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)
58 ((struct cfq_io_context *) (rq)->elevator_private[0])
59 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
60 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
62 static struct kmem_cache
*cfq_pool
;
63 static struct kmem_cache
*cfq_ioc_pool
;
65 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count
);
66 static struct completion
*ioc_gone
;
67 static DEFINE_SPINLOCK(ioc_gone_lock
);
69 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
70 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
71 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
73 #define sample_valid(samples) ((samples) > 80)
74 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
77 * Most of our rbtree usage is for sorting with min extraction, so
78 * if we cache the leftmost node we don't have to walk down the tree
79 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
80 * move this into the elevator for the rq sorting as well.
86 unsigned total_weight
;
88 struct cfq_ttime ttime
;
90 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
91 .ttime = {.last_end_request = jiffies,},}
94 * Per process-grouping structure
99 /* various state flags, see below */
101 /* parent cfq_data */
102 struct cfq_data
*cfqd
;
103 /* service_tree member */
104 struct rb_node rb_node
;
105 /* service_tree key */
106 unsigned long rb_key
;
107 /* prio tree member */
108 struct rb_node p_node
;
109 /* prio tree root we belong to, if any */
110 struct rb_root
*p_root
;
111 /* sorted list of pending requests */
112 struct rb_root sort_list
;
113 /* if fifo isn't expired, next request to serve */
114 struct request
*next_rq
;
115 /* requests queued in sort_list */
117 /* currently allocated requests */
119 /* fifo list of requests in sort_list */
120 struct list_head fifo
;
122 /* time when queue got scheduled in to dispatch first request. */
123 unsigned long dispatch_start
;
124 unsigned int allocated_slice
;
125 unsigned int slice_dispatch
;
126 /* time when first request from queue completed and slice started. */
127 unsigned long slice_start
;
128 unsigned long slice_end
;
131 /* pending priority requests */
133 /* number of requests that are on the dispatch list or inside driver */
136 /* io prio of this group */
137 unsigned short ioprio
, org_ioprio
;
138 unsigned short ioprio_class
;
143 sector_t last_request_pos
;
145 struct cfq_rb_root
*service_tree
;
146 struct cfq_queue
*new_cfqq
;
147 struct cfq_group
*cfqg
;
148 /* Number of sectors dispatched from queue in single dispatch round */
149 unsigned long nr_sectors
;
153 * First index in the service_trees.
154 * IDLE is handled separately, so it has negative index
164 * Second index in the service_trees.
168 SYNC_NOIDLE_WORKLOAD
= 1,
172 /* This is per cgroup per device grouping structure */
174 /* group service_tree member */
175 struct rb_node rb_node
;
177 /* group service_tree key */
180 unsigned int new_weight
;
183 /* number of cfqq currently on this group */
187 * Per group busy queues average. Useful for workload slice calc. We
188 * create the array for each prio class but at run time it is used
189 * only for RT and BE class and slot for IDLE class remains unused.
190 * This is primarily done to avoid confusion and a gcc warning.
192 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
194 * rr lists of queues with requests. We maintain service trees for
195 * RT and BE classes. These trees are subdivided in subclasses
196 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
197 * class there is no subclassification and all the cfq queues go on
198 * a single tree service_tree_idle.
199 * Counts are embedded in the cfq_rb_root
201 struct cfq_rb_root service_trees
[2][3];
202 struct cfq_rb_root service_tree_idle
;
204 unsigned long saved_workload_slice
;
205 enum wl_type_t saved_workload
;
206 enum wl_prio_t saved_serving_prio
;
207 struct blkio_group blkg
;
208 #ifdef CONFIG_CFQ_GROUP_IOSCHED
209 struct hlist_node cfqd_node
;
212 /* number of requests that are on the dispatch list or inside driver */
214 struct cfq_ttime ttime
;
218 * Per block device queue structure
221 struct request_queue
*queue
;
222 /* Root service tree for cfq_groups */
223 struct cfq_rb_root grp_service_tree
;
224 struct cfq_group root_group
;
227 * The priority currently being served
229 enum wl_prio_t serving_prio
;
230 enum wl_type_t serving_type
;
231 unsigned long workload_expires
;
232 struct cfq_group
*serving_group
;
235 * Each priority tree is sorted by next_request position. These
236 * trees are used when determining if two or more queues are
237 * interleaving requests (see cfq_close_cooperator).
239 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
241 unsigned int busy_queues
;
242 unsigned int busy_sync_queues
;
248 * queue-depth detection
254 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
255 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
258 int hw_tag_est_depth
;
259 unsigned int hw_tag_samples
;
262 * idle window management
264 struct timer_list idle_slice_timer
;
265 struct work_struct unplug_work
;
267 struct cfq_queue
*active_queue
;
268 struct cfq_io_context
*active_cic
;
271 * async queue for each priority case
273 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
274 struct cfq_queue
*async_idle_cfqq
;
276 sector_t last_position
;
279 * tunables, see top of file
281 unsigned int cfq_quantum
;
282 unsigned int cfq_fifo_expire
[2];
283 unsigned int cfq_back_penalty
;
284 unsigned int cfq_back_max
;
285 unsigned int cfq_slice
[2];
286 unsigned int cfq_slice_async_rq
;
287 unsigned int cfq_slice_idle
;
288 unsigned int cfq_group_idle
;
289 unsigned int cfq_latency
;
291 struct list_head cic_list
;
294 * Fallback dummy cfqq for extreme OOM conditions
296 struct cfq_queue oom_cfqq
;
298 unsigned long last_delayed_sync
;
300 /* List of cfq groups being managed on this device*/
301 struct hlist_head cfqg_list
;
303 /* Number of groups which are on blkcg->blkg_list */
304 unsigned int nr_blkcg_linked_grps
;
307 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
309 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
316 if (prio
== IDLE_WORKLOAD
)
317 return &cfqg
->service_tree_idle
;
319 return &cfqg
->service_trees
[prio
][type
];
322 enum cfqq_state_flags
{
323 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
324 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
325 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
326 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
327 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
328 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
329 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
330 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
331 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
332 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
333 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
334 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
335 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
338 #define CFQ_CFQQ_FNS(name) \
339 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
341 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
343 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
345 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
347 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
349 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
353 CFQ_CFQQ_FNS(wait_request
);
354 CFQ_CFQQ_FNS(must_dispatch
);
355 CFQ_CFQQ_FNS(must_alloc_slice
);
356 CFQ_CFQQ_FNS(fifo_expire
);
357 CFQ_CFQQ_FNS(idle_window
);
358 CFQ_CFQQ_FNS(prio_changed
);
359 CFQ_CFQQ_FNS(slice_new
);
362 CFQ_CFQQ_FNS(split_coop
);
364 CFQ_CFQQ_FNS(wait_busy
);
367 #ifdef CONFIG_CFQ_GROUP_IOSCHED
368 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
369 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
370 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
371 blkg_path(&(cfqq)->cfqg->blkg), ##args)
373 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
374 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
375 blkg_path(&(cfqg)->blkg), ##args) \
378 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
379 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
380 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
382 #define cfq_log(cfqd, fmt, args...) \
383 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
385 /* Traverses through cfq group service trees */
386 #define for_each_cfqg_st(cfqg, i, j, st) \
387 for (i = 0; i <= IDLE_WORKLOAD; i++) \
388 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
389 : &cfqg->service_tree_idle; \
390 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
391 (i == IDLE_WORKLOAD && j == 0); \
392 j++, st = i < IDLE_WORKLOAD ? \
393 &cfqg->service_trees[i][j]: NULL) \
395 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
396 struct cfq_ttime
*ttime
, bool group_idle
)
399 if (!sample_valid(ttime
->ttime_samples
))
402 slice
= cfqd
->cfq_group_idle
;
404 slice
= cfqd
->cfq_slice_idle
;
405 return ttime
->ttime_mean
> slice
;
408 static inline bool iops_mode(struct cfq_data
*cfqd
)
411 * If we are not idling on queues and it is a NCQ drive, parallel
412 * execution of requests is on and measuring time is not possible
413 * in most of the cases until and unless we drive shallower queue
414 * depths and that becomes a performance bottleneck. In such cases
415 * switch to start providing fairness in terms of number of IOs.
417 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
423 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
425 if (cfq_class_idle(cfqq
))
426 return IDLE_WORKLOAD
;
427 if (cfq_class_rt(cfqq
))
433 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
435 if (!cfq_cfqq_sync(cfqq
))
436 return ASYNC_WORKLOAD
;
437 if (!cfq_cfqq_idle_window(cfqq
))
438 return SYNC_NOIDLE_WORKLOAD
;
439 return SYNC_WORKLOAD
;
442 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
443 struct cfq_data
*cfqd
,
444 struct cfq_group
*cfqg
)
446 if (wl
== IDLE_WORKLOAD
)
447 return cfqg
->service_tree_idle
.count
;
449 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
450 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
451 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
454 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
455 struct cfq_group
*cfqg
)
457 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
458 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
461 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
462 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
463 struct io_context
*, gfp_t
);
464 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
465 struct io_context
*);
467 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
470 return cic
->cfqq
[is_sync
];
473 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
474 struct cfq_queue
*cfqq
, bool is_sync
)
476 cic
->cfqq
[is_sync
] = cfqq
;
479 #define CIC_DEAD_KEY 1ul
480 #define CIC_DEAD_INDEX_SHIFT 1
482 static inline void *cfqd_dead_key(struct cfq_data
*cfqd
)
484 return (void *)(cfqd
->queue
->id
<< CIC_DEAD_INDEX_SHIFT
| CIC_DEAD_KEY
);
487 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_context
*cic
)
489 struct cfq_data
*cfqd
= cic
->key
;
491 if (unlikely((unsigned long) cfqd
& CIC_DEAD_KEY
))
498 * We regard a request as SYNC, if it's either a read or has the SYNC bit
499 * set (in which case it could also be direct WRITE).
501 static inline bool cfq_bio_sync(struct bio
*bio
)
503 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
507 * scheduler run of queue, if there are requests pending and no one in the
508 * driver that will restart queueing
510 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
512 if (cfqd
->busy_queues
) {
513 cfq_log(cfqd
, "schedule dispatch");
514 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
519 * Scale schedule slice based on io priority. Use the sync time slice only
520 * if a queue is marked sync and has sync io queued. A sync queue with async
521 * io only, should not get full sync slice length.
523 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
526 const int base_slice
= cfqd
->cfq_slice
[sync
];
528 WARN_ON(prio
>= IOPRIO_BE_NR
);
530 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
534 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
536 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
539 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
541 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
543 d
= d
* BLKIO_WEIGHT_DEFAULT
;
544 do_div(d
, cfqg
->weight
);
548 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
550 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
552 min_vdisktime
= vdisktime
;
554 return min_vdisktime
;
557 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
559 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
561 min_vdisktime
= vdisktime
;
563 return min_vdisktime
;
566 static void update_min_vdisktime(struct cfq_rb_root
*st
)
568 struct cfq_group
*cfqg
;
571 cfqg
= rb_entry_cfqg(st
->left
);
572 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
578 * get averaged number of queues of RT/BE priority.
579 * average is updated, with a formula that gives more weight to higher numbers,
580 * to quickly follows sudden increases and decrease slowly
583 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
584 struct cfq_group
*cfqg
, bool rt
)
586 unsigned min_q
, max_q
;
587 unsigned mult
= cfq_hist_divisor
- 1;
588 unsigned round
= cfq_hist_divisor
/ 2;
589 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
591 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
592 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
593 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
595 return cfqg
->busy_queues_avg
[rt
];
598 static inline unsigned
599 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
601 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
603 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
606 static inline unsigned
607 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
609 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
610 if (cfqd
->cfq_latency
) {
612 * interested queues (we consider only the ones with the same
613 * priority class in the cfq group)
615 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
617 unsigned sync_slice
= cfqd
->cfq_slice
[1];
618 unsigned expect_latency
= sync_slice
* iq
;
619 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
621 if (expect_latency
> group_slice
) {
622 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
623 /* scale low_slice according to IO priority
624 * and sync vs async */
626 min(slice
, base_low_slice
* slice
/ sync_slice
);
627 /* the adapted slice value is scaled to fit all iqs
628 * into the target latency */
629 slice
= max(slice
* group_slice
/ expect_latency
,
637 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
639 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
641 cfqq
->slice_start
= jiffies
;
642 cfqq
->slice_end
= jiffies
+ slice
;
643 cfqq
->allocated_slice
= slice
;
644 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
648 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
649 * isn't valid until the first request from the dispatch is activated
650 * and the slice time set.
652 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
654 if (cfq_cfqq_slice_new(cfqq
))
656 if (time_before(jiffies
, cfqq
->slice_end
))
663 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
664 * We choose the request that is closest to the head right now. Distance
665 * behind the head is penalized and only allowed to a certain extent.
667 static struct request
*
668 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
670 sector_t s1
, s2
, d1
= 0, d2
= 0;
671 unsigned long back_max
;
672 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
673 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
674 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
676 if (rq1
== NULL
|| rq1
== rq2
)
681 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
682 return rq_is_sync(rq1
) ? rq1
: rq2
;
684 if ((rq1
->cmd_flags
^ rq2
->cmd_flags
) & REQ_PRIO
)
685 return rq1
->cmd_flags
& REQ_PRIO
? rq1
: rq2
;
687 s1
= blk_rq_pos(rq1
);
688 s2
= blk_rq_pos(rq2
);
691 * by definition, 1KiB is 2 sectors
693 back_max
= cfqd
->cfq_back_max
* 2;
696 * Strict one way elevator _except_ in the case where we allow
697 * short backward seeks which are biased as twice the cost of a
698 * similar forward seek.
702 else if (s1
+ back_max
>= last
)
703 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
705 wrap
|= CFQ_RQ1_WRAP
;
709 else if (s2
+ back_max
>= last
)
710 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
712 wrap
|= CFQ_RQ2_WRAP
;
714 /* Found required data */
717 * By doing switch() on the bit mask "wrap" we avoid having to
718 * check two variables for all permutations: --> faster!
721 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
737 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
740 * Since both rqs are wrapped,
741 * start with the one that's further behind head
742 * (--> only *one* back seek required),
743 * since back seek takes more time than forward.
753 * The below is leftmost cache rbtree addon
755 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
757 /* Service tree is empty */
762 root
->left
= rb_first(&root
->rb
);
765 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
770 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
773 root
->left
= rb_first(&root
->rb
);
776 return rb_entry_cfqg(root
->left
);
781 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
787 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
791 rb_erase_init(n
, &root
->rb
);
796 * would be nice to take fifo expire time into account as well
798 static struct request
*
799 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
800 struct request
*last
)
802 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
803 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
804 struct request
*next
= NULL
, *prev
= NULL
;
806 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
809 prev
= rb_entry_rq(rbprev
);
812 next
= rb_entry_rq(rbnext
);
814 rbnext
= rb_first(&cfqq
->sort_list
);
815 if (rbnext
&& rbnext
!= &last
->rb_node
)
816 next
= rb_entry_rq(rbnext
);
819 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
822 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
823 struct cfq_queue
*cfqq
)
826 * just an approximation, should be ok.
828 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
829 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
833 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
835 return cfqg
->vdisktime
- st
->min_vdisktime
;
839 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
841 struct rb_node
**node
= &st
->rb
.rb_node
;
842 struct rb_node
*parent
= NULL
;
843 struct cfq_group
*__cfqg
;
844 s64 key
= cfqg_key(st
, cfqg
);
847 while (*node
!= NULL
) {
849 __cfqg
= rb_entry_cfqg(parent
);
851 if (key
< cfqg_key(st
, __cfqg
))
852 node
= &parent
->rb_left
;
854 node
= &parent
->rb_right
;
860 st
->left
= &cfqg
->rb_node
;
862 rb_link_node(&cfqg
->rb_node
, parent
, node
);
863 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
867 cfq_update_group_weight(struct cfq_group
*cfqg
)
869 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
870 if (cfqg
->needs_update
) {
871 cfqg
->weight
= cfqg
->new_weight
;
872 cfqg
->needs_update
= false;
877 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
879 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
881 cfq_update_group_weight(cfqg
);
882 __cfq_group_service_tree_add(st
, cfqg
);
883 st
->total_weight
+= cfqg
->weight
;
887 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
889 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
890 struct cfq_group
*__cfqg
;
894 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
898 * Currently put the group at the end. Later implement something
899 * so that groups get lesser vtime based on their weights, so that
900 * if group does not loose all if it was not continuously backlogged.
902 n
= rb_last(&st
->rb
);
904 __cfqg
= rb_entry_cfqg(n
);
905 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
907 cfqg
->vdisktime
= st
->min_vdisktime
;
908 cfq_group_service_tree_add(st
, cfqg
);
912 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
914 st
->total_weight
-= cfqg
->weight
;
915 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
916 cfq_rb_erase(&cfqg
->rb_node
, st
);
920 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
922 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
924 BUG_ON(cfqg
->nr_cfqq
< 1);
927 /* If there are other cfq queues under this group, don't delete it */
931 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
932 cfq_group_service_tree_del(st
, cfqg
);
933 cfqg
->saved_workload_slice
= 0;
934 cfq_blkiocg_update_dequeue_stats(&cfqg
->blkg
, 1);
937 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
938 unsigned int *unaccounted_time
)
940 unsigned int slice_used
;
943 * Queue got expired before even a single request completed or
944 * got expired immediately after first request completion.
946 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
948 * Also charge the seek time incurred to the group, otherwise
949 * if there are mutiple queues in the group, each can dispatch
950 * a single request on seeky media and cause lots of seek time
951 * and group will never know it.
953 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
956 slice_used
= jiffies
- cfqq
->slice_start
;
957 if (slice_used
> cfqq
->allocated_slice
) {
958 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
959 slice_used
= cfqq
->allocated_slice
;
961 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
962 *unaccounted_time
+= cfqq
->slice_start
-
963 cfqq
->dispatch_start
;
969 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
970 struct cfq_queue
*cfqq
)
972 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
973 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
974 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
975 - cfqg
->service_tree_idle
.count
;
978 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
981 charge
= cfqq
->slice_dispatch
;
982 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
983 charge
= cfqq
->allocated_slice
;
985 /* Can't update vdisktime while group is on service tree */
986 cfq_group_service_tree_del(st
, cfqg
);
987 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
988 /* If a new weight was requested, update now, off tree */
989 cfq_group_service_tree_add(st
, cfqg
);
991 /* This group is being expired. Save the context */
992 if (time_after(cfqd
->workload_expires
, jiffies
)) {
993 cfqg
->saved_workload_slice
= cfqd
->workload_expires
995 cfqg
->saved_workload
= cfqd
->serving_type
;
996 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
998 cfqg
->saved_workload_slice
= 0;
1000 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
1002 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
1003 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1004 used_sl
, cfqq
->slice_dispatch
, charge
,
1005 iops_mode(cfqd
), cfqq
->nr_sectors
);
1006 cfq_blkiocg_update_timeslice_used(&cfqg
->blkg
, used_sl
,
1008 cfq_blkiocg_set_start_empty_time(&cfqg
->blkg
);
1011 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1012 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
1015 return container_of(blkg
, struct cfq_group
, blkg
);
1019 static void cfq_update_blkio_group_weight(void *key
, struct blkio_group
*blkg
,
1020 unsigned int weight
)
1022 struct cfq_group
*cfqg
= cfqg_of_blkg(blkg
);
1023 cfqg
->new_weight
= weight
;
1024 cfqg
->needs_update
= true;
1027 static void cfq_init_add_cfqg_lists(struct cfq_data
*cfqd
,
1028 struct cfq_group
*cfqg
, struct blkio_cgroup
*blkcg
)
1030 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1031 unsigned int major
, minor
;
1034 * Add group onto cgroup list. It might happen that bdi->dev is
1035 * not initialized yet. Initialize this new group without major
1036 * and minor info and this info will be filled in once a new thread
1040 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1041 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1042 (void *)cfqd
, MKDEV(major
, minor
));
1044 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1047 cfqd
->nr_blkcg_linked_grps
++;
1048 cfqg
->weight
= blkcg_get_weight(blkcg
, cfqg
->blkg
.dev
);
1050 /* Add group on cfqd list */
1051 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
1055 * Should be called from sleepable context. No request queue lock as per
1056 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1057 * from sleepable context.
1059 static struct cfq_group
* cfq_alloc_cfqg(struct cfq_data
*cfqd
)
1061 struct cfq_group
*cfqg
= NULL
;
1063 struct cfq_rb_root
*st
;
1065 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
1069 for_each_cfqg_st(cfqg
, i
, j
, st
)
1071 RB_CLEAR_NODE(&cfqg
->rb_node
);
1073 cfqg
->ttime
.last_end_request
= jiffies
;
1076 * Take the initial reference that will be released on destroy
1077 * This can be thought of a joint reference by cgroup and
1078 * elevator which will be dropped by either elevator exit
1079 * or cgroup deletion path depending on who is exiting first.
1083 ret
= blkio_alloc_blkg_stats(&cfqg
->blkg
);
1092 static struct cfq_group
*
1093 cfq_find_cfqg(struct cfq_data
*cfqd
, struct blkio_cgroup
*blkcg
)
1095 struct cfq_group
*cfqg
= NULL
;
1097 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1098 unsigned int major
, minor
;
1101 * This is the common case when there are no blkio cgroups.
1102 * Avoid lookup in this case
1104 if (blkcg
== &blkio_root_cgroup
)
1105 cfqg
= &cfqd
->root_group
;
1107 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
1109 if (cfqg
&& !cfqg
->blkg
.dev
&& bdi
->dev
&& dev_name(bdi
->dev
)) {
1110 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1111 cfqg
->blkg
.dev
= MKDEV(major
, minor
);
1118 * Search for the cfq group current task belongs to. request_queue lock must
1121 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1123 struct blkio_cgroup
*blkcg
;
1124 struct cfq_group
*cfqg
= NULL
, *__cfqg
= NULL
;
1125 struct request_queue
*q
= cfqd
->queue
;
1128 blkcg
= task_blkio_cgroup(current
);
1129 cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1136 * Need to allocate a group. Allocation of group also needs allocation
1137 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1138 * we need to drop rcu lock and queue_lock before we call alloc.
1140 * Not taking any queue reference here and assuming that queue is
1141 * around by the time we return. CFQ queue allocation code does
1142 * the same. It might be racy though.
1146 spin_unlock_irq(q
->queue_lock
);
1148 cfqg
= cfq_alloc_cfqg(cfqd
);
1150 spin_lock_irq(q
->queue_lock
);
1153 blkcg
= task_blkio_cgroup(current
);
1156 * If some other thread already allocated the group while we were
1157 * not holding queue lock, free up the group
1159 __cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1168 cfqg
= &cfqd
->root_group
;
1170 cfq_init_add_cfqg_lists(cfqd
, cfqg
, blkcg
);
1175 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1181 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1183 /* Currently, all async queues are mapped to root group */
1184 if (!cfq_cfqq_sync(cfqq
))
1185 cfqg
= &cfqq
->cfqd
->root_group
;
1188 /* cfqq reference on cfqg */
1192 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1194 struct cfq_rb_root
*st
;
1197 BUG_ON(cfqg
->ref
<= 0);
1201 for_each_cfqg_st(cfqg
, i
, j
, st
)
1202 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
));
1203 free_percpu(cfqg
->blkg
.stats_cpu
);
1207 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1209 /* Something wrong if we are trying to remove same group twice */
1210 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1212 hlist_del_init(&cfqg
->cfqd_node
);
1214 BUG_ON(cfqd
->nr_blkcg_linked_grps
<= 0);
1215 cfqd
->nr_blkcg_linked_grps
--;
1218 * Put the reference taken at the time of creation so that when all
1219 * queues are gone, group can be destroyed.
1224 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1226 struct hlist_node
*pos
, *n
;
1227 struct cfq_group
*cfqg
;
1229 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1231 * If cgroup removal path got to blk_group first and removed
1232 * it from cgroup list, then it will take care of destroying
1235 if (!cfq_blkiocg_del_blkio_group(&cfqg
->blkg
))
1236 cfq_destroy_cfqg(cfqd
, cfqg
);
1241 * Blk cgroup controller notification saying that blkio_group object is being
1242 * delinked as associated cgroup object is going away. That also means that
1243 * no new IO will come in this group. So get rid of this group as soon as
1244 * any pending IO in the group is finished.
1246 * This function is called under rcu_read_lock(). key is the rcu protected
1247 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1250 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1251 * it should not be NULL as even if elevator was exiting, cgroup deltion
1252 * path got to it first.
1254 static void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1256 unsigned long flags
;
1257 struct cfq_data
*cfqd
= key
;
1259 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1260 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1261 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1264 #else /* GROUP_IOSCHED */
1265 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1267 return &cfqd
->root_group
;
1270 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1276 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1280 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1281 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1283 #endif /* GROUP_IOSCHED */
1286 * The cfqd->service_trees holds all pending cfq_queue's that have
1287 * requests waiting to be processed. It is sorted in the order that
1288 * we will service the queues.
1290 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1293 struct rb_node
**p
, *parent
;
1294 struct cfq_queue
*__cfqq
;
1295 unsigned long rb_key
;
1296 struct cfq_rb_root
*service_tree
;
1300 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1302 if (cfq_class_idle(cfqq
)) {
1303 rb_key
= CFQ_IDLE_DELAY
;
1304 parent
= rb_last(&service_tree
->rb
);
1305 if (parent
&& parent
!= &cfqq
->rb_node
) {
1306 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1307 rb_key
+= __cfqq
->rb_key
;
1310 } else if (!add_front
) {
1312 * Get our rb key offset. Subtract any residual slice
1313 * value carried from last service. A negative resid
1314 * count indicates slice overrun, and this should position
1315 * the next service time further away in the tree.
1317 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1318 rb_key
-= cfqq
->slice_resid
;
1319 cfqq
->slice_resid
= 0;
1322 __cfqq
= cfq_rb_first(service_tree
);
1323 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1326 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1329 * same position, nothing more to do
1331 if (rb_key
== cfqq
->rb_key
&&
1332 cfqq
->service_tree
== service_tree
)
1335 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1336 cfqq
->service_tree
= NULL
;
1341 cfqq
->service_tree
= service_tree
;
1342 p
= &service_tree
->rb
.rb_node
;
1347 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1350 * sort by key, that represents service time.
1352 if (time_before(rb_key
, __cfqq
->rb_key
))
1355 n
= &(*p
)->rb_right
;
1363 service_tree
->left
= &cfqq
->rb_node
;
1365 cfqq
->rb_key
= rb_key
;
1366 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1367 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1368 service_tree
->count
++;
1369 if (add_front
|| !new_cfqq
)
1371 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
1374 static struct cfq_queue
*
1375 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1376 sector_t sector
, struct rb_node
**ret_parent
,
1377 struct rb_node
***rb_link
)
1379 struct rb_node
**p
, *parent
;
1380 struct cfq_queue
*cfqq
= NULL
;
1388 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1391 * Sort strictly based on sector. Smallest to the left,
1392 * largest to the right.
1394 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1395 n
= &(*p
)->rb_right
;
1396 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1404 *ret_parent
= parent
;
1410 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1412 struct rb_node
**p
, *parent
;
1413 struct cfq_queue
*__cfqq
;
1416 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1417 cfqq
->p_root
= NULL
;
1420 if (cfq_class_idle(cfqq
))
1425 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1426 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1427 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1429 rb_link_node(&cfqq
->p_node
, parent
, p
);
1430 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1432 cfqq
->p_root
= NULL
;
1436 * Update cfqq's position in the service tree.
1438 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1441 * Resorting requires the cfqq to be on the RR list already.
1443 if (cfq_cfqq_on_rr(cfqq
)) {
1444 cfq_service_tree_add(cfqd
, cfqq
, 0);
1445 cfq_prio_tree_add(cfqd
, cfqq
);
1450 * add to busy list of queues for service, trying to be fair in ordering
1451 * the pending list according to last request service
1453 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1455 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1456 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1457 cfq_mark_cfqq_on_rr(cfqq
);
1458 cfqd
->busy_queues
++;
1459 if (cfq_cfqq_sync(cfqq
))
1460 cfqd
->busy_sync_queues
++;
1462 cfq_resort_rr_list(cfqd
, cfqq
);
1466 * Called when the cfqq no longer has requests pending, remove it from
1469 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1471 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1472 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1473 cfq_clear_cfqq_on_rr(cfqq
);
1475 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1476 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1477 cfqq
->service_tree
= NULL
;
1480 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1481 cfqq
->p_root
= NULL
;
1484 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
1485 BUG_ON(!cfqd
->busy_queues
);
1486 cfqd
->busy_queues
--;
1487 if (cfq_cfqq_sync(cfqq
))
1488 cfqd
->busy_sync_queues
--;
1492 * rb tree support functions
1494 static void cfq_del_rq_rb(struct request
*rq
)
1496 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1497 const int sync
= rq_is_sync(rq
);
1499 BUG_ON(!cfqq
->queued
[sync
]);
1500 cfqq
->queued
[sync
]--;
1502 elv_rb_del(&cfqq
->sort_list
, rq
);
1504 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1506 * Queue will be deleted from service tree when we actually
1507 * expire it later. Right now just remove it from prio tree
1511 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1512 cfqq
->p_root
= NULL
;
1517 static void cfq_add_rq_rb(struct request
*rq
)
1519 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1520 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1521 struct request
*prev
;
1523 cfqq
->queued
[rq_is_sync(rq
)]++;
1525 elv_rb_add(&cfqq
->sort_list
, rq
);
1527 if (!cfq_cfqq_on_rr(cfqq
))
1528 cfq_add_cfqq_rr(cfqd
, cfqq
);
1531 * check if this request is a better next-serve candidate
1533 prev
= cfqq
->next_rq
;
1534 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1537 * adjust priority tree position, if ->next_rq changes
1539 if (prev
!= cfqq
->next_rq
)
1540 cfq_prio_tree_add(cfqd
, cfqq
);
1542 BUG_ON(!cfqq
->next_rq
);
1545 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1547 elv_rb_del(&cfqq
->sort_list
, rq
);
1548 cfqq
->queued
[rq_is_sync(rq
)]--;
1549 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1550 rq_data_dir(rq
), rq_is_sync(rq
));
1552 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
1553 &cfqq
->cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
1557 static struct request
*
1558 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1560 struct task_struct
*tsk
= current
;
1561 struct cfq_io_context
*cic
;
1562 struct cfq_queue
*cfqq
;
1564 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1568 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1570 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1572 return elv_rb_find(&cfqq
->sort_list
, sector
);
1578 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1580 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1582 cfqd
->rq_in_driver
++;
1583 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1584 cfqd
->rq_in_driver
);
1586 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1589 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1591 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1593 WARN_ON(!cfqd
->rq_in_driver
);
1594 cfqd
->rq_in_driver
--;
1595 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1596 cfqd
->rq_in_driver
);
1599 static void cfq_remove_request(struct request
*rq
)
1601 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1603 if (cfqq
->next_rq
== rq
)
1604 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1606 list_del_init(&rq
->queuelist
);
1609 cfqq
->cfqd
->rq_queued
--;
1610 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1611 rq_data_dir(rq
), rq_is_sync(rq
));
1612 if (rq
->cmd_flags
& REQ_PRIO
) {
1613 WARN_ON(!cfqq
->prio_pending
);
1614 cfqq
->prio_pending
--;
1618 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1621 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1622 struct request
*__rq
;
1624 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1625 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1627 return ELEVATOR_FRONT_MERGE
;
1630 return ELEVATOR_NO_MERGE
;
1633 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1636 if (type
== ELEVATOR_FRONT_MERGE
) {
1637 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1639 cfq_reposition_rq_rb(cfqq
, req
);
1643 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1646 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req
))->blkg
,
1647 bio_data_dir(bio
), cfq_bio_sync(bio
));
1651 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1652 struct request
*next
)
1654 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1656 * reposition in fifo if next is older than rq
1658 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1659 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1660 list_move(&rq
->queuelist
, &next
->queuelist
);
1661 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1664 if (cfqq
->next_rq
== next
)
1666 cfq_remove_request(next
);
1667 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq
))->blkg
,
1668 rq_data_dir(next
), rq_is_sync(next
));
1671 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1674 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1675 struct cfq_io_context
*cic
;
1676 struct cfq_queue
*cfqq
;
1679 * Disallow merge of a sync bio into an async request.
1681 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1685 * Lookup the cfqq that this bio will be queued with and allow
1686 * merge only if rq is queued there. This function can be called
1687 * from plug merge without queue_lock. In such cases, ioc of @rq
1688 * and %current are guaranteed to be equal. Avoid lookup which
1689 * requires queue_lock by using @rq's cic.
1691 if (current
->io_context
== RQ_CIC(rq
)->ioc
) {
1694 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1699 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1700 return cfqq
== RQ_CFQQ(rq
);
1703 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1705 del_timer(&cfqd
->idle_slice_timer
);
1706 cfq_blkiocg_update_idle_time_stats(&cfqq
->cfqg
->blkg
);
1709 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1710 struct cfq_queue
*cfqq
)
1713 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
1714 cfqd
->serving_prio
, cfqd
->serving_type
);
1715 cfq_blkiocg_update_avg_queue_size_stats(&cfqq
->cfqg
->blkg
);
1716 cfqq
->slice_start
= 0;
1717 cfqq
->dispatch_start
= jiffies
;
1718 cfqq
->allocated_slice
= 0;
1719 cfqq
->slice_end
= 0;
1720 cfqq
->slice_dispatch
= 0;
1721 cfqq
->nr_sectors
= 0;
1723 cfq_clear_cfqq_wait_request(cfqq
);
1724 cfq_clear_cfqq_must_dispatch(cfqq
);
1725 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1726 cfq_clear_cfqq_fifo_expire(cfqq
);
1727 cfq_mark_cfqq_slice_new(cfqq
);
1729 cfq_del_timer(cfqd
, cfqq
);
1732 cfqd
->active_queue
= cfqq
;
1736 * current cfqq expired its slice (or was too idle), select new one
1739 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1742 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1744 if (cfq_cfqq_wait_request(cfqq
))
1745 cfq_del_timer(cfqd
, cfqq
);
1747 cfq_clear_cfqq_wait_request(cfqq
);
1748 cfq_clear_cfqq_wait_busy(cfqq
);
1751 * If this cfqq is shared between multiple processes, check to
1752 * make sure that those processes are still issuing I/Os within
1753 * the mean seek distance. If not, it may be time to break the
1754 * queues apart again.
1756 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
1757 cfq_mark_cfqq_split_coop(cfqq
);
1760 * store what was left of this slice, if the queue idled/timed out
1763 if (cfq_cfqq_slice_new(cfqq
))
1764 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
1766 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1767 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1770 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1772 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1773 cfq_del_cfqq_rr(cfqd
, cfqq
);
1775 cfq_resort_rr_list(cfqd
, cfqq
);
1777 if (cfqq
== cfqd
->active_queue
)
1778 cfqd
->active_queue
= NULL
;
1780 if (cfqd
->active_cic
) {
1781 put_io_context(cfqd
->active_cic
->ioc
, cfqd
->queue
);
1782 cfqd
->active_cic
= NULL
;
1786 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1788 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1791 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1795 * Get next queue for service. Unless we have a queue preemption,
1796 * we'll simply select the first cfqq in the service tree.
1798 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1800 struct cfq_rb_root
*service_tree
=
1801 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1802 cfqd
->serving_type
);
1804 if (!cfqd
->rq_queued
)
1807 /* There is nothing to dispatch */
1810 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1812 return cfq_rb_first(service_tree
);
1815 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1817 struct cfq_group
*cfqg
;
1818 struct cfq_queue
*cfqq
;
1820 struct cfq_rb_root
*st
;
1822 if (!cfqd
->rq_queued
)
1825 cfqg
= cfq_get_next_cfqg(cfqd
);
1829 for_each_cfqg_st(cfqg
, i
, j
, st
)
1830 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1836 * Get and set a new active queue for service.
1838 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1839 struct cfq_queue
*cfqq
)
1842 cfqq
= cfq_get_next_queue(cfqd
);
1844 __cfq_set_active_queue(cfqd
, cfqq
);
1848 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1851 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1852 return blk_rq_pos(rq
) - cfqd
->last_position
;
1854 return cfqd
->last_position
- blk_rq_pos(rq
);
1857 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1860 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
1863 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1864 struct cfq_queue
*cur_cfqq
)
1866 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1867 struct rb_node
*parent
, *node
;
1868 struct cfq_queue
*__cfqq
;
1869 sector_t sector
= cfqd
->last_position
;
1871 if (RB_EMPTY_ROOT(root
))
1875 * First, if we find a request starting at the end of the last
1876 * request, choose it.
1878 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1883 * If the exact sector wasn't found, the parent of the NULL leaf
1884 * will contain the closest sector.
1886 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1887 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1890 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1891 node
= rb_next(&__cfqq
->p_node
);
1893 node
= rb_prev(&__cfqq
->p_node
);
1897 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1898 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1906 * cur_cfqq - passed in so that we don't decide that the current queue is
1907 * closely cooperating with itself.
1909 * So, basically we're assuming that that cur_cfqq has dispatched at least
1910 * one request, and that cfqd->last_position reflects a position on the disk
1911 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1914 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1915 struct cfq_queue
*cur_cfqq
)
1917 struct cfq_queue
*cfqq
;
1919 if (cfq_class_idle(cur_cfqq
))
1921 if (!cfq_cfqq_sync(cur_cfqq
))
1923 if (CFQQ_SEEKY(cur_cfqq
))
1927 * Don't search priority tree if it's the only queue in the group.
1929 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1933 * We should notice if some of the queues are cooperating, eg
1934 * working closely on the same area of the disk. In that case,
1935 * we can group them together and don't waste time idling.
1937 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1941 /* If new queue belongs to different cfq_group, don't choose it */
1942 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1946 * It only makes sense to merge sync queues.
1948 if (!cfq_cfqq_sync(cfqq
))
1950 if (CFQQ_SEEKY(cfqq
))
1954 * Do not merge queues of different priority classes
1956 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1963 * Determine whether we should enforce idle window for this queue.
1966 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1968 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1969 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1971 BUG_ON(!service_tree
);
1972 BUG_ON(!service_tree
->count
);
1974 if (!cfqd
->cfq_slice_idle
)
1977 /* We never do for idle class queues. */
1978 if (prio
== IDLE_WORKLOAD
)
1981 /* We do for queues that were marked with idle window flag. */
1982 if (cfq_cfqq_idle_window(cfqq
) &&
1983 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1987 * Otherwise, we do only if they are the last ones
1988 * in their service tree.
1990 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
1991 !cfq_io_thinktime_big(cfqd
, &service_tree
->ttime
, false))
1993 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
1994 service_tree
->count
);
1998 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
2000 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
2001 struct cfq_io_context
*cic
;
2002 unsigned long sl
, group_idle
= 0;
2005 * SSD device without seek penalty, disable idling. But only do so
2006 * for devices that support queuing, otherwise we still have a problem
2007 * with sync vs async workloads.
2009 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
2012 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
2013 WARN_ON(cfq_cfqq_slice_new(cfqq
));
2016 * idle is disabled, either manually or by past process history
2018 if (!cfq_should_idle(cfqd
, cfqq
)) {
2019 /* no queue idling. Check for group idling */
2020 if (cfqd
->cfq_group_idle
)
2021 group_idle
= cfqd
->cfq_group_idle
;
2027 * still active requests from this queue, don't idle
2029 if (cfqq
->dispatched
)
2033 * task has exited, don't wait
2035 cic
= cfqd
->active_cic
;
2036 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
2040 * If our average think time is larger than the remaining time
2041 * slice, then don't idle. This avoids overrunning the allotted
2044 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2045 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2046 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2047 cic
->ttime
.ttime_mean
);
2051 /* There are other queues in the group, don't do group idle */
2052 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2055 cfq_mark_cfqq_wait_request(cfqq
);
2058 sl
= cfqd
->cfq_group_idle
;
2060 sl
= cfqd
->cfq_slice_idle
;
2062 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2063 cfq_blkiocg_update_set_idle_time_stats(&cfqq
->cfqg
->blkg
);
2064 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2065 group_idle
? 1 : 0);
2069 * Move request from internal lists to the request queue dispatch list.
2071 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2073 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2074 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2076 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2078 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2079 cfq_remove_request(rq
);
2081 (RQ_CFQG(rq
))->dispatched
++;
2082 elv_dispatch_sort(q
, rq
);
2084 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2085 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2086 cfq_blkiocg_update_dispatch_stats(&cfqq
->cfqg
->blkg
, blk_rq_bytes(rq
),
2087 rq_data_dir(rq
), rq_is_sync(rq
));
2091 * return expired entry, or NULL to just start from scratch in rbtree
2093 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2095 struct request
*rq
= NULL
;
2097 if (cfq_cfqq_fifo_expire(cfqq
))
2100 cfq_mark_cfqq_fifo_expire(cfqq
);
2102 if (list_empty(&cfqq
->fifo
))
2105 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2106 if (time_before(jiffies
, rq_fifo_time(rq
)))
2109 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2114 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2116 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2118 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2120 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2124 * Must be called with the queue_lock held.
2126 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2128 int process_refs
, io_refs
;
2130 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2131 process_refs
= cfqq
->ref
- io_refs
;
2132 BUG_ON(process_refs
< 0);
2133 return process_refs
;
2136 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2138 int process_refs
, new_process_refs
;
2139 struct cfq_queue
*__cfqq
;
2142 * If there are no process references on the new_cfqq, then it is
2143 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2144 * chain may have dropped their last reference (not just their
2145 * last process reference).
2147 if (!cfqq_process_refs(new_cfqq
))
2150 /* Avoid a circular list and skip interim queue merges */
2151 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2157 process_refs
= cfqq_process_refs(cfqq
);
2158 new_process_refs
= cfqq_process_refs(new_cfqq
);
2160 * If the process for the cfqq has gone away, there is no
2161 * sense in merging the queues.
2163 if (process_refs
== 0 || new_process_refs
== 0)
2167 * Merge in the direction of the lesser amount of work.
2169 if (new_process_refs
>= process_refs
) {
2170 cfqq
->new_cfqq
= new_cfqq
;
2171 new_cfqq
->ref
+= process_refs
;
2173 new_cfqq
->new_cfqq
= cfqq
;
2174 cfqq
->ref
+= new_process_refs
;
2178 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2179 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2181 struct cfq_queue
*queue
;
2183 bool key_valid
= false;
2184 unsigned long lowest_key
= 0;
2185 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2187 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2188 /* select the one with lowest rb_key */
2189 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2191 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2192 lowest_key
= queue
->rb_key
;
2201 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2205 struct cfq_rb_root
*st
;
2206 unsigned group_slice
;
2207 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2209 /* Choose next priority. RT > BE > IDLE */
2210 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2211 cfqd
->serving_prio
= RT_WORKLOAD
;
2212 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2213 cfqd
->serving_prio
= BE_WORKLOAD
;
2215 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2216 cfqd
->workload_expires
= jiffies
+ 1;
2220 if (original_prio
!= cfqd
->serving_prio
)
2224 * For RT and BE, we have to choose also the type
2225 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2228 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2232 * check workload expiration, and that we still have other queues ready
2234 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2238 /* otherwise select new workload type */
2239 cfqd
->serving_type
=
2240 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2241 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2245 * the workload slice is computed as a fraction of target latency
2246 * proportional to the number of queues in that workload, over
2247 * all the queues in the same priority class
2249 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2251 slice
= group_slice
* count
/
2252 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2253 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2255 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2259 * Async queues are currently system wide. Just taking
2260 * proportion of queues with-in same group will lead to higher
2261 * async ratio system wide as generally root group is going
2262 * to have higher weight. A more accurate thing would be to
2263 * calculate system wide asnc/sync ratio.
2265 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2266 tmp
= tmp
/cfqd
->busy_queues
;
2267 slice
= min_t(unsigned, slice
, tmp
);
2269 /* async workload slice is scaled down according to
2270 * the sync/async slice ratio. */
2271 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2273 /* sync workload slice is at least 2 * cfq_slice_idle */
2274 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2276 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2277 cfq_log(cfqd
, "workload slice:%d", slice
);
2278 cfqd
->workload_expires
= jiffies
+ slice
;
2281 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2283 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2284 struct cfq_group
*cfqg
;
2286 if (RB_EMPTY_ROOT(&st
->rb
))
2288 cfqg
= cfq_rb_first_group(st
);
2289 update_min_vdisktime(st
);
2293 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2295 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2297 cfqd
->serving_group
= cfqg
;
2299 /* Restore the workload type data */
2300 if (cfqg
->saved_workload_slice
) {
2301 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2302 cfqd
->serving_type
= cfqg
->saved_workload
;
2303 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2305 cfqd
->workload_expires
= jiffies
- 1;
2307 choose_service_tree(cfqd
, cfqg
);
2311 * Select a queue for service. If we have a current active queue,
2312 * check whether to continue servicing it, or retrieve and set a new one.
2314 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2316 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2318 cfqq
= cfqd
->active_queue
;
2322 if (!cfqd
->rq_queued
)
2326 * We were waiting for group to get backlogged. Expire the queue
2328 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2332 * The active queue has run out of time, expire it and select new.
2334 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2336 * If slice had not expired at the completion of last request
2337 * we might not have turned on wait_busy flag. Don't expire
2338 * the queue yet. Allow the group to get backlogged.
2340 * The very fact that we have used the slice, that means we
2341 * have been idling all along on this queue and it should be
2342 * ok to wait for this request to complete.
2344 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2345 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2349 goto check_group_idle
;
2353 * The active queue has requests and isn't expired, allow it to
2356 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2360 * If another queue has a request waiting within our mean seek
2361 * distance, let it run. The expire code will check for close
2362 * cooperators and put the close queue at the front of the service
2363 * tree. If possible, merge the expiring queue with the new cfqq.
2365 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2367 if (!cfqq
->new_cfqq
)
2368 cfq_setup_merge(cfqq
, new_cfqq
);
2373 * No requests pending. If the active queue still has requests in
2374 * flight or is idling for a new request, allow either of these
2375 * conditions to happen (or time out) before selecting a new queue.
2377 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2383 * This is a deep seek queue, but the device is much faster than
2384 * the queue can deliver, don't idle
2386 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2387 (cfq_cfqq_slice_new(cfqq
) ||
2388 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2389 cfq_clear_cfqq_deep(cfqq
);
2390 cfq_clear_cfqq_idle_window(cfqq
);
2393 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2399 * If group idle is enabled and there are requests dispatched from
2400 * this group, wait for requests to complete.
2403 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
2404 cfqq
->cfqg
->dispatched
&&
2405 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
2411 cfq_slice_expired(cfqd
, 0);
2414 * Current queue expired. Check if we have to switch to a new
2418 cfq_choose_cfqg(cfqd
);
2420 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2425 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2429 while (cfqq
->next_rq
) {
2430 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2434 BUG_ON(!list_empty(&cfqq
->fifo
));
2436 /* By default cfqq is not expired if it is empty. Do it explicitly */
2437 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2442 * Drain our current requests. Used for barriers and when switching
2443 * io schedulers on-the-fly.
2445 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2447 struct cfq_queue
*cfqq
;
2450 /* Expire the timeslice of the current active queue first */
2451 cfq_slice_expired(cfqd
, 0);
2452 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2453 __cfq_set_active_queue(cfqd
, cfqq
);
2454 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2457 BUG_ON(cfqd
->busy_queues
);
2459 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2463 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2464 struct cfq_queue
*cfqq
)
2466 /* the queue hasn't finished any request, can't estimate */
2467 if (cfq_cfqq_slice_new(cfqq
))
2469 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2476 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2478 unsigned int max_dispatch
;
2481 * Drain async requests before we start sync IO
2483 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2487 * If this is an async queue and we have sync IO in flight, let it wait
2489 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2492 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2493 if (cfq_class_idle(cfqq
))
2497 * Does this cfqq already have too much IO in flight?
2499 if (cfqq
->dispatched
>= max_dispatch
) {
2500 bool promote_sync
= false;
2502 * idle queue must always only have a single IO in flight
2504 if (cfq_class_idle(cfqq
))
2508 * If there is only one sync queue
2509 * we can ignore async queue here and give the sync
2510 * queue no dispatch limit. The reason is a sync queue can
2511 * preempt async queue, limiting the sync queue doesn't make
2512 * sense. This is useful for aiostress test.
2514 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
2515 promote_sync
= true;
2518 * We have other queues, don't allow more IO from this one
2520 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
2525 * Sole queue user, no limit
2527 if (cfqd
->busy_queues
== 1 || promote_sync
)
2531 * Normally we start throttling cfqq when cfq_quantum/2
2532 * requests have been dispatched. But we can drive
2533 * deeper queue depths at the beginning of slice
2534 * subjected to upper limit of cfq_quantum.
2536 max_dispatch
= cfqd
->cfq_quantum
;
2540 * Async queues must wait a bit before being allowed dispatch.
2541 * We also ramp up the dispatch depth gradually for async IO,
2542 * based on the last sync IO we serviced
2544 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2545 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2548 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2549 if (!depth
&& !cfqq
->dispatched
)
2551 if (depth
< max_dispatch
)
2552 max_dispatch
= depth
;
2556 * If we're below the current max, allow a dispatch
2558 return cfqq
->dispatched
< max_dispatch
;
2562 * Dispatch a request from cfqq, moving them to the request queue
2565 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2569 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2571 if (!cfq_may_dispatch(cfqd
, cfqq
))
2575 * follow expired path, else get first next available
2577 rq
= cfq_check_fifo(cfqq
);
2582 * insert request into driver dispatch list
2584 cfq_dispatch_insert(cfqd
->queue
, rq
);
2586 if (!cfqd
->active_cic
) {
2587 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2589 atomic_long_inc(&cic
->ioc
->refcount
);
2590 cfqd
->active_cic
= cic
;
2597 * Find the cfqq that we need to service and move a request from that to the
2600 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2602 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2603 struct cfq_queue
*cfqq
;
2605 if (!cfqd
->busy_queues
)
2608 if (unlikely(force
))
2609 return cfq_forced_dispatch(cfqd
);
2611 cfqq
= cfq_select_queue(cfqd
);
2616 * Dispatch a request from this cfqq, if it is allowed
2618 if (!cfq_dispatch_request(cfqd
, cfqq
))
2621 cfqq
->slice_dispatch
++;
2622 cfq_clear_cfqq_must_dispatch(cfqq
);
2625 * expire an async queue immediately if it has used up its slice. idle
2626 * queue always expire after 1 dispatch round.
2628 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2629 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2630 cfq_class_idle(cfqq
))) {
2631 cfqq
->slice_end
= jiffies
+ 1;
2632 cfq_slice_expired(cfqd
, 0);
2635 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2640 * task holds one reference to the queue, dropped when task exits. each rq
2641 * in-flight on this queue also holds a reference, dropped when rq is freed.
2643 * Each cfq queue took a reference on the parent group. Drop it now.
2644 * queue lock must be held here.
2646 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2648 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2649 struct cfq_group
*cfqg
;
2651 BUG_ON(cfqq
->ref
<= 0);
2657 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2658 BUG_ON(rb_first(&cfqq
->sort_list
));
2659 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2662 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2663 __cfq_slice_expired(cfqd
, cfqq
, 0);
2664 cfq_schedule_dispatch(cfqd
);
2667 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2668 kmem_cache_free(cfq_pool
, cfqq
);
2672 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2674 struct cfq_io_context
*cic
;
2676 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
2678 kmem_cache_free(cfq_ioc_pool
, cic
);
2679 elv_ioc_count_dec(cfq_ioc_count
);
2683 * CFQ scheduler is exiting, grab exit lock and check
2684 * the pending io context count. If it hits zero,
2685 * complete ioc_gone and set it back to NULL
2687 spin_lock(&ioc_gone_lock
);
2688 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
2692 spin_unlock(&ioc_gone_lock
);
2696 static void cfq_cic_free(struct cfq_io_context
*cic
)
2698 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2701 static void cfq_release_cic(struct cfq_io_context
*cic
)
2703 struct io_context
*ioc
= cic
->ioc
;
2704 unsigned long dead_key
= (unsigned long) cic
->key
;
2706 BUG_ON(!(dead_key
& CIC_DEAD_KEY
));
2707 radix_tree_delete(&ioc
->radix_root
, dead_key
>> CIC_DEAD_INDEX_SHIFT
);
2708 hlist_del_rcu(&cic
->cic_list
);
2712 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2714 struct cfq_queue
*__cfqq
, *next
;
2717 * If this queue was scheduled to merge with another queue, be
2718 * sure to drop the reference taken on that queue (and others in
2719 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2721 __cfqq
= cfqq
->new_cfqq
;
2723 if (__cfqq
== cfqq
) {
2724 WARN(1, "cfqq->new_cfqq loop detected\n");
2727 next
= __cfqq
->new_cfqq
;
2728 cfq_put_queue(__cfqq
);
2733 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2735 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2736 __cfq_slice_expired(cfqd
, cfqq
, 0);
2737 cfq_schedule_dispatch(cfqd
);
2740 cfq_put_cooperator(cfqq
);
2742 cfq_put_queue(cfqq
);
2745 static void cfq_exit_cic(struct cfq_io_context
*cic
)
2747 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2748 struct io_context
*ioc
= cic
->ioc
;
2750 list_del_init(&cic
->queue_list
);
2751 cic
->key
= cfqd_dead_key(cfqd
);
2754 * Both setting lookup hint to and clearing it from @cic are done
2755 * under queue_lock. If it's not pointing to @cic now, it never
2756 * will. Hint assignment itself can race safely.
2758 if (rcu_dereference_raw(ioc
->ioc_data
) == cic
)
2759 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2761 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2762 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2763 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2766 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2767 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2768 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2772 static struct cfq_io_context
*
2773 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2775 struct cfq_io_context
*cic
;
2777 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2780 cic
->ttime
.last_end_request
= jiffies
;
2781 INIT_LIST_HEAD(&cic
->queue_list
);
2782 INIT_HLIST_NODE(&cic
->cic_list
);
2783 cic
->exit
= cfq_exit_cic
;
2784 cic
->release
= cfq_release_cic
;
2785 elv_ioc_count_inc(cfq_ioc_count
);
2791 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2793 struct task_struct
*tsk
= current
;
2796 if (!cfq_cfqq_prio_changed(cfqq
))
2799 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2800 switch (ioprio_class
) {
2802 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2803 case IOPRIO_CLASS_NONE
:
2805 * no prio set, inherit CPU scheduling settings
2807 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2808 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2810 case IOPRIO_CLASS_RT
:
2811 cfqq
->ioprio
= task_ioprio(ioc
);
2812 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2814 case IOPRIO_CLASS_BE
:
2815 cfqq
->ioprio
= task_ioprio(ioc
);
2816 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2818 case IOPRIO_CLASS_IDLE
:
2819 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2821 cfq_clear_cfqq_idle_window(cfqq
);
2826 * keep track of original prio settings in case we have to temporarily
2827 * elevate the priority of this queue
2829 cfqq
->org_ioprio
= cfqq
->ioprio
;
2830 cfq_clear_cfqq_prio_changed(cfqq
);
2833 static void changed_ioprio(struct cfq_io_context
*cic
)
2835 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2836 struct cfq_queue
*cfqq
;
2838 if (unlikely(!cfqd
))
2841 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2843 struct cfq_queue
*new_cfqq
;
2844 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2847 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2848 cfq_put_queue(cfqq
);
2852 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2854 cfq_mark_cfqq_prio_changed(cfqq
);
2857 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2858 pid_t pid
, bool is_sync
)
2860 RB_CLEAR_NODE(&cfqq
->rb_node
);
2861 RB_CLEAR_NODE(&cfqq
->p_node
);
2862 INIT_LIST_HEAD(&cfqq
->fifo
);
2867 cfq_mark_cfqq_prio_changed(cfqq
);
2870 if (!cfq_class_idle(cfqq
))
2871 cfq_mark_cfqq_idle_window(cfqq
);
2872 cfq_mark_cfqq_sync(cfqq
);
2877 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2878 static void changed_cgroup(struct cfq_io_context
*cic
)
2880 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2881 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2882 struct request_queue
*q
;
2884 if (unlikely(!cfqd
))
2891 * Drop reference to sync queue. A new sync queue will be
2892 * assigned in new group upon arrival of a fresh request.
2894 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2895 cic_set_cfqq(cic
, NULL
, 1);
2896 cfq_put_queue(sync_cfqq
);
2899 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2901 static struct cfq_queue
*
2902 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2903 struct io_context
*ioc
, gfp_t gfp_mask
)
2905 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2906 struct cfq_io_context
*cic
;
2907 struct cfq_group
*cfqg
;
2910 cfqg
= cfq_get_cfqg(cfqd
);
2911 cic
= cfq_cic_lookup(cfqd
, ioc
);
2912 /* cic always exists here */
2913 cfqq
= cic_to_cfqq(cic
, is_sync
);
2916 * Always try a new alloc if we fell back to the OOM cfqq
2917 * originally, since it should just be a temporary situation.
2919 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2924 } else if (gfp_mask
& __GFP_WAIT
) {
2925 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2926 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2927 gfp_mask
| __GFP_ZERO
,
2929 spin_lock_irq(cfqd
->queue
->queue_lock
);
2933 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2934 gfp_mask
| __GFP_ZERO
,
2939 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2940 cfq_init_prio_data(cfqq
, ioc
);
2941 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2942 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2944 cfqq
= &cfqd
->oom_cfqq
;
2948 kmem_cache_free(cfq_pool
, new_cfqq
);
2953 static struct cfq_queue
**
2954 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2956 switch (ioprio_class
) {
2957 case IOPRIO_CLASS_RT
:
2958 return &cfqd
->async_cfqq
[0][ioprio
];
2959 case IOPRIO_CLASS_BE
:
2960 return &cfqd
->async_cfqq
[1][ioprio
];
2961 case IOPRIO_CLASS_IDLE
:
2962 return &cfqd
->async_idle_cfqq
;
2968 static struct cfq_queue
*
2969 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2972 const int ioprio
= task_ioprio(ioc
);
2973 const int ioprio_class
= task_ioprio_class(ioc
);
2974 struct cfq_queue
**async_cfqq
= NULL
;
2975 struct cfq_queue
*cfqq
= NULL
;
2978 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2983 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2986 * pin the queue now that it's allocated, scheduler exit will prune it
2988 if (!is_sync
&& !(*async_cfqq
)) {
2998 * cfq_cic_lookup - lookup cfq_io_context
2999 * @cfqd: the associated cfq_data
3000 * @ioc: the associated io_context
3002 * Look up cfq_io_context associated with @cfqd - @ioc pair. Must be
3003 * called with queue_lock held.
3005 static struct cfq_io_context
*
3006 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
3008 struct cfq_io_context
*cic
;
3010 lockdep_assert_held(cfqd
->queue
->queue_lock
);
3015 * cic's are indexed from @ioc using radix tree and hint pointer,
3016 * both of which are protected with RCU. All removals are done
3017 * holding both q and ioc locks, and we're holding q lock - if we
3018 * find a cic which points to us, it's guaranteed to be valid.
3021 cic
= rcu_dereference(ioc
->ioc_data
);
3022 if (cic
&& cic
->key
== cfqd
)
3025 cic
= radix_tree_lookup(&ioc
->radix_root
, cfqd
->queue
->id
);
3026 if (cic
&& cic
->key
== cfqd
)
3027 rcu_assign_pointer(ioc
->ioc_data
, cic
); /* allowed to race */
3036 * cfq_create_cic - create and link a cfq_io_context
3037 * @cfqd: cfqd of interest
3038 * @gfp_mask: allocation mask
3040 * Make sure cfq_io_context linking %current->io_context and @cfqd exists.
3041 * If ioc and/or cic doesn't exist, they will be created using @gfp_mask.
3043 static int cfq_create_cic(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3045 struct request_queue
*q
= cfqd
->queue
;
3046 struct cfq_io_context
*cic
= NULL
;
3047 struct io_context
*ioc
;
3050 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3052 /* allocate stuff */
3053 ioc
= current_io_context(gfp_mask
, q
->node
);
3057 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
3061 ret
= radix_tree_preload(gfp_mask
);
3067 cic
->q
= cfqd
->queue
;
3069 /* lock both q and ioc and try to link @cic */
3070 spin_lock_irq(q
->queue_lock
);
3071 spin_lock(&ioc
->lock
);
3073 ret
= radix_tree_insert(&ioc
->radix_root
, q
->id
, cic
);
3075 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
3076 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
3078 } else if (ret
== -EEXIST
) {
3079 /* someone else already did it */
3083 spin_unlock(&ioc
->lock
);
3084 spin_unlock_irq(q
->queue_lock
);
3086 radix_tree_preload_end();
3089 printk(KERN_ERR
"cfq: cic link failed!\n");
3096 * cfq_get_io_context - acquire cfq_io_context and bump refcnt on io_context
3097 * @cfqd: cfqd to setup cic for
3098 * @gfp_mask: allocation mask
3100 * Return cfq_io_context associating @cfqd and %current->io_context and
3101 * bump refcnt on io_context. If ioc or cic doesn't exist, they're created
3104 * Must be called under queue_lock which may be released and re-acquired.
3105 * This function also may sleep depending on @gfp_mask.
3107 static struct cfq_io_context
*
3108 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3110 struct request_queue
*q
= cfqd
->queue
;
3111 struct cfq_io_context
*cic
= NULL
;
3112 struct io_context
*ioc
;
3115 lockdep_assert_held(q
->queue_lock
);
3119 ioc
= current
->io_context
;
3121 cic
= cfq_cic_lookup(cfqd
, ioc
);
3126 /* slow path - unlock, create missing ones and retry */
3127 spin_unlock_irq(q
->queue_lock
);
3128 err
= cfq_create_cic(cfqd
, gfp_mask
);
3129 spin_lock_irq(q
->queue_lock
);
3134 /* bump @ioc's refcnt and handle changed notifications */
3135 get_io_context(ioc
);
3137 if (unlikely(cic
->changed
)) {
3138 if (test_and_clear_bit(CIC_IOPRIO_CHANGED
, &cic
->changed
))
3139 changed_ioprio(cic
);
3140 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3141 if (test_and_clear_bit(CIC_CGROUP_CHANGED
, &cic
->changed
))
3142 changed_cgroup(cic
);
3150 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
3152 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
3153 elapsed
= min(elapsed
, 2UL * slice_idle
);
3155 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
3156 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
3157 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
3161 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3162 struct cfq_io_context
*cic
)
3164 if (cfq_cfqq_sync(cfqq
)) {
3165 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
3166 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
3167 cfqd
->cfq_slice_idle
);
3169 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3170 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
3175 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3179 sector_t n_sec
= blk_rq_sectors(rq
);
3180 if (cfqq
->last_request_pos
) {
3181 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3182 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3184 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3187 cfqq
->seek_history
<<= 1;
3188 if (blk_queue_nonrot(cfqd
->queue
))
3189 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3191 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3195 * Disable idle window if the process thinks too long or seeks so much that
3199 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3200 struct cfq_io_context
*cic
)
3202 int old_idle
, enable_idle
;
3205 * Don't idle for async or idle io prio class
3207 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3210 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3212 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3213 cfq_mark_cfqq_deep(cfqq
);
3215 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3217 else if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3218 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3220 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3221 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3227 if (old_idle
!= enable_idle
) {
3228 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3230 cfq_mark_cfqq_idle_window(cfqq
);
3232 cfq_clear_cfqq_idle_window(cfqq
);
3237 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3238 * no or if we aren't sure, a 1 will cause a preempt.
3241 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3244 struct cfq_queue
*cfqq
;
3246 cfqq
= cfqd
->active_queue
;
3250 if (cfq_class_idle(new_cfqq
))
3253 if (cfq_class_idle(cfqq
))
3257 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3259 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3263 * if the new request is sync, but the currently running queue is
3264 * not, let the sync request have priority.
3266 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3269 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3272 if (cfq_slice_used(cfqq
))
3275 /* Allow preemption only if we are idling on sync-noidle tree */
3276 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3277 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3278 new_cfqq
->service_tree
->count
== 2 &&
3279 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3283 * So both queues are sync. Let the new request get disk time if
3284 * it's a metadata request and the current queue is doing regular IO.
3286 if ((rq
->cmd_flags
& REQ_PRIO
) && !cfqq
->prio_pending
)
3290 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3292 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3295 /* An idle queue should not be idle now for some reason */
3296 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3299 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3303 * if this request is as-good as one we would expect from the
3304 * current cfqq, let it preempt
3306 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3313 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3314 * let it have half of its nominal slice.
3316 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3318 struct cfq_queue
*old_cfqq
= cfqd
->active_queue
;
3320 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3321 cfq_slice_expired(cfqd
, 1);
3324 * workload type is changed, don't save slice, otherwise preempt
3327 if (cfqq_type(old_cfqq
) != cfqq_type(cfqq
))
3328 cfqq
->cfqg
->saved_workload_slice
= 0;
3331 * Put the new queue at the front of the of the current list,
3332 * so we know that it will be selected next.
3334 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3336 cfq_service_tree_add(cfqd
, cfqq
, 1);
3338 cfqq
->slice_end
= 0;
3339 cfq_mark_cfqq_slice_new(cfqq
);
3343 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3344 * something we should do about it
3347 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3350 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3353 if (rq
->cmd_flags
& REQ_PRIO
)
3354 cfqq
->prio_pending
++;
3356 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3357 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3358 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3360 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3362 if (cfqq
== cfqd
->active_queue
) {
3364 * Remember that we saw a request from this process, but
3365 * don't start queuing just yet. Otherwise we risk seeing lots
3366 * of tiny requests, because we disrupt the normal plugging
3367 * and merging. If the request is already larger than a single
3368 * page, let it rip immediately. For that case we assume that
3369 * merging is already done. Ditto for a busy system that
3370 * has other work pending, don't risk delaying until the
3371 * idle timer unplug to continue working.
3373 if (cfq_cfqq_wait_request(cfqq
)) {
3374 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3375 cfqd
->busy_queues
> 1) {
3376 cfq_del_timer(cfqd
, cfqq
);
3377 cfq_clear_cfqq_wait_request(cfqq
);
3378 __blk_run_queue(cfqd
->queue
);
3380 cfq_blkiocg_update_idle_time_stats(
3382 cfq_mark_cfqq_must_dispatch(cfqq
);
3385 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3387 * not the active queue - expire current slice if it is
3388 * idle and has expired it's mean thinktime or this new queue
3389 * has some old slice time left and is of higher priority or
3390 * this new queue is RT and the current one is BE
3392 cfq_preempt_queue(cfqd
, cfqq
);
3393 __blk_run_queue(cfqd
->queue
);
3397 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3399 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3400 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3402 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3403 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3405 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3406 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3408 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
3409 &cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
3411 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3415 * Update hw_tag based on peak queue depth over 50 samples under
3418 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3420 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3422 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3423 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3425 if (cfqd
->hw_tag
== 1)
3428 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3429 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3433 * If active queue hasn't enough requests and can idle, cfq might not
3434 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3437 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3438 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3439 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3442 if (cfqd
->hw_tag_samples
++ < 50)
3445 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3451 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3453 struct cfq_io_context
*cic
= cfqd
->active_cic
;
3455 /* If the queue already has requests, don't wait */
3456 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3459 /* If there are other queues in the group, don't wait */
3460 if (cfqq
->cfqg
->nr_cfqq
> 1)
3463 /* the only queue in the group, but think time is big */
3464 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3467 if (cfq_slice_used(cfqq
))
3470 /* if slice left is less than think time, wait busy */
3471 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3472 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
3476 * If think times is less than a jiffy than ttime_mean=0 and above
3477 * will not be true. It might happen that slice has not expired yet
3478 * but will expire soon (4-5 ns) during select_queue(). To cover the
3479 * case where think time is less than a jiffy, mark the queue wait
3480 * busy if only 1 jiffy is left in the slice.
3482 if (cfqq
->slice_end
- jiffies
== 1)
3488 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3490 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3491 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3492 const int sync
= rq_is_sync(rq
);
3496 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3497 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3499 cfq_update_hw_tag(cfqd
);
3501 WARN_ON(!cfqd
->rq_in_driver
);
3502 WARN_ON(!cfqq
->dispatched
);
3503 cfqd
->rq_in_driver
--;
3505 (RQ_CFQG(rq
))->dispatched
--;
3506 cfq_blkiocg_update_completion_stats(&cfqq
->cfqg
->blkg
,
3507 rq_start_time_ns(rq
), rq_io_start_time_ns(rq
),
3508 rq_data_dir(rq
), rq_is_sync(rq
));
3510 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3513 struct cfq_rb_root
*service_tree
;
3515 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
3517 if (cfq_cfqq_on_rr(cfqq
))
3518 service_tree
= cfqq
->service_tree
;
3520 service_tree
= service_tree_for(cfqq
->cfqg
,
3521 cfqq_prio(cfqq
), cfqq_type(cfqq
));
3522 service_tree
->ttime
.last_end_request
= now
;
3523 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3524 cfqd
->last_delayed_sync
= now
;
3527 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3528 cfqq
->cfqg
->ttime
.last_end_request
= now
;
3532 * If this is the active queue, check if it needs to be expired,
3533 * or if we want to idle in case it has no pending requests.
3535 if (cfqd
->active_queue
== cfqq
) {
3536 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3538 if (cfq_cfqq_slice_new(cfqq
)) {
3539 cfq_set_prio_slice(cfqd
, cfqq
);
3540 cfq_clear_cfqq_slice_new(cfqq
);
3544 * Should we wait for next request to come in before we expire
3547 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3548 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3549 if (!cfqd
->cfq_slice_idle
)
3550 extend_sl
= cfqd
->cfq_group_idle
;
3551 cfqq
->slice_end
= jiffies
+ extend_sl
;
3552 cfq_mark_cfqq_wait_busy(cfqq
);
3553 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3557 * Idling is not enabled on:
3559 * - idle-priority queues
3561 * - queues with still some requests queued
3562 * - when there is a close cooperator
3564 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3565 cfq_slice_expired(cfqd
, 1);
3566 else if (sync
&& cfqq_empty
&&
3567 !cfq_close_cooperator(cfqd
, cfqq
)) {
3568 cfq_arm_slice_timer(cfqd
);
3572 if (!cfqd
->rq_in_driver
)
3573 cfq_schedule_dispatch(cfqd
);
3576 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3578 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3579 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3580 return ELV_MQUEUE_MUST
;
3583 return ELV_MQUEUE_MAY
;
3586 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3588 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3589 struct task_struct
*tsk
= current
;
3590 struct cfq_io_context
*cic
;
3591 struct cfq_queue
*cfqq
;
3594 * don't force setup of a queue from here, as a call to may_queue
3595 * does not necessarily imply that a request actually will be queued.
3596 * so just lookup a possibly existing queue, or return 'may queue'
3599 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3601 return ELV_MQUEUE_MAY
;
3603 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3605 cfq_init_prio_data(cfqq
, cic
->ioc
);
3607 return __cfq_may_queue(cfqq
);
3610 return ELV_MQUEUE_MAY
;
3614 * queue lock held here
3616 static void cfq_put_request(struct request
*rq
)
3618 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3621 const int rw
= rq_data_dir(rq
);
3623 BUG_ON(!cfqq
->allocated
[rw
]);
3624 cfqq
->allocated
[rw
]--;
3626 put_io_context(RQ_CIC(rq
)->ioc
, cfqq
->cfqd
->queue
);
3628 rq
->elevator_private
[0] = NULL
;
3629 rq
->elevator_private
[1] = NULL
;
3631 /* Put down rq reference on cfqg */
3632 cfq_put_cfqg(RQ_CFQG(rq
));
3633 rq
->elevator_private
[2] = NULL
;
3635 cfq_put_queue(cfqq
);
3639 static struct cfq_queue
*
3640 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3641 struct cfq_queue
*cfqq
)
3643 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3644 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3645 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3646 cfq_put_queue(cfqq
);
3647 return cic_to_cfqq(cic
, 1);
3651 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3652 * was the last process referring to said cfqq.
3654 static struct cfq_queue
*
3655 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3657 if (cfqq_process_refs(cfqq
) == 1) {
3658 cfqq
->pid
= current
->pid
;
3659 cfq_clear_cfqq_coop(cfqq
);
3660 cfq_clear_cfqq_split_coop(cfqq
);
3664 cic_set_cfqq(cic
, NULL
, 1);
3666 cfq_put_cooperator(cfqq
);
3668 cfq_put_queue(cfqq
);
3672 * Allocate cfq data structures associated with this request.
3675 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3677 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3678 struct cfq_io_context
*cic
;
3679 const int rw
= rq_data_dir(rq
);
3680 const bool is_sync
= rq_is_sync(rq
);
3681 struct cfq_queue
*cfqq
;
3683 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3685 spin_lock_irq(q
->queue_lock
);
3686 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3691 cfqq
= cic_to_cfqq(cic
, is_sync
);
3692 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3693 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3694 cic_set_cfqq(cic
, cfqq
, is_sync
);
3697 * If the queue was seeky for too long, break it apart.
3699 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3700 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3701 cfqq
= split_cfqq(cic
, cfqq
);
3707 * Check to see if this queue is scheduled to merge with
3708 * another, closely cooperating queue. The merging of
3709 * queues happens here as it must be done in process context.
3710 * The reference on new_cfqq was taken in merge_cfqqs.
3713 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3716 cfqq
->allocated
[rw
]++;
3719 rq
->elevator_private
[0] = cic
;
3720 rq
->elevator_private
[1] = cfqq
;
3721 rq
->elevator_private
[2] = cfq_ref_get_cfqg(cfqq
->cfqg
);
3722 spin_unlock_irq(q
->queue_lock
);
3726 cfq_schedule_dispatch(cfqd
);
3727 spin_unlock_irq(q
->queue_lock
);
3728 cfq_log(cfqd
, "set_request fail");
3732 static void cfq_kick_queue(struct work_struct
*work
)
3734 struct cfq_data
*cfqd
=
3735 container_of(work
, struct cfq_data
, unplug_work
);
3736 struct request_queue
*q
= cfqd
->queue
;
3738 spin_lock_irq(q
->queue_lock
);
3739 __blk_run_queue(cfqd
->queue
);
3740 spin_unlock_irq(q
->queue_lock
);
3744 * Timer running if the active_queue is currently idling inside its time slice
3746 static void cfq_idle_slice_timer(unsigned long data
)
3748 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3749 struct cfq_queue
*cfqq
;
3750 unsigned long flags
;
3753 cfq_log(cfqd
, "idle timer fired");
3755 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3757 cfqq
= cfqd
->active_queue
;
3762 * We saw a request before the queue expired, let it through
3764 if (cfq_cfqq_must_dispatch(cfqq
))
3770 if (cfq_slice_used(cfqq
))
3774 * only expire and reinvoke request handler, if there are
3775 * other queues with pending requests
3777 if (!cfqd
->busy_queues
)
3781 * not expired and it has a request pending, let it dispatch
3783 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3787 * Queue depth flag is reset only when the idle didn't succeed
3789 cfq_clear_cfqq_deep(cfqq
);
3792 cfq_slice_expired(cfqd
, timed_out
);
3794 cfq_schedule_dispatch(cfqd
);
3796 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3799 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3801 del_timer_sync(&cfqd
->idle_slice_timer
);
3802 cancel_work_sync(&cfqd
->unplug_work
);
3805 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3809 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3810 if (cfqd
->async_cfqq
[0][i
])
3811 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3812 if (cfqd
->async_cfqq
[1][i
])
3813 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3816 if (cfqd
->async_idle_cfqq
)
3817 cfq_put_queue(cfqd
->async_idle_cfqq
);
3820 static void cfq_exit_queue(struct elevator_queue
*e
)
3822 struct cfq_data
*cfqd
= e
->elevator_data
;
3823 struct request_queue
*q
= cfqd
->queue
;
3826 cfq_shutdown_timer_wq(cfqd
);
3828 spin_lock_irq(q
->queue_lock
);
3830 if (cfqd
->active_queue
)
3831 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3833 while (!list_empty(&cfqd
->cic_list
)) {
3834 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3835 struct cfq_io_context
,
3837 struct io_context
*ioc
= cic
->ioc
;
3839 spin_lock(&ioc
->lock
);
3841 cfq_release_cic(cic
);
3842 spin_unlock(&ioc
->lock
);
3845 cfq_put_async_queues(cfqd
);
3846 cfq_release_cfq_groups(cfqd
);
3849 * If there are groups which we could not unlink from blkcg list,
3850 * wait for a rcu period for them to be freed.
3852 if (cfqd
->nr_blkcg_linked_grps
)
3855 spin_unlock_irq(q
->queue_lock
);
3857 cfq_shutdown_timer_wq(cfqd
);
3860 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3861 * Do this wait only if there are other unlinked groups out
3862 * there. This can happen if cgroup deletion path claimed the
3863 * responsibility of cleaning up a group before queue cleanup code
3866 * Do not call synchronize_rcu() unconditionally as there are drivers
3867 * which create/delete request queue hundreds of times during scan/boot
3868 * and synchronize_rcu() can take significant time and slow down boot.
3873 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3874 /* Free up per cpu stats for root group */
3875 free_percpu(cfqd
->root_group
.blkg
.stats_cpu
);
3880 static void *cfq_init_queue(struct request_queue
*q
)
3882 struct cfq_data
*cfqd
;
3884 struct cfq_group
*cfqg
;
3885 struct cfq_rb_root
*st
;
3887 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3891 /* Init root service tree */
3892 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3894 /* Init root group */
3895 cfqg
= &cfqd
->root_group
;
3896 for_each_cfqg_st(cfqg
, i
, j
, st
)
3898 RB_CLEAR_NODE(&cfqg
->rb_node
);
3900 /* Give preference to root group over other groups */
3901 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3903 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3905 * Set root group reference to 2. One reference will be dropped when
3906 * all groups on cfqd->cfqg_list are being deleted during queue exit.
3907 * Other reference will remain there as we don't want to delete this
3908 * group as it is statically allocated and gets destroyed when
3909 * throtl_data goes away.
3913 if (blkio_alloc_blkg_stats(&cfqg
->blkg
)) {
3921 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
,
3924 cfqd
->nr_blkcg_linked_grps
++;
3926 /* Add group on cfqd->cfqg_list */
3927 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
3930 * Not strictly needed (since RB_ROOT just clears the node and we
3931 * zeroed cfqd on alloc), but better be safe in case someone decides
3932 * to add magic to the rb code
3934 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3935 cfqd
->prio_trees
[i
] = RB_ROOT
;
3938 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3939 * Grab a permanent reference to it, so that the normal code flow
3940 * will not attempt to free it.
3942 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3943 cfqd
->oom_cfqq
.ref
++;
3944 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3946 INIT_LIST_HEAD(&cfqd
->cic_list
);
3950 init_timer(&cfqd
->idle_slice_timer
);
3951 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3952 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3954 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3956 cfqd
->cfq_quantum
= cfq_quantum
;
3957 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3958 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3959 cfqd
->cfq_back_max
= cfq_back_max
;
3960 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3961 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3962 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3963 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3964 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3965 cfqd
->cfq_group_idle
= cfq_group_idle
;
3966 cfqd
->cfq_latency
= 1;
3969 * we optimistically start assuming sync ops weren't delayed in last
3970 * second, in order to have larger depth for async operations.
3972 cfqd
->last_delayed_sync
= jiffies
- HZ
;
3976 static void cfq_slab_kill(void)
3979 * Caller already ensured that pending RCU callbacks are completed,
3980 * so we should have no busy allocations at this point.
3983 kmem_cache_destroy(cfq_pool
);
3985 kmem_cache_destroy(cfq_ioc_pool
);
3988 static int __init
cfq_slab_setup(void)
3990 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3994 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
4005 * sysfs parts below -->
4008 cfq_var_show(unsigned int var
, char *page
)
4010 return sprintf(page
, "%d\n", var
);
4014 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
4016 char *p
= (char *) page
;
4018 *var
= simple_strtoul(p
, &p
, 10);
4022 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4023 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4025 struct cfq_data *cfqd = e->elevator_data; \
4026 unsigned int __data = __VAR; \
4028 __data = jiffies_to_msecs(__data); \
4029 return cfq_var_show(__data, (page)); \
4031 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
4032 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
4033 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
4034 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4035 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4036 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4037 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4038 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4039 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4040 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4041 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4042 #undef SHOW_FUNCTION
4044 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4045 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4047 struct cfq_data *cfqd = e->elevator_data; \
4048 unsigned int __data; \
4049 int ret = cfq_var_store(&__data, (page), count); \
4050 if (__data < (MIN)) \
4052 else if (__data > (MAX)) \
4055 *(__PTR) = msecs_to_jiffies(__data); \
4057 *(__PTR) = __data; \
4060 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4061 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4063 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4065 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4066 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4068 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4069 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4070 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4071 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4072 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4074 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4075 #undef STORE_FUNCTION
4077 #define CFQ_ATTR(name) \
4078 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4080 static struct elv_fs_entry cfq_attrs
[] = {
4082 CFQ_ATTR(fifo_expire_sync
),
4083 CFQ_ATTR(fifo_expire_async
),
4084 CFQ_ATTR(back_seek_max
),
4085 CFQ_ATTR(back_seek_penalty
),
4086 CFQ_ATTR(slice_sync
),
4087 CFQ_ATTR(slice_async
),
4088 CFQ_ATTR(slice_async_rq
),
4089 CFQ_ATTR(slice_idle
),
4090 CFQ_ATTR(group_idle
),
4091 CFQ_ATTR(low_latency
),
4095 static struct elevator_type iosched_cfq
= {
4097 .elevator_merge_fn
= cfq_merge
,
4098 .elevator_merged_fn
= cfq_merged_request
,
4099 .elevator_merge_req_fn
= cfq_merged_requests
,
4100 .elevator_allow_merge_fn
= cfq_allow_merge
,
4101 .elevator_bio_merged_fn
= cfq_bio_merged
,
4102 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4103 .elevator_add_req_fn
= cfq_insert_request
,
4104 .elevator_activate_req_fn
= cfq_activate_request
,
4105 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4106 .elevator_completed_req_fn
= cfq_completed_request
,
4107 .elevator_former_req_fn
= elv_rb_former_request
,
4108 .elevator_latter_req_fn
= elv_rb_latter_request
,
4109 .elevator_set_req_fn
= cfq_set_request
,
4110 .elevator_put_req_fn
= cfq_put_request
,
4111 .elevator_may_queue_fn
= cfq_may_queue
,
4112 .elevator_init_fn
= cfq_init_queue
,
4113 .elevator_exit_fn
= cfq_exit_queue
,
4115 .elevator_attrs
= cfq_attrs
,
4116 .elevator_name
= "cfq",
4117 .elevator_owner
= THIS_MODULE
,
4120 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4121 static struct blkio_policy_type blkio_policy_cfq
= {
4123 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
4124 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
4126 .plid
= BLKIO_POLICY_PROP
,
4129 static struct blkio_policy_type blkio_policy_cfq
;
4132 static int __init
cfq_init(void)
4135 * could be 0 on HZ < 1000 setups
4137 if (!cfq_slice_async
)
4138 cfq_slice_async
= 1;
4139 if (!cfq_slice_idle
)
4142 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4143 if (!cfq_group_idle
)
4148 if (cfq_slab_setup())
4151 elv_register(&iosched_cfq
);
4152 blkio_policy_register(&blkio_policy_cfq
);
4157 static void __exit
cfq_exit(void)
4159 DECLARE_COMPLETION_ONSTACK(all_gone
);
4160 blkio_policy_unregister(&blkio_policy_cfq
);
4161 elv_unregister(&iosched_cfq
);
4162 ioc_gone
= &all_gone
;
4163 /* ioc_gone's update must be visible before reading ioc_count */
4167 * this also protects us from entering cfq_slab_kill() with
4168 * pending RCU callbacks
4170 if (elv_ioc_count_read(cfq_ioc_count
))
4171 wait_for_completion(&all_gone
);
4175 module_init(cfq_init
);
4176 module_exit(cfq_exit
);
4178 MODULE_AUTHOR("Jens Axboe");
4179 MODULE_LICENSE("GPL");
4180 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");