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>
22 /* max queue in one round of service */
23 static const int cfq_quantum
= 8;
24 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
25 /* maximum backwards seek, in KiB */
26 static const int cfq_back_max
= 16 * 1024;
27 /* penalty of a backwards seek */
28 static const int cfq_back_penalty
= 2;
29 static const int cfq_slice_sync
= HZ
/ 10;
30 static int cfq_slice_async
= HZ
/ 25;
31 static const int cfq_slice_async_rq
= 2;
32 static int cfq_slice_idle
= HZ
/ 125;
33 static int cfq_group_idle
= HZ
/ 125;
34 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
35 static const int cfq_hist_divisor
= 4;
38 * offset from end of service tree
40 #define CFQ_IDLE_DELAY (HZ / 5)
43 * below this threshold, we consider thinktime immediate
45 #define CFQ_MIN_TT (2)
47 #define CFQ_SLICE_SCALE (5)
48 #define CFQ_HW_QUEUE_MIN (5)
49 #define CFQ_SERVICE_SHIFT 12
51 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
52 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
53 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
54 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 ((struct cfq_io_context *) (rq)->elevator_private)
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
61 static struct kmem_cache
*cfq_pool
;
62 static struct kmem_cache
*cfq_ioc_pool
;
64 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count
);
65 static struct completion
*ioc_gone
;
66 static DEFINE_SPINLOCK(ioc_gone_lock
);
68 static DEFINE_SPINLOCK(cic_index_lock
);
69 static DEFINE_IDA(cic_index_ida
);
71 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
72 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
73 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
75 #define sample_valid(samples) ((samples) > 80)
76 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
88 unsigned total_weight
;
91 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
92 .count = 0, .min_vdisktime = 0, }
95 * Per process-grouping structure
100 /* various state flags, see below */
102 /* parent cfq_data */
103 struct cfq_data
*cfqd
;
104 /* service_tree member */
105 struct rb_node rb_node
;
106 /* service_tree key */
107 unsigned long rb_key
;
108 /* prio tree member */
109 struct rb_node p_node
;
110 /* prio tree root we belong to, if any */
111 struct rb_root
*p_root
;
112 /* sorted list of pending requests */
113 struct rb_root sort_list
;
114 /* if fifo isn't expired, next request to serve */
115 struct request
*next_rq
;
116 /* requests queued in sort_list */
118 /* currently allocated requests */
120 /* fifo list of requests in sort_list */
121 struct list_head fifo
;
123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start
;
125 unsigned int allocated_slice
;
126 unsigned int slice_dispatch
;
127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start
;
129 unsigned long slice_end
;
132 /* pending metadata requests */
134 /* number of requests that are on the dispatch list or inside driver */
137 /* io prio of this group */
138 unsigned short ioprio
, org_ioprio
;
139 unsigned short ioprio_class
, org_ioprio_class
;
144 sector_t last_request_pos
;
146 struct cfq_rb_root
*service_tree
;
147 struct cfq_queue
*new_cfqq
;
148 struct cfq_group
*cfqg
;
149 struct cfq_group
*orig_cfqg
;
150 /* Number of sectors dispatched from queue in single dispatch round */
151 unsigned long nr_sectors
;
155 * First index in the service_trees.
156 * IDLE is handled separately, so it has negative index
166 * Second index in the service_trees.
170 SYNC_NOIDLE_WORKLOAD
= 1,
174 /* This is per cgroup per device grouping structure */
176 /* group service_tree member */
177 struct rb_node rb_node
;
179 /* group service_tree key */
183 /* number of cfqq currently on this group */
187 * Per group busy queus 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 */
217 * Per block device queue structure
220 struct request_queue
*queue
;
221 /* Root service tree for cfq_groups */
222 struct cfq_rb_root grp_service_tree
;
223 struct cfq_group root_group
;
226 * The priority currently being served
228 enum wl_prio_t serving_prio
;
229 enum wl_type_t serving_type
;
230 unsigned long workload_expires
;
231 struct cfq_group
*serving_group
;
234 * Each priority tree is sorted by next_request position. These
235 * trees are used when determining if two or more queues are
236 * interleaving requests (see cfq_close_cooperator).
238 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
240 unsigned int busy_queues
;
246 * queue-depth detection
252 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
253 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
256 int hw_tag_est_depth
;
257 unsigned int hw_tag_samples
;
260 * idle window management
262 struct timer_list idle_slice_timer
;
263 struct work_struct unplug_work
;
265 struct cfq_queue
*active_queue
;
266 struct cfq_io_context
*active_cic
;
269 * async queue for each priority case
271 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
272 struct cfq_queue
*async_idle_cfqq
;
274 sector_t last_position
;
277 * tunables, see top of file
279 unsigned int cfq_quantum
;
280 unsigned int cfq_fifo_expire
[2];
281 unsigned int cfq_back_penalty
;
282 unsigned int cfq_back_max
;
283 unsigned int cfq_slice
[2];
284 unsigned int cfq_slice_async_rq
;
285 unsigned int cfq_slice_idle
;
286 unsigned int cfq_group_idle
;
287 unsigned int cfq_latency
;
288 unsigned int cfq_group_isolation
;
290 unsigned int cic_index
;
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
;
305 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
307 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
314 if (prio
== IDLE_WORKLOAD
)
315 return &cfqg
->service_tree_idle
;
317 return &cfqg
->service_trees
[prio
][type
];
320 enum cfqq_state_flags
{
321 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
322 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
323 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
324 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
325 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
326 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
327 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
328 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
329 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
330 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
331 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
332 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
333 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
336 #define CFQ_CFQQ_FNS(name) \
337 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
339 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
341 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
343 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
345 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
347 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
351 CFQ_CFQQ_FNS(wait_request
);
352 CFQ_CFQQ_FNS(must_dispatch
);
353 CFQ_CFQQ_FNS(must_alloc_slice
);
354 CFQ_CFQQ_FNS(fifo_expire
);
355 CFQ_CFQQ_FNS(idle_window
);
356 CFQ_CFQQ_FNS(prio_changed
);
357 CFQ_CFQQ_FNS(slice_new
);
360 CFQ_CFQQ_FNS(split_coop
);
362 CFQ_CFQQ_FNS(wait_busy
);
365 #ifdef CONFIG_CFQ_GROUP_IOSCHED
366 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
367 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
368 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
369 blkg_path(&(cfqq)->cfqg->blkg), ##args);
371 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
372 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
373 blkg_path(&(cfqg)->blkg), ##args); \
376 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
377 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
378 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
380 #define cfq_log(cfqd, fmt, args...) \
381 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
383 /* Traverses through cfq group service trees */
384 #define for_each_cfqg_st(cfqg, i, j, st) \
385 for (i = 0; i <= IDLE_WORKLOAD; i++) \
386 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
387 : &cfqg->service_tree_idle; \
388 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
389 (i == IDLE_WORKLOAD && j == 0); \
390 j++, st = i < IDLE_WORKLOAD ? \
391 &cfqg->service_trees[i][j]: NULL) \
394 static inline bool iops_mode(struct cfq_data *cfqd)
397 * If we are not idling on queues and it is a NCQ drive, parallel
398 * execution of requests is on and measuring time is not possible
399 * in most of the cases until and unless we drive shallower queue
400 * depths and that becomes a performance bottleneck. In such cases
401 * switch to start providing fairness in terms of number of IOs.
403 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
409 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
411 if (cfq_class_idle(cfqq
))
412 return IDLE_WORKLOAD
;
413 if (cfq_class_rt(cfqq
))
419 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
421 if (!cfq_cfqq_sync(cfqq
))
422 return ASYNC_WORKLOAD
;
423 if (!cfq_cfqq_idle_window(cfqq
))
424 return SYNC_NOIDLE_WORKLOAD
;
425 return SYNC_WORKLOAD
;
428 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
429 struct cfq_data
*cfqd
,
430 struct cfq_group
*cfqg
)
432 if (wl
== IDLE_WORKLOAD
)
433 return cfqg
->service_tree_idle
.count
;
435 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
436 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
437 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
440 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
441 struct cfq_group
*cfqg
)
443 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
444 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
447 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
448 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
449 struct io_context
*, gfp_t
);
450 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
451 struct io_context
*);
453 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
456 return cic
->cfqq
[is_sync
];
459 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
460 struct cfq_queue
*cfqq
, bool is_sync
)
462 cic
->cfqq
[is_sync
] = cfqq
;
465 #define CIC_DEAD_KEY 1ul
466 #define CIC_DEAD_INDEX_SHIFT 1
468 static inline void *cfqd_dead_key(struct cfq_data
*cfqd
)
470 return (void *)(cfqd
->cic_index
<< CIC_DEAD_INDEX_SHIFT
| CIC_DEAD_KEY
);
473 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_context
*cic
)
475 struct cfq_data
*cfqd
= cic
->key
;
477 if (unlikely((unsigned long) cfqd
& CIC_DEAD_KEY
))
484 * We regard a request as SYNC, if it's either a read or has the SYNC bit
485 * set (in which case it could also be direct WRITE).
487 static inline bool cfq_bio_sync(struct bio
*bio
)
489 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
493 * scheduler run of queue, if there are requests pending and no one in the
494 * driver that will restart queueing
496 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
498 if (cfqd
->busy_queues
) {
499 cfq_log(cfqd
, "schedule dispatch");
500 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
504 static int cfq_queue_empty(struct request_queue
*q
)
506 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
508 return !cfqd
->rq_queued
;
512 * Scale schedule slice based on io priority. Use the sync time slice only
513 * if a queue is marked sync and has sync io queued. A sync queue with async
514 * io only, should not get full sync slice length.
516 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
519 const int base_slice
= cfqd
->cfq_slice
[sync
];
521 WARN_ON(prio
>= IOPRIO_BE_NR
);
523 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
527 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
529 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
532 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
534 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
536 d
= d
* BLKIO_WEIGHT_DEFAULT
;
537 do_div(d
, cfqg
->weight
);
541 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
543 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
545 min_vdisktime
= vdisktime
;
547 return min_vdisktime
;
550 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
552 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
554 min_vdisktime
= vdisktime
;
556 return min_vdisktime
;
559 static void update_min_vdisktime(struct cfq_rb_root
*st
)
561 u64 vdisktime
= st
->min_vdisktime
;
562 struct cfq_group
*cfqg
;
565 cfqg
= rb_entry_cfqg(st
->left
);
566 vdisktime
= min_vdisktime(vdisktime
, cfqg
->vdisktime
);
569 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
, vdisktime
);
573 * get averaged number of queues of RT/BE priority.
574 * average is updated, with a formula that gives more weight to higher numbers,
575 * to quickly follows sudden increases and decrease slowly
578 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
579 struct cfq_group
*cfqg
, bool rt
)
581 unsigned min_q
, max_q
;
582 unsigned mult
= cfq_hist_divisor
- 1;
583 unsigned round
= cfq_hist_divisor
/ 2;
584 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
586 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
587 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
588 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
590 return cfqg
->busy_queues_avg
[rt
];
593 static inline unsigned
594 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
596 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
598 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
602 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
604 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
605 if (cfqd
->cfq_latency
) {
607 * interested queues (we consider only the ones with the same
608 * priority class in the cfq group)
610 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
612 unsigned sync_slice
= cfqd
->cfq_slice
[1];
613 unsigned expect_latency
= sync_slice
* iq
;
614 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
616 if (expect_latency
> group_slice
) {
617 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
618 /* scale low_slice according to IO priority
619 * and sync vs async */
621 min(slice
, base_low_slice
* slice
/ sync_slice
);
622 /* the adapted slice value is scaled to fit all iqs
623 * into the target latency */
624 slice
= max(slice
* group_slice
/ expect_latency
,
628 cfqq
->slice_start
= jiffies
;
629 cfqq
->slice_end
= jiffies
+ slice
;
630 cfqq
->allocated_slice
= slice
;
631 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
635 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
636 * isn't valid until the first request from the dispatch is activated
637 * and the slice time set.
639 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
641 if (cfq_cfqq_slice_new(cfqq
))
643 if (time_before(jiffies
, cfqq
->slice_end
))
650 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
651 * We choose the request that is closest to the head right now. Distance
652 * behind the head is penalized and only allowed to a certain extent.
654 static struct request
*
655 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
657 sector_t s1
, s2
, d1
= 0, d2
= 0;
658 unsigned long back_max
;
659 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
660 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
661 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
663 if (rq1
== NULL
|| rq1
== rq2
)
668 if (rq_is_sync(rq1
) && !rq_is_sync(rq2
))
670 else if (rq_is_sync(rq2
) && !rq_is_sync(rq1
))
672 if ((rq1
->cmd_flags
& REQ_META
) && !(rq2
->cmd_flags
& REQ_META
))
674 else if ((rq2
->cmd_flags
& REQ_META
) &&
675 !(rq1
->cmd_flags
& REQ_META
))
678 s1
= blk_rq_pos(rq1
);
679 s2
= blk_rq_pos(rq2
);
682 * by definition, 1KiB is 2 sectors
684 back_max
= cfqd
->cfq_back_max
* 2;
687 * Strict one way elevator _except_ in the case where we allow
688 * short backward seeks which are biased as twice the cost of a
689 * similar forward seek.
693 else if (s1
+ back_max
>= last
)
694 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
696 wrap
|= CFQ_RQ1_WRAP
;
700 else if (s2
+ back_max
>= last
)
701 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
703 wrap
|= CFQ_RQ2_WRAP
;
705 /* Found required data */
708 * By doing switch() on the bit mask "wrap" we avoid having to
709 * check two variables for all permutations: --> faster!
712 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
728 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
731 * Since both rqs are wrapped,
732 * start with the one that's further behind head
733 * (--> only *one* back seek required),
734 * since back seek takes more time than forward.
744 * The below is leftmost cache rbtree addon
746 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
748 /* Service tree is empty */
753 root
->left
= rb_first(&root
->rb
);
756 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
761 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
764 root
->left
= rb_first(&root
->rb
);
767 return rb_entry_cfqg(root
->left
);
772 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
778 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
782 rb_erase_init(n
, &root
->rb
);
787 * would be nice to take fifo expire time into account as well
789 static struct request
*
790 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
791 struct request
*last
)
793 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
794 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
795 struct request
*next
= NULL
, *prev
= NULL
;
797 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
800 prev
= rb_entry_rq(rbprev
);
803 next
= rb_entry_rq(rbnext
);
805 rbnext
= rb_first(&cfqq
->sort_list
);
806 if (rbnext
&& rbnext
!= &last
->rb_node
)
807 next
= rb_entry_rq(rbnext
);
810 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
813 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
814 struct cfq_queue
*cfqq
)
817 * just an approximation, should be ok.
819 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
820 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
824 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
826 return cfqg
->vdisktime
- st
->min_vdisktime
;
830 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
832 struct rb_node
**node
= &st
->rb
.rb_node
;
833 struct rb_node
*parent
= NULL
;
834 struct cfq_group
*__cfqg
;
835 s64 key
= cfqg_key(st
, cfqg
);
838 while (*node
!= NULL
) {
840 __cfqg
= rb_entry_cfqg(parent
);
842 if (key
< cfqg_key(st
, __cfqg
))
843 node
= &parent
->rb_left
;
845 node
= &parent
->rb_right
;
851 st
->left
= &cfqg
->rb_node
;
853 rb_link_node(&cfqg
->rb_node
, parent
, node
);
854 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
858 cfq_group_service_tree_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
860 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
861 struct cfq_group
*__cfqg
;
865 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
869 * Currently put the group at the end. Later implement something
870 * so that groups get lesser vtime based on their weights, so that
871 * if group does not loose all if it was not continously backlogged.
873 n
= rb_last(&st
->rb
);
875 __cfqg
= rb_entry_cfqg(n
);
876 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
878 cfqg
->vdisktime
= st
->min_vdisktime
;
880 __cfq_group_service_tree_add(st
, cfqg
);
881 st
->total_weight
+= cfqg
->weight
;
885 cfq_group_service_tree_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
887 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
889 BUG_ON(cfqg
->nr_cfqq
< 1);
892 /* If there are other cfq queues under this group, don't delete it */
896 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
897 st
->total_weight
-= cfqg
->weight
;
898 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
899 cfq_rb_erase(&cfqg
->rb_node
, st
);
900 cfqg
->saved_workload_slice
= 0;
901 cfq_blkiocg_update_dequeue_stats(&cfqg
->blkg
, 1);
904 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
)
906 unsigned int slice_used
;
909 * Queue got expired before even a single request completed or
910 * got expired immediately after first request completion.
912 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
914 * Also charge the seek time incurred to the group, otherwise
915 * if there are mutiple queues in the group, each can dispatch
916 * a single request on seeky media and cause lots of seek time
917 * and group will never know it.
919 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
922 slice_used
= jiffies
- cfqq
->slice_start
;
923 if (slice_used
> cfqq
->allocated_slice
)
924 slice_used
= cfqq
->allocated_slice
;
930 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
931 struct cfq_queue
*cfqq
)
933 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
934 unsigned int used_sl
, charge
;
935 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
936 - cfqg
->service_tree_idle
.count
;
939 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
);
942 charge
= cfqq
->slice_dispatch
;
943 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
944 charge
= cfqq
->allocated_slice
;
946 /* Can't update vdisktime while group is on service tree */
947 cfq_rb_erase(&cfqg
->rb_node
, st
);
948 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
949 __cfq_group_service_tree_add(st
, cfqg
);
951 /* This group is being expired. Save the context */
952 if (time_after(cfqd
->workload_expires
, jiffies
)) {
953 cfqg
->saved_workload_slice
= cfqd
->workload_expires
955 cfqg
->saved_workload
= cfqd
->serving_type
;
956 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
958 cfqg
->saved_workload_slice
= 0;
960 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
962 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "sl_used=%u disp=%u charge=%u iops=%u"
963 " sect=%u", used_sl
, cfqq
->slice_dispatch
, charge
,
964 iops_mode(cfqd
), cfqq
->nr_sectors
);
965 cfq_blkiocg_update_timeslice_used(&cfqg
->blkg
, used_sl
);
966 cfq_blkiocg_set_start_empty_time(&cfqg
->blkg
);
969 #ifdef CONFIG_CFQ_GROUP_IOSCHED
970 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
973 return container_of(blkg
, struct cfq_group
, blkg
);
977 void cfq_update_blkio_group_weight(void *key
, struct blkio_group
*blkg
,
980 cfqg_of_blkg(blkg
)->weight
= weight
;
983 static struct cfq_group
*
984 cfq_find_alloc_cfqg(struct cfq_data
*cfqd
, struct cgroup
*cgroup
, int create
)
986 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgroup
);
987 struct cfq_group
*cfqg
= NULL
;
990 struct cfq_rb_root
*st
;
991 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
992 unsigned int major
, minor
;
994 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
995 if (cfqg
&& !cfqg
->blkg
.dev
&& bdi
->dev
&& dev_name(bdi
->dev
)) {
996 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
997 cfqg
->blkg
.dev
= MKDEV(major
, minor
);
1000 if (cfqg
|| !create
)
1003 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
1007 for_each_cfqg_st(cfqg
, i
, j
, st
)
1009 RB_CLEAR_NODE(&cfqg
->rb_node
);
1012 * Take the initial reference that will be released on destroy
1013 * This can be thought of a joint reference by cgroup and
1014 * elevator which will be dropped by either elevator exit
1015 * or cgroup deletion path depending on who is exiting first.
1020 * Add group onto cgroup list. It might happen that bdi->dev is
1021 * not initialized yet. Initialize this new group without major
1022 * and minor info and this info will be filled in once a new thread
1023 * comes for IO. See code above.
1026 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1027 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
, (void *)cfqd
,
1028 MKDEV(major
, minor
));
1030 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
, (void *)cfqd
,
1033 cfqg
->weight
= blkcg_get_weight(blkcg
, cfqg
->blkg
.dev
);
1035 /* Add group on cfqd list */
1036 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
1043 * Search for the cfq group current task belongs to. If create = 1, then also
1044 * create the cfq group if it does not exist. request_queue lock must be held.
1046 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1048 struct cgroup
*cgroup
;
1049 struct cfq_group
*cfqg
= NULL
;
1052 cgroup
= task_cgroup(current
, blkio_subsys_id
);
1053 cfqg
= cfq_find_alloc_cfqg(cfqd
, cgroup
, create
);
1054 if (!cfqg
&& create
)
1055 cfqg
= &cfqd
->root_group
;
1060 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1066 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1068 /* Currently, all async queues are mapped to root group */
1069 if (!cfq_cfqq_sync(cfqq
))
1070 cfqg
= &cfqq
->cfqd
->root_group
;
1073 /* cfqq reference on cfqg */
1077 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1079 struct cfq_rb_root
*st
;
1082 BUG_ON(cfqg
->ref
<= 0);
1086 for_each_cfqg_st(cfqg
, i
, j
, st
)
1087 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
));
1091 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1093 /* Something wrong if we are trying to remove same group twice */
1094 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1096 hlist_del_init(&cfqg
->cfqd_node
);
1099 * Put the reference taken at the time of creation so that when all
1100 * queues are gone, group can be destroyed.
1105 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1107 struct hlist_node
*pos
, *n
;
1108 struct cfq_group
*cfqg
;
1110 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1112 * If cgroup removal path got to blk_group first and removed
1113 * it from cgroup list, then it will take care of destroying
1116 if (!cfq_blkiocg_del_blkio_group(&cfqg
->blkg
))
1117 cfq_destroy_cfqg(cfqd
, cfqg
);
1122 * Blk cgroup controller notification saying that blkio_group object is being
1123 * delinked as associated cgroup object is going away. That also means that
1124 * no new IO will come in this group. So get rid of this group as soon as
1125 * any pending IO in the group is finished.
1127 * This function is called under rcu_read_lock(). key is the rcu protected
1128 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1131 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1132 * it should not be NULL as even if elevator was exiting, cgroup deltion
1133 * path got to it first.
1135 void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1137 unsigned long flags
;
1138 struct cfq_data
*cfqd
= key
;
1140 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1141 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1142 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1145 #else /* GROUP_IOSCHED */
1146 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1148 return &cfqd
->root_group
;
1151 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1157 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1161 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1162 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1164 #endif /* GROUP_IOSCHED */
1167 * The cfqd->service_trees holds all pending cfq_queue's that have
1168 * requests waiting to be processed. It is sorted in the order that
1169 * we will service the queues.
1171 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1174 struct rb_node
**p
, *parent
;
1175 struct cfq_queue
*__cfqq
;
1176 unsigned long rb_key
;
1177 struct cfq_rb_root
*service_tree
;
1180 int group_changed
= 0;
1182 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1183 if (!cfqd
->cfq_group_isolation
1184 && cfqq_type(cfqq
) == SYNC_NOIDLE_WORKLOAD
1185 && cfqq
->cfqg
&& cfqq
->cfqg
!= &cfqd
->root_group
) {
1186 /* Move this cfq to root group */
1187 cfq_log_cfqq(cfqd
, cfqq
, "moving to root group");
1188 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1189 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1190 cfqq
->orig_cfqg
= cfqq
->cfqg
;
1191 cfqq
->cfqg
= &cfqd
->root_group
;
1192 cfqd
->root_group
.ref
++;
1194 } else if (!cfqd
->cfq_group_isolation
1195 && cfqq_type(cfqq
) == SYNC_WORKLOAD
&& cfqq
->orig_cfqg
) {
1196 /* cfqq is sequential now needs to go to its original group */
1197 BUG_ON(cfqq
->cfqg
!= &cfqd
->root_group
);
1198 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1199 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1200 cfq_put_cfqg(cfqq
->cfqg
);
1201 cfqq
->cfqg
= cfqq
->orig_cfqg
;
1202 cfqq
->orig_cfqg
= NULL
;
1204 cfq_log_cfqq(cfqd
, cfqq
, "moved to origin group");
1208 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1210 if (cfq_class_idle(cfqq
)) {
1211 rb_key
= CFQ_IDLE_DELAY
;
1212 parent
= rb_last(&service_tree
->rb
);
1213 if (parent
&& parent
!= &cfqq
->rb_node
) {
1214 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1215 rb_key
+= __cfqq
->rb_key
;
1218 } else if (!add_front
) {
1220 * Get our rb key offset. Subtract any residual slice
1221 * value carried from last service. A negative resid
1222 * count indicates slice overrun, and this should position
1223 * the next service time further away in the tree.
1225 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1226 rb_key
-= cfqq
->slice_resid
;
1227 cfqq
->slice_resid
= 0;
1230 __cfqq
= cfq_rb_first(service_tree
);
1231 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1234 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1237 * same position, nothing more to do
1239 if (rb_key
== cfqq
->rb_key
&&
1240 cfqq
->service_tree
== service_tree
)
1243 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1244 cfqq
->service_tree
= NULL
;
1249 cfqq
->service_tree
= service_tree
;
1250 p
= &service_tree
->rb
.rb_node
;
1255 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1258 * sort by key, that represents service time.
1260 if (time_before(rb_key
, __cfqq
->rb_key
))
1263 n
= &(*p
)->rb_right
;
1271 service_tree
->left
= &cfqq
->rb_node
;
1273 cfqq
->rb_key
= rb_key
;
1274 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1275 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1276 service_tree
->count
++;
1277 if ((add_front
|| !new_cfqq
) && !group_changed
)
1279 cfq_group_service_tree_add(cfqd
, cfqq
->cfqg
);
1282 static struct cfq_queue
*
1283 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1284 sector_t sector
, struct rb_node
**ret_parent
,
1285 struct rb_node
***rb_link
)
1287 struct rb_node
**p
, *parent
;
1288 struct cfq_queue
*cfqq
= NULL
;
1296 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1299 * Sort strictly based on sector. Smallest to the left,
1300 * largest to the right.
1302 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1303 n
= &(*p
)->rb_right
;
1304 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1312 *ret_parent
= parent
;
1318 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1320 struct rb_node
**p
, *parent
;
1321 struct cfq_queue
*__cfqq
;
1324 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1325 cfqq
->p_root
= NULL
;
1328 if (cfq_class_idle(cfqq
))
1333 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1334 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1335 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1337 rb_link_node(&cfqq
->p_node
, parent
, p
);
1338 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1340 cfqq
->p_root
= NULL
;
1344 * Update cfqq's position in the service tree.
1346 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1349 * Resorting requires the cfqq to be on the RR list already.
1351 if (cfq_cfqq_on_rr(cfqq
)) {
1352 cfq_service_tree_add(cfqd
, cfqq
, 0);
1353 cfq_prio_tree_add(cfqd
, cfqq
);
1358 * add to busy list of queues for service, trying to be fair in ordering
1359 * the pending list according to last request service
1361 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1363 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1364 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1365 cfq_mark_cfqq_on_rr(cfqq
);
1366 cfqd
->busy_queues
++;
1368 cfq_resort_rr_list(cfqd
, cfqq
);
1372 * Called when the cfqq no longer has requests pending, remove it from
1375 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1377 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1378 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1379 cfq_clear_cfqq_on_rr(cfqq
);
1381 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1382 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1383 cfqq
->service_tree
= NULL
;
1386 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1387 cfqq
->p_root
= NULL
;
1390 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1391 BUG_ON(!cfqd
->busy_queues
);
1392 cfqd
->busy_queues
--;
1396 * rb tree support functions
1398 static void cfq_del_rq_rb(struct request
*rq
)
1400 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1401 const int sync
= rq_is_sync(rq
);
1403 BUG_ON(!cfqq
->queued
[sync
]);
1404 cfqq
->queued
[sync
]--;
1406 elv_rb_del(&cfqq
->sort_list
, rq
);
1408 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1410 * Queue will be deleted from service tree when we actually
1411 * expire it later. Right now just remove it from prio tree
1415 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1416 cfqq
->p_root
= NULL
;
1421 static void cfq_add_rq_rb(struct request
*rq
)
1423 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1424 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1425 struct request
*__alias
, *prev
;
1427 cfqq
->queued
[rq_is_sync(rq
)]++;
1430 * looks a little odd, but the first insert might return an alias.
1431 * if that happens, put the alias on the dispatch list
1433 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
1434 cfq_dispatch_insert(cfqd
->queue
, __alias
);
1436 if (!cfq_cfqq_on_rr(cfqq
))
1437 cfq_add_cfqq_rr(cfqd
, cfqq
);
1440 * check if this request is a better next-serve candidate
1442 prev
= cfqq
->next_rq
;
1443 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1446 * adjust priority tree position, if ->next_rq changes
1448 if (prev
!= cfqq
->next_rq
)
1449 cfq_prio_tree_add(cfqd
, cfqq
);
1451 BUG_ON(!cfqq
->next_rq
);
1454 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1456 elv_rb_del(&cfqq
->sort_list
, rq
);
1457 cfqq
->queued
[rq_is_sync(rq
)]--;
1458 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1459 rq_data_dir(rq
), rq_is_sync(rq
));
1461 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
1462 &cfqq
->cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
1466 static struct request
*
1467 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1469 struct task_struct
*tsk
= current
;
1470 struct cfq_io_context
*cic
;
1471 struct cfq_queue
*cfqq
;
1473 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1477 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1479 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1481 return elv_rb_find(&cfqq
->sort_list
, sector
);
1487 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1489 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1491 cfqd
->rq_in_driver
++;
1492 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1493 cfqd
->rq_in_driver
);
1495 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1498 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1500 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1502 WARN_ON(!cfqd
->rq_in_driver
);
1503 cfqd
->rq_in_driver
--;
1504 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1505 cfqd
->rq_in_driver
);
1508 static void cfq_remove_request(struct request
*rq
)
1510 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1512 if (cfqq
->next_rq
== rq
)
1513 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1515 list_del_init(&rq
->queuelist
);
1518 cfqq
->cfqd
->rq_queued
--;
1519 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1520 rq_data_dir(rq
), rq_is_sync(rq
));
1521 if (rq
->cmd_flags
& REQ_META
) {
1522 WARN_ON(!cfqq
->meta_pending
);
1523 cfqq
->meta_pending
--;
1527 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1530 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1531 struct request
*__rq
;
1533 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1534 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1536 return ELEVATOR_FRONT_MERGE
;
1539 return ELEVATOR_NO_MERGE
;
1542 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1545 if (type
== ELEVATOR_FRONT_MERGE
) {
1546 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1548 cfq_reposition_rq_rb(cfqq
, req
);
1552 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1555 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req
))->blkg
,
1556 bio_data_dir(bio
), cfq_bio_sync(bio
));
1560 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1561 struct request
*next
)
1563 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1565 * reposition in fifo if next is older than rq
1567 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1568 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1569 list_move(&rq
->queuelist
, &next
->queuelist
);
1570 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1573 if (cfqq
->next_rq
== next
)
1575 cfq_remove_request(next
);
1576 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq
))->blkg
,
1577 rq_data_dir(next
), rq_is_sync(next
));
1580 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1583 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1584 struct cfq_io_context
*cic
;
1585 struct cfq_queue
*cfqq
;
1588 * Disallow merge of a sync bio into an async request.
1590 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1594 * Lookup the cfqq that this bio will be queued with. Allow
1595 * merge only if rq is queued there.
1597 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1601 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1602 return cfqq
== RQ_CFQQ(rq
);
1605 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1607 del_timer(&cfqd
->idle_slice_timer
);
1608 cfq_blkiocg_update_idle_time_stats(&cfqq
->cfqg
->blkg
);
1611 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1612 struct cfq_queue
*cfqq
)
1615 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
1616 cfqd
->serving_prio
, cfqd
->serving_type
);
1617 cfq_blkiocg_update_avg_queue_size_stats(&cfqq
->cfqg
->blkg
);
1618 cfqq
->slice_start
= 0;
1619 cfqq
->dispatch_start
= jiffies
;
1620 cfqq
->allocated_slice
= 0;
1621 cfqq
->slice_end
= 0;
1622 cfqq
->slice_dispatch
= 0;
1623 cfqq
->nr_sectors
= 0;
1625 cfq_clear_cfqq_wait_request(cfqq
);
1626 cfq_clear_cfqq_must_dispatch(cfqq
);
1627 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1628 cfq_clear_cfqq_fifo_expire(cfqq
);
1629 cfq_mark_cfqq_slice_new(cfqq
);
1631 cfq_del_timer(cfqd
, cfqq
);
1634 cfqd
->active_queue
= cfqq
;
1638 * current cfqq expired its slice (or was too idle), select new one
1641 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1644 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1646 if (cfq_cfqq_wait_request(cfqq
))
1647 cfq_del_timer(cfqd
, cfqq
);
1649 cfq_clear_cfqq_wait_request(cfqq
);
1650 cfq_clear_cfqq_wait_busy(cfqq
);
1653 * If this cfqq is shared between multiple processes, check to
1654 * make sure that those processes are still issuing I/Os within
1655 * the mean seek distance. If not, it may be time to break the
1656 * queues apart again.
1658 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
1659 cfq_mark_cfqq_split_coop(cfqq
);
1662 * store what was left of this slice, if the queue idled/timed out
1664 if (timed_out
&& !cfq_cfqq_slice_new(cfqq
)) {
1665 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1666 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1669 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1671 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1672 cfq_del_cfqq_rr(cfqd
, cfqq
);
1674 cfq_resort_rr_list(cfqd
, cfqq
);
1676 if (cfqq
== cfqd
->active_queue
)
1677 cfqd
->active_queue
= NULL
;
1679 if (cfqd
->active_cic
) {
1680 put_io_context(cfqd
->active_cic
->ioc
);
1681 cfqd
->active_cic
= NULL
;
1685 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1687 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1690 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1694 * Get next queue for service. Unless we have a queue preemption,
1695 * we'll simply select the first cfqq in the service tree.
1697 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1699 struct cfq_rb_root
*service_tree
=
1700 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1701 cfqd
->serving_type
);
1703 if (!cfqd
->rq_queued
)
1706 /* There is nothing to dispatch */
1709 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1711 return cfq_rb_first(service_tree
);
1714 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1716 struct cfq_group
*cfqg
;
1717 struct cfq_queue
*cfqq
;
1719 struct cfq_rb_root
*st
;
1721 if (!cfqd
->rq_queued
)
1724 cfqg
= cfq_get_next_cfqg(cfqd
);
1728 for_each_cfqg_st(cfqg
, i
, j
, st
)
1729 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1735 * Get and set a new active queue for service.
1737 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1738 struct cfq_queue
*cfqq
)
1741 cfqq
= cfq_get_next_queue(cfqd
);
1743 __cfq_set_active_queue(cfqd
, cfqq
);
1747 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1750 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1751 return blk_rq_pos(rq
) - cfqd
->last_position
;
1753 return cfqd
->last_position
- blk_rq_pos(rq
);
1756 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1759 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
1762 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1763 struct cfq_queue
*cur_cfqq
)
1765 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1766 struct rb_node
*parent
, *node
;
1767 struct cfq_queue
*__cfqq
;
1768 sector_t sector
= cfqd
->last_position
;
1770 if (RB_EMPTY_ROOT(root
))
1774 * First, if we find a request starting at the end of the last
1775 * request, choose it.
1777 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1782 * If the exact sector wasn't found, the parent of the NULL leaf
1783 * will contain the closest sector.
1785 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1786 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1789 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1790 node
= rb_next(&__cfqq
->p_node
);
1792 node
= rb_prev(&__cfqq
->p_node
);
1796 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1797 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1805 * cur_cfqq - passed in so that we don't decide that the current queue is
1806 * closely cooperating with itself.
1808 * So, basically we're assuming that that cur_cfqq has dispatched at least
1809 * one request, and that cfqd->last_position reflects a position on the disk
1810 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1813 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1814 struct cfq_queue
*cur_cfqq
)
1816 struct cfq_queue
*cfqq
;
1818 if (cfq_class_idle(cur_cfqq
))
1820 if (!cfq_cfqq_sync(cur_cfqq
))
1822 if (CFQQ_SEEKY(cur_cfqq
))
1826 * Don't search priority tree if it's the only queue in the group.
1828 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1832 * We should notice if some of the queues are cooperating, eg
1833 * working closely on the same area of the disk. In that case,
1834 * we can group them together and don't waste time idling.
1836 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1840 /* If new queue belongs to different cfq_group, don't choose it */
1841 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1845 * It only makes sense to merge sync queues.
1847 if (!cfq_cfqq_sync(cfqq
))
1849 if (CFQQ_SEEKY(cfqq
))
1853 * Do not merge queues of different priority classes
1855 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1862 * Determine whether we should enforce idle window for this queue.
1865 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1867 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1868 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1870 BUG_ON(!service_tree
);
1871 BUG_ON(!service_tree
->count
);
1873 if (!cfqd
->cfq_slice_idle
)
1876 /* We never do for idle class queues. */
1877 if (prio
== IDLE_WORKLOAD
)
1880 /* We do for queues that were marked with idle window flag. */
1881 if (cfq_cfqq_idle_window(cfqq
) &&
1882 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1886 * Otherwise, we do only if they are the last ones
1887 * in their service tree.
1889 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
))
1891 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
1892 service_tree
->count
);
1896 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1898 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1899 struct cfq_io_context
*cic
;
1900 unsigned long sl
, group_idle
= 0;
1903 * SSD device without seek penalty, disable idling. But only do so
1904 * for devices that support queuing, otherwise we still have a problem
1905 * with sync vs async workloads.
1907 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1910 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1911 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1914 * idle is disabled, either manually or by past process history
1916 if (!cfq_should_idle(cfqd
, cfqq
)) {
1917 /* no queue idling. Check for group idling */
1918 if (cfqd
->cfq_group_idle
)
1919 group_idle
= cfqd
->cfq_group_idle
;
1925 * still active requests from this queue, don't idle
1927 if (cfqq
->dispatched
)
1931 * task has exited, don't wait
1933 cic
= cfqd
->active_cic
;
1934 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1938 * If our average think time is larger than the remaining time
1939 * slice, then don't idle. This avoids overrunning the allotted
1942 if (sample_valid(cic
->ttime_samples
) &&
1943 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
)) {
1944 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%d",
1949 /* There are other queues in the group, don't do group idle */
1950 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
1953 cfq_mark_cfqq_wait_request(cfqq
);
1956 sl
= cfqd
->cfq_group_idle
;
1958 sl
= cfqd
->cfq_slice_idle
;
1960 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1961 cfq_blkiocg_update_set_idle_time_stats(&cfqq
->cfqg
->blkg
);
1962 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
1963 group_idle
? 1 : 0);
1967 * Move request from internal lists to the request queue dispatch list.
1969 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1971 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1972 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1974 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1976 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1977 cfq_remove_request(rq
);
1979 (RQ_CFQG(rq
))->dispatched
++;
1980 elv_dispatch_sort(q
, rq
);
1982 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
1983 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
1984 cfq_blkiocg_update_dispatch_stats(&cfqq
->cfqg
->blkg
, blk_rq_bytes(rq
),
1985 rq_data_dir(rq
), rq_is_sync(rq
));
1989 * return expired entry, or NULL to just start from scratch in rbtree
1991 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1993 struct request
*rq
= NULL
;
1995 if (cfq_cfqq_fifo_expire(cfqq
))
1998 cfq_mark_cfqq_fifo_expire(cfqq
);
2000 if (list_empty(&cfqq
->fifo
))
2003 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2004 if (time_before(jiffies
, rq_fifo_time(rq
)))
2007 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2012 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2014 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2016 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2018 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
2022 * Must be called with the queue_lock held.
2024 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2026 int process_refs
, io_refs
;
2028 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2029 process_refs
= cfqq
->ref
- io_refs
;
2030 BUG_ON(process_refs
< 0);
2031 return process_refs
;
2034 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2036 int process_refs
, new_process_refs
;
2037 struct cfq_queue
*__cfqq
;
2040 * If there are no process references on the new_cfqq, then it is
2041 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2042 * chain may have dropped their last reference (not just their
2043 * last process reference).
2045 if (!cfqq_process_refs(new_cfqq
))
2048 /* Avoid a circular list and skip interim queue merges */
2049 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2055 process_refs
= cfqq_process_refs(cfqq
);
2056 new_process_refs
= cfqq_process_refs(new_cfqq
);
2058 * If the process for the cfqq has gone away, there is no
2059 * sense in merging the queues.
2061 if (process_refs
== 0 || new_process_refs
== 0)
2065 * Merge in the direction of the lesser amount of work.
2067 if (new_process_refs
>= process_refs
) {
2068 cfqq
->new_cfqq
= new_cfqq
;
2069 new_cfqq
->ref
+= process_refs
;
2071 new_cfqq
->new_cfqq
= cfqq
;
2072 cfqq
->ref
+= new_process_refs
;
2076 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2077 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2079 struct cfq_queue
*queue
;
2081 bool key_valid
= false;
2082 unsigned long lowest_key
= 0;
2083 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2085 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2086 /* select the one with lowest rb_key */
2087 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2089 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2090 lowest_key
= queue
->rb_key
;
2099 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2103 struct cfq_rb_root
*st
;
2104 unsigned group_slice
;
2105 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2107 /* Choose next priority. RT > BE > IDLE */
2108 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2109 cfqd
->serving_prio
= RT_WORKLOAD
;
2110 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2111 cfqd
->serving_prio
= BE_WORKLOAD
;
2113 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2114 cfqd
->workload_expires
= jiffies
+ 1;
2118 if (original_prio
!= cfqd
->serving_prio
)
2122 * For RT and BE, we have to choose also the type
2123 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2126 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2130 * check workload expiration, and that we still have other queues ready
2132 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2136 /* otherwise select new workload type */
2137 cfqd
->serving_type
=
2138 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2139 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2143 * the workload slice is computed as a fraction of target latency
2144 * proportional to the number of queues in that workload, over
2145 * all the queues in the same priority class
2147 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2149 slice
= group_slice
* count
/
2150 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2151 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2153 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2157 * Async queues are currently system wide. Just taking
2158 * proportion of queues with-in same group will lead to higher
2159 * async ratio system wide as generally root group is going
2160 * to have higher weight. A more accurate thing would be to
2161 * calculate system wide asnc/sync ratio.
2163 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2164 tmp
= tmp
/cfqd
->busy_queues
;
2165 slice
= min_t(unsigned, slice
, tmp
);
2167 /* async workload slice is scaled down according to
2168 * the sync/async slice ratio. */
2169 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2171 /* sync workload slice is at least 2 * cfq_slice_idle */
2172 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2174 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2175 cfq_log(cfqd
, "workload slice:%d", slice
);
2176 cfqd
->workload_expires
= jiffies
+ slice
;
2179 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2181 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2182 struct cfq_group
*cfqg
;
2184 if (RB_EMPTY_ROOT(&st
->rb
))
2186 cfqg
= cfq_rb_first_group(st
);
2187 update_min_vdisktime(st
);
2191 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2193 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2195 cfqd
->serving_group
= cfqg
;
2197 /* Restore the workload type data */
2198 if (cfqg
->saved_workload_slice
) {
2199 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2200 cfqd
->serving_type
= cfqg
->saved_workload
;
2201 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2203 cfqd
->workload_expires
= jiffies
- 1;
2205 choose_service_tree(cfqd
, cfqg
);
2209 * Select a queue for service. If we have a current active queue,
2210 * check whether to continue servicing it, or retrieve and set a new one.
2212 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2214 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2216 cfqq
= cfqd
->active_queue
;
2220 if (!cfqd
->rq_queued
)
2224 * We were waiting for group to get backlogged. Expire the queue
2226 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2230 * The active queue has run out of time, expire it and select new.
2232 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2234 * If slice had not expired at the completion of last request
2235 * we might not have turned on wait_busy flag. Don't expire
2236 * the queue yet. Allow the group to get backlogged.
2238 * The very fact that we have used the slice, that means we
2239 * have been idling all along on this queue and it should be
2240 * ok to wait for this request to complete.
2242 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2243 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2247 goto check_group_idle
;
2251 * The active queue has requests and isn't expired, allow it to
2254 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2258 * If another queue has a request waiting within our mean seek
2259 * distance, let it run. The expire code will check for close
2260 * cooperators and put the close queue at the front of the service
2261 * tree. If possible, merge the expiring queue with the new cfqq.
2263 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2265 if (!cfqq
->new_cfqq
)
2266 cfq_setup_merge(cfqq
, new_cfqq
);
2271 * No requests pending. If the active queue still has requests in
2272 * flight or is idling for a new request, allow either of these
2273 * conditions to happen (or time out) before selecting a new queue.
2275 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2281 * This is a deep seek queue, but the device is much faster than
2282 * the queue can deliver, don't idle
2284 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2285 (cfq_cfqq_slice_new(cfqq
) ||
2286 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2287 cfq_clear_cfqq_deep(cfqq
);
2288 cfq_clear_cfqq_idle_window(cfqq
);
2291 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2297 * If group idle is enabled and there are requests dispatched from
2298 * this group, wait for requests to complete.
2301 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1
2302 && cfqq
->cfqg
->dispatched
) {
2308 cfq_slice_expired(cfqd
, 0);
2311 * Current queue expired. Check if we have to switch to a new
2315 cfq_choose_cfqg(cfqd
);
2317 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2322 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2326 while (cfqq
->next_rq
) {
2327 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2331 BUG_ON(!list_empty(&cfqq
->fifo
));
2333 /* By default cfqq is not expired if it is empty. Do it explicitly */
2334 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2339 * Drain our current requests. Used for barriers and when switching
2340 * io schedulers on-the-fly.
2342 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2344 struct cfq_queue
*cfqq
;
2347 /* Expire the timeslice of the current active queue first */
2348 cfq_slice_expired(cfqd
, 0);
2349 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2350 __cfq_set_active_queue(cfqd
, cfqq
);
2351 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2354 BUG_ON(cfqd
->busy_queues
);
2356 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2360 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2361 struct cfq_queue
*cfqq
)
2363 /* the queue hasn't finished any request, can't estimate */
2364 if (cfq_cfqq_slice_new(cfqq
))
2366 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2373 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2375 unsigned int max_dispatch
;
2378 * Drain async requests before we start sync IO
2380 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2384 * If this is an async queue and we have sync IO in flight, let it wait
2386 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2389 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2390 if (cfq_class_idle(cfqq
))
2394 * Does this cfqq already have too much IO in flight?
2396 if (cfqq
->dispatched
>= max_dispatch
) {
2398 * idle queue must always only have a single IO in flight
2400 if (cfq_class_idle(cfqq
))
2404 * We have other queues, don't allow more IO from this one
2406 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
))
2410 * Sole queue user, no limit
2412 if (cfqd
->busy_queues
== 1)
2416 * Normally we start throttling cfqq when cfq_quantum/2
2417 * requests have been dispatched. But we can drive
2418 * deeper queue depths at the beginning of slice
2419 * subjected to upper limit of cfq_quantum.
2421 max_dispatch
= cfqd
->cfq_quantum
;
2425 * Async queues must wait a bit before being allowed dispatch.
2426 * We also ramp up the dispatch depth gradually for async IO,
2427 * based on the last sync IO we serviced
2429 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2430 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2433 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2434 if (!depth
&& !cfqq
->dispatched
)
2436 if (depth
< max_dispatch
)
2437 max_dispatch
= depth
;
2441 * If we're below the current max, allow a dispatch
2443 return cfqq
->dispatched
< max_dispatch
;
2447 * Dispatch a request from cfqq, moving them to the request queue
2450 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2454 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2456 if (!cfq_may_dispatch(cfqd
, cfqq
))
2460 * follow expired path, else get first next available
2462 rq
= cfq_check_fifo(cfqq
);
2467 * insert request into driver dispatch list
2469 cfq_dispatch_insert(cfqd
->queue
, rq
);
2471 if (!cfqd
->active_cic
) {
2472 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2474 atomic_long_inc(&cic
->ioc
->refcount
);
2475 cfqd
->active_cic
= cic
;
2482 * Find the cfqq that we need to service and move a request from that to the
2485 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2487 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2488 struct cfq_queue
*cfqq
;
2490 if (!cfqd
->busy_queues
)
2493 if (unlikely(force
))
2494 return cfq_forced_dispatch(cfqd
);
2496 cfqq
= cfq_select_queue(cfqd
);
2501 * Dispatch a request from this cfqq, if it is allowed
2503 if (!cfq_dispatch_request(cfqd
, cfqq
))
2506 cfqq
->slice_dispatch
++;
2507 cfq_clear_cfqq_must_dispatch(cfqq
);
2510 * expire an async queue immediately if it has used up its slice. idle
2511 * queue always expire after 1 dispatch round.
2513 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2514 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2515 cfq_class_idle(cfqq
))) {
2516 cfqq
->slice_end
= jiffies
+ 1;
2517 cfq_slice_expired(cfqd
, 0);
2520 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2525 * task holds one reference to the queue, dropped when task exits. each rq
2526 * in-flight on this queue also holds a reference, dropped when rq is freed.
2528 * Each cfq queue took a reference on the parent group. Drop it now.
2529 * queue lock must be held here.
2531 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2533 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2534 struct cfq_group
*cfqg
, *orig_cfqg
;
2536 BUG_ON(cfqq
->ref
<= 0);
2542 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2543 BUG_ON(rb_first(&cfqq
->sort_list
));
2544 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2546 orig_cfqg
= cfqq
->orig_cfqg
;
2548 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2549 __cfq_slice_expired(cfqd
, cfqq
, 0);
2550 cfq_schedule_dispatch(cfqd
);
2553 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2554 kmem_cache_free(cfq_pool
, cfqq
);
2557 cfq_put_cfqg(orig_cfqg
);
2561 * Must always be called with the rcu_read_lock() held
2564 __call_for_each_cic(struct io_context
*ioc
,
2565 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2567 struct cfq_io_context
*cic
;
2568 struct hlist_node
*n
;
2570 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
2575 * Call func for each cic attached to this ioc.
2578 call_for_each_cic(struct io_context
*ioc
,
2579 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2582 __call_for_each_cic(ioc
, func
);
2586 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2588 struct cfq_io_context
*cic
;
2590 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
2592 kmem_cache_free(cfq_ioc_pool
, cic
);
2593 elv_ioc_count_dec(cfq_ioc_count
);
2597 * CFQ scheduler is exiting, grab exit lock and check
2598 * the pending io context count. If it hits zero,
2599 * complete ioc_gone and set it back to NULL
2601 spin_lock(&ioc_gone_lock
);
2602 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
2606 spin_unlock(&ioc_gone_lock
);
2610 static void cfq_cic_free(struct cfq_io_context
*cic
)
2612 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2615 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2617 unsigned long flags
;
2618 unsigned long dead_key
= (unsigned long) cic
->key
;
2620 BUG_ON(!(dead_key
& CIC_DEAD_KEY
));
2622 spin_lock_irqsave(&ioc
->lock
, flags
);
2623 radix_tree_delete(&ioc
->radix_root
, dead_key
>> CIC_DEAD_INDEX_SHIFT
);
2624 hlist_del_rcu(&cic
->cic_list
);
2625 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2631 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2632 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2633 * and ->trim() which is called with the task lock held
2635 static void cfq_free_io_context(struct io_context
*ioc
)
2638 * ioc->refcount is zero here, or we are called from elv_unregister(),
2639 * so no more cic's are allowed to be linked into this ioc. So it
2640 * should be ok to iterate over the known list, we will see all cic's
2641 * since no new ones are added.
2643 __call_for_each_cic(ioc
, cic_free_func
);
2646 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2648 struct cfq_queue
*__cfqq
, *next
;
2651 * If this queue was scheduled to merge with another queue, be
2652 * sure to drop the reference taken on that queue (and others in
2653 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2655 __cfqq
= cfqq
->new_cfqq
;
2657 if (__cfqq
== cfqq
) {
2658 WARN(1, "cfqq->new_cfqq loop detected\n");
2661 next
= __cfqq
->new_cfqq
;
2662 cfq_put_queue(__cfqq
);
2667 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2669 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2670 __cfq_slice_expired(cfqd
, cfqq
, 0);
2671 cfq_schedule_dispatch(cfqd
);
2674 cfq_put_cooperator(cfqq
);
2676 cfq_put_queue(cfqq
);
2679 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
2680 struct cfq_io_context
*cic
)
2682 struct io_context
*ioc
= cic
->ioc
;
2684 list_del_init(&cic
->queue_list
);
2687 * Make sure dead mark is seen for dead queues
2690 cic
->key
= cfqd_dead_key(cfqd
);
2692 if (ioc
->ioc_data
== cic
)
2693 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2695 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2696 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2697 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2700 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2701 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2702 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2706 static void cfq_exit_single_io_context(struct io_context
*ioc
,
2707 struct cfq_io_context
*cic
)
2709 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2712 struct request_queue
*q
= cfqd
->queue
;
2713 unsigned long flags
;
2715 spin_lock_irqsave(q
->queue_lock
, flags
);
2718 * Ensure we get a fresh copy of the ->key to prevent
2719 * race between exiting task and queue
2721 smp_read_barrier_depends();
2722 if (cic
->key
== cfqd
)
2723 __cfq_exit_single_io_context(cfqd
, cic
);
2725 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2730 * The process that ioc belongs to has exited, we need to clean up
2731 * and put the internal structures we have that belongs to that process.
2733 static void cfq_exit_io_context(struct io_context
*ioc
)
2735 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
2738 static struct cfq_io_context
*
2739 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2741 struct cfq_io_context
*cic
;
2743 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2746 cic
->last_end_request
= jiffies
;
2747 INIT_LIST_HEAD(&cic
->queue_list
);
2748 INIT_HLIST_NODE(&cic
->cic_list
);
2749 cic
->dtor
= cfq_free_io_context
;
2750 cic
->exit
= cfq_exit_io_context
;
2751 elv_ioc_count_inc(cfq_ioc_count
);
2757 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2759 struct task_struct
*tsk
= current
;
2762 if (!cfq_cfqq_prio_changed(cfqq
))
2765 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2766 switch (ioprio_class
) {
2768 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2769 case IOPRIO_CLASS_NONE
:
2771 * no prio set, inherit CPU scheduling settings
2773 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2774 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2776 case IOPRIO_CLASS_RT
:
2777 cfqq
->ioprio
= task_ioprio(ioc
);
2778 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2780 case IOPRIO_CLASS_BE
:
2781 cfqq
->ioprio
= task_ioprio(ioc
);
2782 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2784 case IOPRIO_CLASS_IDLE
:
2785 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2787 cfq_clear_cfqq_idle_window(cfqq
);
2792 * keep track of original prio settings in case we have to temporarily
2793 * elevate the priority of this queue
2795 cfqq
->org_ioprio
= cfqq
->ioprio
;
2796 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2797 cfq_clear_cfqq_prio_changed(cfqq
);
2800 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2802 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2803 struct cfq_queue
*cfqq
;
2804 unsigned long flags
;
2806 if (unlikely(!cfqd
))
2809 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2811 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2813 struct cfq_queue
*new_cfqq
;
2814 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2817 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2818 cfq_put_queue(cfqq
);
2822 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2824 cfq_mark_cfqq_prio_changed(cfqq
);
2826 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2829 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2831 call_for_each_cic(ioc
, changed_ioprio
);
2832 ioc
->ioprio_changed
= 0;
2835 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2836 pid_t pid
, bool is_sync
)
2838 RB_CLEAR_NODE(&cfqq
->rb_node
);
2839 RB_CLEAR_NODE(&cfqq
->p_node
);
2840 INIT_LIST_HEAD(&cfqq
->fifo
);
2845 cfq_mark_cfqq_prio_changed(cfqq
);
2848 if (!cfq_class_idle(cfqq
))
2849 cfq_mark_cfqq_idle_window(cfqq
);
2850 cfq_mark_cfqq_sync(cfqq
);
2855 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2856 static void changed_cgroup(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2858 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2859 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2860 unsigned long flags
;
2861 struct request_queue
*q
;
2863 if (unlikely(!cfqd
))
2868 spin_lock_irqsave(q
->queue_lock
, flags
);
2872 * Drop reference to sync queue. A new sync queue will be
2873 * assigned in new group upon arrival of a fresh request.
2875 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2876 cic_set_cfqq(cic
, NULL
, 1);
2877 cfq_put_queue(sync_cfqq
);
2880 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2883 static void cfq_ioc_set_cgroup(struct io_context
*ioc
)
2885 call_for_each_cic(ioc
, changed_cgroup
);
2886 ioc
->cgroup_changed
= 0;
2888 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2890 static struct cfq_queue
*
2891 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2892 struct io_context
*ioc
, gfp_t gfp_mask
)
2894 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2895 struct cfq_io_context
*cic
;
2896 struct cfq_group
*cfqg
;
2899 cfqg
= cfq_get_cfqg(cfqd
, 1);
2900 cic
= cfq_cic_lookup(cfqd
, ioc
);
2901 /* cic always exists here */
2902 cfqq
= cic_to_cfqq(cic
, is_sync
);
2905 * Always try a new alloc if we fell back to the OOM cfqq
2906 * originally, since it should just be a temporary situation.
2908 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2913 } else if (gfp_mask
& __GFP_WAIT
) {
2914 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2915 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2916 gfp_mask
| __GFP_ZERO
,
2918 spin_lock_irq(cfqd
->queue
->queue_lock
);
2922 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2923 gfp_mask
| __GFP_ZERO
,
2928 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2929 cfq_init_prio_data(cfqq
, ioc
);
2930 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2931 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2933 cfqq
= &cfqd
->oom_cfqq
;
2937 kmem_cache_free(cfq_pool
, new_cfqq
);
2942 static struct cfq_queue
**
2943 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2945 switch (ioprio_class
) {
2946 case IOPRIO_CLASS_RT
:
2947 return &cfqd
->async_cfqq
[0][ioprio
];
2948 case IOPRIO_CLASS_BE
:
2949 return &cfqd
->async_cfqq
[1][ioprio
];
2950 case IOPRIO_CLASS_IDLE
:
2951 return &cfqd
->async_idle_cfqq
;
2957 static struct cfq_queue
*
2958 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2961 const int ioprio
= task_ioprio(ioc
);
2962 const int ioprio_class
= task_ioprio_class(ioc
);
2963 struct cfq_queue
**async_cfqq
= NULL
;
2964 struct cfq_queue
*cfqq
= NULL
;
2967 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2972 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2975 * pin the queue now that it's allocated, scheduler exit will prune it
2977 if (!is_sync
&& !(*async_cfqq
)) {
2987 * We drop cfq io contexts lazily, so we may find a dead one.
2990 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2991 struct cfq_io_context
*cic
)
2993 unsigned long flags
;
2995 WARN_ON(!list_empty(&cic
->queue_list
));
2996 BUG_ON(cic
->key
!= cfqd_dead_key(cfqd
));
2998 spin_lock_irqsave(&ioc
->lock
, flags
);
3000 BUG_ON(ioc
->ioc_data
== cic
);
3002 radix_tree_delete(&ioc
->radix_root
, cfqd
->cic_index
);
3003 hlist_del_rcu(&cic
->cic_list
);
3004 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3009 static struct cfq_io_context
*
3010 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
3012 struct cfq_io_context
*cic
;
3013 unsigned long flags
;
3021 * we maintain a last-hit cache, to avoid browsing over the tree
3023 cic
= rcu_dereference(ioc
->ioc_data
);
3024 if (cic
&& cic
->key
== cfqd
) {
3030 cic
= radix_tree_lookup(&ioc
->radix_root
, cfqd
->cic_index
);
3034 if (unlikely(cic
->key
!= cfqd
)) {
3035 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
3040 spin_lock_irqsave(&ioc
->lock
, flags
);
3041 rcu_assign_pointer(ioc
->ioc_data
, cic
);
3042 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3050 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3051 * the process specific cfq io context when entered from the block layer.
3052 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3054 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
3055 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
3057 unsigned long flags
;
3060 ret
= radix_tree_preload(gfp_mask
);
3065 spin_lock_irqsave(&ioc
->lock
, flags
);
3066 ret
= radix_tree_insert(&ioc
->radix_root
,
3067 cfqd
->cic_index
, cic
);
3069 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
3070 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3072 radix_tree_preload_end();
3075 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3076 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
3077 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3082 printk(KERN_ERR
"cfq: cic link failed!\n");
3088 * Setup general io context and cfq io context. There can be several cfq
3089 * io contexts per general io context, if this process is doing io to more
3090 * than one device managed by cfq.
3092 static struct cfq_io_context
*
3093 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3095 struct io_context
*ioc
= NULL
;
3096 struct cfq_io_context
*cic
;
3098 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3100 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
3104 cic
= cfq_cic_lookup(cfqd
, ioc
);
3108 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
3112 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
3116 smp_read_barrier_depends();
3117 if (unlikely(ioc
->ioprio_changed
))
3118 cfq_ioc_set_ioprio(ioc
);
3120 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3121 if (unlikely(ioc
->cgroup_changed
))
3122 cfq_ioc_set_cgroup(ioc
);
3128 put_io_context(ioc
);
3133 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
3135 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
3136 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
3138 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
3139 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
3140 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
3144 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3148 sector_t n_sec
= blk_rq_sectors(rq
);
3149 if (cfqq
->last_request_pos
) {
3150 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3151 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3153 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3156 cfqq
->seek_history
<<= 1;
3157 if (blk_queue_nonrot(cfqd
->queue
))
3158 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3160 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3164 * Disable idle window if the process thinks too long or seeks so much that
3168 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3169 struct cfq_io_context
*cic
)
3171 int old_idle
, enable_idle
;
3174 * Don't idle for async or idle io prio class
3176 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3179 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3181 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3182 cfq_mark_cfqq_deep(cfqq
);
3184 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3186 else if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3187 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3189 else if (sample_valid(cic
->ttime_samples
)) {
3190 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
3196 if (old_idle
!= enable_idle
) {
3197 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3199 cfq_mark_cfqq_idle_window(cfqq
);
3201 cfq_clear_cfqq_idle_window(cfqq
);
3206 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3207 * no or if we aren't sure, a 1 will cause a preempt.
3210 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3213 struct cfq_queue
*cfqq
;
3215 cfqq
= cfqd
->active_queue
;
3219 if (cfq_class_idle(new_cfqq
))
3222 if (cfq_class_idle(cfqq
))
3226 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3228 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3232 * if the new request is sync, but the currently running queue is
3233 * not, let the sync request have priority.
3235 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3238 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3241 if (cfq_slice_used(cfqq
))
3244 /* Allow preemption only if we are idling on sync-noidle tree */
3245 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3246 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3247 new_cfqq
->service_tree
->count
== 2 &&
3248 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3252 * So both queues are sync. Let the new request get disk time if
3253 * it's a metadata request and the current queue is doing regular IO.
3255 if ((rq
->cmd_flags
& REQ_META
) && !cfqq
->meta_pending
)
3259 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3261 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3264 /* An idle queue should not be idle now for some reason */
3265 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3268 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3272 * if this request is as-good as one we would expect from the
3273 * current cfqq, let it preempt
3275 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3282 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3283 * let it have half of its nominal slice.
3285 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3287 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3288 cfq_slice_expired(cfqd
, 1);
3291 * Put the new queue at the front of the of the current list,
3292 * so we know that it will be selected next.
3294 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3296 cfq_service_tree_add(cfqd
, cfqq
, 1);
3298 cfqq
->slice_end
= 0;
3299 cfq_mark_cfqq_slice_new(cfqq
);
3303 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3304 * something we should do about it
3307 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3310 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3313 if (rq
->cmd_flags
& REQ_META
)
3314 cfqq
->meta_pending
++;
3316 cfq_update_io_thinktime(cfqd
, cic
);
3317 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3318 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3320 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3322 if (cfqq
== cfqd
->active_queue
) {
3324 * Remember that we saw a request from this process, but
3325 * don't start queuing just yet. Otherwise we risk seeing lots
3326 * of tiny requests, because we disrupt the normal plugging
3327 * and merging. If the request is already larger than a single
3328 * page, let it rip immediately. For that case we assume that
3329 * merging is already done. Ditto for a busy system that
3330 * has other work pending, don't risk delaying until the
3331 * idle timer unplug to continue working.
3333 if (cfq_cfqq_wait_request(cfqq
)) {
3334 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3335 cfqd
->busy_queues
> 1) {
3336 cfq_del_timer(cfqd
, cfqq
);
3337 cfq_clear_cfqq_wait_request(cfqq
);
3338 __blk_run_queue(cfqd
->queue
);
3340 cfq_blkiocg_update_idle_time_stats(
3342 cfq_mark_cfqq_must_dispatch(cfqq
);
3345 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3347 * not the active queue - expire current slice if it is
3348 * idle and has expired it's mean thinktime or this new queue
3349 * has some old slice time left and is of higher priority or
3350 * this new queue is RT and the current one is BE
3352 cfq_preempt_queue(cfqd
, cfqq
);
3353 __blk_run_queue(cfqd
->queue
);
3357 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3359 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3360 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3362 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3363 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3365 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3366 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3368 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
3369 &cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
3371 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3375 * Update hw_tag based on peak queue depth over 50 samples under
3378 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3380 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3382 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3383 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3385 if (cfqd
->hw_tag
== 1)
3388 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3389 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3393 * If active queue hasn't enough requests and can idle, cfq might not
3394 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3397 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3398 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3399 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3402 if (cfqd
->hw_tag_samples
++ < 50)
3405 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3411 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3413 struct cfq_io_context
*cic
= cfqd
->active_cic
;
3415 /* If there are other queues in the group, don't wait */
3416 if (cfqq
->cfqg
->nr_cfqq
> 1)
3419 if (cfq_slice_used(cfqq
))
3422 /* if slice left is less than think time, wait busy */
3423 if (cic
&& sample_valid(cic
->ttime_samples
)
3424 && (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
3428 * If think times is less than a jiffy than ttime_mean=0 and above
3429 * will not be true. It might happen that slice has not expired yet
3430 * but will expire soon (4-5 ns) during select_queue(). To cover the
3431 * case where think time is less than a jiffy, mark the queue wait
3432 * busy if only 1 jiffy is left in the slice.
3434 if (cfqq
->slice_end
- jiffies
== 1)
3440 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3442 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3443 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3444 const int sync
= rq_is_sync(rq
);
3448 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3449 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3451 cfq_update_hw_tag(cfqd
);
3453 WARN_ON(!cfqd
->rq_in_driver
);
3454 WARN_ON(!cfqq
->dispatched
);
3455 cfqd
->rq_in_driver
--;
3457 (RQ_CFQG(rq
))->dispatched
--;
3458 cfq_blkiocg_update_completion_stats(&cfqq
->cfqg
->blkg
,
3459 rq_start_time_ns(rq
), rq_io_start_time_ns(rq
),
3460 rq_data_dir(rq
), rq_is_sync(rq
));
3462 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3465 RQ_CIC(rq
)->last_end_request
= now
;
3466 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3467 cfqd
->last_delayed_sync
= now
;
3471 * If this is the active queue, check if it needs to be expired,
3472 * or if we want to idle in case it has no pending requests.
3474 if (cfqd
->active_queue
== cfqq
) {
3475 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3477 if (cfq_cfqq_slice_new(cfqq
)) {
3478 cfq_set_prio_slice(cfqd
, cfqq
);
3479 cfq_clear_cfqq_slice_new(cfqq
);
3483 * Should we wait for next request to come in before we expire
3486 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3487 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3488 if (!cfqd
->cfq_slice_idle
)
3489 extend_sl
= cfqd
->cfq_group_idle
;
3490 cfqq
->slice_end
= jiffies
+ extend_sl
;
3491 cfq_mark_cfqq_wait_busy(cfqq
);
3492 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3496 * Idling is not enabled on:
3498 * - idle-priority queues
3500 * - queues with still some requests queued
3501 * - when there is a close cooperator
3503 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3504 cfq_slice_expired(cfqd
, 1);
3505 else if (sync
&& cfqq_empty
&&
3506 !cfq_close_cooperator(cfqd
, cfqq
)) {
3507 cfq_arm_slice_timer(cfqd
);
3511 if (!cfqd
->rq_in_driver
)
3512 cfq_schedule_dispatch(cfqd
);
3516 * we temporarily boost lower priority queues if they are holding fs exclusive
3517 * resources. they are boosted to normal prio (CLASS_BE/4)
3519 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
3521 if (has_fs_excl()) {
3523 * boost idle prio on transactions that would lock out other
3524 * users of the filesystem
3526 if (cfq_class_idle(cfqq
))
3527 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3528 if (cfqq
->ioprio
> IOPRIO_NORM
)
3529 cfqq
->ioprio
= IOPRIO_NORM
;
3532 * unboost the queue (if needed)
3534 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
3535 cfqq
->ioprio
= cfqq
->org_ioprio
;
3539 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3541 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3542 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3543 return ELV_MQUEUE_MUST
;
3546 return ELV_MQUEUE_MAY
;
3549 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3551 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3552 struct task_struct
*tsk
= current
;
3553 struct cfq_io_context
*cic
;
3554 struct cfq_queue
*cfqq
;
3557 * don't force setup of a queue from here, as a call to may_queue
3558 * does not necessarily imply that a request actually will be queued.
3559 * so just lookup a possibly existing queue, or return 'may queue'
3562 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3564 return ELV_MQUEUE_MAY
;
3566 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3568 cfq_init_prio_data(cfqq
, cic
->ioc
);
3569 cfq_prio_boost(cfqq
);
3571 return __cfq_may_queue(cfqq
);
3574 return ELV_MQUEUE_MAY
;
3578 * queue lock held here
3580 static void cfq_put_request(struct request
*rq
)
3582 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3585 const int rw
= rq_data_dir(rq
);
3587 BUG_ON(!cfqq
->allocated
[rw
]);
3588 cfqq
->allocated
[rw
]--;
3590 put_io_context(RQ_CIC(rq
)->ioc
);
3592 rq
->elevator_private
= NULL
;
3593 rq
->elevator_private2
= NULL
;
3595 /* Put down rq reference on cfqg */
3596 cfq_put_cfqg(RQ_CFQG(rq
));
3597 rq
->elevator_private3
= NULL
;
3599 cfq_put_queue(cfqq
);
3603 static struct cfq_queue
*
3604 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3605 struct cfq_queue
*cfqq
)
3607 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3608 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3609 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3610 cfq_put_queue(cfqq
);
3611 return cic_to_cfqq(cic
, 1);
3615 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3616 * was the last process referring to said cfqq.
3618 static struct cfq_queue
*
3619 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3621 if (cfqq_process_refs(cfqq
) == 1) {
3622 cfqq
->pid
= current
->pid
;
3623 cfq_clear_cfqq_coop(cfqq
);
3624 cfq_clear_cfqq_split_coop(cfqq
);
3628 cic_set_cfqq(cic
, NULL
, 1);
3630 cfq_put_cooperator(cfqq
);
3632 cfq_put_queue(cfqq
);
3636 * Allocate cfq data structures associated with this request.
3639 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3641 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3642 struct cfq_io_context
*cic
;
3643 const int rw
= rq_data_dir(rq
);
3644 const bool is_sync
= rq_is_sync(rq
);
3645 struct cfq_queue
*cfqq
;
3646 unsigned long flags
;
3648 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3650 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3652 spin_lock_irqsave(q
->queue_lock
, flags
);
3658 cfqq
= cic_to_cfqq(cic
, is_sync
);
3659 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3660 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3661 cic_set_cfqq(cic
, cfqq
, is_sync
);
3664 * If the queue was seeky for too long, break it apart.
3666 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3667 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3668 cfqq
= split_cfqq(cic
, cfqq
);
3674 * Check to see if this queue is scheduled to merge with
3675 * another, closely cooperating queue. The merging of
3676 * queues happens here as it must be done in process context.
3677 * The reference on new_cfqq was taken in merge_cfqqs.
3680 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3683 cfqq
->allocated
[rw
]++;
3685 rq
->elevator_private
= cic
;
3686 rq
->elevator_private2
= cfqq
;
3687 rq
->elevator_private3
= cfq_ref_get_cfqg(cfqq
->cfqg
);
3689 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3695 put_io_context(cic
->ioc
);
3697 cfq_schedule_dispatch(cfqd
);
3698 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3699 cfq_log(cfqd
, "set_request fail");
3703 static void cfq_kick_queue(struct work_struct
*work
)
3705 struct cfq_data
*cfqd
=
3706 container_of(work
, struct cfq_data
, unplug_work
);
3707 struct request_queue
*q
= cfqd
->queue
;
3709 spin_lock_irq(q
->queue_lock
);
3710 __blk_run_queue(cfqd
->queue
);
3711 spin_unlock_irq(q
->queue_lock
);
3715 * Timer running if the active_queue is currently idling inside its time slice
3717 static void cfq_idle_slice_timer(unsigned long data
)
3719 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3720 struct cfq_queue
*cfqq
;
3721 unsigned long flags
;
3724 cfq_log(cfqd
, "idle timer fired");
3726 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3728 cfqq
= cfqd
->active_queue
;
3733 * We saw a request before the queue expired, let it through
3735 if (cfq_cfqq_must_dispatch(cfqq
))
3741 if (cfq_slice_used(cfqq
))
3745 * only expire and reinvoke request handler, if there are
3746 * other queues with pending requests
3748 if (!cfqd
->busy_queues
)
3752 * not expired and it has a request pending, let it dispatch
3754 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3758 * Queue depth flag is reset only when the idle didn't succeed
3760 cfq_clear_cfqq_deep(cfqq
);
3763 cfq_slice_expired(cfqd
, timed_out
);
3765 cfq_schedule_dispatch(cfqd
);
3767 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3770 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3772 del_timer_sync(&cfqd
->idle_slice_timer
);
3773 cancel_work_sync(&cfqd
->unplug_work
);
3776 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3780 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3781 if (cfqd
->async_cfqq
[0][i
])
3782 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3783 if (cfqd
->async_cfqq
[1][i
])
3784 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3787 if (cfqd
->async_idle_cfqq
)
3788 cfq_put_queue(cfqd
->async_idle_cfqq
);
3791 static void cfq_cfqd_free(struct rcu_head
*head
)
3793 kfree(container_of(head
, struct cfq_data
, rcu
));
3796 static void cfq_exit_queue(struct elevator_queue
*e
)
3798 struct cfq_data
*cfqd
= e
->elevator_data
;
3799 struct request_queue
*q
= cfqd
->queue
;
3801 cfq_shutdown_timer_wq(cfqd
);
3803 spin_lock_irq(q
->queue_lock
);
3805 if (cfqd
->active_queue
)
3806 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3808 while (!list_empty(&cfqd
->cic_list
)) {
3809 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3810 struct cfq_io_context
,
3813 __cfq_exit_single_io_context(cfqd
, cic
);
3816 cfq_put_async_queues(cfqd
);
3817 cfq_release_cfq_groups(cfqd
);
3818 cfq_blkiocg_del_blkio_group(&cfqd
->root_group
.blkg
);
3820 spin_unlock_irq(q
->queue_lock
);
3822 cfq_shutdown_timer_wq(cfqd
);
3824 spin_lock(&cic_index_lock
);
3825 ida_remove(&cic_index_ida
, cfqd
->cic_index
);
3826 spin_unlock(&cic_index_lock
);
3828 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3829 call_rcu(&cfqd
->rcu
, cfq_cfqd_free
);
3832 static int cfq_alloc_cic_index(void)
3837 if (!ida_pre_get(&cic_index_ida
, GFP_KERNEL
))
3840 spin_lock(&cic_index_lock
);
3841 error
= ida_get_new(&cic_index_ida
, &index
);
3842 spin_unlock(&cic_index_lock
);
3843 if (error
&& error
!= -EAGAIN
)
3850 static void *cfq_init_queue(struct request_queue
*q
)
3852 struct cfq_data
*cfqd
;
3854 struct cfq_group
*cfqg
;
3855 struct cfq_rb_root
*st
;
3857 i
= cfq_alloc_cic_index();
3861 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3866 * Don't need take queue_lock in the routine, since we are
3867 * initializing the ioscheduler, and nobody is using cfqd
3869 cfqd
->cic_index
= i
;
3871 /* Init root service tree */
3872 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3874 /* Init root group */
3875 cfqg
= &cfqd
->root_group
;
3876 for_each_cfqg_st(cfqg
, i
, j
, st
)
3878 RB_CLEAR_NODE(&cfqg
->rb_node
);
3880 /* Give preference to root group over other groups */
3881 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3883 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3885 * Take a reference to root group which we never drop. This is just
3886 * to make sure that cfq_put_cfqg() does not try to kfree root group
3890 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
,
3895 * Not strictly needed (since RB_ROOT just clears the node and we
3896 * zeroed cfqd on alloc), but better be safe in case someone decides
3897 * to add magic to the rb code
3899 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3900 cfqd
->prio_trees
[i
] = RB_ROOT
;
3903 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3904 * Grab a permanent reference to it, so that the normal code flow
3905 * will not attempt to free it.
3907 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3908 cfqd
->oom_cfqq
.ref
++;
3909 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3911 INIT_LIST_HEAD(&cfqd
->cic_list
);
3915 init_timer(&cfqd
->idle_slice_timer
);
3916 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3917 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3919 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3921 cfqd
->cfq_quantum
= cfq_quantum
;
3922 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3923 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3924 cfqd
->cfq_back_max
= cfq_back_max
;
3925 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3926 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3927 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3928 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3929 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3930 cfqd
->cfq_group_idle
= cfq_group_idle
;
3931 cfqd
->cfq_latency
= 1;
3932 cfqd
->cfq_group_isolation
= 0;
3935 * we optimistically start assuming sync ops weren't delayed in last
3936 * second, in order to have larger depth for async operations.
3938 cfqd
->last_delayed_sync
= jiffies
- HZ
;
3942 static void cfq_slab_kill(void)
3945 * Caller already ensured that pending RCU callbacks are completed,
3946 * so we should have no busy allocations at this point.
3949 kmem_cache_destroy(cfq_pool
);
3951 kmem_cache_destroy(cfq_ioc_pool
);
3954 static int __init
cfq_slab_setup(void)
3956 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3960 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3971 * sysfs parts below -->
3974 cfq_var_show(unsigned int var
, char *page
)
3976 return sprintf(page
, "%d\n", var
);
3980 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3982 char *p
= (char *) page
;
3984 *var
= simple_strtoul(p
, &p
, 10);
3988 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3989 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3991 struct cfq_data *cfqd = e->elevator_data; \
3992 unsigned int __data = __VAR; \
3994 __data = jiffies_to_msecs(__data); \
3995 return cfq_var_show(__data, (page)); \
3997 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3998 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3999 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
4000 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4001 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4002 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4003 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4004 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4005 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4006 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4007 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4008 SHOW_FUNCTION(cfq_group_isolation_show
, cfqd
->cfq_group_isolation
, 0);
4009 #undef SHOW_FUNCTION
4011 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4012 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4014 struct cfq_data *cfqd = e->elevator_data; \
4015 unsigned int __data; \
4016 int ret = cfq_var_store(&__data, (page), count); \
4017 if (__data < (MIN)) \
4019 else if (__data > (MAX)) \
4022 *(__PTR) = msecs_to_jiffies(__data); \
4024 *(__PTR) = __data; \
4027 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4028 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4030 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4032 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4033 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4035 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4036 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4037 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4038 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4039 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4041 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4042 STORE_FUNCTION(cfq_group_isolation_store
, &cfqd
->cfq_group_isolation
, 0, 1, 0);
4043 #undef STORE_FUNCTION
4045 #define CFQ_ATTR(name) \
4046 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4048 static struct elv_fs_entry cfq_attrs
[] = {
4050 CFQ_ATTR(fifo_expire_sync
),
4051 CFQ_ATTR(fifo_expire_async
),
4052 CFQ_ATTR(back_seek_max
),
4053 CFQ_ATTR(back_seek_penalty
),
4054 CFQ_ATTR(slice_sync
),
4055 CFQ_ATTR(slice_async
),
4056 CFQ_ATTR(slice_async_rq
),
4057 CFQ_ATTR(slice_idle
),
4058 CFQ_ATTR(group_idle
),
4059 CFQ_ATTR(low_latency
),
4060 CFQ_ATTR(group_isolation
),
4064 static struct elevator_type iosched_cfq
= {
4066 .elevator_merge_fn
= cfq_merge
,
4067 .elevator_merged_fn
= cfq_merged_request
,
4068 .elevator_merge_req_fn
= cfq_merged_requests
,
4069 .elevator_allow_merge_fn
= cfq_allow_merge
,
4070 .elevator_bio_merged_fn
= cfq_bio_merged
,
4071 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4072 .elevator_add_req_fn
= cfq_insert_request
,
4073 .elevator_activate_req_fn
= cfq_activate_request
,
4074 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4075 .elevator_queue_empty_fn
= cfq_queue_empty
,
4076 .elevator_completed_req_fn
= cfq_completed_request
,
4077 .elevator_former_req_fn
= elv_rb_former_request
,
4078 .elevator_latter_req_fn
= elv_rb_latter_request
,
4079 .elevator_set_req_fn
= cfq_set_request
,
4080 .elevator_put_req_fn
= cfq_put_request
,
4081 .elevator_may_queue_fn
= cfq_may_queue
,
4082 .elevator_init_fn
= cfq_init_queue
,
4083 .elevator_exit_fn
= cfq_exit_queue
,
4084 .trim
= cfq_free_io_context
,
4086 .elevator_attrs
= cfq_attrs
,
4087 .elevator_name
= "cfq",
4088 .elevator_owner
= THIS_MODULE
,
4091 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4092 static struct blkio_policy_type blkio_policy_cfq
= {
4094 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
4095 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
4097 .plid
= BLKIO_POLICY_PROP
,
4100 static struct blkio_policy_type blkio_policy_cfq
;
4103 static int __init
cfq_init(void)
4106 * could be 0 on HZ < 1000 setups
4108 if (!cfq_slice_async
)
4109 cfq_slice_async
= 1;
4110 if (!cfq_slice_idle
)
4113 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4114 if (!cfq_group_idle
)
4119 if (cfq_slab_setup())
4122 elv_register(&iosched_cfq
);
4123 blkio_policy_register(&blkio_policy_cfq
);
4128 static void __exit
cfq_exit(void)
4130 DECLARE_COMPLETION_ONSTACK(all_gone
);
4131 blkio_policy_unregister(&blkio_policy_cfq
);
4132 elv_unregister(&iosched_cfq
);
4133 ioc_gone
= &all_gone
;
4134 /* ioc_gone's update must be visible before reading ioc_count */
4138 * this also protects us from entering cfq_slab_kill() with
4139 * pending RCU callbacks
4141 if (elv_ioc_count_read(cfq_ioc_count
))
4142 wait_for_completion(&all_gone
);
4143 ida_destroy(&cic_index_ida
);
4147 module_init(cfq_init
);
4148 module_exit(cfq_exit
);
4150 MODULE_AUTHOR("Jens Axboe");
4151 MODULE_LICENSE("GPL");
4152 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");