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.
1017 atomic_set(&cfqg
->ref
, 1);
1020 * Add group onto cgroup list. It might happen that bdi->dev is
1021 * not initiliazed 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
)
1062 atomic_inc(&cfqg
->ref
);
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 */
1074 atomic_inc(&cfqq
->cfqg
->ref
);
1077 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1079 struct cfq_rb_root
*st
;
1082 BUG_ON(atomic_read(&cfqg
->ref
) <= 0);
1083 if (!atomic_dec_and_test(&cfqg
->ref
))
1085 for_each_cfqg_st(cfqg
, i
, j
, st
)
1086 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
));
1090 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1092 /* Something wrong if we are trying to remove same group twice */
1093 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1095 hlist_del_init(&cfqg
->cfqd_node
);
1098 * Put the reference taken at the time of creation so that when all
1099 * queues are gone, group can be destroyed.
1104 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1106 struct hlist_node
*pos
, *n
;
1107 struct cfq_group
*cfqg
;
1109 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1111 * If cgroup removal path got to blk_group first and removed
1112 * it from cgroup list, then it will take care of destroying
1115 if (!cfq_blkiocg_del_blkio_group(&cfqg
->blkg
))
1116 cfq_destroy_cfqg(cfqd
, cfqg
);
1121 * Blk cgroup controller notification saying that blkio_group object is being
1122 * delinked as associated cgroup object is going away. That also means that
1123 * no new IO will come in this group. So get rid of this group as soon as
1124 * any pending IO in the group is finished.
1126 * This function is called under rcu_read_lock(). key is the rcu protected
1127 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1130 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1131 * it should not be NULL as even if elevator was exiting, cgroup deltion
1132 * path got to it first.
1134 void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1136 unsigned long flags
;
1137 struct cfq_data
*cfqd
= key
;
1139 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1140 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1141 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1144 #else /* GROUP_IOSCHED */
1145 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1147 return &cfqd
->root_group
;
1150 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1156 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1160 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1161 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1163 #endif /* GROUP_IOSCHED */
1166 * The cfqd->service_trees holds all pending cfq_queue's that have
1167 * requests waiting to be processed. It is sorted in the order that
1168 * we will service the queues.
1170 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1173 struct rb_node
**p
, *parent
;
1174 struct cfq_queue
*__cfqq
;
1175 unsigned long rb_key
;
1176 struct cfq_rb_root
*service_tree
;
1179 int group_changed
= 0;
1181 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1182 if (!cfqd
->cfq_group_isolation
1183 && cfqq_type(cfqq
) == SYNC_NOIDLE_WORKLOAD
1184 && cfqq
->cfqg
&& cfqq
->cfqg
!= &cfqd
->root_group
) {
1185 /* Move this cfq to root group */
1186 cfq_log_cfqq(cfqd
, cfqq
, "moving to root group");
1187 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1188 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1189 cfqq
->orig_cfqg
= cfqq
->cfqg
;
1190 cfqq
->cfqg
= &cfqd
->root_group
;
1191 atomic_inc(&cfqd
->root_group
.ref
);
1193 } else if (!cfqd
->cfq_group_isolation
1194 && cfqq_type(cfqq
) == SYNC_WORKLOAD
&& cfqq
->orig_cfqg
) {
1195 /* cfqq is sequential now needs to go to its original group */
1196 BUG_ON(cfqq
->cfqg
!= &cfqd
->root_group
);
1197 if (!RB_EMPTY_NODE(&cfqq
->rb_node
))
1198 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1199 cfq_put_cfqg(cfqq
->cfqg
);
1200 cfqq
->cfqg
= cfqq
->orig_cfqg
;
1201 cfqq
->orig_cfqg
= NULL
;
1203 cfq_log_cfqq(cfqd
, cfqq
, "moved to origin group");
1207 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1209 if (cfq_class_idle(cfqq
)) {
1210 rb_key
= CFQ_IDLE_DELAY
;
1211 parent
= rb_last(&service_tree
->rb
);
1212 if (parent
&& parent
!= &cfqq
->rb_node
) {
1213 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1214 rb_key
+= __cfqq
->rb_key
;
1217 } else if (!add_front
) {
1219 * Get our rb key offset. Subtract any residual slice
1220 * value carried from last service. A negative resid
1221 * count indicates slice overrun, and this should position
1222 * the next service time further away in the tree.
1224 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1225 rb_key
-= cfqq
->slice_resid
;
1226 cfqq
->slice_resid
= 0;
1229 __cfqq
= cfq_rb_first(service_tree
);
1230 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1233 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1236 * same position, nothing more to do
1238 if (rb_key
== cfqq
->rb_key
&&
1239 cfqq
->service_tree
== service_tree
)
1242 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1243 cfqq
->service_tree
= NULL
;
1248 cfqq
->service_tree
= service_tree
;
1249 p
= &service_tree
->rb
.rb_node
;
1254 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1257 * sort by key, that represents service time.
1259 if (time_before(rb_key
, __cfqq
->rb_key
))
1262 n
= &(*p
)->rb_right
;
1270 service_tree
->left
= &cfqq
->rb_node
;
1272 cfqq
->rb_key
= rb_key
;
1273 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1274 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1275 service_tree
->count
++;
1276 if ((add_front
|| !new_cfqq
) && !group_changed
)
1278 cfq_group_service_tree_add(cfqd
, cfqq
->cfqg
);
1281 static struct cfq_queue
*
1282 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1283 sector_t sector
, struct rb_node
**ret_parent
,
1284 struct rb_node
***rb_link
)
1286 struct rb_node
**p
, *parent
;
1287 struct cfq_queue
*cfqq
= NULL
;
1295 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1298 * Sort strictly based on sector. Smallest to the left,
1299 * largest to the right.
1301 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1302 n
= &(*p
)->rb_right
;
1303 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1311 *ret_parent
= parent
;
1317 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1319 struct rb_node
**p
, *parent
;
1320 struct cfq_queue
*__cfqq
;
1323 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1324 cfqq
->p_root
= NULL
;
1327 if (cfq_class_idle(cfqq
))
1332 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1333 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1334 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1336 rb_link_node(&cfqq
->p_node
, parent
, p
);
1337 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1339 cfqq
->p_root
= NULL
;
1343 * Update cfqq's position in the service tree.
1345 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1348 * Resorting requires the cfqq to be on the RR list already.
1350 if (cfq_cfqq_on_rr(cfqq
)) {
1351 cfq_service_tree_add(cfqd
, cfqq
, 0);
1352 cfq_prio_tree_add(cfqd
, cfqq
);
1357 * add to busy list of queues for service, trying to be fair in ordering
1358 * the pending list according to last request service
1360 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1362 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1363 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1364 cfq_mark_cfqq_on_rr(cfqq
);
1365 cfqd
->busy_queues
++;
1367 cfq_resort_rr_list(cfqd
, cfqq
);
1371 * Called when the cfqq no longer has requests pending, remove it from
1374 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1376 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1377 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1378 cfq_clear_cfqq_on_rr(cfqq
);
1380 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1381 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1382 cfqq
->service_tree
= NULL
;
1385 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1386 cfqq
->p_root
= NULL
;
1389 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1390 BUG_ON(!cfqd
->busy_queues
);
1391 cfqd
->busy_queues
--;
1395 * rb tree support functions
1397 static void cfq_del_rq_rb(struct request
*rq
)
1399 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1400 const int sync
= rq_is_sync(rq
);
1402 BUG_ON(!cfqq
->queued
[sync
]);
1403 cfqq
->queued
[sync
]--;
1405 elv_rb_del(&cfqq
->sort_list
, rq
);
1407 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1409 * Queue will be deleted from service tree when we actually
1410 * expire it later. Right now just remove it from prio tree
1414 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1415 cfqq
->p_root
= NULL
;
1420 static void cfq_add_rq_rb(struct request
*rq
)
1422 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1423 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1424 struct request
*__alias
, *prev
;
1426 cfqq
->queued
[rq_is_sync(rq
)]++;
1429 * looks a little odd, but the first insert might return an alias.
1430 * if that happens, put the alias on the dispatch list
1432 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
1433 cfq_dispatch_insert(cfqd
->queue
, __alias
);
1435 if (!cfq_cfqq_on_rr(cfqq
))
1436 cfq_add_cfqq_rr(cfqd
, cfqq
);
1439 * check if this request is a better next-serve candidate
1441 prev
= cfqq
->next_rq
;
1442 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1445 * adjust priority tree position, if ->next_rq changes
1447 if (prev
!= cfqq
->next_rq
)
1448 cfq_prio_tree_add(cfqd
, cfqq
);
1450 BUG_ON(!cfqq
->next_rq
);
1453 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1455 elv_rb_del(&cfqq
->sort_list
, rq
);
1456 cfqq
->queued
[rq_is_sync(rq
)]--;
1457 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1458 rq_data_dir(rq
), rq_is_sync(rq
));
1460 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
1461 &cfqq
->cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
1465 static struct request
*
1466 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1468 struct task_struct
*tsk
= current
;
1469 struct cfq_io_context
*cic
;
1470 struct cfq_queue
*cfqq
;
1472 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1476 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1478 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1480 return elv_rb_find(&cfqq
->sort_list
, sector
);
1486 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1488 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1490 cfqd
->rq_in_driver
++;
1491 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1492 cfqd
->rq_in_driver
);
1494 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1497 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1499 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1501 WARN_ON(!cfqd
->rq_in_driver
);
1502 cfqd
->rq_in_driver
--;
1503 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1504 cfqd
->rq_in_driver
);
1507 static void cfq_remove_request(struct request
*rq
)
1509 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1511 if (cfqq
->next_rq
== rq
)
1512 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1514 list_del_init(&rq
->queuelist
);
1517 cfqq
->cfqd
->rq_queued
--;
1518 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1519 rq_data_dir(rq
), rq_is_sync(rq
));
1520 if (rq
->cmd_flags
& REQ_META
) {
1521 WARN_ON(!cfqq
->meta_pending
);
1522 cfqq
->meta_pending
--;
1526 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1529 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1530 struct request
*__rq
;
1532 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1533 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1535 return ELEVATOR_FRONT_MERGE
;
1538 return ELEVATOR_NO_MERGE
;
1541 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1544 if (type
== ELEVATOR_FRONT_MERGE
) {
1545 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1547 cfq_reposition_rq_rb(cfqq
, req
);
1551 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1554 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req
))->blkg
,
1555 bio_data_dir(bio
), cfq_bio_sync(bio
));
1559 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1560 struct request
*next
)
1562 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1564 * reposition in fifo if next is older than rq
1566 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1567 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1568 list_move(&rq
->queuelist
, &next
->queuelist
);
1569 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1572 if (cfqq
->next_rq
== next
)
1574 cfq_remove_request(next
);
1575 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq
))->blkg
,
1576 rq_data_dir(next
), rq_is_sync(next
));
1579 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1582 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1583 struct cfq_io_context
*cic
;
1584 struct cfq_queue
*cfqq
;
1587 * Disallow merge of a sync bio into an async request.
1589 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1593 * Lookup the cfqq that this bio will be queued with. Allow
1594 * merge only if rq is queued there.
1596 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1600 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1601 return cfqq
== RQ_CFQQ(rq
);
1604 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1606 del_timer(&cfqd
->idle_slice_timer
);
1607 cfq_blkiocg_update_idle_time_stats(&cfqq
->cfqg
->blkg
);
1610 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1611 struct cfq_queue
*cfqq
)
1614 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
1615 cfqd
->serving_prio
, cfqd
->serving_type
);
1616 cfq_blkiocg_update_avg_queue_size_stats(&cfqq
->cfqg
->blkg
);
1617 cfqq
->slice_start
= 0;
1618 cfqq
->dispatch_start
= jiffies
;
1619 cfqq
->allocated_slice
= 0;
1620 cfqq
->slice_end
= 0;
1621 cfqq
->slice_dispatch
= 0;
1622 cfqq
->nr_sectors
= 0;
1624 cfq_clear_cfqq_wait_request(cfqq
);
1625 cfq_clear_cfqq_must_dispatch(cfqq
);
1626 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1627 cfq_clear_cfqq_fifo_expire(cfqq
);
1628 cfq_mark_cfqq_slice_new(cfqq
);
1630 cfq_del_timer(cfqd
, cfqq
);
1633 cfqd
->active_queue
= cfqq
;
1637 * current cfqq expired its slice (or was too idle), select new one
1640 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1643 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1645 if (cfq_cfqq_wait_request(cfqq
))
1646 cfq_del_timer(cfqd
, cfqq
);
1648 cfq_clear_cfqq_wait_request(cfqq
);
1649 cfq_clear_cfqq_wait_busy(cfqq
);
1652 * If this cfqq is shared between multiple processes, check to
1653 * make sure that those processes are still issuing I/Os within
1654 * the mean seek distance. If not, it may be time to break the
1655 * queues apart again.
1657 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
1658 cfq_mark_cfqq_split_coop(cfqq
);
1661 * store what was left of this slice, if the queue idled/timed out
1663 if (timed_out
&& !cfq_cfqq_slice_new(cfqq
)) {
1664 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1665 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1668 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1670 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1671 cfq_del_cfqq_rr(cfqd
, cfqq
);
1673 cfq_resort_rr_list(cfqd
, cfqq
);
1675 if (cfqq
== cfqd
->active_queue
)
1676 cfqd
->active_queue
= NULL
;
1678 if (cfqd
->active_cic
) {
1679 put_io_context(cfqd
->active_cic
->ioc
);
1680 cfqd
->active_cic
= NULL
;
1684 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1686 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1689 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1693 * Get next queue for service. Unless we have a queue preemption,
1694 * we'll simply select the first cfqq in the service tree.
1696 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1698 struct cfq_rb_root
*service_tree
=
1699 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1700 cfqd
->serving_type
);
1702 if (!cfqd
->rq_queued
)
1705 /* There is nothing to dispatch */
1708 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1710 return cfq_rb_first(service_tree
);
1713 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1715 struct cfq_group
*cfqg
;
1716 struct cfq_queue
*cfqq
;
1718 struct cfq_rb_root
*st
;
1720 if (!cfqd
->rq_queued
)
1723 cfqg
= cfq_get_next_cfqg(cfqd
);
1727 for_each_cfqg_st(cfqg
, i
, j
, st
)
1728 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1734 * Get and set a new active queue for service.
1736 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1737 struct cfq_queue
*cfqq
)
1740 cfqq
= cfq_get_next_queue(cfqd
);
1742 __cfq_set_active_queue(cfqd
, cfqq
);
1746 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1749 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1750 return blk_rq_pos(rq
) - cfqd
->last_position
;
1752 return cfqd
->last_position
- blk_rq_pos(rq
);
1755 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1758 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
1761 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1762 struct cfq_queue
*cur_cfqq
)
1764 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1765 struct rb_node
*parent
, *node
;
1766 struct cfq_queue
*__cfqq
;
1767 sector_t sector
= cfqd
->last_position
;
1769 if (RB_EMPTY_ROOT(root
))
1773 * First, if we find a request starting at the end of the last
1774 * request, choose it.
1776 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1781 * If the exact sector wasn't found, the parent of the NULL leaf
1782 * will contain the closest sector.
1784 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1785 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1788 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1789 node
= rb_next(&__cfqq
->p_node
);
1791 node
= rb_prev(&__cfqq
->p_node
);
1795 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1796 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1804 * cur_cfqq - passed in so that we don't decide that the current queue is
1805 * closely cooperating with itself.
1807 * So, basically we're assuming that that cur_cfqq has dispatched at least
1808 * one request, and that cfqd->last_position reflects a position on the disk
1809 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1812 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1813 struct cfq_queue
*cur_cfqq
)
1815 struct cfq_queue
*cfqq
;
1817 if (cfq_class_idle(cur_cfqq
))
1819 if (!cfq_cfqq_sync(cur_cfqq
))
1821 if (CFQQ_SEEKY(cur_cfqq
))
1825 * Don't search priority tree if it's the only queue in the group.
1827 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1831 * We should notice if some of the queues are cooperating, eg
1832 * working closely on the same area of the disk. In that case,
1833 * we can group them together and don't waste time idling.
1835 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1839 /* If new queue belongs to different cfq_group, don't choose it */
1840 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1844 * It only makes sense to merge sync queues.
1846 if (!cfq_cfqq_sync(cfqq
))
1848 if (CFQQ_SEEKY(cfqq
))
1852 * Do not merge queues of different priority classes
1854 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1861 * Determine whether we should enforce idle window for this queue.
1864 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1866 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1867 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1869 BUG_ON(!service_tree
);
1870 BUG_ON(!service_tree
->count
);
1872 if (!cfqd
->cfq_slice_idle
)
1875 /* We never do for idle class queues. */
1876 if (prio
== IDLE_WORKLOAD
)
1879 /* We do for queues that were marked with idle window flag. */
1880 if (cfq_cfqq_idle_window(cfqq
) &&
1881 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1885 * Otherwise, we do only if they are the last ones
1886 * in their service tree.
1888 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
))
1890 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
1891 service_tree
->count
);
1895 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1897 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1898 struct cfq_io_context
*cic
;
1899 unsigned long sl
, group_idle
= 0;
1902 * SSD device without seek penalty, disable idling. But only do so
1903 * for devices that support queuing, otherwise we still have a problem
1904 * with sync vs async workloads.
1906 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1909 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1910 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1913 * idle is disabled, either manually or by past process history
1915 if (!cfq_should_idle(cfqd
, cfqq
)) {
1916 /* no queue idling. Check for group idling */
1917 if (cfqd
->cfq_group_idle
)
1918 group_idle
= cfqd
->cfq_group_idle
;
1924 * still active requests from this queue, don't idle
1926 if (cfqq
->dispatched
)
1930 * task has exited, don't wait
1932 cic
= cfqd
->active_cic
;
1933 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1937 * If our average think time is larger than the remaining time
1938 * slice, then don't idle. This avoids overrunning the allotted
1941 if (sample_valid(cic
->ttime_samples
) &&
1942 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
)) {
1943 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%d",
1948 /* There are other queues in the group, don't do group idle */
1949 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
1952 cfq_mark_cfqq_wait_request(cfqq
);
1955 sl
= cfqd
->cfq_group_idle
;
1957 sl
= cfqd
->cfq_slice_idle
;
1959 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1960 cfq_blkiocg_update_set_idle_time_stats(&cfqq
->cfqg
->blkg
);
1961 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
1962 group_idle
? 1 : 0);
1966 * Move request from internal lists to the request queue dispatch list.
1968 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1970 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1971 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1973 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1975 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1976 cfq_remove_request(rq
);
1978 (RQ_CFQG(rq
))->dispatched
++;
1979 elv_dispatch_sort(q
, rq
);
1981 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
1982 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
1983 cfq_blkiocg_update_dispatch_stats(&cfqq
->cfqg
->blkg
, blk_rq_bytes(rq
),
1984 rq_data_dir(rq
), rq_is_sync(rq
));
1988 * return expired entry, or NULL to just start from scratch in rbtree
1990 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1992 struct request
*rq
= NULL
;
1994 if (cfq_cfqq_fifo_expire(cfqq
))
1997 cfq_mark_cfqq_fifo_expire(cfqq
);
1999 if (list_empty(&cfqq
->fifo
))
2002 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2003 if (time_before(jiffies
, rq_fifo_time(rq
)))
2006 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2011 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2013 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2015 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2017 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
2021 * Must be called with the queue_lock held.
2023 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2025 int process_refs
, io_refs
;
2027 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2028 process_refs
= cfqq
->ref
- io_refs
;
2029 BUG_ON(process_refs
< 0);
2030 return process_refs
;
2033 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2035 int process_refs
, new_process_refs
;
2036 struct cfq_queue
*__cfqq
;
2039 * If there are no process references on the new_cfqq, then it is
2040 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2041 * chain may have dropped their last reference (not just their
2042 * last process reference).
2044 if (!cfqq_process_refs(new_cfqq
))
2047 /* Avoid a circular list and skip interim queue merges */
2048 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2054 process_refs
= cfqq_process_refs(cfqq
);
2055 new_process_refs
= cfqq_process_refs(new_cfqq
);
2057 * If the process for the cfqq has gone away, there is no
2058 * sense in merging the queues.
2060 if (process_refs
== 0 || new_process_refs
== 0)
2064 * Merge in the direction of the lesser amount of work.
2066 if (new_process_refs
>= process_refs
) {
2067 cfqq
->new_cfqq
= new_cfqq
;
2068 new_cfqq
->ref
+= process_refs
;
2070 new_cfqq
->new_cfqq
= cfqq
;
2071 cfqq
->ref
+= new_process_refs
;
2075 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2076 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2078 struct cfq_queue
*queue
;
2080 bool key_valid
= false;
2081 unsigned long lowest_key
= 0;
2082 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2084 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2085 /* select the one with lowest rb_key */
2086 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2088 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2089 lowest_key
= queue
->rb_key
;
2098 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2102 struct cfq_rb_root
*st
;
2103 unsigned group_slice
;
2104 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2106 /* Choose next priority. RT > BE > IDLE */
2107 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2108 cfqd
->serving_prio
= RT_WORKLOAD
;
2109 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2110 cfqd
->serving_prio
= BE_WORKLOAD
;
2112 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2113 cfqd
->workload_expires
= jiffies
+ 1;
2117 if (original_prio
!= cfqd
->serving_prio
)
2121 * For RT and BE, we have to choose also the type
2122 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2125 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2129 * check workload expiration, and that we still have other queues ready
2131 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2135 /* otherwise select new workload type */
2136 cfqd
->serving_type
=
2137 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2138 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2142 * the workload slice is computed as a fraction of target latency
2143 * proportional to the number of queues in that workload, over
2144 * all the queues in the same priority class
2146 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2148 slice
= group_slice
* count
/
2149 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2150 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2152 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2156 * Async queues are currently system wide. Just taking
2157 * proportion of queues with-in same group will lead to higher
2158 * async ratio system wide as generally root group is going
2159 * to have higher weight. A more accurate thing would be to
2160 * calculate system wide asnc/sync ratio.
2162 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2163 tmp
= tmp
/cfqd
->busy_queues
;
2164 slice
= min_t(unsigned, slice
, tmp
);
2166 /* async workload slice is scaled down according to
2167 * the sync/async slice ratio. */
2168 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2170 /* sync workload slice is at least 2 * cfq_slice_idle */
2171 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2173 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2174 cfq_log(cfqd
, "workload slice:%d", slice
);
2175 cfqd
->workload_expires
= jiffies
+ slice
;
2178 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2180 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2181 struct cfq_group
*cfqg
;
2183 if (RB_EMPTY_ROOT(&st
->rb
))
2185 cfqg
= cfq_rb_first_group(st
);
2186 update_min_vdisktime(st
);
2190 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2192 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2194 cfqd
->serving_group
= cfqg
;
2196 /* Restore the workload type data */
2197 if (cfqg
->saved_workload_slice
) {
2198 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2199 cfqd
->serving_type
= cfqg
->saved_workload
;
2200 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2202 cfqd
->workload_expires
= jiffies
- 1;
2204 choose_service_tree(cfqd
, cfqg
);
2208 * Select a queue for service. If we have a current active queue,
2209 * check whether to continue servicing it, or retrieve and set a new one.
2211 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2213 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2215 cfqq
= cfqd
->active_queue
;
2219 if (!cfqd
->rq_queued
)
2223 * We were waiting for group to get backlogged. Expire the queue
2225 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2229 * The active queue has run out of time, expire it and select new.
2231 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2233 * If slice had not expired at the completion of last request
2234 * we might not have turned on wait_busy flag. Don't expire
2235 * the queue yet. Allow the group to get backlogged.
2237 * The very fact that we have used the slice, that means we
2238 * have been idling all along on this queue and it should be
2239 * ok to wait for this request to complete.
2241 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2242 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2246 goto check_group_idle
;
2250 * The active queue has requests and isn't expired, allow it to
2253 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2257 * If another queue has a request waiting within our mean seek
2258 * distance, let it run. The expire code will check for close
2259 * cooperators and put the close queue at the front of the service
2260 * tree. If possible, merge the expiring queue with the new cfqq.
2262 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2264 if (!cfqq
->new_cfqq
)
2265 cfq_setup_merge(cfqq
, new_cfqq
);
2270 * No requests pending. If the active queue still has requests in
2271 * flight or is idling for a new request, allow either of these
2272 * conditions to happen (or time out) before selecting a new queue.
2274 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2280 * This is a deep seek queue, but the device is much faster than
2281 * the queue can deliver, don't idle
2283 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2284 (cfq_cfqq_slice_new(cfqq
) ||
2285 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2286 cfq_clear_cfqq_deep(cfqq
);
2287 cfq_clear_cfqq_idle_window(cfqq
);
2290 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2296 * If group idle is enabled and there are requests dispatched from
2297 * this group, wait for requests to complete.
2300 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1
2301 && cfqq
->cfqg
->dispatched
) {
2307 cfq_slice_expired(cfqd
, 0);
2310 * Current queue expired. Check if we have to switch to a new
2314 cfq_choose_cfqg(cfqd
);
2316 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2321 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2325 while (cfqq
->next_rq
) {
2326 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2330 BUG_ON(!list_empty(&cfqq
->fifo
));
2332 /* By default cfqq is not expired if it is empty. Do it explicitly */
2333 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2338 * Drain our current requests. Used for barriers and when switching
2339 * io schedulers on-the-fly.
2341 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2343 struct cfq_queue
*cfqq
;
2346 /* Expire the timeslice of the current active queue first */
2347 cfq_slice_expired(cfqd
, 0);
2348 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2349 __cfq_set_active_queue(cfqd
, cfqq
);
2350 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2353 BUG_ON(cfqd
->busy_queues
);
2355 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2359 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2360 struct cfq_queue
*cfqq
)
2362 /* the queue hasn't finished any request, can't estimate */
2363 if (cfq_cfqq_slice_new(cfqq
))
2365 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2372 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2374 unsigned int max_dispatch
;
2377 * Drain async requests before we start sync IO
2379 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2383 * If this is an async queue and we have sync IO in flight, let it wait
2385 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2388 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2389 if (cfq_class_idle(cfqq
))
2393 * Does this cfqq already have too much IO in flight?
2395 if (cfqq
->dispatched
>= max_dispatch
) {
2397 * idle queue must always only have a single IO in flight
2399 if (cfq_class_idle(cfqq
))
2403 * We have other queues, don't allow more IO from this one
2405 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
))
2409 * Sole queue user, no limit
2411 if (cfqd
->busy_queues
== 1)
2415 * Normally we start throttling cfqq when cfq_quantum/2
2416 * requests have been dispatched. But we can drive
2417 * deeper queue depths at the beginning of slice
2418 * subjected to upper limit of cfq_quantum.
2420 max_dispatch
= cfqd
->cfq_quantum
;
2424 * Async queues must wait a bit before being allowed dispatch.
2425 * We also ramp up the dispatch depth gradually for async IO,
2426 * based on the last sync IO we serviced
2428 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2429 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2432 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2433 if (!depth
&& !cfqq
->dispatched
)
2435 if (depth
< max_dispatch
)
2436 max_dispatch
= depth
;
2440 * If we're below the current max, allow a dispatch
2442 return cfqq
->dispatched
< max_dispatch
;
2446 * Dispatch a request from cfqq, moving them to the request queue
2449 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2453 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2455 if (!cfq_may_dispatch(cfqd
, cfqq
))
2459 * follow expired path, else get first next available
2461 rq
= cfq_check_fifo(cfqq
);
2466 * insert request into driver dispatch list
2468 cfq_dispatch_insert(cfqd
->queue
, rq
);
2470 if (!cfqd
->active_cic
) {
2471 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2473 atomic_long_inc(&cic
->ioc
->refcount
);
2474 cfqd
->active_cic
= cic
;
2481 * Find the cfqq that we need to service and move a request from that to the
2484 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2486 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2487 struct cfq_queue
*cfqq
;
2489 if (!cfqd
->busy_queues
)
2492 if (unlikely(force
))
2493 return cfq_forced_dispatch(cfqd
);
2495 cfqq
= cfq_select_queue(cfqd
);
2500 * Dispatch a request from this cfqq, if it is allowed
2502 if (!cfq_dispatch_request(cfqd
, cfqq
))
2505 cfqq
->slice_dispatch
++;
2506 cfq_clear_cfqq_must_dispatch(cfqq
);
2509 * expire an async queue immediately if it has used up its slice. idle
2510 * queue always expire after 1 dispatch round.
2512 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2513 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2514 cfq_class_idle(cfqq
))) {
2515 cfqq
->slice_end
= jiffies
+ 1;
2516 cfq_slice_expired(cfqd
, 0);
2519 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2524 * task holds one reference to the queue, dropped when task exits. each rq
2525 * in-flight on this queue also holds a reference, dropped when rq is freed.
2527 * Each cfq queue took a reference on the parent group. Drop it now.
2528 * queue lock must be held here.
2530 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2532 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2533 struct cfq_group
*cfqg
, *orig_cfqg
;
2535 BUG_ON(cfqq
->ref
<= 0);
2541 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2542 BUG_ON(rb_first(&cfqq
->sort_list
));
2543 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2545 orig_cfqg
= cfqq
->orig_cfqg
;
2547 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2548 __cfq_slice_expired(cfqd
, cfqq
, 0);
2549 cfq_schedule_dispatch(cfqd
);
2552 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2553 kmem_cache_free(cfq_pool
, cfqq
);
2556 cfq_put_cfqg(orig_cfqg
);
2560 * Must always be called with the rcu_read_lock() held
2563 __call_for_each_cic(struct io_context
*ioc
,
2564 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2566 struct cfq_io_context
*cic
;
2567 struct hlist_node
*n
;
2569 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
2574 * Call func for each cic attached to this ioc.
2577 call_for_each_cic(struct io_context
*ioc
,
2578 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2581 __call_for_each_cic(ioc
, func
);
2585 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2587 struct cfq_io_context
*cic
;
2589 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
2591 kmem_cache_free(cfq_ioc_pool
, cic
);
2592 elv_ioc_count_dec(cfq_ioc_count
);
2596 * CFQ scheduler is exiting, grab exit lock and check
2597 * the pending io context count. If it hits zero,
2598 * complete ioc_gone and set it back to NULL
2600 spin_lock(&ioc_gone_lock
);
2601 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
2605 spin_unlock(&ioc_gone_lock
);
2609 static void cfq_cic_free(struct cfq_io_context
*cic
)
2611 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2614 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2616 unsigned long flags
;
2617 unsigned long dead_key
= (unsigned long) cic
->key
;
2619 BUG_ON(!(dead_key
& CIC_DEAD_KEY
));
2621 spin_lock_irqsave(&ioc
->lock
, flags
);
2622 radix_tree_delete(&ioc
->radix_root
, dead_key
>> CIC_DEAD_INDEX_SHIFT
);
2623 hlist_del_rcu(&cic
->cic_list
);
2624 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2630 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2631 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2632 * and ->trim() which is called with the task lock held
2634 static void cfq_free_io_context(struct io_context
*ioc
)
2637 * ioc->refcount is zero here, or we are called from elv_unregister(),
2638 * so no more cic's are allowed to be linked into this ioc. So it
2639 * should be ok to iterate over the known list, we will see all cic's
2640 * since no new ones are added.
2642 __call_for_each_cic(ioc
, cic_free_func
);
2645 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2647 struct cfq_queue
*__cfqq
, *next
;
2650 * If this queue was scheduled to merge with another queue, be
2651 * sure to drop the reference taken on that queue (and others in
2652 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2654 __cfqq
= cfqq
->new_cfqq
;
2656 if (__cfqq
== cfqq
) {
2657 WARN(1, "cfqq->new_cfqq loop detected\n");
2660 next
= __cfqq
->new_cfqq
;
2661 cfq_put_queue(__cfqq
);
2666 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2668 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2669 __cfq_slice_expired(cfqd
, cfqq
, 0);
2670 cfq_schedule_dispatch(cfqd
);
2673 cfq_put_cooperator(cfqq
);
2675 cfq_put_queue(cfqq
);
2678 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
2679 struct cfq_io_context
*cic
)
2681 struct io_context
*ioc
= cic
->ioc
;
2683 list_del_init(&cic
->queue_list
);
2686 * Make sure dead mark is seen for dead queues
2689 cic
->key
= cfqd_dead_key(cfqd
);
2691 if (ioc
->ioc_data
== cic
)
2692 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2694 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2695 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2696 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2699 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2700 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2701 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2705 static void cfq_exit_single_io_context(struct io_context
*ioc
,
2706 struct cfq_io_context
*cic
)
2708 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2711 struct request_queue
*q
= cfqd
->queue
;
2712 unsigned long flags
;
2714 spin_lock_irqsave(q
->queue_lock
, flags
);
2717 * Ensure we get a fresh copy of the ->key to prevent
2718 * race between exiting task and queue
2720 smp_read_barrier_depends();
2721 if (cic
->key
== cfqd
)
2722 __cfq_exit_single_io_context(cfqd
, cic
);
2724 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2729 * The process that ioc belongs to has exited, we need to clean up
2730 * and put the internal structures we have that belongs to that process.
2732 static void cfq_exit_io_context(struct io_context
*ioc
)
2734 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
2737 static struct cfq_io_context
*
2738 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2740 struct cfq_io_context
*cic
;
2742 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2745 cic
->last_end_request
= jiffies
;
2746 INIT_LIST_HEAD(&cic
->queue_list
);
2747 INIT_HLIST_NODE(&cic
->cic_list
);
2748 cic
->dtor
= cfq_free_io_context
;
2749 cic
->exit
= cfq_exit_io_context
;
2750 elv_ioc_count_inc(cfq_ioc_count
);
2756 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2758 struct task_struct
*tsk
= current
;
2761 if (!cfq_cfqq_prio_changed(cfqq
))
2764 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2765 switch (ioprio_class
) {
2767 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2768 case IOPRIO_CLASS_NONE
:
2770 * no prio set, inherit CPU scheduling settings
2772 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2773 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2775 case IOPRIO_CLASS_RT
:
2776 cfqq
->ioprio
= task_ioprio(ioc
);
2777 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2779 case IOPRIO_CLASS_BE
:
2780 cfqq
->ioprio
= task_ioprio(ioc
);
2781 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2783 case IOPRIO_CLASS_IDLE
:
2784 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2786 cfq_clear_cfqq_idle_window(cfqq
);
2791 * keep track of original prio settings in case we have to temporarily
2792 * elevate the priority of this queue
2794 cfqq
->org_ioprio
= cfqq
->ioprio
;
2795 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2796 cfq_clear_cfqq_prio_changed(cfqq
);
2799 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2801 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2802 struct cfq_queue
*cfqq
;
2803 unsigned long flags
;
2805 if (unlikely(!cfqd
))
2808 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2810 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2812 struct cfq_queue
*new_cfqq
;
2813 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2816 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2817 cfq_put_queue(cfqq
);
2821 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2823 cfq_mark_cfqq_prio_changed(cfqq
);
2825 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2828 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2830 call_for_each_cic(ioc
, changed_ioprio
);
2831 ioc
->ioprio_changed
= 0;
2834 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2835 pid_t pid
, bool is_sync
)
2837 RB_CLEAR_NODE(&cfqq
->rb_node
);
2838 RB_CLEAR_NODE(&cfqq
->p_node
);
2839 INIT_LIST_HEAD(&cfqq
->fifo
);
2844 cfq_mark_cfqq_prio_changed(cfqq
);
2847 if (!cfq_class_idle(cfqq
))
2848 cfq_mark_cfqq_idle_window(cfqq
);
2849 cfq_mark_cfqq_sync(cfqq
);
2854 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2855 static void changed_cgroup(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2857 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2858 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2859 unsigned long flags
;
2860 struct request_queue
*q
;
2862 if (unlikely(!cfqd
))
2867 spin_lock_irqsave(q
->queue_lock
, flags
);
2871 * Drop reference to sync queue. A new sync queue will be
2872 * assigned in new group upon arrival of a fresh request.
2874 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2875 cic_set_cfqq(cic
, NULL
, 1);
2876 cfq_put_queue(sync_cfqq
);
2879 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2882 static void cfq_ioc_set_cgroup(struct io_context
*ioc
)
2884 call_for_each_cic(ioc
, changed_cgroup
);
2885 ioc
->cgroup_changed
= 0;
2887 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2889 static struct cfq_queue
*
2890 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2891 struct io_context
*ioc
, gfp_t gfp_mask
)
2893 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2894 struct cfq_io_context
*cic
;
2895 struct cfq_group
*cfqg
;
2898 cfqg
= cfq_get_cfqg(cfqd
, 1);
2899 cic
= cfq_cic_lookup(cfqd
, ioc
);
2900 /* cic always exists here */
2901 cfqq
= cic_to_cfqq(cic
, is_sync
);
2904 * Always try a new alloc if we fell back to the OOM cfqq
2905 * originally, since it should just be a temporary situation.
2907 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2912 } else if (gfp_mask
& __GFP_WAIT
) {
2913 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2914 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2915 gfp_mask
| __GFP_ZERO
,
2917 spin_lock_irq(cfqd
->queue
->queue_lock
);
2921 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2922 gfp_mask
| __GFP_ZERO
,
2927 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2928 cfq_init_prio_data(cfqq
, ioc
);
2929 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2930 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2932 cfqq
= &cfqd
->oom_cfqq
;
2936 kmem_cache_free(cfq_pool
, new_cfqq
);
2941 static struct cfq_queue
**
2942 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2944 switch (ioprio_class
) {
2945 case IOPRIO_CLASS_RT
:
2946 return &cfqd
->async_cfqq
[0][ioprio
];
2947 case IOPRIO_CLASS_BE
:
2948 return &cfqd
->async_cfqq
[1][ioprio
];
2949 case IOPRIO_CLASS_IDLE
:
2950 return &cfqd
->async_idle_cfqq
;
2956 static struct cfq_queue
*
2957 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2960 const int ioprio
= task_ioprio(ioc
);
2961 const int ioprio_class
= task_ioprio_class(ioc
);
2962 struct cfq_queue
**async_cfqq
= NULL
;
2963 struct cfq_queue
*cfqq
= NULL
;
2966 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2971 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2974 * pin the queue now that it's allocated, scheduler exit will prune it
2976 if (!is_sync
&& !(*async_cfqq
)) {
2986 * We drop cfq io contexts lazily, so we may find a dead one.
2989 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2990 struct cfq_io_context
*cic
)
2992 unsigned long flags
;
2994 WARN_ON(!list_empty(&cic
->queue_list
));
2995 BUG_ON(cic
->key
!= cfqd_dead_key(cfqd
));
2997 spin_lock_irqsave(&ioc
->lock
, flags
);
2999 BUG_ON(ioc
->ioc_data
== cic
);
3001 radix_tree_delete(&ioc
->radix_root
, cfqd
->cic_index
);
3002 hlist_del_rcu(&cic
->cic_list
);
3003 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3008 static struct cfq_io_context
*
3009 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
3011 struct cfq_io_context
*cic
;
3012 unsigned long flags
;
3020 * we maintain a last-hit cache, to avoid browsing over the tree
3022 cic
= rcu_dereference(ioc
->ioc_data
);
3023 if (cic
&& cic
->key
== cfqd
) {
3029 cic
= radix_tree_lookup(&ioc
->radix_root
, cfqd
->cic_index
);
3033 if (unlikely(cic
->key
!= cfqd
)) {
3034 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
3039 spin_lock_irqsave(&ioc
->lock
, flags
);
3040 rcu_assign_pointer(ioc
->ioc_data
, cic
);
3041 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3049 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3050 * the process specific cfq io context when entered from the block layer.
3051 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3053 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
3054 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
3056 unsigned long flags
;
3059 ret
= radix_tree_preload(gfp_mask
);
3064 spin_lock_irqsave(&ioc
->lock
, flags
);
3065 ret
= radix_tree_insert(&ioc
->radix_root
,
3066 cfqd
->cic_index
, cic
);
3068 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
3069 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3071 radix_tree_preload_end();
3074 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3075 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
3076 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3081 printk(KERN_ERR
"cfq: cic link failed!\n");
3087 * Setup general io context and cfq io context. There can be several cfq
3088 * io contexts per general io context, if this process is doing io to more
3089 * than one device managed by cfq.
3091 static struct cfq_io_context
*
3092 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3094 struct io_context
*ioc
= NULL
;
3095 struct cfq_io_context
*cic
;
3097 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3099 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
3103 cic
= cfq_cic_lookup(cfqd
, ioc
);
3107 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
3111 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
3115 smp_read_barrier_depends();
3116 if (unlikely(ioc
->ioprio_changed
))
3117 cfq_ioc_set_ioprio(ioc
);
3119 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3120 if (unlikely(ioc
->cgroup_changed
))
3121 cfq_ioc_set_cgroup(ioc
);
3127 put_io_context(ioc
);
3132 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
3134 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
3135 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
3137 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
3138 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
3139 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
3143 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3147 sector_t n_sec
= blk_rq_sectors(rq
);
3148 if (cfqq
->last_request_pos
) {
3149 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3150 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3152 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3155 cfqq
->seek_history
<<= 1;
3156 if (blk_queue_nonrot(cfqd
->queue
))
3157 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3159 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3163 * Disable idle window if the process thinks too long or seeks so much that
3167 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3168 struct cfq_io_context
*cic
)
3170 int old_idle
, enable_idle
;
3173 * Don't idle for async or idle io prio class
3175 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3178 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3180 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3181 cfq_mark_cfqq_deep(cfqq
);
3183 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3185 else if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3186 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3188 else if (sample_valid(cic
->ttime_samples
)) {
3189 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
3195 if (old_idle
!= enable_idle
) {
3196 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3198 cfq_mark_cfqq_idle_window(cfqq
);
3200 cfq_clear_cfqq_idle_window(cfqq
);
3205 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3206 * no or if we aren't sure, a 1 will cause a preempt.
3209 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3212 struct cfq_queue
*cfqq
;
3214 cfqq
= cfqd
->active_queue
;
3218 if (cfq_class_idle(new_cfqq
))
3221 if (cfq_class_idle(cfqq
))
3225 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3227 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3231 * if the new request is sync, but the currently running queue is
3232 * not, let the sync request have priority.
3234 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3237 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3240 if (cfq_slice_used(cfqq
))
3243 /* Allow preemption only if we are idling on sync-noidle tree */
3244 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3245 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3246 new_cfqq
->service_tree
->count
== 2 &&
3247 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3251 * So both queues are sync. Let the new request get disk time if
3252 * it's a metadata request and the current queue is doing regular IO.
3254 if ((rq
->cmd_flags
& REQ_META
) && !cfqq
->meta_pending
)
3258 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3260 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3263 /* An idle queue should not be idle now for some reason */
3264 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3267 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3271 * if this request is as-good as one we would expect from the
3272 * current cfqq, let it preempt
3274 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3281 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3282 * let it have half of its nominal slice.
3284 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3286 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3287 cfq_slice_expired(cfqd
, 1);
3290 * Put the new queue at the front of the of the current list,
3291 * so we know that it will be selected next.
3293 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3295 cfq_service_tree_add(cfqd
, cfqq
, 1);
3297 cfqq
->slice_end
= 0;
3298 cfq_mark_cfqq_slice_new(cfqq
);
3302 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3303 * something we should do about it
3306 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3309 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3312 if (rq
->cmd_flags
& REQ_META
)
3313 cfqq
->meta_pending
++;
3315 cfq_update_io_thinktime(cfqd
, cic
);
3316 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3317 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3319 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3321 if (cfqq
== cfqd
->active_queue
) {
3323 * Remember that we saw a request from this process, but
3324 * don't start queuing just yet. Otherwise we risk seeing lots
3325 * of tiny requests, because we disrupt the normal plugging
3326 * and merging. If the request is already larger than a single
3327 * page, let it rip immediately. For that case we assume that
3328 * merging is already done. Ditto for a busy system that
3329 * has other work pending, don't risk delaying until the
3330 * idle timer unplug to continue working.
3332 if (cfq_cfqq_wait_request(cfqq
)) {
3333 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3334 cfqd
->busy_queues
> 1) {
3335 cfq_del_timer(cfqd
, cfqq
);
3336 cfq_clear_cfqq_wait_request(cfqq
);
3337 __blk_run_queue(cfqd
->queue
);
3339 cfq_blkiocg_update_idle_time_stats(
3341 cfq_mark_cfqq_must_dispatch(cfqq
);
3344 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3346 * not the active queue - expire current slice if it is
3347 * idle and has expired it's mean thinktime or this new queue
3348 * has some old slice time left and is of higher priority or
3349 * this new queue is RT and the current one is BE
3351 cfq_preempt_queue(cfqd
, cfqq
);
3352 __blk_run_queue(cfqd
->queue
);
3356 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3358 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3359 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3361 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3362 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3364 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3365 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3367 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
3368 &cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
3370 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3374 * Update hw_tag based on peak queue depth over 50 samples under
3377 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3379 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3381 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3382 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3384 if (cfqd
->hw_tag
== 1)
3387 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3388 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3392 * If active queue hasn't enough requests and can idle, cfq might not
3393 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3396 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3397 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3398 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3401 if (cfqd
->hw_tag_samples
++ < 50)
3404 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3410 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3412 struct cfq_io_context
*cic
= cfqd
->active_cic
;
3414 /* If there are other queues in the group, don't wait */
3415 if (cfqq
->cfqg
->nr_cfqq
> 1)
3418 if (cfq_slice_used(cfqq
))
3421 /* if slice left is less than think time, wait busy */
3422 if (cic
&& sample_valid(cic
->ttime_samples
)
3423 && (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
3427 * If think times is less than a jiffy than ttime_mean=0 and above
3428 * will not be true. It might happen that slice has not expired yet
3429 * but will expire soon (4-5 ns) during select_queue(). To cover the
3430 * case where think time is less than a jiffy, mark the queue wait
3431 * busy if only 1 jiffy is left in the slice.
3433 if (cfqq
->slice_end
- jiffies
== 1)
3439 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3441 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3442 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3443 const int sync
= rq_is_sync(rq
);
3447 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3448 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3450 cfq_update_hw_tag(cfqd
);
3452 WARN_ON(!cfqd
->rq_in_driver
);
3453 WARN_ON(!cfqq
->dispatched
);
3454 cfqd
->rq_in_driver
--;
3456 (RQ_CFQG(rq
))->dispatched
--;
3457 cfq_blkiocg_update_completion_stats(&cfqq
->cfqg
->blkg
,
3458 rq_start_time_ns(rq
), rq_io_start_time_ns(rq
),
3459 rq_data_dir(rq
), rq_is_sync(rq
));
3461 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3464 RQ_CIC(rq
)->last_end_request
= now
;
3465 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3466 cfqd
->last_delayed_sync
= now
;
3470 * If this is the active queue, check if it needs to be expired,
3471 * or if we want to idle in case it has no pending requests.
3473 if (cfqd
->active_queue
== cfqq
) {
3474 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3476 if (cfq_cfqq_slice_new(cfqq
)) {
3477 cfq_set_prio_slice(cfqd
, cfqq
);
3478 cfq_clear_cfqq_slice_new(cfqq
);
3482 * Should we wait for next request to come in before we expire
3485 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3486 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3487 if (!cfqd
->cfq_slice_idle
)
3488 extend_sl
= cfqd
->cfq_group_idle
;
3489 cfqq
->slice_end
= jiffies
+ extend_sl
;
3490 cfq_mark_cfqq_wait_busy(cfqq
);
3491 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3495 * Idling is not enabled on:
3497 * - idle-priority queues
3499 * - queues with still some requests queued
3500 * - when there is a close cooperator
3502 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3503 cfq_slice_expired(cfqd
, 1);
3504 else if (sync
&& cfqq_empty
&&
3505 !cfq_close_cooperator(cfqd
, cfqq
)) {
3506 cfq_arm_slice_timer(cfqd
);
3510 if (!cfqd
->rq_in_driver
)
3511 cfq_schedule_dispatch(cfqd
);
3515 * we temporarily boost lower priority queues if they are holding fs exclusive
3516 * resources. they are boosted to normal prio (CLASS_BE/4)
3518 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
3520 if (has_fs_excl()) {
3522 * boost idle prio on transactions that would lock out other
3523 * users of the filesystem
3525 if (cfq_class_idle(cfqq
))
3526 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3527 if (cfqq
->ioprio
> IOPRIO_NORM
)
3528 cfqq
->ioprio
= IOPRIO_NORM
;
3531 * unboost the queue (if needed)
3533 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
3534 cfqq
->ioprio
= cfqq
->org_ioprio
;
3538 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3540 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3541 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3542 return ELV_MQUEUE_MUST
;
3545 return ELV_MQUEUE_MAY
;
3548 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3550 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3551 struct task_struct
*tsk
= current
;
3552 struct cfq_io_context
*cic
;
3553 struct cfq_queue
*cfqq
;
3556 * don't force setup of a queue from here, as a call to may_queue
3557 * does not necessarily imply that a request actually will be queued.
3558 * so just lookup a possibly existing queue, or return 'may queue'
3561 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3563 return ELV_MQUEUE_MAY
;
3565 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3567 cfq_init_prio_data(cfqq
, cic
->ioc
);
3568 cfq_prio_boost(cfqq
);
3570 return __cfq_may_queue(cfqq
);
3573 return ELV_MQUEUE_MAY
;
3577 * queue lock held here
3579 static void cfq_put_request(struct request
*rq
)
3581 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3584 const int rw
= rq_data_dir(rq
);
3586 BUG_ON(!cfqq
->allocated
[rw
]);
3587 cfqq
->allocated
[rw
]--;
3589 put_io_context(RQ_CIC(rq
)->ioc
);
3591 rq
->elevator_private
= NULL
;
3592 rq
->elevator_private2
= NULL
;
3594 /* Put down rq reference on cfqg */
3595 cfq_put_cfqg(RQ_CFQG(rq
));
3596 rq
->elevator_private3
= NULL
;
3598 cfq_put_queue(cfqq
);
3602 static struct cfq_queue
*
3603 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3604 struct cfq_queue
*cfqq
)
3606 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3607 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3608 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3609 cfq_put_queue(cfqq
);
3610 return cic_to_cfqq(cic
, 1);
3614 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3615 * was the last process referring to said cfqq.
3617 static struct cfq_queue
*
3618 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3620 if (cfqq_process_refs(cfqq
) == 1) {
3621 cfqq
->pid
= current
->pid
;
3622 cfq_clear_cfqq_coop(cfqq
);
3623 cfq_clear_cfqq_split_coop(cfqq
);
3627 cic_set_cfqq(cic
, NULL
, 1);
3629 cfq_put_cooperator(cfqq
);
3631 cfq_put_queue(cfqq
);
3635 * Allocate cfq data structures associated with this request.
3638 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3640 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3641 struct cfq_io_context
*cic
;
3642 const int rw
= rq_data_dir(rq
);
3643 const bool is_sync
= rq_is_sync(rq
);
3644 struct cfq_queue
*cfqq
;
3645 unsigned long flags
;
3647 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3649 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3651 spin_lock_irqsave(q
->queue_lock
, flags
);
3657 cfqq
= cic_to_cfqq(cic
, is_sync
);
3658 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3659 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3660 cic_set_cfqq(cic
, cfqq
, is_sync
);
3663 * If the queue was seeky for too long, break it apart.
3665 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3666 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3667 cfqq
= split_cfqq(cic
, cfqq
);
3673 * Check to see if this queue is scheduled to merge with
3674 * another, closely cooperating queue. The merging of
3675 * queues happens here as it must be done in process context.
3676 * The reference on new_cfqq was taken in merge_cfqqs.
3679 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3682 cfqq
->allocated
[rw
]++;
3685 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3687 rq
->elevator_private
= cic
;
3688 rq
->elevator_private2
= cfqq
;
3689 rq
->elevator_private3
= cfq_ref_get_cfqg(cfqq
->cfqg
);
3694 put_io_context(cic
->ioc
);
3696 cfq_schedule_dispatch(cfqd
);
3697 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3698 cfq_log(cfqd
, "set_request fail");
3702 static void cfq_kick_queue(struct work_struct
*work
)
3704 struct cfq_data
*cfqd
=
3705 container_of(work
, struct cfq_data
, unplug_work
);
3706 struct request_queue
*q
= cfqd
->queue
;
3708 spin_lock_irq(q
->queue_lock
);
3709 __blk_run_queue(cfqd
->queue
);
3710 spin_unlock_irq(q
->queue_lock
);
3714 * Timer running if the active_queue is currently idling inside its time slice
3716 static void cfq_idle_slice_timer(unsigned long data
)
3718 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3719 struct cfq_queue
*cfqq
;
3720 unsigned long flags
;
3723 cfq_log(cfqd
, "idle timer fired");
3725 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3727 cfqq
= cfqd
->active_queue
;
3732 * We saw a request before the queue expired, let it through
3734 if (cfq_cfqq_must_dispatch(cfqq
))
3740 if (cfq_slice_used(cfqq
))
3744 * only expire and reinvoke request handler, if there are
3745 * other queues with pending requests
3747 if (!cfqd
->busy_queues
)
3751 * not expired and it has a request pending, let it dispatch
3753 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3757 * Queue depth flag is reset only when the idle didn't succeed
3759 cfq_clear_cfqq_deep(cfqq
);
3762 cfq_slice_expired(cfqd
, timed_out
);
3764 cfq_schedule_dispatch(cfqd
);
3766 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3769 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3771 del_timer_sync(&cfqd
->idle_slice_timer
);
3772 cancel_work_sync(&cfqd
->unplug_work
);
3775 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3779 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3780 if (cfqd
->async_cfqq
[0][i
])
3781 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3782 if (cfqd
->async_cfqq
[1][i
])
3783 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3786 if (cfqd
->async_idle_cfqq
)
3787 cfq_put_queue(cfqd
->async_idle_cfqq
);
3790 static void cfq_cfqd_free(struct rcu_head
*head
)
3792 kfree(container_of(head
, struct cfq_data
, rcu
));
3795 static void cfq_exit_queue(struct elevator_queue
*e
)
3797 struct cfq_data
*cfqd
= e
->elevator_data
;
3798 struct request_queue
*q
= cfqd
->queue
;
3800 cfq_shutdown_timer_wq(cfqd
);
3802 spin_lock_irq(q
->queue_lock
);
3804 if (cfqd
->active_queue
)
3805 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3807 while (!list_empty(&cfqd
->cic_list
)) {
3808 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3809 struct cfq_io_context
,
3812 __cfq_exit_single_io_context(cfqd
, cic
);
3815 cfq_put_async_queues(cfqd
);
3816 cfq_release_cfq_groups(cfqd
);
3817 cfq_blkiocg_del_blkio_group(&cfqd
->root_group
.blkg
);
3819 spin_unlock_irq(q
->queue_lock
);
3821 cfq_shutdown_timer_wq(cfqd
);
3823 spin_lock(&cic_index_lock
);
3824 ida_remove(&cic_index_ida
, cfqd
->cic_index
);
3825 spin_unlock(&cic_index_lock
);
3827 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3828 call_rcu(&cfqd
->rcu
, cfq_cfqd_free
);
3831 static int cfq_alloc_cic_index(void)
3836 if (!ida_pre_get(&cic_index_ida
, GFP_KERNEL
))
3839 spin_lock(&cic_index_lock
);
3840 error
= ida_get_new(&cic_index_ida
, &index
);
3841 spin_unlock(&cic_index_lock
);
3842 if (error
&& error
!= -EAGAIN
)
3849 static void *cfq_init_queue(struct request_queue
*q
)
3851 struct cfq_data
*cfqd
;
3853 struct cfq_group
*cfqg
;
3854 struct cfq_rb_root
*st
;
3856 i
= cfq_alloc_cic_index();
3860 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3865 * Don't need take queue_lock in the routine, since we are
3866 * initializing the ioscheduler, and nobody is using cfqd
3868 cfqd
->cic_index
= i
;
3870 /* Init root service tree */
3871 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3873 /* Init root group */
3874 cfqg
= &cfqd
->root_group
;
3875 for_each_cfqg_st(cfqg
, i
, j
, st
)
3877 RB_CLEAR_NODE(&cfqg
->rb_node
);
3879 /* Give preference to root group over other groups */
3880 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3882 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3884 * Take a reference to root group which we never drop. This is just
3885 * to make sure that cfq_put_cfqg() does not try to kfree root group
3887 atomic_set(&cfqg
->ref
, 1);
3889 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
,
3894 * Not strictly needed (since RB_ROOT just clears the node and we
3895 * zeroed cfqd on alloc), but better be safe in case someone decides
3896 * to add magic to the rb code
3898 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3899 cfqd
->prio_trees
[i
] = RB_ROOT
;
3902 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3903 * Grab a permanent reference to it, so that the normal code flow
3904 * will not attempt to free it.
3906 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3907 cfqd
->oom_cfqq
.ref
++;
3908 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3910 INIT_LIST_HEAD(&cfqd
->cic_list
);
3914 init_timer(&cfqd
->idle_slice_timer
);
3915 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3916 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3918 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3920 cfqd
->cfq_quantum
= cfq_quantum
;
3921 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3922 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3923 cfqd
->cfq_back_max
= cfq_back_max
;
3924 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3925 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3926 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3927 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3928 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3929 cfqd
->cfq_group_idle
= cfq_group_idle
;
3930 cfqd
->cfq_latency
= 1;
3931 cfqd
->cfq_group_isolation
= 0;
3934 * we optimistically start assuming sync ops weren't delayed in last
3935 * second, in order to have larger depth for async operations.
3937 cfqd
->last_delayed_sync
= jiffies
- HZ
;
3941 static void cfq_slab_kill(void)
3944 * Caller already ensured that pending RCU callbacks are completed,
3945 * so we should have no busy allocations at this point.
3948 kmem_cache_destroy(cfq_pool
);
3950 kmem_cache_destroy(cfq_ioc_pool
);
3953 static int __init
cfq_slab_setup(void)
3955 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3959 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3970 * sysfs parts below -->
3973 cfq_var_show(unsigned int var
, char *page
)
3975 return sprintf(page
, "%d\n", var
);
3979 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3981 char *p
= (char *) page
;
3983 *var
= simple_strtoul(p
, &p
, 10);
3987 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3988 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3990 struct cfq_data *cfqd = e->elevator_data; \
3991 unsigned int __data = __VAR; \
3993 __data = jiffies_to_msecs(__data); \
3994 return cfq_var_show(__data, (page)); \
3996 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3997 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3998 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3999 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4000 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4001 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4002 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4003 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4004 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4005 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4006 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4007 SHOW_FUNCTION(cfq_group_isolation_show
, cfqd
->cfq_group_isolation
, 0);
4008 #undef SHOW_FUNCTION
4010 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4011 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4013 struct cfq_data *cfqd = e->elevator_data; \
4014 unsigned int __data; \
4015 int ret = cfq_var_store(&__data, (page), count); \
4016 if (__data < (MIN)) \
4018 else if (__data > (MAX)) \
4021 *(__PTR) = msecs_to_jiffies(__data); \
4023 *(__PTR) = __data; \
4026 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4027 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4029 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4031 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4032 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4034 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4035 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4036 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4037 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4038 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4040 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4041 STORE_FUNCTION(cfq_group_isolation_store
, &cfqd
->cfq_group_isolation
, 0, 1, 0);
4042 #undef STORE_FUNCTION
4044 #define CFQ_ATTR(name) \
4045 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4047 static struct elv_fs_entry cfq_attrs
[] = {
4049 CFQ_ATTR(fifo_expire_sync
),
4050 CFQ_ATTR(fifo_expire_async
),
4051 CFQ_ATTR(back_seek_max
),
4052 CFQ_ATTR(back_seek_penalty
),
4053 CFQ_ATTR(slice_sync
),
4054 CFQ_ATTR(slice_async
),
4055 CFQ_ATTR(slice_async_rq
),
4056 CFQ_ATTR(slice_idle
),
4057 CFQ_ATTR(group_idle
),
4058 CFQ_ATTR(low_latency
),
4059 CFQ_ATTR(group_isolation
),
4063 static struct elevator_type iosched_cfq
= {
4065 .elevator_merge_fn
= cfq_merge
,
4066 .elevator_merged_fn
= cfq_merged_request
,
4067 .elevator_merge_req_fn
= cfq_merged_requests
,
4068 .elevator_allow_merge_fn
= cfq_allow_merge
,
4069 .elevator_bio_merged_fn
= cfq_bio_merged
,
4070 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4071 .elevator_add_req_fn
= cfq_insert_request
,
4072 .elevator_activate_req_fn
= cfq_activate_request
,
4073 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4074 .elevator_queue_empty_fn
= cfq_queue_empty
,
4075 .elevator_completed_req_fn
= cfq_completed_request
,
4076 .elevator_former_req_fn
= elv_rb_former_request
,
4077 .elevator_latter_req_fn
= elv_rb_latter_request
,
4078 .elevator_set_req_fn
= cfq_set_request
,
4079 .elevator_put_req_fn
= cfq_put_request
,
4080 .elevator_may_queue_fn
= cfq_may_queue
,
4081 .elevator_init_fn
= cfq_init_queue
,
4082 .elevator_exit_fn
= cfq_exit_queue
,
4083 .trim
= cfq_free_io_context
,
4085 .elevator_attrs
= cfq_attrs
,
4086 .elevator_name
= "cfq",
4087 .elevator_owner
= THIS_MODULE
,
4090 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4091 static struct blkio_policy_type blkio_policy_cfq
= {
4093 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
4094 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
4096 .plid
= BLKIO_POLICY_PROP
,
4099 static struct blkio_policy_type blkio_policy_cfq
;
4102 static int __init
cfq_init(void)
4105 * could be 0 on HZ < 1000 setups
4107 if (!cfq_slice_async
)
4108 cfq_slice_async
= 1;
4109 if (!cfq_slice_idle
)
4112 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4113 if (!cfq_group_idle
)
4118 if (cfq_slab_setup())
4121 elv_register(&iosched_cfq
);
4122 blkio_policy_register(&blkio_policy_cfq
);
4127 static void __exit
cfq_exit(void)
4129 DECLARE_COMPLETION_ONSTACK(all_gone
);
4130 blkio_policy_unregister(&blkio_policy_cfq
);
4131 elv_unregister(&iosched_cfq
);
4132 ioc_gone
= &all_gone
;
4133 /* ioc_gone's update must be visible before reading ioc_count */
4137 * this also protects us from entering cfq_slab_kill() with
4138 * pending RCU callbacks
4140 if (elv_ioc_count_read(cfq_ioc_count
))
4141 wait_for_completion(&all_gone
);
4142 ida_destroy(&cic_index_ida
);
4146 module_init(cfq_init
);
4147 module_exit(cfq_exit
);
4149 MODULE_AUTHOR("Jens Axboe");
4150 MODULE_LICENSE("GPL");
4151 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");