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[0])
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
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
;
90 struct cfq_ttime ttime
;
92 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
93 .ttime = {.last_end_request = jiffies,},}
96 * Per process-grouping structure
101 /* various state flags, see below */
103 /* parent cfq_data */
104 struct cfq_data
*cfqd
;
105 /* service_tree member */
106 struct rb_node rb_node
;
107 /* service_tree key */
108 unsigned long rb_key
;
109 /* prio tree member */
110 struct rb_node p_node
;
111 /* prio tree root we belong to, if any */
112 struct rb_root
*p_root
;
113 /* sorted list of pending requests */
114 struct rb_root sort_list
;
115 /* if fifo isn't expired, next request to serve */
116 struct request
*next_rq
;
117 /* requests queued in sort_list */
119 /* currently allocated requests */
121 /* fifo list of requests in sort_list */
122 struct list_head fifo
;
124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start
;
126 unsigned int allocated_slice
;
127 unsigned int slice_dispatch
;
128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start
;
130 unsigned long slice_end
;
133 /* number of requests that are on the dispatch list or inside driver */
136 /* io prio of this group */
137 unsigned short ioprio
, org_ioprio
;
138 unsigned short ioprio_class
;
143 sector_t last_request_pos
;
145 struct cfq_rb_root
*service_tree
;
146 struct cfq_queue
*new_cfqq
;
147 struct cfq_group
*cfqg
;
148 /* Number of sectors dispatched from queue in single dispatch round */
149 unsigned long nr_sectors
;
153 * First index in the service_trees.
154 * IDLE is handled separately, so it has negative index
164 * Second index in the service_trees.
168 SYNC_NOIDLE_WORKLOAD
= 1,
172 /* This is per cgroup per device grouping structure */
174 /* group service_tree member */
175 struct rb_node rb_node
;
177 /* group service_tree key */
180 unsigned int new_weight
;
183 /* number of cfqq currently on this group */
187 * Per group busy queues average. Useful for workload slice calc. We
188 * create the array for each prio class but at run time it is used
189 * only for RT and BE class and slot for IDLE class remains unused.
190 * This is primarily done to avoid confusion and a gcc warning.
192 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
194 * rr lists of queues with requests. We maintain service trees for
195 * RT and BE classes. These trees are subdivided in subclasses
196 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
197 * class there is no subclassification and all the cfq queues go on
198 * a single tree service_tree_idle.
199 * Counts are embedded in the cfq_rb_root
201 struct cfq_rb_root service_trees
[2][3];
202 struct cfq_rb_root service_tree_idle
;
204 unsigned long saved_workload_slice
;
205 enum wl_type_t saved_workload
;
206 enum wl_prio_t saved_serving_prio
;
207 struct blkio_group blkg
;
208 #ifdef CONFIG_CFQ_GROUP_IOSCHED
209 struct hlist_node cfqd_node
;
212 /* number of requests that are on the dispatch list or inside driver */
214 struct cfq_ttime ttime
;
218 * Per block device queue structure
221 struct request_queue
*queue
;
222 /* Root service tree for cfq_groups */
223 struct cfq_rb_root grp_service_tree
;
224 struct cfq_group root_group
;
227 * The priority currently being served
229 enum wl_prio_t serving_prio
;
230 enum wl_type_t serving_type
;
231 unsigned long workload_expires
;
232 struct cfq_group
*serving_group
;
235 * Each priority tree is sorted by next_request position. These
236 * trees are used when determining if two or more queues are
237 * interleaving requests (see cfq_close_cooperator).
239 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
241 unsigned int busy_queues
;
242 unsigned int busy_sync_queues
;
248 * queue-depth detection
254 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
255 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
258 int hw_tag_est_depth
;
259 unsigned int hw_tag_samples
;
262 * idle window management
264 struct timer_list idle_slice_timer
;
265 struct work_struct unplug_work
;
267 struct cfq_queue
*active_queue
;
268 struct cfq_io_context
*active_cic
;
271 * async queue for each priority case
273 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
274 struct cfq_queue
*async_idle_cfqq
;
276 sector_t last_position
;
279 * tunables, see top of file
281 unsigned int cfq_quantum
;
282 unsigned int cfq_fifo_expire
[2];
283 unsigned int cfq_back_penalty
;
284 unsigned int cfq_back_max
;
285 unsigned int cfq_slice
[2];
286 unsigned int cfq_slice_async_rq
;
287 unsigned int cfq_slice_idle
;
288 unsigned int cfq_group_idle
;
289 unsigned int cfq_latency
;
291 unsigned int cic_index
;
292 struct list_head cic_list
;
295 * Fallback dummy cfqq for extreme OOM conditions
297 struct cfq_queue oom_cfqq
;
299 unsigned long last_delayed_sync
;
301 /* List of cfq groups being managed on this device*/
302 struct hlist_head cfqg_list
;
304 /* Number of groups which are on blkcg->blkg_list */
305 unsigned int nr_blkcg_linked_grps
;
308 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
310 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
317 if (prio
== IDLE_WORKLOAD
)
318 return &cfqg
->service_tree_idle
;
320 return &cfqg
->service_trees
[prio
][type
];
323 enum cfqq_state_flags
{
324 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
325 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
326 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
327 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
328 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
329 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
330 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
331 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
332 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
333 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
334 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
335 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
336 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
339 #define CFQ_CFQQ_FNS(name) \
340 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
342 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
344 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
346 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
348 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
350 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
354 CFQ_CFQQ_FNS(wait_request
);
355 CFQ_CFQQ_FNS(must_dispatch
);
356 CFQ_CFQQ_FNS(must_alloc_slice
);
357 CFQ_CFQQ_FNS(fifo_expire
);
358 CFQ_CFQQ_FNS(idle_window
);
359 CFQ_CFQQ_FNS(prio_changed
);
360 CFQ_CFQQ_FNS(slice_new
);
363 CFQ_CFQQ_FNS(split_coop
);
365 CFQ_CFQQ_FNS(wait_busy
);
368 #ifdef CONFIG_CFQ_GROUP_IOSCHED
369 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
370 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
371 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
372 blkg_path(&(cfqq)->cfqg->blkg), ##args)
374 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
375 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
376 blkg_path(&(cfqg)->blkg), ##args) \
379 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
380 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
381 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
383 #define cfq_log(cfqd, fmt, args...) \
384 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
386 /* Traverses through cfq group service trees */
387 #define for_each_cfqg_st(cfqg, i, j, st) \
388 for (i = 0; i <= IDLE_WORKLOAD; i++) \
389 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
390 : &cfqg->service_tree_idle; \
391 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
392 (i == IDLE_WORKLOAD && j == 0); \
393 j++, st = i < IDLE_WORKLOAD ? \
394 &cfqg->service_trees[i][j]: NULL) \
396 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
397 struct cfq_ttime
*ttime
, bool group_idle
)
400 if (!sample_valid(ttime
->ttime_samples
))
403 slice
= cfqd
->cfq_group_idle
;
405 slice
= cfqd
->cfq_slice_idle
;
406 return ttime
->ttime_mean
> slice
;
409 static inline bool iops_mode(struct cfq_data
*cfqd
)
412 * If we are not idling on queues and it is a NCQ drive, parallel
413 * execution of requests is on and measuring time is not possible
414 * in most of the cases until and unless we drive shallower queue
415 * depths and that becomes a performance bottleneck. In such cases
416 * switch to start providing fairness in terms of number of IOs.
418 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
424 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
426 if (cfq_class_idle(cfqq
))
427 return IDLE_WORKLOAD
;
428 if (cfq_class_rt(cfqq
))
434 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
436 if (!cfq_cfqq_sync(cfqq
))
437 return ASYNC_WORKLOAD
;
438 if (!cfq_cfqq_idle_window(cfqq
))
439 return SYNC_NOIDLE_WORKLOAD
;
440 return SYNC_WORKLOAD
;
443 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
444 struct cfq_data
*cfqd
,
445 struct cfq_group
*cfqg
)
447 if (wl
== IDLE_WORKLOAD
)
448 return cfqg
->service_tree_idle
.count
;
450 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
451 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
452 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
455 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
456 struct cfq_group
*cfqg
)
458 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
459 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
462 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
463 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
464 struct io_context
*, gfp_t
);
465 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
466 struct io_context
*);
468 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
471 return cic
->cfqq
[is_sync
];
474 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
475 struct cfq_queue
*cfqq
, bool is_sync
)
477 cic
->cfqq
[is_sync
] = cfqq
;
480 #define CIC_DEAD_KEY 1ul
481 #define CIC_DEAD_INDEX_SHIFT 1
483 static inline void *cfqd_dead_key(struct cfq_data
*cfqd
)
485 return (void *)(cfqd
->cic_index
<< CIC_DEAD_INDEX_SHIFT
| CIC_DEAD_KEY
);
488 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_context
*cic
)
490 struct cfq_data
*cfqd
= cic
->key
;
492 if (unlikely((unsigned long) cfqd
& CIC_DEAD_KEY
))
499 * We regard a request as SYNC, if it's either a read or has the SYNC bit
500 * set (in which case it could also be direct WRITE).
502 static inline bool cfq_bio_sync(struct bio
*bio
)
504 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
508 * scheduler run of queue, if there are requests pending and no one in the
509 * driver that will restart queueing
511 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
513 if (cfqd
->busy_queues
) {
514 cfq_log(cfqd
, "schedule dispatch");
515 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
520 * Scale schedule slice based on io priority. Use the sync time slice only
521 * if a queue is marked sync and has sync io queued. A sync queue with async
522 * io only, should not get full sync slice length.
524 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
527 const int base_slice
= cfqd
->cfq_slice
[sync
];
529 WARN_ON(prio
>= IOPRIO_BE_NR
);
531 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
535 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
537 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
540 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
542 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
544 d
= d
* BLKIO_WEIGHT_DEFAULT
;
545 do_div(d
, cfqg
->weight
);
549 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
551 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
553 min_vdisktime
= vdisktime
;
555 return min_vdisktime
;
558 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
560 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
562 min_vdisktime
= vdisktime
;
564 return min_vdisktime
;
567 static void update_min_vdisktime(struct cfq_rb_root
*st
)
569 struct cfq_group
*cfqg
;
572 cfqg
= rb_entry_cfqg(st
->left
);
573 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
,
579 * get averaged number of queues of RT/BE priority.
580 * average is updated, with a formula that gives more weight to higher numbers,
581 * to quickly follows sudden increases and decrease slowly
584 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
585 struct cfq_group
*cfqg
, bool rt
)
587 unsigned min_q
, max_q
;
588 unsigned mult
= cfq_hist_divisor
- 1;
589 unsigned round
= cfq_hist_divisor
/ 2;
590 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
592 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
593 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
594 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
596 return cfqg
->busy_queues_avg
[rt
];
599 static inline unsigned
600 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
602 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
604 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
607 static inline unsigned
608 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
610 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
611 if (cfqd
->cfq_latency
) {
613 * interested queues (we consider only the ones with the same
614 * priority class in the cfq group)
616 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
618 unsigned sync_slice
= cfqd
->cfq_slice
[1];
619 unsigned expect_latency
= sync_slice
* iq
;
620 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
622 if (expect_latency
> group_slice
) {
623 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
624 /* scale low_slice according to IO priority
625 * and sync vs async */
627 min(slice
, base_low_slice
* slice
/ sync_slice
);
628 /* the adapted slice value is scaled to fit all iqs
629 * into the target latency */
630 slice
= max(slice
* group_slice
/ expect_latency
,
638 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
640 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
642 cfqq
->slice_start
= jiffies
;
643 cfqq
->slice_end
= jiffies
+ slice
;
644 cfqq
->allocated_slice
= slice
;
645 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
649 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
650 * isn't valid until the first request from the dispatch is activated
651 * and the slice time set.
653 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
655 if (cfq_cfqq_slice_new(cfqq
))
657 if (time_before(jiffies
, cfqq
->slice_end
))
664 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
665 * We choose the request that is closest to the head right now. Distance
666 * behind the head is penalized and only allowed to a certain extent.
668 static struct request
*
669 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
671 sector_t s1
, s2
, d1
= 0, d2
= 0;
672 unsigned long back_max
;
673 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
674 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
675 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
677 if (rq1
== NULL
|| rq1
== rq2
)
682 if (rq_is_sync(rq1
) != rq_is_sync(rq2
))
683 return rq_is_sync(rq1
) ? rq1
: rq2
;
685 s1
= blk_rq_pos(rq1
);
686 s2
= blk_rq_pos(rq2
);
689 * by definition, 1KiB is 2 sectors
691 back_max
= cfqd
->cfq_back_max
* 2;
694 * Strict one way elevator _except_ in the case where we allow
695 * short backward seeks which are biased as twice the cost of a
696 * similar forward seek.
700 else if (s1
+ back_max
>= last
)
701 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
703 wrap
|= CFQ_RQ1_WRAP
;
707 else if (s2
+ back_max
>= last
)
708 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
710 wrap
|= CFQ_RQ2_WRAP
;
712 /* Found required data */
715 * By doing switch() on the bit mask "wrap" we avoid having to
716 * check two variables for all permutations: --> faster!
719 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
735 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
738 * Since both rqs are wrapped,
739 * start with the one that's further behind head
740 * (--> only *one* back seek required),
741 * since back seek takes more time than forward.
751 * The below is leftmost cache rbtree addon
753 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
755 /* Service tree is empty */
760 root
->left
= rb_first(&root
->rb
);
763 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
768 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
771 root
->left
= rb_first(&root
->rb
);
774 return rb_entry_cfqg(root
->left
);
779 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
785 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
789 rb_erase_init(n
, &root
->rb
);
794 * would be nice to take fifo expire time into account as well
796 static struct request
*
797 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
798 struct request
*last
)
800 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
801 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
802 struct request
*next
= NULL
, *prev
= NULL
;
804 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
807 prev
= rb_entry_rq(rbprev
);
810 next
= rb_entry_rq(rbnext
);
812 rbnext
= rb_first(&cfqq
->sort_list
);
813 if (rbnext
&& rbnext
!= &last
->rb_node
)
814 next
= rb_entry_rq(rbnext
);
817 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
820 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
821 struct cfq_queue
*cfqq
)
824 * just an approximation, should be ok.
826 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
827 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
831 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
833 return cfqg
->vdisktime
- st
->min_vdisktime
;
837 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
839 struct rb_node
**node
= &st
->rb
.rb_node
;
840 struct rb_node
*parent
= NULL
;
841 struct cfq_group
*__cfqg
;
842 s64 key
= cfqg_key(st
, cfqg
);
845 while (*node
!= NULL
) {
847 __cfqg
= rb_entry_cfqg(parent
);
849 if (key
< cfqg_key(st
, __cfqg
))
850 node
= &parent
->rb_left
;
852 node
= &parent
->rb_right
;
858 st
->left
= &cfqg
->rb_node
;
860 rb_link_node(&cfqg
->rb_node
, parent
, node
);
861 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
865 cfq_update_group_weight(struct cfq_group
*cfqg
)
867 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
868 if (cfqg
->needs_update
) {
869 cfqg
->weight
= cfqg
->new_weight
;
870 cfqg
->needs_update
= false;
875 cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
877 BUG_ON(!RB_EMPTY_NODE(&cfqg
->rb_node
));
879 cfq_update_group_weight(cfqg
);
880 __cfq_group_service_tree_add(st
, cfqg
);
881 st
->total_weight
+= cfqg
->weight
;
885 cfq_group_notify_queue_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
887 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
888 struct cfq_group
*__cfqg
;
892 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
896 * Currently put the group at the end. Later implement something
897 * so that groups get lesser vtime based on their weights, so that
898 * if group does not loose all if it was not continuously backlogged.
900 n
= rb_last(&st
->rb
);
902 __cfqg
= rb_entry_cfqg(n
);
903 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
905 cfqg
->vdisktime
= st
->min_vdisktime
;
906 cfq_group_service_tree_add(st
, cfqg
);
910 cfq_group_service_tree_del(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
912 st
->total_weight
-= cfqg
->weight
;
913 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
914 cfq_rb_erase(&cfqg
->rb_node
, st
);
918 cfq_group_notify_queue_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
920 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
922 BUG_ON(cfqg
->nr_cfqq
< 1);
925 /* If there are other cfq queues under this group, don't delete it */
929 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
930 cfq_group_service_tree_del(st
, cfqg
);
931 cfqg
->saved_workload_slice
= 0;
932 cfq_blkiocg_update_dequeue_stats(&cfqg
->blkg
, 1);
935 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
,
936 unsigned int *unaccounted_time
)
938 unsigned int slice_used
;
941 * Queue got expired before even a single request completed or
942 * got expired immediately after first request completion.
944 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
946 * Also charge the seek time incurred to the group, otherwise
947 * if there are mutiple queues in the group, each can dispatch
948 * a single request on seeky media and cause lots of seek time
949 * and group will never know it.
951 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
954 slice_used
= jiffies
- cfqq
->slice_start
;
955 if (slice_used
> cfqq
->allocated_slice
) {
956 *unaccounted_time
= slice_used
- cfqq
->allocated_slice
;
957 slice_used
= cfqq
->allocated_slice
;
959 if (time_after(cfqq
->slice_start
, cfqq
->dispatch_start
))
960 *unaccounted_time
+= cfqq
->slice_start
-
961 cfqq
->dispatch_start
;
967 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
968 struct cfq_queue
*cfqq
)
970 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
971 unsigned int used_sl
, charge
, unaccounted_sl
= 0;
972 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
973 - cfqg
->service_tree_idle
.count
;
976 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
, &unaccounted_sl
);
979 charge
= cfqq
->slice_dispatch
;
980 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
981 charge
= cfqq
->allocated_slice
;
983 /* Can't update vdisktime while group is on service tree */
984 cfq_group_service_tree_del(st
, cfqg
);
985 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
986 /* If a new weight was requested, update now, off tree */
987 cfq_group_service_tree_add(st
, cfqg
);
989 /* This group is being expired. Save the context */
990 if (time_after(cfqd
->workload_expires
, jiffies
)) {
991 cfqg
->saved_workload_slice
= cfqd
->workload_expires
993 cfqg
->saved_workload
= cfqd
->serving_type
;
994 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
996 cfqg
->saved_workload_slice
= 0;
998 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
1000 cfq_log_cfqq(cfqq
->cfqd
, cfqq
,
1001 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1002 used_sl
, cfqq
->slice_dispatch
, charge
,
1003 iops_mode(cfqd
), cfqq
->nr_sectors
);
1004 cfq_blkiocg_update_timeslice_used(&cfqg
->blkg
, used_sl
,
1006 cfq_blkiocg_set_start_empty_time(&cfqg
->blkg
);
1009 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1010 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
1013 return container_of(blkg
, struct cfq_group
, blkg
);
1017 static void cfq_update_blkio_group_weight(void *key
, struct blkio_group
*blkg
,
1018 unsigned int weight
)
1020 struct cfq_group
*cfqg
= cfqg_of_blkg(blkg
);
1021 cfqg
->new_weight
= weight
;
1022 cfqg
->needs_update
= true;
1025 static void cfq_init_add_cfqg_lists(struct cfq_data
*cfqd
,
1026 struct cfq_group
*cfqg
, struct blkio_cgroup
*blkcg
)
1028 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1029 unsigned int major
, minor
;
1032 * Add group onto cgroup list. It might happen that bdi->dev is
1033 * not initialized yet. Initialize this new group without major
1034 * and minor info and this info will be filled in once a new thread
1038 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1039 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1040 (void *)cfqd
, MKDEV(major
, minor
));
1042 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
,
1045 cfqd
->nr_blkcg_linked_grps
++;
1046 cfqg
->weight
= blkcg_get_weight(blkcg
, cfqg
->blkg
.dev
);
1048 /* Add group on cfqd list */
1049 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
1053 * Should be called from sleepable context. No request queue lock as per
1054 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1055 * from sleepable context.
1057 static struct cfq_group
* cfq_alloc_cfqg(struct cfq_data
*cfqd
)
1059 struct cfq_group
*cfqg
= NULL
;
1061 struct cfq_rb_root
*st
;
1063 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
1067 for_each_cfqg_st(cfqg
, i
, j
, st
)
1069 RB_CLEAR_NODE(&cfqg
->rb_node
);
1071 cfqg
->ttime
.last_end_request
= jiffies
;
1074 * Take the initial reference that will be released on destroy
1075 * This can be thought of a joint reference by cgroup and
1076 * elevator which will be dropped by either elevator exit
1077 * or cgroup deletion path depending on who is exiting first.
1081 ret
= blkio_alloc_blkg_stats(&cfqg
->blkg
);
1090 static struct cfq_group
*
1091 cfq_find_cfqg(struct cfq_data
*cfqd
, struct blkio_cgroup
*blkcg
)
1093 struct cfq_group
*cfqg
= NULL
;
1095 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
1096 unsigned int major
, minor
;
1099 * This is the common case when there are no blkio cgroups.
1100 * Avoid lookup in this case
1102 if (blkcg
== &blkio_root_cgroup
)
1103 cfqg
= &cfqd
->root_group
;
1105 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
1107 if (cfqg
&& !cfqg
->blkg
.dev
&& bdi
->dev
&& dev_name(bdi
->dev
)) {
1108 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1109 cfqg
->blkg
.dev
= MKDEV(major
, minor
);
1116 * Search for the cfq group current task belongs to. request_queue lock must
1119 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1121 struct blkio_cgroup
*blkcg
;
1122 struct cfq_group
*cfqg
= NULL
, *__cfqg
= NULL
;
1123 struct request_queue
*q
= cfqd
->queue
;
1126 blkcg
= task_blkio_cgroup(current
);
1127 cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1134 * Need to allocate a group. Allocation of group also needs allocation
1135 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1136 * we need to drop rcu lock and queue_lock before we call alloc.
1138 * Not taking any queue reference here and assuming that queue is
1139 * around by the time we return. CFQ queue allocation code does
1140 * the same. It might be racy though.
1144 spin_unlock_irq(q
->queue_lock
);
1146 cfqg
= cfq_alloc_cfqg(cfqd
);
1148 spin_lock_irq(q
->queue_lock
);
1151 blkcg
= task_blkio_cgroup(current
);
1154 * If some other thread already allocated the group while we were
1155 * not holding queue lock, free up the group
1157 __cfqg
= cfq_find_cfqg(cfqd
, blkcg
);
1166 cfqg
= &cfqd
->root_group
;
1168 cfq_init_add_cfqg_lists(cfqd
, cfqg
, blkcg
);
1173 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1179 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1181 /* Currently, all async queues are mapped to root group */
1182 if (!cfq_cfqq_sync(cfqq
))
1183 cfqg
= &cfqq
->cfqd
->root_group
;
1186 /* cfqq reference on cfqg */
1190 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1192 struct cfq_rb_root
*st
;
1195 BUG_ON(cfqg
->ref
<= 0);
1199 for_each_cfqg_st(cfqg
, i
, j
, st
)
1200 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
));
1201 free_percpu(cfqg
->blkg
.stats_cpu
);
1205 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1207 /* Something wrong if we are trying to remove same group twice */
1208 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1210 hlist_del_init(&cfqg
->cfqd_node
);
1212 BUG_ON(cfqd
->nr_blkcg_linked_grps
<= 0);
1213 cfqd
->nr_blkcg_linked_grps
--;
1216 * Put the reference taken at the time of creation so that when all
1217 * queues are gone, group can be destroyed.
1222 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1224 struct hlist_node
*pos
, *n
;
1225 struct cfq_group
*cfqg
;
1227 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1229 * If cgroup removal path got to blk_group first and removed
1230 * it from cgroup list, then it will take care of destroying
1233 if (!cfq_blkiocg_del_blkio_group(&cfqg
->blkg
))
1234 cfq_destroy_cfqg(cfqd
, cfqg
);
1239 * Blk cgroup controller notification saying that blkio_group object is being
1240 * delinked as associated cgroup object is going away. That also means that
1241 * no new IO will come in this group. So get rid of this group as soon as
1242 * any pending IO in the group is finished.
1244 * This function is called under rcu_read_lock(). key is the rcu protected
1245 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1248 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1249 * it should not be NULL as even if elevator was exiting, cgroup deltion
1250 * path got to it first.
1252 static void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1254 unsigned long flags
;
1255 struct cfq_data
*cfqd
= key
;
1257 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1258 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1259 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1262 #else /* GROUP_IOSCHED */
1263 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
)
1265 return &cfqd
->root_group
;
1268 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1274 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1278 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1279 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1281 #endif /* GROUP_IOSCHED */
1284 * The cfqd->service_trees holds all pending cfq_queue's that have
1285 * requests waiting to be processed. It is sorted in the order that
1286 * we will service the queues.
1288 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1291 struct rb_node
**p
, *parent
;
1292 struct cfq_queue
*__cfqq
;
1293 unsigned long rb_key
;
1294 struct cfq_rb_root
*service_tree
;
1298 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1300 if (cfq_class_idle(cfqq
)) {
1301 rb_key
= CFQ_IDLE_DELAY
;
1302 parent
= rb_last(&service_tree
->rb
);
1303 if (parent
&& parent
!= &cfqq
->rb_node
) {
1304 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1305 rb_key
+= __cfqq
->rb_key
;
1308 } else if (!add_front
) {
1310 * Get our rb key offset. Subtract any residual slice
1311 * value carried from last service. A negative resid
1312 * count indicates slice overrun, and this should position
1313 * the next service time further away in the tree.
1315 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1316 rb_key
-= cfqq
->slice_resid
;
1317 cfqq
->slice_resid
= 0;
1320 __cfqq
= cfq_rb_first(service_tree
);
1321 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1324 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1327 * same position, nothing more to do
1329 if (rb_key
== cfqq
->rb_key
&&
1330 cfqq
->service_tree
== service_tree
)
1333 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1334 cfqq
->service_tree
= NULL
;
1339 cfqq
->service_tree
= service_tree
;
1340 p
= &service_tree
->rb
.rb_node
;
1345 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1348 * sort by key, that represents service time.
1350 if (time_before(rb_key
, __cfqq
->rb_key
))
1353 n
= &(*p
)->rb_right
;
1361 service_tree
->left
= &cfqq
->rb_node
;
1363 cfqq
->rb_key
= rb_key
;
1364 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1365 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1366 service_tree
->count
++;
1367 if (add_front
|| !new_cfqq
)
1369 cfq_group_notify_queue_add(cfqd
, cfqq
->cfqg
);
1372 static struct cfq_queue
*
1373 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1374 sector_t sector
, struct rb_node
**ret_parent
,
1375 struct rb_node
***rb_link
)
1377 struct rb_node
**p
, *parent
;
1378 struct cfq_queue
*cfqq
= NULL
;
1386 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1389 * Sort strictly based on sector. Smallest to the left,
1390 * largest to the right.
1392 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1393 n
= &(*p
)->rb_right
;
1394 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1402 *ret_parent
= parent
;
1408 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1410 struct rb_node
**p
, *parent
;
1411 struct cfq_queue
*__cfqq
;
1414 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1415 cfqq
->p_root
= NULL
;
1418 if (cfq_class_idle(cfqq
))
1423 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1424 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1425 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1427 rb_link_node(&cfqq
->p_node
, parent
, p
);
1428 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1430 cfqq
->p_root
= NULL
;
1434 * Update cfqq's position in the service tree.
1436 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1439 * Resorting requires the cfqq to be on the RR list already.
1441 if (cfq_cfqq_on_rr(cfqq
)) {
1442 cfq_service_tree_add(cfqd
, cfqq
, 0);
1443 cfq_prio_tree_add(cfqd
, cfqq
);
1448 * add to busy list of queues for service, trying to be fair in ordering
1449 * the pending list according to last request service
1451 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1453 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1454 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1455 cfq_mark_cfqq_on_rr(cfqq
);
1456 cfqd
->busy_queues
++;
1457 if (cfq_cfqq_sync(cfqq
))
1458 cfqd
->busy_sync_queues
++;
1460 cfq_resort_rr_list(cfqd
, cfqq
);
1464 * Called when the cfqq no longer has requests pending, remove it from
1467 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1469 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1470 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1471 cfq_clear_cfqq_on_rr(cfqq
);
1473 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1474 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1475 cfqq
->service_tree
= NULL
;
1478 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1479 cfqq
->p_root
= NULL
;
1482 cfq_group_notify_queue_del(cfqd
, cfqq
->cfqg
);
1483 BUG_ON(!cfqd
->busy_queues
);
1484 cfqd
->busy_queues
--;
1485 if (cfq_cfqq_sync(cfqq
))
1486 cfqd
->busy_sync_queues
--;
1490 * rb tree support functions
1492 static void cfq_del_rq_rb(struct request
*rq
)
1494 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1495 const int sync
= rq_is_sync(rq
);
1497 BUG_ON(!cfqq
->queued
[sync
]);
1498 cfqq
->queued
[sync
]--;
1500 elv_rb_del(&cfqq
->sort_list
, rq
);
1502 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1504 * Queue will be deleted from service tree when we actually
1505 * expire it later. Right now just remove it from prio tree
1509 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1510 cfqq
->p_root
= NULL
;
1515 static void cfq_add_rq_rb(struct request
*rq
)
1517 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1518 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1519 struct request
*prev
;
1521 cfqq
->queued
[rq_is_sync(rq
)]++;
1523 elv_rb_add(&cfqq
->sort_list
, rq
);
1525 if (!cfq_cfqq_on_rr(cfqq
))
1526 cfq_add_cfqq_rr(cfqd
, cfqq
);
1529 * check if this request is a better next-serve candidate
1531 prev
= cfqq
->next_rq
;
1532 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1535 * adjust priority tree position, if ->next_rq changes
1537 if (prev
!= cfqq
->next_rq
)
1538 cfq_prio_tree_add(cfqd
, cfqq
);
1540 BUG_ON(!cfqq
->next_rq
);
1543 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1545 elv_rb_del(&cfqq
->sort_list
, rq
);
1546 cfqq
->queued
[rq_is_sync(rq
)]--;
1547 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1548 rq_data_dir(rq
), rq_is_sync(rq
));
1550 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
1551 &cfqq
->cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
1555 static struct request
*
1556 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1558 struct task_struct
*tsk
= current
;
1559 struct cfq_io_context
*cic
;
1560 struct cfq_queue
*cfqq
;
1562 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1566 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1568 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1570 return elv_rb_find(&cfqq
->sort_list
, sector
);
1576 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1578 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1580 cfqd
->rq_in_driver
++;
1581 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1582 cfqd
->rq_in_driver
);
1584 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1587 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1589 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1591 WARN_ON(!cfqd
->rq_in_driver
);
1592 cfqd
->rq_in_driver
--;
1593 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1594 cfqd
->rq_in_driver
);
1597 static void cfq_remove_request(struct request
*rq
)
1599 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1601 if (cfqq
->next_rq
== rq
)
1602 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1604 list_del_init(&rq
->queuelist
);
1607 cfqq
->cfqd
->rq_queued
--;
1608 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1609 rq_data_dir(rq
), rq_is_sync(rq
));
1612 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1615 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1616 struct request
*__rq
;
1618 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1619 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1621 return ELEVATOR_FRONT_MERGE
;
1624 return ELEVATOR_NO_MERGE
;
1627 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1630 if (type
== ELEVATOR_FRONT_MERGE
) {
1631 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1633 cfq_reposition_rq_rb(cfqq
, req
);
1637 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1640 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req
))->blkg
,
1641 bio_data_dir(bio
), cfq_bio_sync(bio
));
1645 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1646 struct request
*next
)
1648 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1650 * reposition in fifo if next is older than rq
1652 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1653 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1654 list_move(&rq
->queuelist
, &next
->queuelist
);
1655 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1658 if (cfqq
->next_rq
== next
)
1660 cfq_remove_request(next
);
1661 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq
))->blkg
,
1662 rq_data_dir(next
), rq_is_sync(next
));
1665 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1668 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1669 struct cfq_io_context
*cic
;
1670 struct cfq_queue
*cfqq
;
1673 * Disallow merge of a sync bio into an async request.
1675 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1679 * Lookup the cfqq that this bio will be queued with. Allow
1680 * merge only if rq is queued there.
1682 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1686 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1687 return cfqq
== RQ_CFQQ(rq
);
1690 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1692 del_timer(&cfqd
->idle_slice_timer
);
1693 cfq_blkiocg_update_idle_time_stats(&cfqq
->cfqg
->blkg
);
1696 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1697 struct cfq_queue
*cfqq
)
1700 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
1701 cfqd
->serving_prio
, cfqd
->serving_type
);
1702 cfq_blkiocg_update_avg_queue_size_stats(&cfqq
->cfqg
->blkg
);
1703 cfqq
->slice_start
= 0;
1704 cfqq
->dispatch_start
= jiffies
;
1705 cfqq
->allocated_slice
= 0;
1706 cfqq
->slice_end
= 0;
1707 cfqq
->slice_dispatch
= 0;
1708 cfqq
->nr_sectors
= 0;
1710 cfq_clear_cfqq_wait_request(cfqq
);
1711 cfq_clear_cfqq_must_dispatch(cfqq
);
1712 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1713 cfq_clear_cfqq_fifo_expire(cfqq
);
1714 cfq_mark_cfqq_slice_new(cfqq
);
1716 cfq_del_timer(cfqd
, cfqq
);
1719 cfqd
->active_queue
= cfqq
;
1723 * current cfqq expired its slice (or was too idle), select new one
1726 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1729 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1731 if (cfq_cfqq_wait_request(cfqq
))
1732 cfq_del_timer(cfqd
, cfqq
);
1734 cfq_clear_cfqq_wait_request(cfqq
);
1735 cfq_clear_cfqq_wait_busy(cfqq
);
1738 * If this cfqq is shared between multiple processes, check to
1739 * make sure that those processes are still issuing I/Os within
1740 * the mean seek distance. If not, it may be time to break the
1741 * queues apart again.
1743 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
1744 cfq_mark_cfqq_split_coop(cfqq
);
1747 * store what was left of this slice, if the queue idled/timed out
1750 if (cfq_cfqq_slice_new(cfqq
))
1751 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
1753 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1754 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1757 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1759 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1760 cfq_del_cfqq_rr(cfqd
, cfqq
);
1762 cfq_resort_rr_list(cfqd
, cfqq
);
1764 if (cfqq
== cfqd
->active_queue
)
1765 cfqd
->active_queue
= NULL
;
1767 if (cfqd
->active_cic
) {
1768 put_io_context(cfqd
->active_cic
->ioc
);
1769 cfqd
->active_cic
= NULL
;
1773 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1775 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1778 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1782 * Get next queue for service. Unless we have a queue preemption,
1783 * we'll simply select the first cfqq in the service tree.
1785 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1787 struct cfq_rb_root
*service_tree
=
1788 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1789 cfqd
->serving_type
);
1791 if (!cfqd
->rq_queued
)
1794 /* There is nothing to dispatch */
1797 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1799 return cfq_rb_first(service_tree
);
1802 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1804 struct cfq_group
*cfqg
;
1805 struct cfq_queue
*cfqq
;
1807 struct cfq_rb_root
*st
;
1809 if (!cfqd
->rq_queued
)
1812 cfqg
= cfq_get_next_cfqg(cfqd
);
1816 for_each_cfqg_st(cfqg
, i
, j
, st
)
1817 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1823 * Get and set a new active queue for service.
1825 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1826 struct cfq_queue
*cfqq
)
1829 cfqq
= cfq_get_next_queue(cfqd
);
1831 __cfq_set_active_queue(cfqd
, cfqq
);
1835 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1838 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1839 return blk_rq_pos(rq
) - cfqd
->last_position
;
1841 return cfqd
->last_position
- blk_rq_pos(rq
);
1844 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1847 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
1850 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1851 struct cfq_queue
*cur_cfqq
)
1853 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1854 struct rb_node
*parent
, *node
;
1855 struct cfq_queue
*__cfqq
;
1856 sector_t sector
= cfqd
->last_position
;
1858 if (RB_EMPTY_ROOT(root
))
1862 * First, if we find a request starting at the end of the last
1863 * request, choose it.
1865 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1870 * If the exact sector wasn't found, the parent of the NULL leaf
1871 * will contain the closest sector.
1873 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1874 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1877 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1878 node
= rb_next(&__cfqq
->p_node
);
1880 node
= rb_prev(&__cfqq
->p_node
);
1884 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1885 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1893 * cur_cfqq - passed in so that we don't decide that the current queue is
1894 * closely cooperating with itself.
1896 * So, basically we're assuming that that cur_cfqq has dispatched at least
1897 * one request, and that cfqd->last_position reflects a position on the disk
1898 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1901 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1902 struct cfq_queue
*cur_cfqq
)
1904 struct cfq_queue
*cfqq
;
1906 if (cfq_class_idle(cur_cfqq
))
1908 if (!cfq_cfqq_sync(cur_cfqq
))
1910 if (CFQQ_SEEKY(cur_cfqq
))
1914 * Don't search priority tree if it's the only queue in the group.
1916 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1920 * We should notice if some of the queues are cooperating, eg
1921 * working closely on the same area of the disk. In that case,
1922 * we can group them together and don't waste time idling.
1924 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1928 /* If new queue belongs to different cfq_group, don't choose it */
1929 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1933 * It only makes sense to merge sync queues.
1935 if (!cfq_cfqq_sync(cfqq
))
1937 if (CFQQ_SEEKY(cfqq
))
1941 * Do not merge queues of different priority classes
1943 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1950 * Determine whether we should enforce idle window for this queue.
1953 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1955 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1956 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1958 BUG_ON(!service_tree
);
1959 BUG_ON(!service_tree
->count
);
1961 if (!cfqd
->cfq_slice_idle
)
1964 /* We never do for idle class queues. */
1965 if (prio
== IDLE_WORKLOAD
)
1968 /* We do for queues that were marked with idle window flag. */
1969 if (cfq_cfqq_idle_window(cfqq
) &&
1970 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1974 * Otherwise, we do only if they are the last ones
1975 * in their service tree.
1977 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
) &&
1978 !cfq_io_thinktime_big(cfqd
, &service_tree
->ttime
, false))
1980 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
1981 service_tree
->count
);
1985 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1987 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1988 struct cfq_io_context
*cic
;
1989 unsigned long sl
, group_idle
= 0;
1992 * SSD device without seek penalty, disable idling. But only do so
1993 * for devices that support queuing, otherwise we still have a problem
1994 * with sync vs async workloads.
1996 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1999 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
2000 WARN_ON(cfq_cfqq_slice_new(cfqq
));
2003 * idle is disabled, either manually or by past process history
2005 if (!cfq_should_idle(cfqd
, cfqq
)) {
2006 /* no queue idling. Check for group idling */
2007 if (cfqd
->cfq_group_idle
)
2008 group_idle
= cfqd
->cfq_group_idle
;
2014 * still active requests from this queue, don't idle
2016 if (cfqq
->dispatched
)
2020 * task has exited, don't wait
2022 cic
= cfqd
->active_cic
;
2023 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
2027 * If our average think time is larger than the remaining time
2028 * slice, then don't idle. This avoids overrunning the allotted
2031 if (sample_valid(cic
->ttime
.ttime_samples
) &&
2032 (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
)) {
2033 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%lu",
2034 cic
->ttime
.ttime_mean
);
2038 /* There are other queues in the group, don't do group idle */
2039 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
2042 cfq_mark_cfqq_wait_request(cfqq
);
2045 sl
= cfqd
->cfq_group_idle
;
2047 sl
= cfqd
->cfq_slice_idle
;
2049 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
2050 cfq_blkiocg_update_set_idle_time_stats(&cfqq
->cfqg
->blkg
);
2051 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
2052 group_idle
? 1 : 0);
2056 * Move request from internal lists to the request queue dispatch list.
2058 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
2060 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2061 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
2063 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
2065 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
2066 cfq_remove_request(rq
);
2068 (RQ_CFQG(rq
))->dispatched
++;
2069 elv_dispatch_sort(q
, rq
);
2071 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
2072 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
2073 cfq_blkiocg_update_dispatch_stats(&cfqq
->cfqg
->blkg
, blk_rq_bytes(rq
),
2074 rq_data_dir(rq
), rq_is_sync(rq
));
2078 * return expired entry, or NULL to just start from scratch in rbtree
2080 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
2082 struct request
*rq
= NULL
;
2084 if (cfq_cfqq_fifo_expire(cfqq
))
2087 cfq_mark_cfqq_fifo_expire(cfqq
);
2089 if (list_empty(&cfqq
->fifo
))
2092 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
2093 if (time_before(jiffies
, rq_fifo_time(rq
)))
2096 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
2101 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2103 const int base_rq
= cfqd
->cfq_slice_async_rq
;
2105 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2107 return 2 * base_rq
* (IOPRIO_BE_NR
- cfqq
->ioprio
);
2111 * Must be called with the queue_lock held.
2113 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2115 int process_refs
, io_refs
;
2117 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2118 process_refs
= cfqq
->ref
- io_refs
;
2119 BUG_ON(process_refs
< 0);
2120 return process_refs
;
2123 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2125 int process_refs
, new_process_refs
;
2126 struct cfq_queue
*__cfqq
;
2129 * If there are no process references on the new_cfqq, then it is
2130 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2131 * chain may have dropped their last reference (not just their
2132 * last process reference).
2134 if (!cfqq_process_refs(new_cfqq
))
2137 /* Avoid a circular list and skip interim queue merges */
2138 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2144 process_refs
= cfqq_process_refs(cfqq
);
2145 new_process_refs
= cfqq_process_refs(new_cfqq
);
2147 * If the process for the cfqq has gone away, there is no
2148 * sense in merging the queues.
2150 if (process_refs
== 0 || new_process_refs
== 0)
2154 * Merge in the direction of the lesser amount of work.
2156 if (new_process_refs
>= process_refs
) {
2157 cfqq
->new_cfqq
= new_cfqq
;
2158 new_cfqq
->ref
+= process_refs
;
2160 new_cfqq
->new_cfqq
= cfqq
;
2161 cfqq
->ref
+= new_process_refs
;
2165 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2166 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2168 struct cfq_queue
*queue
;
2170 bool key_valid
= false;
2171 unsigned long lowest_key
= 0;
2172 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2174 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2175 /* select the one with lowest rb_key */
2176 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2178 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2179 lowest_key
= queue
->rb_key
;
2188 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2192 struct cfq_rb_root
*st
;
2193 unsigned group_slice
;
2194 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2196 /* Choose next priority. RT > BE > IDLE */
2197 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2198 cfqd
->serving_prio
= RT_WORKLOAD
;
2199 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2200 cfqd
->serving_prio
= BE_WORKLOAD
;
2202 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2203 cfqd
->workload_expires
= jiffies
+ 1;
2207 if (original_prio
!= cfqd
->serving_prio
)
2211 * For RT and BE, we have to choose also the type
2212 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2215 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2219 * check workload expiration, and that we still have other queues ready
2221 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2225 /* otherwise select new workload type */
2226 cfqd
->serving_type
=
2227 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2228 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2232 * the workload slice is computed as a fraction of target latency
2233 * proportional to the number of queues in that workload, over
2234 * all the queues in the same priority class
2236 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2238 slice
= group_slice
* count
/
2239 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2240 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2242 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2246 * Async queues are currently system wide. Just taking
2247 * proportion of queues with-in same group will lead to higher
2248 * async ratio system wide as generally root group is going
2249 * to have higher weight. A more accurate thing would be to
2250 * calculate system wide asnc/sync ratio.
2252 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2253 tmp
= tmp
/cfqd
->busy_queues
;
2254 slice
= min_t(unsigned, slice
, tmp
);
2256 /* async workload slice is scaled down according to
2257 * the sync/async slice ratio. */
2258 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2260 /* sync workload slice is at least 2 * cfq_slice_idle */
2261 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2263 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2264 cfq_log(cfqd
, "workload slice:%d", slice
);
2265 cfqd
->workload_expires
= jiffies
+ slice
;
2268 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2270 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2271 struct cfq_group
*cfqg
;
2273 if (RB_EMPTY_ROOT(&st
->rb
))
2275 cfqg
= cfq_rb_first_group(st
);
2276 update_min_vdisktime(st
);
2280 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2282 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2284 cfqd
->serving_group
= cfqg
;
2286 /* Restore the workload type data */
2287 if (cfqg
->saved_workload_slice
) {
2288 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2289 cfqd
->serving_type
= cfqg
->saved_workload
;
2290 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2292 cfqd
->workload_expires
= jiffies
- 1;
2294 choose_service_tree(cfqd
, cfqg
);
2298 * Select a queue for service. If we have a current active queue,
2299 * check whether to continue servicing it, or retrieve and set a new one.
2301 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2303 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2305 cfqq
= cfqd
->active_queue
;
2309 if (!cfqd
->rq_queued
)
2313 * We were waiting for group to get backlogged. Expire the queue
2315 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2319 * The active queue has run out of time, expire it and select new.
2321 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2323 * If slice had not expired at the completion of last request
2324 * we might not have turned on wait_busy flag. Don't expire
2325 * the queue yet. Allow the group to get backlogged.
2327 * The very fact that we have used the slice, that means we
2328 * have been idling all along on this queue and it should be
2329 * ok to wait for this request to complete.
2331 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2332 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2336 goto check_group_idle
;
2340 * The active queue has requests and isn't expired, allow it to
2343 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2347 * If another queue has a request waiting within our mean seek
2348 * distance, let it run. The expire code will check for close
2349 * cooperators and put the close queue at the front of the service
2350 * tree. If possible, merge the expiring queue with the new cfqq.
2352 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2354 if (!cfqq
->new_cfqq
)
2355 cfq_setup_merge(cfqq
, new_cfqq
);
2360 * No requests pending. If the active queue still has requests in
2361 * flight or is idling for a new request, allow either of these
2362 * conditions to happen (or time out) before selecting a new queue.
2364 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2370 * This is a deep seek queue, but the device is much faster than
2371 * the queue can deliver, don't idle
2373 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2374 (cfq_cfqq_slice_new(cfqq
) ||
2375 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2376 cfq_clear_cfqq_deep(cfqq
);
2377 cfq_clear_cfqq_idle_window(cfqq
);
2380 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2386 * If group idle is enabled and there are requests dispatched from
2387 * this group, wait for requests to complete.
2390 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1 &&
2391 cfqq
->cfqg
->dispatched
&&
2392 !cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true)) {
2398 cfq_slice_expired(cfqd
, 0);
2401 * Current queue expired. Check if we have to switch to a new
2405 cfq_choose_cfqg(cfqd
);
2407 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2412 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2416 while (cfqq
->next_rq
) {
2417 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2421 BUG_ON(!list_empty(&cfqq
->fifo
));
2423 /* By default cfqq is not expired if it is empty. Do it explicitly */
2424 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2429 * Drain our current requests. Used for barriers and when switching
2430 * io schedulers on-the-fly.
2432 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2434 struct cfq_queue
*cfqq
;
2437 /* Expire the timeslice of the current active queue first */
2438 cfq_slice_expired(cfqd
, 0);
2439 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2440 __cfq_set_active_queue(cfqd
, cfqq
);
2441 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2444 BUG_ON(cfqd
->busy_queues
);
2446 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2450 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2451 struct cfq_queue
*cfqq
)
2453 /* the queue hasn't finished any request, can't estimate */
2454 if (cfq_cfqq_slice_new(cfqq
))
2456 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2463 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2465 unsigned int max_dispatch
;
2468 * Drain async requests before we start sync IO
2470 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2474 * If this is an async queue and we have sync IO in flight, let it wait
2476 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2479 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2480 if (cfq_class_idle(cfqq
))
2484 * Does this cfqq already have too much IO in flight?
2486 if (cfqq
->dispatched
>= max_dispatch
) {
2487 bool promote_sync
= false;
2489 * idle queue must always only have a single IO in flight
2491 if (cfq_class_idle(cfqq
))
2495 * If there is only one sync queue
2496 * we can ignore async queue here and give the sync
2497 * queue no dispatch limit. The reason is a sync queue can
2498 * preempt async queue, limiting the sync queue doesn't make
2499 * sense. This is useful for aiostress test.
2501 if (cfq_cfqq_sync(cfqq
) && cfqd
->busy_sync_queues
== 1)
2502 promote_sync
= true;
2505 * We have other queues, don't allow more IO from this one
2507 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
) &&
2512 * Sole queue user, no limit
2514 if (cfqd
->busy_queues
== 1 || promote_sync
)
2518 * Normally we start throttling cfqq when cfq_quantum/2
2519 * requests have been dispatched. But we can drive
2520 * deeper queue depths at the beginning of slice
2521 * subjected to upper limit of cfq_quantum.
2523 max_dispatch
= cfqd
->cfq_quantum
;
2527 * Async queues must wait a bit before being allowed dispatch.
2528 * We also ramp up the dispatch depth gradually for async IO,
2529 * based on the last sync IO we serviced
2531 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2532 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2535 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2536 if (!depth
&& !cfqq
->dispatched
)
2538 if (depth
< max_dispatch
)
2539 max_dispatch
= depth
;
2543 * If we're below the current max, allow a dispatch
2545 return cfqq
->dispatched
< max_dispatch
;
2549 * Dispatch a request from cfqq, moving them to the request queue
2552 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2556 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2558 if (!cfq_may_dispatch(cfqd
, cfqq
))
2562 * follow expired path, else get first next available
2564 rq
= cfq_check_fifo(cfqq
);
2569 * insert request into driver dispatch list
2571 cfq_dispatch_insert(cfqd
->queue
, rq
);
2573 if (!cfqd
->active_cic
) {
2574 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2576 atomic_long_inc(&cic
->ioc
->refcount
);
2577 cfqd
->active_cic
= cic
;
2584 * Find the cfqq that we need to service and move a request from that to the
2587 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2589 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2590 struct cfq_queue
*cfqq
;
2592 if (!cfqd
->busy_queues
)
2595 if (unlikely(force
))
2596 return cfq_forced_dispatch(cfqd
);
2598 cfqq
= cfq_select_queue(cfqd
);
2603 * Dispatch a request from this cfqq, if it is allowed
2605 if (!cfq_dispatch_request(cfqd
, cfqq
))
2608 cfqq
->slice_dispatch
++;
2609 cfq_clear_cfqq_must_dispatch(cfqq
);
2612 * expire an async queue immediately if it has used up its slice. idle
2613 * queue always expire after 1 dispatch round.
2615 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2616 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2617 cfq_class_idle(cfqq
))) {
2618 cfqq
->slice_end
= jiffies
+ 1;
2619 cfq_slice_expired(cfqd
, 0);
2622 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2627 * task holds one reference to the queue, dropped when task exits. each rq
2628 * in-flight on this queue also holds a reference, dropped when rq is freed.
2630 * Each cfq queue took a reference on the parent group. Drop it now.
2631 * queue lock must be held here.
2633 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2635 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2636 struct cfq_group
*cfqg
;
2638 BUG_ON(cfqq
->ref
<= 0);
2644 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2645 BUG_ON(rb_first(&cfqq
->sort_list
));
2646 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2649 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2650 __cfq_slice_expired(cfqd
, cfqq
, 0);
2651 cfq_schedule_dispatch(cfqd
);
2654 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2655 kmem_cache_free(cfq_pool
, cfqq
);
2660 * Call func for each cic attached to this ioc.
2663 call_for_each_cic(struct io_context
*ioc
,
2664 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2666 struct cfq_io_context
*cic
;
2667 struct hlist_node
*n
;
2671 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
2677 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2679 struct cfq_io_context
*cic
;
2681 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
2683 kmem_cache_free(cfq_ioc_pool
, cic
);
2684 elv_ioc_count_dec(cfq_ioc_count
);
2688 * CFQ scheduler is exiting, grab exit lock and check
2689 * the pending io context count. If it hits zero,
2690 * complete ioc_gone and set it back to NULL
2692 spin_lock(&ioc_gone_lock
);
2693 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
2697 spin_unlock(&ioc_gone_lock
);
2701 static void cfq_cic_free(struct cfq_io_context
*cic
)
2703 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2706 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2708 unsigned long flags
;
2709 unsigned long dead_key
= (unsigned long) cic
->key
;
2711 BUG_ON(!(dead_key
& CIC_DEAD_KEY
));
2713 spin_lock_irqsave(&ioc
->lock
, flags
);
2714 radix_tree_delete(&ioc
->radix_root
, dead_key
>> CIC_DEAD_INDEX_SHIFT
);
2715 hlist_del_rcu(&cic
->cic_list
);
2716 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2722 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2723 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2724 * and ->trim() which is called with the task lock held
2726 static void cfq_free_io_context(struct io_context
*ioc
)
2729 * ioc->refcount is zero here, or we are called from elv_unregister(),
2730 * so no more cic's are allowed to be linked into this ioc. So it
2731 * should be ok to iterate over the known list, we will see all cic's
2732 * since no new ones are added.
2734 call_for_each_cic(ioc
, cic_free_func
);
2737 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2739 struct cfq_queue
*__cfqq
, *next
;
2742 * If this queue was scheduled to merge with another queue, be
2743 * sure to drop the reference taken on that queue (and others in
2744 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2746 __cfqq
= cfqq
->new_cfqq
;
2748 if (__cfqq
== cfqq
) {
2749 WARN(1, "cfqq->new_cfqq loop detected\n");
2752 next
= __cfqq
->new_cfqq
;
2753 cfq_put_queue(__cfqq
);
2758 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2760 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2761 __cfq_slice_expired(cfqd
, cfqq
, 0);
2762 cfq_schedule_dispatch(cfqd
);
2765 cfq_put_cooperator(cfqq
);
2767 cfq_put_queue(cfqq
);
2770 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
2771 struct cfq_io_context
*cic
)
2773 struct io_context
*ioc
= cic
->ioc
;
2775 list_del_init(&cic
->queue_list
);
2778 * Make sure dead mark is seen for dead queues
2781 cic
->key
= cfqd_dead_key(cfqd
);
2784 if (rcu_dereference(ioc
->ioc_data
) == cic
) {
2786 spin_lock(&ioc
->lock
);
2787 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2788 spin_unlock(&ioc
->lock
);
2792 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2793 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2794 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2797 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2798 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2799 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2803 static void cfq_exit_single_io_context(struct io_context
*ioc
,
2804 struct cfq_io_context
*cic
)
2806 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2809 struct request_queue
*q
= cfqd
->queue
;
2810 unsigned long flags
;
2812 spin_lock_irqsave(q
->queue_lock
, flags
);
2815 * Ensure we get a fresh copy of the ->key to prevent
2816 * race between exiting task and queue
2818 smp_read_barrier_depends();
2819 if (cic
->key
== cfqd
)
2820 __cfq_exit_single_io_context(cfqd
, cic
);
2822 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2827 * The process that ioc belongs to has exited, we need to clean up
2828 * and put the internal structures we have that belongs to that process.
2830 static void cfq_exit_io_context(struct io_context
*ioc
)
2832 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
2835 static struct cfq_io_context
*
2836 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2838 struct cfq_io_context
*cic
;
2840 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2843 cic
->ttime
.last_end_request
= jiffies
;
2844 INIT_LIST_HEAD(&cic
->queue_list
);
2845 INIT_HLIST_NODE(&cic
->cic_list
);
2846 cic
->dtor
= cfq_free_io_context
;
2847 cic
->exit
= cfq_exit_io_context
;
2848 elv_ioc_count_inc(cfq_ioc_count
);
2854 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2856 struct task_struct
*tsk
= current
;
2859 if (!cfq_cfqq_prio_changed(cfqq
))
2862 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2863 switch (ioprio_class
) {
2865 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2866 case IOPRIO_CLASS_NONE
:
2868 * no prio set, inherit CPU scheduling settings
2870 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2871 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2873 case IOPRIO_CLASS_RT
:
2874 cfqq
->ioprio
= task_ioprio(ioc
);
2875 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2877 case IOPRIO_CLASS_BE
:
2878 cfqq
->ioprio
= task_ioprio(ioc
);
2879 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2881 case IOPRIO_CLASS_IDLE
:
2882 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2884 cfq_clear_cfqq_idle_window(cfqq
);
2889 * keep track of original prio settings in case we have to temporarily
2890 * elevate the priority of this queue
2892 cfqq
->org_ioprio
= cfqq
->ioprio
;
2893 cfq_clear_cfqq_prio_changed(cfqq
);
2896 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2898 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2899 struct cfq_queue
*cfqq
;
2900 unsigned long flags
;
2902 if (unlikely(!cfqd
))
2905 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2907 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2909 struct cfq_queue
*new_cfqq
;
2910 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2913 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2914 cfq_put_queue(cfqq
);
2918 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2920 cfq_mark_cfqq_prio_changed(cfqq
);
2922 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2925 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2927 call_for_each_cic(ioc
, changed_ioprio
);
2928 ioc
->ioprio_changed
= 0;
2931 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2932 pid_t pid
, bool is_sync
)
2934 RB_CLEAR_NODE(&cfqq
->rb_node
);
2935 RB_CLEAR_NODE(&cfqq
->p_node
);
2936 INIT_LIST_HEAD(&cfqq
->fifo
);
2941 cfq_mark_cfqq_prio_changed(cfqq
);
2944 if (!cfq_class_idle(cfqq
))
2945 cfq_mark_cfqq_idle_window(cfqq
);
2946 cfq_mark_cfqq_sync(cfqq
);
2951 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2952 static void changed_cgroup(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2954 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2955 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2956 unsigned long flags
;
2957 struct request_queue
*q
;
2959 if (unlikely(!cfqd
))
2964 spin_lock_irqsave(q
->queue_lock
, flags
);
2968 * Drop reference to sync queue. A new sync queue will be
2969 * assigned in new group upon arrival of a fresh request.
2971 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2972 cic_set_cfqq(cic
, NULL
, 1);
2973 cfq_put_queue(sync_cfqq
);
2976 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2979 static void cfq_ioc_set_cgroup(struct io_context
*ioc
)
2981 call_for_each_cic(ioc
, changed_cgroup
);
2982 ioc
->cgroup_changed
= 0;
2984 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2986 static struct cfq_queue
*
2987 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2988 struct io_context
*ioc
, gfp_t gfp_mask
)
2990 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2991 struct cfq_io_context
*cic
;
2992 struct cfq_group
*cfqg
;
2995 cfqg
= cfq_get_cfqg(cfqd
);
2996 cic
= cfq_cic_lookup(cfqd
, ioc
);
2997 /* cic always exists here */
2998 cfqq
= cic_to_cfqq(cic
, is_sync
);
3001 * Always try a new alloc if we fell back to the OOM cfqq
3002 * originally, since it should just be a temporary situation.
3004 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3009 } else if (gfp_mask
& __GFP_WAIT
) {
3010 spin_unlock_irq(cfqd
->queue
->queue_lock
);
3011 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
3012 gfp_mask
| __GFP_ZERO
,
3014 spin_lock_irq(cfqd
->queue
->queue_lock
);
3018 cfqq
= kmem_cache_alloc_node(cfq_pool
,
3019 gfp_mask
| __GFP_ZERO
,
3024 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
3025 cfq_init_prio_data(cfqq
, ioc
);
3026 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
3027 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
3029 cfqq
= &cfqd
->oom_cfqq
;
3033 kmem_cache_free(cfq_pool
, new_cfqq
);
3038 static struct cfq_queue
**
3039 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
3041 switch (ioprio_class
) {
3042 case IOPRIO_CLASS_RT
:
3043 return &cfqd
->async_cfqq
[0][ioprio
];
3044 case IOPRIO_CLASS_BE
:
3045 return &cfqd
->async_cfqq
[1][ioprio
];
3046 case IOPRIO_CLASS_IDLE
:
3047 return &cfqd
->async_idle_cfqq
;
3053 static struct cfq_queue
*
3054 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
3057 const int ioprio
= task_ioprio(ioc
);
3058 const int ioprio_class
= task_ioprio_class(ioc
);
3059 struct cfq_queue
**async_cfqq
= NULL
;
3060 struct cfq_queue
*cfqq
= NULL
;
3063 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
3068 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
3071 * pin the queue now that it's allocated, scheduler exit will prune it
3073 if (!is_sync
&& !(*async_cfqq
)) {
3083 * We drop cfq io contexts lazily, so we may find a dead one.
3086 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
3087 struct cfq_io_context
*cic
)
3089 unsigned long flags
;
3091 WARN_ON(!list_empty(&cic
->queue_list
));
3092 BUG_ON(cic
->key
!= cfqd_dead_key(cfqd
));
3094 spin_lock_irqsave(&ioc
->lock
, flags
);
3096 BUG_ON(rcu_dereference_check(ioc
->ioc_data
,
3097 lockdep_is_held(&ioc
->lock
)) == cic
);
3099 radix_tree_delete(&ioc
->radix_root
, cfqd
->cic_index
);
3100 hlist_del_rcu(&cic
->cic_list
);
3101 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3106 static struct cfq_io_context
*
3107 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
3109 struct cfq_io_context
*cic
;
3110 unsigned long flags
;
3118 * we maintain a last-hit cache, to avoid browsing over the tree
3120 cic
= rcu_dereference(ioc
->ioc_data
);
3121 if (cic
&& cic
->key
== cfqd
) {
3127 cic
= radix_tree_lookup(&ioc
->radix_root
, cfqd
->cic_index
);
3131 if (unlikely(cic
->key
!= cfqd
)) {
3132 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
3137 spin_lock_irqsave(&ioc
->lock
, flags
);
3138 rcu_assign_pointer(ioc
->ioc_data
, cic
);
3139 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3147 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3148 * the process specific cfq io context when entered from the block layer.
3149 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3151 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
3152 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
3154 unsigned long flags
;
3157 ret
= radix_tree_preload(gfp_mask
);
3162 spin_lock_irqsave(&ioc
->lock
, flags
);
3163 ret
= radix_tree_insert(&ioc
->radix_root
,
3164 cfqd
->cic_index
, cic
);
3166 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
3167 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3169 radix_tree_preload_end();
3172 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3173 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
3174 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3179 printk(KERN_ERR
"cfq: cic link failed!\n");
3185 * Setup general io context and cfq io context. There can be several cfq
3186 * io contexts per general io context, if this process is doing io to more
3187 * than one device managed by cfq.
3189 static struct cfq_io_context
*
3190 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3192 struct io_context
*ioc
= NULL
;
3193 struct cfq_io_context
*cic
;
3195 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3197 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
3201 cic
= cfq_cic_lookup(cfqd
, ioc
);
3205 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
3209 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
3213 smp_read_barrier_depends();
3214 if (unlikely(ioc
->ioprio_changed
))
3215 cfq_ioc_set_ioprio(ioc
);
3217 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3218 if (unlikely(ioc
->cgroup_changed
))
3219 cfq_ioc_set_cgroup(ioc
);
3225 put_io_context(ioc
);
3230 __cfq_update_io_thinktime(struct cfq_ttime
*ttime
, unsigned long slice_idle
)
3232 unsigned long elapsed
= jiffies
- ttime
->last_end_request
;
3233 elapsed
= min(elapsed
, 2UL * slice_idle
);
3235 ttime
->ttime_samples
= (7*ttime
->ttime_samples
+ 256) / 8;
3236 ttime
->ttime_total
= (7*ttime
->ttime_total
+ 256*elapsed
) / 8;
3237 ttime
->ttime_mean
= (ttime
->ttime_total
+ 128) / ttime
->ttime_samples
;
3241 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3242 struct cfq_io_context
*cic
)
3244 if (cfq_cfqq_sync(cfqq
)) {
3245 __cfq_update_io_thinktime(&cic
->ttime
, cfqd
->cfq_slice_idle
);
3246 __cfq_update_io_thinktime(&cfqq
->service_tree
->ttime
,
3247 cfqd
->cfq_slice_idle
);
3249 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3250 __cfq_update_io_thinktime(&cfqq
->cfqg
->ttime
, cfqd
->cfq_group_idle
);
3255 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3259 sector_t n_sec
= blk_rq_sectors(rq
);
3260 if (cfqq
->last_request_pos
) {
3261 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3262 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3264 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3267 cfqq
->seek_history
<<= 1;
3268 if (blk_queue_nonrot(cfqd
->queue
))
3269 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3271 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3275 * Disable idle window if the process thinks too long or seeks so much that
3279 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3280 struct cfq_io_context
*cic
)
3282 int old_idle
, enable_idle
;
3285 * Don't idle for async or idle io prio class
3287 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3290 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3292 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3293 cfq_mark_cfqq_deep(cfqq
);
3295 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3297 else if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3298 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3300 else if (sample_valid(cic
->ttime
.ttime_samples
)) {
3301 if (cic
->ttime
.ttime_mean
> cfqd
->cfq_slice_idle
)
3307 if (old_idle
!= enable_idle
) {
3308 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3310 cfq_mark_cfqq_idle_window(cfqq
);
3312 cfq_clear_cfqq_idle_window(cfqq
);
3317 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3318 * no or if we aren't sure, a 1 will cause a preempt.
3321 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3324 struct cfq_queue
*cfqq
;
3326 cfqq
= cfqd
->active_queue
;
3330 if (cfq_class_idle(new_cfqq
))
3333 if (cfq_class_idle(cfqq
))
3337 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3339 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3343 * if the new request is sync, but the currently running queue is
3344 * not, let the sync request have priority.
3346 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3349 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3352 if (cfq_slice_used(cfqq
))
3355 /* Allow preemption only if we are idling on sync-noidle tree */
3356 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3357 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3358 new_cfqq
->service_tree
->count
== 2 &&
3359 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3363 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3365 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3368 /* An idle queue should not be idle now for some reason */
3369 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3372 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3376 * if this request is as-good as one we would expect from the
3377 * current cfqq, let it preempt
3379 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3386 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3387 * let it have half of its nominal slice.
3389 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3391 struct cfq_queue
*old_cfqq
= cfqd
->active_queue
;
3393 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3394 cfq_slice_expired(cfqd
, 1);
3397 * workload type is changed, don't save slice, otherwise preempt
3400 if (cfqq_type(old_cfqq
) != cfqq_type(cfqq
))
3401 cfqq
->cfqg
->saved_workload_slice
= 0;
3404 * Put the new queue at the front of the of the current list,
3405 * so we know that it will be selected next.
3407 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3409 cfq_service_tree_add(cfqd
, cfqq
, 1);
3411 cfqq
->slice_end
= 0;
3412 cfq_mark_cfqq_slice_new(cfqq
);
3416 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3417 * something we should do about it
3420 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3423 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3427 cfq_update_io_thinktime(cfqd
, cfqq
, cic
);
3428 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3429 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3431 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3433 if (cfqq
== cfqd
->active_queue
) {
3435 * Remember that we saw a request from this process, but
3436 * don't start queuing just yet. Otherwise we risk seeing lots
3437 * of tiny requests, because we disrupt the normal plugging
3438 * and merging. If the request is already larger than a single
3439 * page, let it rip immediately. For that case we assume that
3440 * merging is already done. Ditto for a busy system that
3441 * has other work pending, don't risk delaying until the
3442 * idle timer unplug to continue working.
3444 if (cfq_cfqq_wait_request(cfqq
)) {
3445 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3446 cfqd
->busy_queues
> 1) {
3447 cfq_del_timer(cfqd
, cfqq
);
3448 cfq_clear_cfqq_wait_request(cfqq
);
3449 __blk_run_queue(cfqd
->queue
);
3451 cfq_blkiocg_update_idle_time_stats(
3453 cfq_mark_cfqq_must_dispatch(cfqq
);
3456 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3458 * not the active queue - expire current slice if it is
3459 * idle and has expired it's mean thinktime or this new queue
3460 * has some old slice time left and is of higher priority or
3461 * this new queue is RT and the current one is BE
3463 cfq_preempt_queue(cfqd
, cfqq
);
3464 __blk_run_queue(cfqd
->queue
);
3468 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3470 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3471 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3473 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3474 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3476 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3477 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3479 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
3480 &cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
3482 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3486 * Update hw_tag based on peak queue depth over 50 samples under
3489 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3491 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3493 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3494 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3496 if (cfqd
->hw_tag
== 1)
3499 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3500 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3504 * If active queue hasn't enough requests and can idle, cfq might not
3505 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3508 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3509 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3510 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3513 if (cfqd
->hw_tag_samples
++ < 50)
3516 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3522 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3524 struct cfq_io_context
*cic
= cfqd
->active_cic
;
3526 /* If the queue already has requests, don't wait */
3527 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3530 /* If there are other queues in the group, don't wait */
3531 if (cfqq
->cfqg
->nr_cfqq
> 1)
3534 /* the only queue in the group, but think time is big */
3535 if (cfq_io_thinktime_big(cfqd
, &cfqq
->cfqg
->ttime
, true))
3538 if (cfq_slice_used(cfqq
))
3541 /* if slice left is less than think time, wait busy */
3542 if (cic
&& sample_valid(cic
->ttime
.ttime_samples
)
3543 && (cfqq
->slice_end
- jiffies
< cic
->ttime
.ttime_mean
))
3547 * If think times is less than a jiffy than ttime_mean=0 and above
3548 * will not be true. It might happen that slice has not expired yet
3549 * but will expire soon (4-5 ns) during select_queue(). To cover the
3550 * case where think time is less than a jiffy, mark the queue wait
3551 * busy if only 1 jiffy is left in the slice.
3553 if (cfqq
->slice_end
- jiffies
== 1)
3559 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3561 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3562 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3563 const int sync
= rq_is_sync(rq
);
3567 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3568 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3570 cfq_update_hw_tag(cfqd
);
3572 WARN_ON(!cfqd
->rq_in_driver
);
3573 WARN_ON(!cfqq
->dispatched
);
3574 cfqd
->rq_in_driver
--;
3576 (RQ_CFQG(rq
))->dispatched
--;
3577 cfq_blkiocg_update_completion_stats(&cfqq
->cfqg
->blkg
,
3578 rq_start_time_ns(rq
), rq_io_start_time_ns(rq
),
3579 rq_data_dir(rq
), rq_is_sync(rq
));
3581 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3584 struct cfq_rb_root
*service_tree
;
3586 RQ_CIC(rq
)->ttime
.last_end_request
= now
;
3588 if (cfq_cfqq_on_rr(cfqq
))
3589 service_tree
= cfqq
->service_tree
;
3591 service_tree
= service_tree_for(cfqq
->cfqg
,
3592 cfqq_prio(cfqq
), cfqq_type(cfqq
));
3593 service_tree
->ttime
.last_end_request
= now
;
3594 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3595 cfqd
->last_delayed_sync
= now
;
3598 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3599 cfqq
->cfqg
->ttime
.last_end_request
= now
;
3603 * If this is the active queue, check if it needs to be expired,
3604 * or if we want to idle in case it has no pending requests.
3606 if (cfqd
->active_queue
== cfqq
) {
3607 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3609 if (cfq_cfqq_slice_new(cfqq
)) {
3610 cfq_set_prio_slice(cfqd
, cfqq
);
3611 cfq_clear_cfqq_slice_new(cfqq
);
3615 * Should we wait for next request to come in before we expire
3618 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3619 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3620 if (!cfqd
->cfq_slice_idle
)
3621 extend_sl
= cfqd
->cfq_group_idle
;
3622 cfqq
->slice_end
= jiffies
+ extend_sl
;
3623 cfq_mark_cfqq_wait_busy(cfqq
);
3624 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3628 * Idling is not enabled on:
3630 * - idle-priority queues
3632 * - queues with still some requests queued
3633 * - when there is a close cooperator
3635 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3636 cfq_slice_expired(cfqd
, 1);
3637 else if (sync
&& cfqq_empty
&&
3638 !cfq_close_cooperator(cfqd
, cfqq
)) {
3639 cfq_arm_slice_timer(cfqd
);
3643 if (!cfqd
->rq_in_driver
)
3644 cfq_schedule_dispatch(cfqd
);
3647 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3649 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3650 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3651 return ELV_MQUEUE_MUST
;
3654 return ELV_MQUEUE_MAY
;
3657 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3659 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3660 struct task_struct
*tsk
= current
;
3661 struct cfq_io_context
*cic
;
3662 struct cfq_queue
*cfqq
;
3665 * don't force setup of a queue from here, as a call to may_queue
3666 * does not necessarily imply that a request actually will be queued.
3667 * so just lookup a possibly existing queue, or return 'may queue'
3670 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3672 return ELV_MQUEUE_MAY
;
3674 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3676 cfq_init_prio_data(cfqq
, cic
->ioc
);
3678 return __cfq_may_queue(cfqq
);
3681 return ELV_MQUEUE_MAY
;
3685 * queue lock held here
3687 static void cfq_put_request(struct request
*rq
)
3689 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3692 const int rw
= rq_data_dir(rq
);
3694 BUG_ON(!cfqq
->allocated
[rw
]);
3695 cfqq
->allocated
[rw
]--;
3697 put_io_context(RQ_CIC(rq
)->ioc
);
3699 rq
->elevator_private
[0] = NULL
;
3700 rq
->elevator_private
[1] = NULL
;
3702 /* Put down rq reference on cfqg */
3703 cfq_put_cfqg(RQ_CFQG(rq
));
3704 rq
->elevator_private
[2] = NULL
;
3706 cfq_put_queue(cfqq
);
3710 static struct cfq_queue
*
3711 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3712 struct cfq_queue
*cfqq
)
3714 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3715 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3716 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3717 cfq_put_queue(cfqq
);
3718 return cic_to_cfqq(cic
, 1);
3722 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3723 * was the last process referring to said cfqq.
3725 static struct cfq_queue
*
3726 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3728 if (cfqq_process_refs(cfqq
) == 1) {
3729 cfqq
->pid
= current
->pid
;
3730 cfq_clear_cfqq_coop(cfqq
);
3731 cfq_clear_cfqq_split_coop(cfqq
);
3735 cic_set_cfqq(cic
, NULL
, 1);
3737 cfq_put_cooperator(cfqq
);
3739 cfq_put_queue(cfqq
);
3743 * Allocate cfq data structures associated with this request.
3746 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3748 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3749 struct cfq_io_context
*cic
;
3750 const int rw
= rq_data_dir(rq
);
3751 const bool is_sync
= rq_is_sync(rq
);
3752 struct cfq_queue
*cfqq
;
3753 unsigned long flags
;
3755 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3757 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3759 spin_lock_irqsave(q
->queue_lock
, flags
);
3765 cfqq
= cic_to_cfqq(cic
, is_sync
);
3766 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3767 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3768 cic_set_cfqq(cic
, cfqq
, is_sync
);
3771 * If the queue was seeky for too long, break it apart.
3773 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3774 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3775 cfqq
= split_cfqq(cic
, cfqq
);
3781 * Check to see if this queue is scheduled to merge with
3782 * another, closely cooperating queue. The merging of
3783 * queues happens here as it must be done in process context.
3784 * The reference on new_cfqq was taken in merge_cfqqs.
3787 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3790 cfqq
->allocated
[rw
]++;
3793 rq
->elevator_private
[0] = cic
;
3794 rq
->elevator_private
[1] = cfqq
;
3795 rq
->elevator_private
[2] = cfq_ref_get_cfqg(cfqq
->cfqg
);
3796 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3800 cfq_schedule_dispatch(cfqd
);
3801 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3802 cfq_log(cfqd
, "set_request fail");
3806 static void cfq_kick_queue(struct work_struct
*work
)
3808 struct cfq_data
*cfqd
=
3809 container_of(work
, struct cfq_data
, unplug_work
);
3810 struct request_queue
*q
= cfqd
->queue
;
3812 spin_lock_irq(q
->queue_lock
);
3813 __blk_run_queue(cfqd
->queue
);
3814 spin_unlock_irq(q
->queue_lock
);
3818 * Timer running if the active_queue is currently idling inside its time slice
3820 static void cfq_idle_slice_timer(unsigned long data
)
3822 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3823 struct cfq_queue
*cfqq
;
3824 unsigned long flags
;
3827 cfq_log(cfqd
, "idle timer fired");
3829 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3831 cfqq
= cfqd
->active_queue
;
3836 * We saw a request before the queue expired, let it through
3838 if (cfq_cfqq_must_dispatch(cfqq
))
3844 if (cfq_slice_used(cfqq
))
3848 * only expire and reinvoke request handler, if there are
3849 * other queues with pending requests
3851 if (!cfqd
->busy_queues
)
3855 * not expired and it has a request pending, let it dispatch
3857 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3861 * Queue depth flag is reset only when the idle didn't succeed
3863 cfq_clear_cfqq_deep(cfqq
);
3866 cfq_slice_expired(cfqd
, timed_out
);
3868 cfq_schedule_dispatch(cfqd
);
3870 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3873 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3875 del_timer_sync(&cfqd
->idle_slice_timer
);
3876 cancel_work_sync(&cfqd
->unplug_work
);
3879 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3883 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3884 if (cfqd
->async_cfqq
[0][i
])
3885 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3886 if (cfqd
->async_cfqq
[1][i
])
3887 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3890 if (cfqd
->async_idle_cfqq
)
3891 cfq_put_queue(cfqd
->async_idle_cfqq
);
3894 static void cfq_exit_queue(struct elevator_queue
*e
)
3896 struct cfq_data
*cfqd
= e
->elevator_data
;
3897 struct request_queue
*q
= cfqd
->queue
;
3900 cfq_shutdown_timer_wq(cfqd
);
3902 spin_lock_irq(q
->queue_lock
);
3904 if (cfqd
->active_queue
)
3905 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3907 while (!list_empty(&cfqd
->cic_list
)) {
3908 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3909 struct cfq_io_context
,
3912 __cfq_exit_single_io_context(cfqd
, cic
);
3915 cfq_put_async_queues(cfqd
);
3916 cfq_release_cfq_groups(cfqd
);
3919 * If there are groups which we could not unlink from blkcg list,
3920 * wait for a rcu period for them to be freed.
3922 if (cfqd
->nr_blkcg_linked_grps
)
3925 spin_unlock_irq(q
->queue_lock
);
3927 cfq_shutdown_timer_wq(cfqd
);
3929 spin_lock(&cic_index_lock
);
3930 ida_remove(&cic_index_ida
, cfqd
->cic_index
);
3931 spin_unlock(&cic_index_lock
);
3934 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3935 * Do this wait only if there are other unlinked groups out
3936 * there. This can happen if cgroup deletion path claimed the
3937 * responsibility of cleaning up a group before queue cleanup code
3940 * Do not call synchronize_rcu() unconditionally as there are drivers
3941 * which create/delete request queue hundreds of times during scan/boot
3942 * and synchronize_rcu() can take significant time and slow down boot.
3947 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3948 /* Free up per cpu stats for root group */
3949 free_percpu(cfqd
->root_group
.blkg
.stats_cpu
);
3954 static int cfq_alloc_cic_index(void)
3959 if (!ida_pre_get(&cic_index_ida
, GFP_KERNEL
))
3962 spin_lock(&cic_index_lock
);
3963 error
= ida_get_new(&cic_index_ida
, &index
);
3964 spin_unlock(&cic_index_lock
);
3965 if (error
&& error
!= -EAGAIN
)
3972 static void *cfq_init_queue(struct request_queue
*q
)
3974 struct cfq_data
*cfqd
;
3976 struct cfq_group
*cfqg
;
3977 struct cfq_rb_root
*st
;
3979 i
= cfq_alloc_cic_index();
3983 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3985 spin_lock(&cic_index_lock
);
3986 ida_remove(&cic_index_ida
, i
);
3987 spin_unlock(&cic_index_lock
);
3992 * Don't need take queue_lock in the routine, since we are
3993 * initializing the ioscheduler, and nobody is using cfqd
3995 cfqd
->cic_index
= i
;
3997 /* Init root service tree */
3998 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
4000 /* Init root group */
4001 cfqg
= &cfqd
->root_group
;
4002 for_each_cfqg_st(cfqg
, i
, j
, st
)
4004 RB_CLEAR_NODE(&cfqg
->rb_node
);
4006 /* Give preference to root group over other groups */
4007 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
4009 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4011 * Set root group reference to 2. One reference will be dropped when
4012 * all groups on cfqd->cfqg_list are being deleted during queue exit.
4013 * Other reference will remain there as we don't want to delete this
4014 * group as it is statically allocated and gets destroyed when
4015 * throtl_data goes away.
4019 if (blkio_alloc_blkg_stats(&cfqg
->blkg
)) {
4027 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
,
4030 cfqd
->nr_blkcg_linked_grps
++;
4032 /* Add group on cfqd->cfqg_list */
4033 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
4036 * Not strictly needed (since RB_ROOT just clears the node and we
4037 * zeroed cfqd on alloc), but better be safe in case someone decides
4038 * to add magic to the rb code
4040 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
4041 cfqd
->prio_trees
[i
] = RB_ROOT
;
4044 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4045 * Grab a permanent reference to it, so that the normal code flow
4046 * will not attempt to free it.
4048 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
4049 cfqd
->oom_cfqq
.ref
++;
4050 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
4052 INIT_LIST_HEAD(&cfqd
->cic_list
);
4056 init_timer(&cfqd
->idle_slice_timer
);
4057 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
4058 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
4060 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
4062 cfqd
->cfq_quantum
= cfq_quantum
;
4063 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
4064 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
4065 cfqd
->cfq_back_max
= cfq_back_max
;
4066 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
4067 cfqd
->cfq_slice
[0] = cfq_slice_async
;
4068 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
4069 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
4070 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
4071 cfqd
->cfq_group_idle
= cfq_group_idle
;
4072 cfqd
->cfq_latency
= 1;
4075 * we optimistically start assuming sync ops weren't delayed in last
4076 * second, in order to have larger depth for async operations.
4078 cfqd
->last_delayed_sync
= jiffies
- HZ
;
4082 static void cfq_slab_kill(void)
4085 * Caller already ensured that pending RCU callbacks are completed,
4086 * so we should have no busy allocations at this point.
4089 kmem_cache_destroy(cfq_pool
);
4091 kmem_cache_destroy(cfq_ioc_pool
);
4094 static int __init
cfq_slab_setup(void)
4096 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
4100 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
4111 * sysfs parts below -->
4114 cfq_var_show(unsigned int var
, char *page
)
4116 return sprintf(page
, "%d\n", var
);
4120 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
4122 char *p
= (char *) page
;
4124 *var
= simple_strtoul(p
, &p
, 10);
4128 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
4129 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
4131 struct cfq_data *cfqd = e->elevator_data; \
4132 unsigned int __data = __VAR; \
4134 __data = jiffies_to_msecs(__data); \
4135 return cfq_var_show(__data, (page)); \
4137 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
4138 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
4139 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
4140 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
4141 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
4142 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
4143 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
4144 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
4145 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
4146 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
4147 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
4148 #undef SHOW_FUNCTION
4150 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4151 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4153 struct cfq_data *cfqd = e->elevator_data; \
4154 unsigned int __data; \
4155 int ret = cfq_var_store(&__data, (page), count); \
4156 if (__data < (MIN)) \
4158 else if (__data > (MAX)) \
4161 *(__PTR) = msecs_to_jiffies(__data); \
4163 *(__PTR) = __data; \
4166 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4167 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4169 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4171 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4172 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4174 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4175 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4176 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4177 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4178 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4180 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4181 #undef STORE_FUNCTION
4183 #define CFQ_ATTR(name) \
4184 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4186 static struct elv_fs_entry cfq_attrs
[] = {
4188 CFQ_ATTR(fifo_expire_sync
),
4189 CFQ_ATTR(fifo_expire_async
),
4190 CFQ_ATTR(back_seek_max
),
4191 CFQ_ATTR(back_seek_penalty
),
4192 CFQ_ATTR(slice_sync
),
4193 CFQ_ATTR(slice_async
),
4194 CFQ_ATTR(slice_async_rq
),
4195 CFQ_ATTR(slice_idle
),
4196 CFQ_ATTR(group_idle
),
4197 CFQ_ATTR(low_latency
),
4201 static struct elevator_type iosched_cfq
= {
4203 .elevator_merge_fn
= cfq_merge
,
4204 .elevator_merged_fn
= cfq_merged_request
,
4205 .elevator_merge_req_fn
= cfq_merged_requests
,
4206 .elevator_allow_merge_fn
= cfq_allow_merge
,
4207 .elevator_bio_merged_fn
= cfq_bio_merged
,
4208 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4209 .elevator_add_req_fn
= cfq_insert_request
,
4210 .elevator_activate_req_fn
= cfq_activate_request
,
4211 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4212 .elevator_completed_req_fn
= cfq_completed_request
,
4213 .elevator_former_req_fn
= elv_rb_former_request
,
4214 .elevator_latter_req_fn
= elv_rb_latter_request
,
4215 .elevator_set_req_fn
= cfq_set_request
,
4216 .elevator_put_req_fn
= cfq_put_request
,
4217 .elevator_may_queue_fn
= cfq_may_queue
,
4218 .elevator_init_fn
= cfq_init_queue
,
4219 .elevator_exit_fn
= cfq_exit_queue
,
4220 .trim
= cfq_free_io_context
,
4222 .elevator_attrs
= cfq_attrs
,
4223 .elevator_name
= "cfq",
4224 .elevator_owner
= THIS_MODULE
,
4227 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4228 static struct blkio_policy_type blkio_policy_cfq
= {
4230 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
4231 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
4233 .plid
= BLKIO_POLICY_PROP
,
4236 static struct blkio_policy_type blkio_policy_cfq
;
4239 static int __init
cfq_init(void)
4242 * could be 0 on HZ < 1000 setups
4244 if (!cfq_slice_async
)
4245 cfq_slice_async
= 1;
4246 if (!cfq_slice_idle
)
4249 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4250 if (!cfq_group_idle
)
4255 if (cfq_slab_setup())
4258 elv_register(&iosched_cfq
);
4259 blkio_policy_register(&blkio_policy_cfq
);
4264 static void __exit
cfq_exit(void)
4266 DECLARE_COMPLETION_ONSTACK(all_gone
);
4267 blkio_policy_unregister(&blkio_policy_cfq
);
4268 elv_unregister(&iosched_cfq
);
4269 ioc_gone
= &all_gone
;
4270 /* ioc_gone's update must be visible before reading ioc_count */
4274 * this also protects us from entering cfq_slab_kill() with
4275 * pending RCU callbacks
4277 if (elv_ioc_count_read(cfq_ioc_count
))
4278 wait_for_completion(&all_gone
);
4279 ida_destroy(&cic_index_ida
);
4283 module_init(cfq_init
);
4284 module_exit(cfq_exit
);
4286 MODULE_AUTHOR("Jens Axboe");
4287 MODULE_LICENSE("GPL");
4288 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");