
, is_sync
);
2862 * Always try a new alloc if we fell back to the OOM cfqq
2863 * originally, since it should just be a temporary situation.
2865 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2870 } else if (gfp_mask
& __GFP_WAIT
) {
2871 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2872 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2873 gfp_mask
| __GFP_ZERO
,
2875 spin_lock_irq(cfqd
->queue
->queue_lock
);
2879 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2880 gfp_mask
| __GFP_ZERO
,
2885 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2886 cfq_init_prio_data(cfqq
, ioc
);
2887 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2888 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2890 cfqq
= &cfqd
->oom_cfqq
;
2894 kmem_cache_free(cfq_pool
, new_cfqq
);
2899 static struct cfq_queue
**
2900 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2902 switch (ioprio_class
) {
2903 case IOPRIO_CLASS_RT
:
2904 return &cfqd
->async_cfqq
[0][ioprio
];
2905 case IOPRIO_CLASS_BE
:
2906 return &cfqd
->async_cfqq
[1][ioprio
];
2907 case IOPRIO_CLASS_IDLE
:
2908 return &cfqd
->async_idle_cfqq
;
2914 static struct cfq_queue
*
2915 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2918 const int ioprio
= task_ioprio(ioc
);
2919 const int ioprio_class
= task_ioprio_class(ioc
);
2920 struct cfq_queue
**async_cfqq
= NULL
;
2921 struct cfq_queue
*cfqq
= NULL
;
2924 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2929 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2932 * pin the queue now that it's allocated, scheduler exit will prune it
2934 if (!is_sync
&& !(*async_cfqq
)) {
2944 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
2946 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
2947 elapsed
= min(elapsed
, 2UL * slice_idle
);
2949 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
2950 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
2951 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
2955 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2956 struct cfq_io_cq
*cic
)
2958 if (cfq_cfqq_sync(cfqq
)) {
2959 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
2960 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
2961 cfqd
->cfq_slice_idle
);
2963 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2964 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
2969 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2973 sector_t n_sec
= blk_rq_sectors(rq
);
2974 if (cfqq
->last_request_pos
) {
2975 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
2976 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
2978 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
2981 cfqq
->seek_history
<<= 1;
2982 if (blk_queue_nonrot(cfqd
->queue
))
2983 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
2985 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
2989 * Disable idle window if the process thinks too long or seeks so much that
2993 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2994 struct cfq_io_cq
*cic
)
2996 int old_idle
, enable_idle
;
2999 * Don't idle for async or idle io prio class
3001 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3004 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3006 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3007 cfq_mark_cfqq_deep(cfqq
);
3009 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3011 else if (!atomic_read(&cic
->icq
.ioc
->nr_tasks
) ||
3012 !cfqd
->cfq_slice_idle
||
3013 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3015 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3016 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3022 if (old_idle
!= enable_idle
) {
3023 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3025 cfq_mark_cfqq_idle_window(cfqq
);
3027 cfq_clear_cfqq_idle_window(cfqq
);
3032 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3033 * no or if we aren't sure, a 1 will cause a preempt.
3036 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3039 struct cfq_queue
*cfqq
;
3041 cfqq
= cfqd
->active_queue
;
3045 if (cfq_class_idle(new_cfqq
))
3048 if (cfq_class_idle(cfqq
))
3052 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3054 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3058 * if the new request is sync, but the currently running queue is
3059 * not, let the sync request have priority.
3061 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3064 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3067 if (cfq_slice_used(cfqq
))
3070 /* Allow preemption only if we are idling on sync-noidle tree */
3071 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3072 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3073 new_cfqq
->service_tree
->count
== 2 &&
3074 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3078 * So both queues are sync. Let the new request get disk time if
3079 * it's a metadata request and the current queue is doing regular IO.
3081 if ((rq
->cmd_flags
& REQ_PRIO
) && !cfqq
->prio_pending
)
3085 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3087 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3090 /* An idle queue should not be idle now for some reason */
3091 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3094 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3098 * if this request is as-good as one we would expect from the
3099 * current cfqq, let it preempt
3101 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3108 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3109 * let it have half of its nominal slice.
3111 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3113 enum wl_type_t old_type
= cfqq_type(cfqd
->active_queue
);
3115 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3116 cfq_slice_expired(cfqd
, 1);
3119 * workload type is changed, don't save slice, otherwise preempt
3122 if (old_type
!= cfqq_type(cfqq
))
3123 cfqq
->cfqg
->saved_workload_slice
= 0;
3126 * Put the new queue at the front of the of the current list,
3127 * so we know that it will be selected next.
3129 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3131 cfq_service_tree_add(cfqd
, cfqq
, 1);
3133 cfqq
->slice_end
= 0;
3134 cfq_mark_cfqq_slice_new(cfqq
);
3138 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3139 * something we should do about it
3142 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3145 struct cfq_io_cq
*cic
= RQ_CIC(rq
);
3148 if (rq
->cmd_flags
& REQ_PRIO
)
3149 cfqq
->prio_pending
++;
3151 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3152 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3153 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3155 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3157 if (cfqq
== cfqd
->active_queue
) {
3159 * Remember that we saw a request from this process, but
3160 * don't start queuing just yet. Otherwise we risk seeing lots
3161 * of tiny requests, because we disrupt the normal plugging
3162 * and merging. If the request is already larger than a single
3163 * page, let it rip immediately. For that case we assume that
3164 * merging is already done. Ditto for a busy system that
3165 * has other work pending, don't risk delaying until the
3166 * idle timer unplug to continue working.
3168 if (cfq_cfqq_wait_request(cfqq
)) {
3169 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3170 cfqd
->busy_queues
> 1) {
3171 cfq_del_timer(cfqd
, cfqq
);
3172 cfq_clear_cfqq_wait_request(cfqq
);
3173 __blk_run_queue(cfqd
->queue
);
3175 cfq_blkiocg_update_idle_time_stats(
3177 cfq_mark_cfqq_must_dispatch(cfqq
);
3180 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3182 * not the active queue - expire current slice if it is
3183 * idle and has expired it's mean thinktime or this new queue
3184 * has some old slice time left and is of higher priority or
3185 * this new queue is RT and the current one is BE
3187 cfq_preempt_queue(cfqd
, cfqq
);
3188 __blk_run_queue(cfqd
->queue
);
3192 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3194 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3195 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3197 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3198 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->icq
.ioc
);
3200 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3201 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3203 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
3204 &cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
3206 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3210 * Update hw_tag based on peak queue depth over 50 samples under
3213 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3215 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3217 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3218 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3220 if (cfqd
->hw_tag
== 1)
3223 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3224 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3228 * If active queue hasn't enough requests and can idle, cfq might not
3229 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3232 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3233 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3234 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3237 if (cfqd
->hw_tag_samples
++ < 50)
3240 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3246 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3248 struct cfq_io_cq
*cic
= cfqd
->active_cic
;
3250 /* If the queue already has requests, don't wait */
3251 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3254 /* If there are other queues in the group, don't wait */
3255 if (cfqq
->cfqg
->nr_cfqq
> 1)
3258 /* the only queue in the group, but think time is big */
3259 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3262 if (cfq_slice_used(cfqq
))
3265 /* if slice left is less than think time, wait busy */
3266 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3267 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
3271 * If think times is less than a jiffy than ttime_mean=0 and above
3272 * will not be true. It might happen that slice has not expired yet
3273 * but will expire soon (4-5 ns) during select_queue(). To cover the
3274 * case where think time is less than a jiffy, mark the queue wait
3275 * busy if only 1 jiffy is left in the slice.
3277 if (cfqq
->slice_end
- jiffies
== 1)
3283 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3285 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3286 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3287 const int sync
= rq_is_sync(rq
);
3291 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3292 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3294 cfq_update_hw_tag(cfqd
);
3296 WARN_ON(!cfqd
->rq_in_driver
);
3297 WARN_ON(!cfqq
->dispatched
);
3298 cfqd
->rq_in_driver
--;
3300 (RQ_CFQG(rq
))->dispatched
--;
3301 cfq_blkiocg_update_completion_stats(&cfqq
->cfqg
->blkg
,
3302 rq_start_time_ns(rq
), rq_io_start_time_ns(rq
),
3303 rq_data_dir(rq
), rq_is_sync(rq
));
3305 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3308 struct cfq_rb_root
*service_tree
;
3310 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
3312 if (cfq_cfqq_on_rr(cfqq
))
3313 service_tree
= cfqq
->service_tree
;
3315 service_tree
= service_tree_for(cfqq
->cfqg
,
3316 cfqq_prio(cfqq
), cfqq_type(cfqq
));
3317 service_tree
->ttime
.last_end_request
= now
;
3318 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3319 cfqd
->last_delayed_sync
= now
;
3322 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3323 cfqq
->cfqg
->ttime
.last_end_request
= now
;
3327 * If this is the active queue, check if it needs to be expired,
3328 * or if we want to idle in case it has no pending requests.
3330 if (cfqd
->active_queue
== cfqq
) {
3331 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3333 if (cfq_cfqq_slice_new(cfqq
)) {
3334 cfq_set_prio_slice(cfqd
, cfqq
);
3335 cfq_clear_cfqq_slice_new(cfqq
);
3339 * Should we wait for next request to come in before we expire
3342 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3343 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3344 if (!cfqd
->cfq_slice_idle
)
3345 extend_sl
= cfqd
->cfq_group_idle
;
3346 cfqq
->slice_end
= jiffies
+ extend_sl
;
3347 cfq_mark_cfqq_wait_busy(cfqq
);
3348 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3352 * Idling is not enabled on:
3354 * - idle-priority queues
3356 * - queues with still some requests queued
3357 * - when there is a close cooperator
3359 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3360 cfq_slice_expired(cfqd
, 1);
3361 else if (sync
&& cfqq_empty
&&
3362 !cfq_close_cooperator(cfqd
, cfqq
)) {
3363 cfq_arm_slice_timer(cfqd
);
3367 if (!cfqd
->rq_in_driver
)
3368 cfq_schedule_dispatch(cfqd
);
3371 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3373 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3374 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3375 return ELV_MQUEUE_MUST
;
3378 return ELV_MQUEUE_MAY
;
3381 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3383 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3384 struct task_struct
*tsk
= current
;
3385 struct cfq_io_cq
*cic
;
3386 struct cfq_queue
*cfqq
;
3389 * don't force setup of a queue from here, as a call to may_queue
3390 * does not necessarily imply that a request actually will be queued.
3391 * so just lookup a possibly existing queue, or return 'may queue'
3394 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3396 return ELV_MQUEUE_MAY
;
3398 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3400 cfq_init_prio_data(cfqq
, cic
->icq
.ioc
);
3402 return __cfq_may_queue(cfqq
);
3405 return ELV_MQUEUE_MAY
;
3409 * queue lock held here
3411 static void cfq_put_request(struct request
*rq
)
3413 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3416 const int rw
= rq_data_dir(rq
);
3418 BUG_ON(!cfqq
->allocated
[rw
]);
3419 cfqq
->allocated
[rw
]--;
3421 /* Put down rq reference on cfqg */
3422 cfq_put_cfqg(RQ_CFQG(rq
));
3423 rq
->elv
.priv
[0] = NULL
;
3424 rq
->elv
.priv
[1] = NULL
;
3426 cfq_put_queue(cfqq
);
3430 static struct cfq_queue
*
3431 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_cq
*cic
,
3432 struct cfq_queue
*cfqq
)
3434 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3435 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3436 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3437 cfq_put_queue(cfqq
);
3438 return cic_to_cfqq(cic
, 1);
3442 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3443 * was the last process referring to said cfqq.
3445 static struct cfq_queue
*
3446 split_cfqq(struct cfq_io_cq
*cic
, struct cfq_queue
*cfqq
)
3448 if (cfqq_process_refs(cfqq
) == 1) {
3449 cfqq
->pid
= current
->pid
;
3450 cfq_clear_cfqq_coop(cfqq
);
3451 cfq_clear_cfqq_split_coop(cfqq
);
3455 cic_set_cfqq(cic
, NULL
, 1);
3457 cfq_put_cooperator(cfqq
);
3459 cfq_put_queue(cfqq
);
3463 * Allocate cfq data structures associated with this request.
3466 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3468 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3469 struct cfq_io_cq
*cic
= icq_to_cic(rq
->elv
.icq
);
3470 const int rw
= rq_data_dir(rq
);
3471 const bool is_sync
= rq_is_sync(rq
);
3472 struct cfq_queue
*cfqq
;
3473 unsigned int changed
;
3475 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3477 spin_lock_irq(q
->queue_lock
);
3479 /* handle changed notifications */
3480 changed
= icq_get_changed(&cic
->icq
);
3481 if (unlikely(changed
& ICQ_IOPRIO_CHANGED
))
3482 changed_ioprio(cic
);
3483 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3484 if (unlikely(changed
& ICQ_CGROUP_CHANGED
))
3485 changed_cgroup(cic
);
3489 cfqq
= cic_to_cfqq(cic
, is_sync
);
3490 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3491 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->icq
.ioc
, gfp_mask
);
3492 cic_set_cfqq(cic
, cfqq
, is_sync
);
3495 * If the queue was seeky for too long, break it apart.
3497 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3498 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3499 cfqq
= split_cfqq(cic
, cfqq
);
3505 * Check to see if this queue is scheduled to merge with
3506 * another, closely cooperating queue. The merging of
3507 * queues happens here as it must be done in process context.
3508 * The reference on new_cfqq was taken in merge_cfqqs.
3511 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3514 cfqq
->allocated
[rw
]++;
3517 rq
->elv
.priv
[0] = cfqq
;
3518 rq
->elv
.priv
[1] = cfq_ref_get_cfqg(cfqq
->cfqg
);
3519 spin_unlock_irq(q
->queue_lock
);
3523 static void cfq_kick_queue(struct work_struct
*work
)
3525 struct cfq_data
*cfqd
=
3526 container_of(work
, struct cfq_data
, unplug_work
);
3527 struct request_queue
*q
= cfqd
->queue
;
3529 spin_lock_irq(q
->queue_lock
);
3530 __blk_run_queue(cfqd
->queue
);
3531 spin_unlock_irq(q
->queue_lock
);
3535 * Timer running if the active_queue is currently idling inside its time slice
3537 static void cfq_idle_slice_timer(unsigned long data
)
3539 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3540 struct cfq_queue
*cfqq
;
3541 unsigned long flags
;
3544 cfq_log(cfqd
, "idle timer fired");
3546 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3548 cfqq
= cfqd
->active_queue
;
3553 * We saw a request before the queue expired, let it through
3555 if (cfq_cfqq_must_dispatch(cfqq
))
3561 if (cfq_slice_used(cfqq
))
3565 * only expire and reinvoke request handler, if there are
3566 * other queues with pending requests
3568 if (!cfqd
->busy_queues
)
3572 * not expired and it has a request pending, let it dispatch
3574 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3578 * Queue depth flag is reset only when the idle didn't succeed
3580 cfq_clear_cfqq_deep(cfqq
);
3583 cfq_slice_expired(cfqd
, timed_out
);
3585 cfq_schedule_dispatch(cfqd
);
3587 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3590 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3592 del_timer_sync(&cfqd
->idle_slice_timer
);
3593 cancel_work_sync(&cfqd
->unplug_work
);
3596 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3600 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3601 if (cfqd
->async_cfqq
[0][i
])
3602 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3603 if (cfqd
->async_cfqq
[1][i
])
3604 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3607 if (cfqd
->async_idle_cfqq
)
3608 cfq_put_queue(cfqd
->async_idle_cfqq
);
3611 static void cfq_exit_queue(struct elevator_queue
*e
)
3613 struct cfq_data
*cfqd
= e
->elevator_data
;
3614 struct request_queue
*q
= cfqd
->queue
;
3617 cfq_shutdown_timer_wq(cfqd
);
3619 spin_lock_irq(q
->queue_lock
);
3621 if (cfqd
->active_queue
)
3622 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3624 cfq_put_async_queues(cfqd
);
3625 cfq_release_cfq_groups(cfqd
);
3628 * If there are groups which we could not unlink from blkcg list,
3629 * wait for a rcu period for them to be freed.
3631 if (cfqd
->nr_blkcg_linked_grps
)
3634 spin_unlock_irq(q
->queue_lock
);
3636 cfq_shutdown_timer_wq(cfqd
);
3639 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3640 * Do this wait only if there are other unlinked groups out
3641 * there. This can happen if cgroup deletion path claimed the
3642 * responsibility of cleaning up a group before queue cleanup code
3645 * Do not call synchronize_rcu() unconditionally as there are drivers
3646 * which create/delete request queue hundreds of times during scan/boot
3647 * and synchronize_rcu() can take significant time and slow down boot.
3652 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3653 /* Free up per cpu stats for root group */
3654 free_percpu(cfqd
->root_group
.blkg
.stats_cpu
);
3659 static void *cfq_init_queue(struct request_queue
*q
)
3661 struct cfq_data
*cfqd
;
3663 struct cfq_group
*cfqg
;
3664 struct cfq_rb_root
*st
;
3666 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3670 /* Init root service tree */
3671 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3673 /* Init root group */
3674 cfqg
= &cfqd
->root_group
;
3675 for_each_cfqg_st(cfqg
, i
, j
, st
)
3677 RB_CLEAR_NODE(&cfqg
->rb_node
);
3679 /* Give preference to root group over other groups */
3680 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3682 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3684 * Set root group reference to 2. One reference will be dropped when
3685 * all groups on cfqd->cfqg_list are being deleted during queue exit.
3686 * Other reference will remain there as we don't want to delete this
3687 * group as it is statically allocated and gets destroyed when
3688 * throtl_data goes away.
3692 if (blkio_alloc_blkg_stats(&cfqg
->blkg
)) {
3700 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
,
3703 cfqd
->nr_blkcg_linked_grps
++;
3705 /* Add group on cfqd->cfqg_list */
3706 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
3709 * Not strictly needed (since RB_ROOT just clears the node and we
3710 * zeroed cfqd on alloc), but better be safe in case someone decides
3711 * to add magic to the rb code
3713 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3714 cfqd
->prio_trees
[i
] = RB_ROOT
;
3717 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3718 * Grab a permanent reference to it, so that the normal code flow
3719 * will not attempt to free it.
3721 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3722 cfqd
->oom_cfqq
.ref
++;
3723 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3727 init_timer(&cfqd
->idle_slice_timer
);
3728 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3729 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3731 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3733 cfqd
->cfq_quantum
= cfq_quantum
;
3734 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3735 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3736 cfqd
->cfq_back_max
= cfq_back_max
;
3737 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3738 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3739 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3740 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3741 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3742 cfqd
->cfq_group_idle
= cfq_group_idle
;
3743 cfqd
->cfq_latency
= 1;
3746 * we optimistically start assuming sync ops weren't delayed in last
3747 * second, in order to have larger depth for async operations.
3749 cfqd
->last_delayed_sync
= jiffies
- HZ
;
3754 * sysfs parts below -->
3757 cfq_var_show(unsigned int var
, char *page
)
3759 return sprintf(page
, "%d\n", var
);
3763 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3765 char *p
= (char *) page
;
3767 *var
= simple_strtoul(p
, &p
, 10);
3771 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3772 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3774 struct cfq_data *cfqd = e->elevator_data; \
3775 unsigned int __data = __VAR; \
3777 __data = jiffies_to_msecs(__data); \
3778 return cfq_var_show(__data, (page)); \
3780 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3781 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3782 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3783 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3784 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3785 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3786 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
3787 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
3788 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
3789 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
3790 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
3791 #undef SHOW_FUNCTION
3793 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3794 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3796 struct cfq_data *cfqd = e->elevator_data; \
3797 unsigned int __data; \
3798 int ret = cfq_var_store(&__data, (page), count); \
3799 if (__data < (MIN)) \
3801 else if (__data > (MAX)) \
3804 *(__PTR) = msecs_to_jiffies(__data); \
3806 *(__PTR) = __data; \
3809 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
3810 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
3812 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
3814 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
3815 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
3817 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
3818 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
3819 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
3820 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
3821 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
3823 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
3824 #undef STORE_FUNCTION
3826 #define CFQ_ATTR(name) \
3827 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3829 static struct elv_fs_entry cfq_attrs
[] = {
3831 CFQ_ATTR(fifo_expire_sync
),
3832 CFQ_ATTR(fifo_expire_async
),
3833 CFQ_ATTR(back_seek_max
),
3834 CFQ_ATTR(back_seek_penalty
),
3835 CFQ_ATTR(slice_sync
),
3836 CFQ_ATTR(slice_async
),
3837 CFQ_ATTR(slice_async_rq
),
3838 CFQ_ATTR(slice_idle
),
3839 CFQ_ATTR(group_idle
),
3840 CFQ_ATTR(low_latency
),
3844 static struct elevator_type iosched_cfq
= {
3846 .elevator_merge_fn
= cfq_merge
,
3847 .elevator_merged_fn
= cfq_merged_request
,
3848 .elevator_merge_req_fn
= cfq_merged_requests
,
3849 .elevator_allow_merge_fn
= cfq_allow_merge
,
3850 .elevator_bio_merged_fn
= cfq_bio_merged
,
3851 .elevator_dispatch_fn
= cfq_dispatch_requests
,
3852 .elevator_add_req_fn
= cfq_insert_request
,
3853 .elevator_activate_req_fn
= cfq_activate_request
,
3854 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
3855 .elevator_completed_req_fn
= cfq_completed_request
,
3856 .elevator_former_req_fn
= elv_rb_former_request
,
3857 .elevator_latter_req_fn
= elv_rb_latter_request
,
3858 .elevator_init_icq_fn
= cfq_init_icq
,
3859 .elevator_exit_icq_fn
= cfq_exit_icq
,
3860 .elevator_set_req_fn
= cfq_set_request
,
3861 .elevator_put_req_fn
= cfq_put_request
,
3862 .elevator_may_queue_fn
= cfq_may_queue
,
3863 .elevator_init_fn
= cfq_init_queue
,
3864 .elevator_exit_fn
= cfq_exit_queue
,
3866 .icq_size
= sizeof(struct cfq_io_cq
),
3867 .icq_align
= __alignof__(struct cfq_io_cq
),
3868 .elevator_attrs
= cfq_attrs
,
3869 .elevator_name
= "cfq",
3870 .elevator_owner
= THIS_MODULE
,
3873 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3874 static struct blkio_policy_type blkio_policy_cfq
= {
3876 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
3877 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
3879 .plid
= BLKIO_POLICY_PROP
,
3882 static struct blkio_policy_type blkio_policy_cfq
;
3885 static int __init
cfq_init(void)
3890 * could be 0 on HZ < 1000 setups
3892 if (!cfq_slice_async
)
3893 cfq_slice_async
= 1;
3894 if (!cfq_slice_idle
)
3897 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3898 if (!cfq_group_idle
)
3903 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3907 ret
= elv_register(&iosched_cfq
);
3909 kmem_cache_destroy(cfq_pool
);
3913 blkio_policy_register(&blkio_policy_cfq
);
3918 static void __exit
cfq_exit(void)
3920 blkio_policy_unregister(&blkio_policy_cfq
);
3921 elv_unregister(&iosched_cfq
);
3922 kmem_cache_destroy(cfq_pool
);
3925 module_init(cfq_init
);
3926 module_exit(cfq_exit
);
3928 MODULE_AUTHOR("Jens Axboe");
3929 MODULE_LICENSE("GPL");
3930 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");