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linux-next/block/cfq-iosched.c
Jens Axboe 206dc69b31 [BLOCK] cfq-iosched: seek and async performance fixes 
Detect whether a given process is seeky and if so disable (mostly) the
idle window if it is. We still allow just a little idle time, just enough
to allow that process to submit a new request. That is needed to maintain
fairness across priority groups.

In some cases, we could setup several async queues. This is not optimal
from a performance POV, since we want all async io in one queue to perform
good sorting on it. It also impacted sync queues, as async io got too much
slice time.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-03-28 13:03:44 +02:00

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/*
* CFQ, or complete fairness queueing, disk scheduler.
*
* Based on ideas from a previously unfinished io
* scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
*
* Copyright (C) 2003 Jens Axboe <axboe@suse.de>
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/hash.h>
#include <linux/rbtree.h>
#include <linux/ioprio.h>
/*
* tunables
*/
static const int cfq_quantum = 4; /* max queue in one round of service */
static const int cfq_queued = 8; /* minimum rq allocate limit per-queue*/
static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
static const int cfq_back_penalty = 2; /* penalty of a backwards seek */
static const int cfq_slice_sync = HZ / 10;
static int cfq_slice_async = HZ / 25;
static const int cfq_slice_async_rq = 2;
static int cfq_slice_idle = HZ / 70;
#define CFQ_IDLE_GRACE (HZ / 10)
#define CFQ_SLICE_SCALE (5)
#define CFQ_KEY_ASYNC (0)
static DEFINE_RWLOCK(cfq_exit_lock);
/*
* for the hash of cfqq inside the cfqd
*/
#define CFQ_QHASH_SHIFT 6
#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
#define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash)
/*
* for the hash of crq inside the cfqq
*/
#define CFQ_MHASH_SHIFT 6
#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
#define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT)
#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
#define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash)
#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
#define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
#define RQ_DATA(rq) (rq)->elevator_private
/*
* rb-tree defines
*/
#define RB_NONE (2)
#define RB_EMPTY(node) ((node)->rb_node == NULL)
#define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE
#define RB_CLEAR(node) do { \
(node)->rb_parent = NULL; \
RB_CLEAR_COLOR((node)); \
(node)->rb_right = NULL; \
(node)->rb_left = NULL; \
} while (0)
#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
#define rq_rb_key(rq) (rq)->sector
static kmem_cache_t *crq_pool;
static kmem_cache_t *cfq_pool;
static kmem_cache_t *cfq_ioc_pool;
static atomic_t ioc_count = ATOMIC_INIT(0);
static struct completion *ioc_gone;
#define CFQ_PRIO_LISTS IOPRIO_BE_NR
#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
#define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
#define ASYNC (0)
#define SYNC (1)
#define cfq_cfqq_dispatched(cfqq) \
((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC])
#define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC)
#define cfq_cfqq_sync(cfqq) \
(cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC])
#define sample_valid(samples) ((samples) > 80)
/*
* Per block device queue structure
*/
struct cfq_data {
request_queue_t *queue;
/*
* rr list of queues with requests and the count of them
*/
struct list_head rr_list[CFQ_PRIO_LISTS];
struct list_head busy_rr;
struct list_head cur_rr;
struct list_head idle_rr;
unsigned int busy_queues;
/*
* non-ordered list of empty cfqq's
*/
struct list_head empty_list;
/*
* cfqq lookup hash
*/
struct hlist_head *cfq_hash;
/*
* global crq hash for all queues
*/
struct hlist_head *crq_hash;
unsigned int max_queued;
mempool_t *crq_pool;
int rq_in_driver;
/*
* schedule slice state info
*/
/*
* idle window management
*/
struct timer_list idle_slice_timer;
struct work_struct unplug_work;
struct cfq_queue *active_queue;
struct cfq_io_context *active_cic;
int cur_prio, cur_end_prio;
unsigned int dispatch_slice;
struct timer_list idle_class_timer;
sector_t last_sector;
unsigned long last_end_request;
unsigned int rq_starved;
/*
* tunables, see top of file
*/
unsigned int cfq_quantum;
unsigned int cfq_queued;
unsigned int cfq_fifo_expire[2];
unsigned int cfq_back_penalty;
unsigned int cfq_back_max;
unsigned int cfq_slice[2];
unsigned int cfq_slice_async_rq;
unsigned int cfq_slice_idle;
struct list_head cic_list;
};
/*
* Per process-grouping structure
*/
struct cfq_queue {
/* reference count */
atomic_t ref;
/* parent cfq_data */
struct cfq_data *cfqd;
/* cfqq lookup hash */
struct hlist_node cfq_hash;
/* hash key */
unsigned int key;
/* on either rr or empty list of cfqd */
struct list_head cfq_list;
/* sorted list of pending requests */
struct rb_root sort_list;
/* if fifo isn't expired, next request to serve */
struct cfq_rq *next_crq;
/* requests queued in sort_list */
int queued[2];
/* currently allocated requests */
int allocated[2];
/* fifo list of requests in sort_list */
struct list_head fifo;
unsigned long slice_start;
unsigned long slice_end;
unsigned long slice_left;
unsigned long service_last;
/* number of requests that are on the dispatch list */
int on_dispatch[2];
/* io prio of this group */
unsigned short ioprio, org_ioprio;
unsigned short ioprio_class, org_ioprio_class;
/* various state flags, see below */
unsigned int flags;
};
struct cfq_rq {
struct rb_node rb_node;
sector_t rb_key;
struct request *request;
struct hlist_node hash;
struct cfq_queue *cfq_queue;
struct cfq_io_context *io_context;
unsigned int crq_flags;
};
enum cfqq_state_flags {
CFQ_CFQQ_FLAG_on_rr = 0,
CFQ_CFQQ_FLAG_wait_request,
CFQ_CFQQ_FLAG_must_alloc,
CFQ_CFQQ_FLAG_must_alloc_slice,
CFQ_CFQQ_FLAG_must_dispatch,
CFQ_CFQQ_FLAG_fifo_expire,
CFQ_CFQQ_FLAG_idle_window,
CFQ_CFQQ_FLAG_prio_changed,
};
#define CFQ_CFQQ_FNS(name) \
static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
{ \
cfqq->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
} \
static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
{ \
cfqq->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
} \
static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
{ \
return (cfqq->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
}
CFQ_CFQQ_FNS(on_rr);
CFQ_CFQQ_FNS(wait_request);
CFQ_CFQQ_FNS(must_alloc);
CFQ_CFQQ_FNS(must_alloc_slice);
CFQ_CFQQ_FNS(must_dispatch);
CFQ_CFQQ_FNS(fifo_expire);
CFQ_CFQQ_FNS(idle_window);
CFQ_CFQQ_FNS(prio_changed);
#undef CFQ_CFQQ_FNS
enum cfq_rq_state_flags {
CFQ_CRQ_FLAG_is_sync = 0,
};
#define CFQ_CRQ_FNS(name) \
static inline void cfq_mark_crq_##name(struct cfq_rq *crq) \
{ \
crq->crq_flags |= (1 << CFQ_CRQ_FLAG_##name); \
} \
static inline void cfq_clear_crq_##name(struct cfq_rq *crq) \
{ \
crq->crq_flags &= ~(1 << CFQ_CRQ_FLAG_##name); \
} \
static inline int cfq_crq_##name(const struct cfq_rq *crq) \
{ \
return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
}
CFQ_CRQ_FNS(is_sync);
#undef CFQ_CRQ_FNS
static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *);
static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask);
#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
/*
* lots of deadline iosched dupes, can be abstracted later...
*/
static inline void cfq_del_crq_hash(struct cfq_rq *crq)
{
hlist_del_init(&crq->hash);
}
static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
{
const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request));
hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]);
}
static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
{
struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)];
struct hlist_node *entry, *next;
hlist_for_each_safe(entry, next, hash_list) {
struct cfq_rq *crq = list_entry_hash(entry);
struct request *__rq = crq->request;
if (!rq_mergeable(__rq)) {
cfq_del_crq_hash(crq);
continue;
}
if (rq_hash_key(__rq) == offset)
return __rq;
}
return NULL;
}
/*
* scheduler run of queue, if there are requests pending and no one in the
* driver that will restart queueing
*/
static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
{
if (cfqd->busy_queues)
kblockd_schedule_work(&cfqd->unplug_work);
}
static int cfq_queue_empty(request_queue_t *q)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
return !cfqd->busy_queues;
}
static inline pid_t cfq_queue_pid(struct task_struct *task, int rw)
{
if (rw == READ || process_sync(task))
return task->pid;
return CFQ_KEY_ASYNC;
}
/*
* Lifted from AS - choose which of crq1 and crq2 that is best served now.
* We choose the request that is closest to the head right now. Distance
* behind the head is penalized and only allowed to a certain extent.
*/
static struct cfq_rq *
cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
{
sector_t last, s1, s2, d1 = 0, d2 = 0;
unsigned long back_max;
#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
unsigned wrap = 0; /* bit mask: requests behind the disk head? */
if (crq1 == NULL || crq1 == crq2)
return crq2;
if (crq2 == NULL)
return crq1;
if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2))
return crq1;
else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1))
return crq2;
s1 = crq1->request->sector;
s2 = crq2->request->sector;
last = cfqd->last_sector;
/*
* by definition, 1KiB is 2 sectors
*/
back_max = cfqd->cfq_back_max * 2;
/*
* Strict one way elevator _except_ in the case where we allow
* short backward seeks which are biased as twice the cost of a
* similar forward seek.
*/
if (s1 >= last)
d1 = s1 - last;
else if (s1 + back_max >= last)
d1 = (last - s1) * cfqd->cfq_back_penalty;
else
wrap |= CFQ_RQ1_WRAP;
if (s2 >= last)
d2 = s2 - last;
else if (s2 + back_max >= last)
d2 = (last - s2) * cfqd->cfq_back_penalty;
else
wrap |= CFQ_RQ2_WRAP;
/* Found required data */
/*
* By doing switch() on the bit mask "wrap" we avoid having to
* check two variables for all permutations: --> faster!
*/
switch (wrap) {
case 0: /* common case for CFQ: crq1 and crq2 not wrapped */
if (d1 < d2)
return crq1;
else if (d2 < d1)
return crq2;
else {
if (s1 >= s2)
return crq1;
else
return crq2;
}
case CFQ_RQ2_WRAP:
return crq1;
case CFQ_RQ1_WRAP:
return crq2;
case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both crqs wrapped */
default:
/*
* Since both rqs are wrapped,
* start with the one that's further behind head
* (--> only *one* back seek required),
* since back seek takes more time than forward.
*/
if (s1 <= s2)
return crq1;
else
return crq2;
}
}
/*
* would be nice to take fifo expire time into account as well
*/
static struct cfq_rq *
cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_rq *last)
{
struct cfq_rq *crq_next = NULL, *crq_prev = NULL;
struct rb_node *rbnext, *rbprev;
if (!(rbnext = rb_next(&last->rb_node))) {
rbnext = rb_first(&cfqq->sort_list);
if (rbnext == &last->rb_node)
rbnext = NULL;
}
rbprev = rb_prev(&last->rb_node);
if (rbprev)
crq_prev = rb_entry_crq(rbprev);
if (rbnext)
crq_next = rb_entry_crq(rbnext);
return cfq_choose_req(cfqd, crq_next, crq_prev);
}
static void cfq_update_next_crq(struct cfq_rq *crq)
{
struct cfq_queue *cfqq = crq->cfq_queue;
if (cfqq->next_crq == crq)
cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq);
}
static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
{
struct cfq_data *cfqd = cfqq->cfqd;
struct list_head *list, *entry;
BUG_ON(!cfq_cfqq_on_rr(cfqq));
list_del(&cfqq->cfq_list);
if (cfq_class_rt(cfqq))
list = &cfqd->cur_rr;
else if (cfq_class_idle(cfqq))
list = &cfqd->idle_rr;
else {
/*
* if cfqq has requests in flight, don't allow it to be
* found in cfq_set_active_queue before it has finished them.
* this is done to increase fairness between a process that
* has lots of io pending vs one that only generates one
* sporadically or synchronously
*/
if (cfq_cfqq_dispatched(cfqq))
list = &cfqd->busy_rr;
else
list = &cfqd->rr_list[cfqq->ioprio];
}
/*
* if queue was preempted, just add to front to be fair. busy_rr
* isn't sorted.
*/
if (preempted || list == &cfqd->busy_rr) {
list_add(&cfqq->cfq_list, list);
return;
}
/*
* sort by when queue was last serviced
*/
entry = list;
while ((entry = entry->prev) != list) {
struct cfq_queue *__cfqq = list_entry_cfqq(entry);
if (!__cfqq->service_last)
break;
if (time_before(__cfqq->service_last, cfqq->service_last))
break;
}
list_add(&cfqq->cfq_list, entry);
}
/*
* add to busy list of queues for service, trying to be fair in ordering
* the pending list according to last request service
*/
static inline void
cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
BUG_ON(cfq_cfqq_on_rr(cfqq));
cfq_mark_cfqq_on_rr(cfqq);
cfqd->busy_queues++;
cfq_resort_rr_list(cfqq, 0);
}
static inline void
cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
BUG_ON(!cfq_cfqq_on_rr(cfqq));
cfq_clear_cfqq_on_rr(cfqq);
list_move(&cfqq->cfq_list, &cfqd->empty_list);
BUG_ON(!cfqd->busy_queues);
cfqd->busy_queues--;
}
/*
* rb tree support functions
*/
static inline void cfq_del_crq_rb(struct cfq_rq *crq)
{
struct cfq_queue *cfqq = crq->cfq_queue;
struct cfq_data *cfqd = cfqq->cfqd;
const int sync = cfq_crq_is_sync(crq);
BUG_ON(!cfqq->queued[sync]);
cfqq->queued[sync]--;
cfq_update_next_crq(crq);
rb_erase(&crq->rb_node, &cfqq->sort_list);
RB_CLEAR_COLOR(&crq->rb_node);
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
cfq_del_cfqq_rr(cfqd, cfqq);
}
static struct cfq_rq *
__cfq_add_crq_rb(struct cfq_rq *crq)
{
struct rb_node **p = &crq->cfq_queue->sort_list.rb_node;
struct rb_node *parent = NULL;
struct cfq_rq *__crq;
while (*p) {
parent = *p;
__crq = rb_entry_crq(parent);
if (crq->rb_key < __crq->rb_key)
p = &(*p)->rb_left;
else if (crq->rb_key > __crq->rb_key)
p = &(*p)->rb_right;
else
return __crq;
}
rb_link_node(&crq->rb_node, parent, p);
return NULL;
}
static void cfq_add_crq_rb(struct cfq_rq *crq)
{
struct cfq_queue *cfqq = crq->cfq_queue;
struct cfq_data *cfqd = cfqq->cfqd;
struct request *rq = crq->request;
struct cfq_rq *__alias;
crq->rb_key = rq_rb_key(rq);
cfqq->queued[cfq_crq_is_sync(crq)]++;
/*
* looks a little odd, but the first insert might return an alias.
* if that happens, put the alias on the dispatch list
*/
while ((__alias = __cfq_add_crq_rb(crq)) != NULL)
cfq_dispatch_insert(cfqd->queue, __alias);
rb_insert_color(&crq->rb_node, &cfqq->sort_list);
if (!cfq_cfqq_on_rr(cfqq))
cfq_add_cfqq_rr(cfqd, cfqq);
/*
* check if this request is a better next-serve candidate
*/
cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
}
static inline void
cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
{
rb_erase(&crq->rb_node, &cfqq->sort_list);
cfqq->queued[cfq_crq_is_sync(crq)]--;
cfq_add_crq_rb(crq);
}
static struct request *
cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
{
struct task_struct *tsk = current;
pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio));
struct cfq_queue *cfqq;
struct rb_node *n;
sector_t sector;
cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio);
if (!cfqq)
goto out;
sector = bio->bi_sector + bio_sectors(bio);
n = cfqq->sort_list.rb_node;
while (n) {
struct cfq_rq *crq = rb_entry_crq(n);
if (sector < crq->rb_key)
n = n->rb_left;
else if (sector > crq->rb_key)
n = n->rb_right;
else
return crq->request;
}
out:
return NULL;
}
static void cfq_activate_request(request_queue_t *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
cfqd->rq_in_driver++;
}
static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
WARN_ON(!cfqd->rq_in_driver);
cfqd->rq_in_driver--;
}
static void cfq_remove_request(struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
list_del_init(&rq->queuelist);
cfq_del_crq_rb(crq);
cfq_del_crq_hash(crq);
}
static int
cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct request *__rq;
int ret;
__rq = cfq_find_rq_hash(cfqd, bio->bi_sector);
if (__rq && elv_rq_merge_ok(__rq, bio)) {
ret = ELEVATOR_BACK_MERGE;
goto out;
}
__rq = cfq_find_rq_fmerge(cfqd, bio);
if (__rq && elv_rq_merge_ok(__rq, bio)) {
ret = ELEVATOR_FRONT_MERGE;
goto out;
}
return ELEVATOR_NO_MERGE;
out:
*req = __rq;
return ret;
}
static void cfq_merged_request(request_queue_t *q, struct request *req)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_rq *crq = RQ_DATA(req);
cfq_del_crq_hash(crq);
cfq_add_crq_hash(cfqd, crq);
if (rq_rb_key(req) != crq->rb_key) {
struct cfq_queue *cfqq = crq->cfq_queue;
cfq_update_next_crq(crq);
cfq_reposition_crq_rb(cfqq, crq);
}
}
static void
cfq_merged_requests(request_queue_t *q, struct request *rq,
struct request *next)
{
cfq_merged_request(q, rq);
/*
* reposition in fifo if next is older than rq
*/
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
time_before(next->start_time, rq->start_time))
list_move(&rq->queuelist, &next->queuelist);
cfq_remove_request(next);
}
static inline void
__cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
if (cfqq) {
/*
* stop potential idle class queues waiting service
*/
del_timer(&cfqd->idle_class_timer);
cfqq->slice_start = jiffies;
cfqq->slice_end = 0;
cfqq->slice_left = 0;
cfq_clear_cfqq_must_alloc_slice(cfqq);
cfq_clear_cfqq_fifo_expire(cfqq);
}
cfqd->active_queue = cfqq;
}
/*
* current cfqq expired its slice (or was too idle), select new one
*/
static void
__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
int preempted)
{
unsigned long now = jiffies;
if (cfq_cfqq_wait_request(cfqq))
del_timer(&cfqd->idle_slice_timer);
if (!preempted && !cfq_cfqq_dispatched(cfqq)) {
cfqq->service_last = now;
cfq_schedule_dispatch(cfqd);
}
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_wait_request(cfqq);
/*
* store what was left of this slice, if the queue idled out
* or was preempted
*/
if (time_after(cfqq->slice_end, now))
cfqq->slice_left = cfqq->slice_end - now;
else
cfqq->slice_left = 0;
if (cfq_cfqq_on_rr(cfqq))
cfq_resort_rr_list(cfqq, preempted);
if (cfqq == cfqd->active_queue)
cfqd->active_queue = NULL;
if (cfqd->active_cic) {
put_io_context(cfqd->active_cic->ioc);
cfqd->active_cic = NULL;
}
cfqd->dispatch_slice = 0;
}
static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted)
{
struct cfq_queue *cfqq = cfqd->active_queue;
if (cfqq)
__cfq_slice_expired(cfqd, cfqq, preempted);
}
/*
* 0
* 0,1
* 0,1,2
* 0,1,2,3
* 0,1,2,3,4
* 0,1,2,3,4,5
* 0,1,2,3,4,5,6
* 0,1,2,3,4,5,6,7
*/
static int cfq_get_next_prio_level(struct cfq_data *cfqd)
{
int prio, wrap;
prio = -1;
wrap = 0;
do {
int p;
for (p = cfqd->cur_prio; p <= cfqd->cur_end_prio; p++) {
if (!list_empty(&cfqd->rr_list[p])) {
prio = p;
break;
}
}
if (prio != -1)
break;
cfqd->cur_prio = 0;
if (++cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
cfqd->cur_end_prio = 0;
if (wrap)
break;
wrap = 1;
}
} while (1);
if (unlikely(prio == -1))
return -1;
BUG_ON(prio >= CFQ_PRIO_LISTS);
list_splice_init(&cfqd->rr_list[prio], &cfqd->cur_rr);
cfqd->cur_prio = prio + 1;
if (cfqd->cur_prio > cfqd->cur_end_prio) {
cfqd->cur_end_prio = cfqd->cur_prio;
cfqd->cur_prio = 0;
}
if (cfqd->cur_end_prio == CFQ_PRIO_LISTS) {
cfqd->cur_prio = 0;
cfqd->cur_end_prio = 0;
}
return prio;
}
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = NULL;
/*
* if current list is non-empty, grab first entry. if it is empty,
* get next prio level and grab first entry then if any are spliced
*/
if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1)
cfqq = list_entry_cfqq(cfqd->cur_rr.next);
/*
* if we have idle queues and no rt or be queues had pending
* requests, either allow immediate service if the grace period
* has passed or arm the idle grace timer
*/
if (!cfqq && !list_empty(&cfqd->idle_rr)) {
unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE;
if (time_after_eq(jiffies, end))
cfqq = list_entry_cfqq(cfqd->idle_rr.next);
else
mod_timer(&cfqd->idle_class_timer, end);
}
__cfq_set_active_queue(cfqd, cfqq);
return cfqq;
}
static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
struct cfq_io_context *cic;
unsigned long sl;
WARN_ON(!RB_EMPTY(&cfqq->sort_list));
WARN_ON(cfqq != cfqd->active_queue);
/*
* idle is disabled, either manually or by past process history
*/
if (!cfqd->cfq_slice_idle)
return 0;
if (!cfq_cfqq_idle_window(cfqq))
return 0;
/*
* task has exited, don't wait
*/
cic = cfqd->active_cic;
if (!cic || !cic->ioc->task)
return 0;
cfq_mark_cfqq_must_dispatch(cfqq);
cfq_mark_cfqq_wait_request(cfqq);
sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle);
/*
* we don't want to idle for seeks, but we do want to allow
* fair distribution of slice time for a process doing back-to-back
* seeks. so allow a little bit of time for him to submit a new rq
*/
if (sample_valid(cic->seek_samples) && cic->seek_mean > 131072)
sl = 2;
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
return 1;
}
static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq = crq->cfq_queue;
cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq);
cfq_remove_request(crq->request);
cfqq->on_dispatch[cfq_crq_is_sync(crq)]++;
elv_dispatch_sort(q, crq->request);
}
/*
* return expired entry, or NULL to just start from scratch in rbtree
*/
static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq)
{
struct cfq_data *cfqd = cfqq->cfqd;
struct request *rq;
struct cfq_rq *crq;
if (cfq_cfqq_fifo_expire(cfqq))
return NULL;
if (!list_empty(&cfqq->fifo)) {
int fifo = cfq_cfqq_class_sync(cfqq);
crq = RQ_DATA(list_entry_fifo(cfqq->fifo.next));
rq = crq->request;
if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
cfq_mark_cfqq_fifo_expire(cfqq);
return crq;
}
}
return NULL;
}
/*
* Scale schedule slice based on io priority. Use the sync time slice only
* if a queue is marked sync and has sync io queued. A sync queue with async
* io only, should not get full sync slice length.
*/
static inline int
cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
const int base_slice = cfqd->cfq_slice[cfq_cfqq_sync(cfqq)];
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - cfqq->ioprio));
}
static inline void
cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
}
static inline int
cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
const int base_rq = cfqd->cfq_slice_async_rq;
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
}
/*
* get next queue for service
*/
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
{
unsigned long now = jiffies;
struct cfq_queue *cfqq;
cfqq = cfqd->active_queue;
if (!cfqq)
goto new_queue;
/*
* slice has expired
*/
if (!cfq_cfqq_must_dispatch(cfqq) && time_after(now, cfqq->slice_end))
goto expire;
/*
* if queue has requests, dispatch one. if not, check if
* enough slice is left to wait for one
*/
if (!RB_EMPTY(&cfqq->sort_list))
goto keep_queue;
else if (cfq_cfqq_class_sync(cfqq) &&
time_before(now, cfqq->slice_end)) {
if (cfq_arm_slice_timer(cfqd, cfqq))
return NULL;
}
expire:
cfq_slice_expired(cfqd, 0);
new_queue:
cfqq = cfq_set_active_queue(cfqd);
keep_queue:
return cfqq;
}
static int
__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
int max_dispatch)
{
int dispatched = 0;
BUG_ON(RB_EMPTY(&cfqq->sort_list));
do {
struct cfq_rq *crq;
/*
* follow expired path, else get first next available
*/
if ((crq = cfq_check_fifo(cfqq)) == NULL)
crq = cfqq->next_crq;
/*
* finally, insert request into driver dispatch list
*/
cfq_dispatch_insert(cfqd->queue, crq);
cfqd->dispatch_slice++;
dispatched++;
if (!cfqd->active_cic) {
atomic_inc(&crq->io_context->ioc->refcount);
cfqd->active_cic = crq->io_context;
}
if (RB_EMPTY(&cfqq->sort_list))
break;
} while (dispatched < max_dispatch);
/*
* if slice end isn't set yet, set it. if at least one request was
* sync, use the sync time slice value
*/
if (!cfqq->slice_end)
cfq_set_prio_slice(cfqd, cfqq);
/*
* expire an async queue immediately if it has used up its slice. idle
* queue always expire after 1 dispatch round.
*/
if ((!cfq_cfqq_sync(cfqq) &&
cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
cfq_class_idle(cfqq))
cfq_slice_expired(cfqd, 0);
return dispatched;
}
static int
cfq_forced_dispatch_cfqqs(struct list_head *list)
{
int dispatched = 0;
struct cfq_queue *cfqq, *next;
struct cfq_rq *crq;
list_for_each_entry_safe(cfqq, next, list, cfq_list) {
while ((crq = cfqq->next_crq)) {
cfq_dispatch_insert(cfqq->cfqd->queue, crq);
dispatched++;
}
BUG_ON(!list_empty(&cfqq->fifo));
}
return dispatched;
}
static int
cfq_forced_dispatch(struct cfq_data *cfqd)
{
int i, dispatched = 0;
for (i = 0; i < CFQ_PRIO_LISTS; i++)
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr);
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);
dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
cfq_slice_expired(cfqd, 0);
BUG_ON(cfqd->busy_queues);
return dispatched;
}
static int
cfq_dispatch_requests(request_queue_t *q, int force)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq;
if (!cfqd->busy_queues)
return 0;
if (unlikely(force))
return cfq_forced_dispatch(cfqd);
cfqq = cfq_select_queue(cfqd);
if (cfqq) {
int max_dispatch;
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_wait_request(cfqq);
del_timer(&cfqd->idle_slice_timer);
max_dispatch = cfqd->cfq_quantum;
if (cfq_class_idle(cfqq))
max_dispatch = 1;
return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
}
return 0;
}
/*
* task holds one reference to the queue, dropped when task exits. each crq
* in-flight on this queue also holds a reference, dropped when crq is freed.
*
* queue lock must be held here.
*/
static void cfq_put_queue(struct cfq_queue *cfqq)
{
struct cfq_data *cfqd = cfqq->cfqd;
BUG_ON(atomic_read(&cfqq->ref) <= 0);
if (!atomic_dec_and_test(&cfqq->ref))
return;
BUG_ON(rb_first(&cfqq->sort_list));
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
BUG_ON(cfq_cfqq_on_rr(cfqq));
if (unlikely(cfqd->active_queue == cfqq))
__cfq_slice_expired(cfqd, cfqq, 0);
/*
* it's on the empty list and still hashed
*/
list_del(&cfqq->cfq_list);
hlist_del(&cfqq->cfq_hash);
kmem_cache_free(cfq_pool, cfqq);
}
static inline struct cfq_queue *
__cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned int prio,
const int hashval)
{
struct hlist_head *hash_list = &cfqd->cfq_hash[hashval];
struct hlist_node *entry;
struct cfq_queue *__cfqq;
hlist_for_each_entry(__cfqq, entry, hash_list, cfq_hash) {
const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->org_ioprio_class, __cfqq->org_ioprio);
if (__cfqq->key == key && (__p == prio || !prio))
return __cfqq;
}
return NULL;
}
static struct cfq_queue *
cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned int key, unsigned short prio)
{
return __cfq_find_cfq_hash(cfqd, key, prio, hash_long(key, CFQ_QHASH_SHIFT));
}
static void cfq_free_io_context(struct io_context *ioc)
{
struct cfq_io_context *__cic;
struct rb_node *n;
int freed = 0;
while ((n = rb_first(&ioc->cic_root)) != NULL) {
__cic = rb_entry(n, struct cfq_io_context, rb_node);
rb_erase(&__cic->rb_node, &ioc->cic_root);
kmem_cache_free(cfq_ioc_pool, __cic);
freed++;
}
if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone)
complete(ioc_gone);
}
static void cfq_trim(struct io_context *ioc)
{
ioc->set_ioprio = NULL;
cfq_free_io_context(ioc);
}
/*
* Called with interrupts disabled
*/
static void cfq_exit_single_io_context(struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
request_queue_t *q;
if (!cfqd)
return;
q = cfqd->queue;
WARN_ON(!irqs_disabled());
spin_lock(q->queue_lock);
if (cic->cfqq[ASYNC]) {
if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue))
__cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0);
cfq_put_queue(cic->cfqq[ASYNC]);
cic->cfqq[ASYNC] = NULL;
}
if (cic->cfqq[SYNC]) {
if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue))
__cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0);
cfq_put_queue(cic->cfqq[SYNC]);
cic->cfqq[SYNC] = NULL;
}
cic->key = NULL;
list_del_init(&cic->queue_list);
spin_unlock(q->queue_lock);
}
static void cfq_exit_io_context(struct io_context *ioc)
{
struct cfq_io_context *__cic;
unsigned long flags;
struct rb_node *n;
/*
* put the reference this task is holding to the various queues
*/
read_lock_irqsave(&cfq_exit_lock, flags);
n = rb_first(&ioc->cic_root);
while (n != NULL) {
__cic = rb_entry(n, struct cfq_io_context, rb_node);
cfq_exit_single_io_context(__cic);
n = rb_next(n);
}
read_unlock_irqrestore(&cfq_exit_lock, flags);
}
static struct cfq_io_context *
cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
{
struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask);
if (cic) {
RB_CLEAR(&cic->rb_node);
cic->key = NULL;
cic->cfqq[ASYNC] = NULL;
cic->cfqq[SYNC] = NULL;
cic->last_end_request = jiffies;
cic->ttime_total = 0;
cic->ttime_samples = 0;
cic->ttime_mean = 0;
cic->dtor = cfq_free_io_context;
cic->exit = cfq_exit_io_context;
INIT_LIST_HEAD(&cic->queue_list);
atomic_inc(&ioc_count);
}
return cic;
}
static void cfq_init_prio_data(struct cfq_queue *cfqq)
{
struct task_struct *tsk = current;
int ioprio_class;
if (!cfq_cfqq_prio_changed(cfqq))
return;
ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio);
switch (ioprio_class) {
default:
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
case IOPRIO_CLASS_NONE:
/*
* no prio set, place us in the middle of the BE classes
*/
cfqq->ioprio = task_nice_ioprio(tsk);
cfqq->ioprio_class = IOPRIO_CLASS_BE;
break;
case IOPRIO_CLASS_RT:
cfqq->ioprio = task_ioprio(tsk);
cfqq->ioprio_class = IOPRIO_CLASS_RT;
break;
case IOPRIO_CLASS_BE:
cfqq->ioprio = task_ioprio(tsk);
cfqq->ioprio_class = IOPRIO_CLASS_BE;
break;
case IOPRIO_CLASS_IDLE:
cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
cfqq->ioprio = 7;
cfq_clear_cfqq_idle_window(cfqq);
break;
}
/*
* keep track of original prio settings in case we have to temporarily
* elevate the priority of this queue
*/
cfqq->org_ioprio = cfqq->ioprio;
cfqq->org_ioprio_class = cfqq->ioprio_class;
if (cfq_cfqq_on_rr(cfqq))
cfq_resort_rr_list(cfqq, 0);
cfq_clear_cfqq_prio_changed(cfqq);
}
static inline void changed_ioprio(struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
struct cfq_queue *cfqq;
if (cfqd) {
spin_lock(cfqd->queue->queue_lock);
cfqq = cic->cfqq[ASYNC];
if (cfqq) {
struct cfq_queue *new_cfqq;
new_cfqq = cfq_get_queue(cfqd, CFQ_KEY_ASYNC,
cic->ioc->task, GFP_ATOMIC);
if (new_cfqq) {
cic->cfqq[ASYNC] = new_cfqq;
cfq_put_queue(cfqq);
}
}
cfqq = cic->cfqq[SYNC];
if (cfqq) {
cfq_mark_cfqq_prio_changed(cfqq);
cfq_init_prio_data(cfqq);
}
spin_unlock(cfqd->queue->queue_lock);
}
}
/*
* callback from sys_ioprio_set, irqs are disabled
*/
static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
{
struct cfq_io_context *cic;
struct rb_node *n;
write_lock(&cfq_exit_lock);
n = rb_first(&ioc->cic_root);
while (n != NULL) {
cic = rb_entry(n, struct cfq_io_context, rb_node);
changed_ioprio(cic);
n = rb_next(n);
}
write_unlock(&cfq_exit_lock);
return 0;
}
static struct cfq_queue *
cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk,
gfp_t gfp_mask)
{
const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
struct cfq_queue *cfqq, *new_cfqq = NULL;
unsigned short ioprio;
retry:
ioprio = tsk->ioprio;
cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval);
if (!cfqq) {
if (new_cfqq) {
cfqq = new_cfqq;
new_cfqq = NULL;
} else if (gfp_mask & __GFP_WAIT) {
spin_unlock_irq(cfqd->queue->queue_lock);
new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
spin_lock_irq(cfqd->queue->queue_lock);
goto retry;
} else {
cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
if (!cfqq)
goto out;
}
memset(cfqq, 0, sizeof(*cfqq));
INIT_HLIST_NODE(&cfqq->cfq_hash);
INIT_LIST_HEAD(&cfqq->cfq_list);
RB_CLEAR_ROOT(&cfqq->sort_list);
INIT_LIST_HEAD(&cfqq->fifo);
cfqq->key = key;
hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
atomic_set(&cfqq->ref, 0);
cfqq->cfqd = cfqd;
cfqq->service_last = 0;
/*
* set ->slice_left to allow preemption for a new process
*/
cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
cfq_mark_cfqq_idle_window(cfqq);
cfq_mark_cfqq_prio_changed(cfqq);
cfq_init_prio_data(cfqq);
}
if (new_cfqq)
kmem_cache_free(cfq_pool, new_cfqq);
atomic_inc(&cfqq->ref);
out:
WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
return cfqq;
}
static struct cfq_io_context *
cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)
{
struct rb_node *n = ioc->cic_root.rb_node;
struct cfq_io_context *cic;
void *key = cfqd;
while (n) {
cic = rb_entry(n, struct cfq_io_context, rb_node);
if (key < cic->key)
n = n->rb_left;
else if (key > cic->key)
n = n->rb_right;
else
return cic;
}
return NULL;
}
static inline void
cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
struct cfq_io_context *cic)
{
struct rb_node **p = &ioc->cic_root.rb_node;
struct rb_node *parent = NULL;
struct cfq_io_context *__cic;
read_lock(&cfq_exit_lock);
cic->ioc = ioc;
cic->key = cfqd;
ioc->set_ioprio = cfq_ioc_set_ioprio;
while (*p) {
parent = *p;
__cic = rb_entry(parent, struct cfq_io_context, rb_node);
if (cic->key < __cic->key)
p = &(*p)->rb_left;
else if (cic->key > __cic->key)
p = &(*p)->rb_right;
else
BUG();
}
rb_link_node(&cic->rb_node, parent, p);
rb_insert_color(&cic->rb_node, &ioc->cic_root);
list_add(&cic->queue_list, &cfqd->cic_list);
read_unlock(&cfq_exit_lock);
}
/*
* Setup general io context and cfq io context. There can be several cfq
* io contexts per general io context, if this process is doing io to more
* than one device managed by cfq.
*/
static struct cfq_io_context *
cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
{
struct io_context *ioc = NULL;
struct cfq_io_context *cic;
might_sleep_if(gfp_mask & __GFP_WAIT);
ioc = get_io_context(gfp_mask);
if (!ioc)
return NULL;
cic = cfq_cic_rb_lookup(cfqd, ioc);
if (cic)
goto out;
cic = cfq_alloc_io_context(cfqd, gfp_mask);
if (cic == NULL)
goto err;
cfq_cic_link(cfqd, ioc, cic);
out:
return cic;
err:
put_io_context(ioc);
return NULL;
}
static void
cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
{
unsigned long elapsed, ttime;
/*
* if this context already has stuff queued, thinktime is from
* last queue not last end
*/
#if 0
if (time_after(cic->last_end_request, cic->last_queue))
elapsed = jiffies - cic->last_end_request;
else
elapsed = jiffies - cic->last_queue;
#else
elapsed = jiffies - cic->last_end_request;
#endif
ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
}
static void
cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
struct cfq_rq *crq)
{
sector_t sdist;
u64 total;
if (cic->last_request_pos < crq->request->sector)
sdist = crq->request->sector - cic->last_request_pos;
else
sdist = cic->last_request_pos - crq->request->sector;
/*
* Don't allow the seek distance to get too large from the
* odd fragment, pagein, etc
*/
if (cic->seek_samples <= 60) /* second&third seek */
sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
else
sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
cic->seek_samples = (7*cic->seek_samples + 256) / 8;
cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
total = cic->seek_total + (cic->seek_samples/2);
do_div(total, cic->seek_samples);
cic->seek_mean = (sector_t)total;
}
/*
* Disable idle window if the process thinks too long or seeks so much that
* it doesn't matter
*/
static void
cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_io_context *cic)
{
int enable_idle = cfq_cfqq_idle_window(cfqq);
if (!cic->ioc->task || !cfqd->cfq_slice_idle)
enable_idle = 0;
else if (sample_valid(cic->ttime_samples)) {
if (cic->ttime_mean > cfqd->cfq_slice_idle)
enable_idle = 0;
else
enable_idle = 1;
}
if (enable_idle)
cfq_mark_cfqq_idle_window(cfqq);
else
cfq_clear_cfqq_idle_window(cfqq);
}
/*
* Check if new_cfqq should preempt the currently active queue. Return 0 for
* no or if we aren't sure, a 1 will cause a preempt.
*/
static int
cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
struct cfq_rq *crq)
{
struct cfq_queue *cfqq = cfqd->active_queue;
if (cfq_class_idle(new_cfqq))
return 0;
if (!cfqq)
return 1;
if (cfq_class_idle(cfqq))
return 1;
if (!cfq_cfqq_wait_request(new_cfqq))
return 0;
/*
* if it doesn't have slice left, forget it
*/
if (new_cfqq->slice_left < cfqd->cfq_slice_idle)
return 0;
if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq))
return 1;
return 0;
}
/*
* cfqq preempts the active queue. if we allowed preempt with no slice left,
* let it have half of its nominal slice.
*/
static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
struct cfq_queue *__cfqq, *next;
list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list)
cfq_resort_rr_list(__cfqq, 1);
if (!cfqq->slice_left)
cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;
cfqq->slice_end = cfqq->slice_left + jiffies;
__cfq_slice_expired(cfqd, cfqq, 1);
__cfq_set_active_queue(cfqd, cfqq);
}
/*
* should really be a ll_rw_blk.c helper
*/
static void cfq_start_queueing(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
request_queue_t *q = cfqd->queue;
if (!blk_queue_plugged(q))
q->request_fn(q);
else
__generic_unplug_device(q);
}
/*
* Called when a new fs request (crq) is added (to cfqq). Check if there's
* something we should do about it
*/
static void
cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_rq *crq)
{
struct cfq_io_context *cic;
cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
/*
* we never wait for an async request and we don't allow preemption
* of an async request. so just return early
*/
if (!cfq_crq_is_sync(crq))
return;
cic = crq->io_context;
cfq_update_io_thinktime(cfqd, cic);
cfq_update_io_seektime(cfqd, cic, crq);
cfq_update_idle_window(cfqd, cfqq, cic);
cic->last_queue = jiffies;
cic->last_request_pos = crq->request->sector + crq->request->nr_sectors;
if (cfqq == cfqd->active_queue) {
/*
* if we are waiting for a request for this queue, let it rip
* immediately and flag that we must not expire this queue
* just now
*/
if (cfq_cfqq_wait_request(cfqq)) {
cfq_mark_cfqq_must_dispatch(cfqq);
del_timer(&cfqd->idle_slice_timer);
cfq_start_queueing(cfqd, cfqq);
}
} else if (cfq_should_preempt(cfqd, cfqq, crq)) {
/*
* not the active queue - expire current slice if it is
* idle and has expired it's mean thinktime or this new queue
* has some old slice time left and is of higher priority
*/
cfq_preempt_queue(cfqd, cfqq);
cfq_mark_cfqq_must_dispatch(cfqq);
cfq_start_queueing(cfqd, cfqq);
}
}
static void cfq_insert_request(request_queue_t *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_rq *crq = RQ_DATA(rq);
struct cfq_queue *cfqq = crq->cfq_queue;
cfq_init_prio_data(cfqq);
cfq_add_crq_rb(crq);
list_add_tail(&rq->queuelist, &cfqq->fifo);
if (rq_mergeable(rq))
cfq_add_crq_hash(cfqd, crq);
cfq_crq_enqueued(cfqd, cfqq, crq);
}
static void cfq_completed_request(request_queue_t *q, struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
struct cfq_queue *cfqq = crq->cfq_queue;
struct cfq_data *cfqd = cfqq->cfqd;
const int sync = cfq_crq_is_sync(crq);
unsigned long now;
now = jiffies;
WARN_ON(!cfqd->rq_in_driver);
WARN_ON(!cfqq->on_dispatch[sync]);
cfqd->rq_in_driver--;
cfqq->on_dispatch[sync]--;
if (!cfq_class_idle(cfqq))
cfqd->last_end_request = now;
if (!cfq_cfqq_dispatched(cfqq)) {
if (cfq_cfqq_on_rr(cfqq)) {
cfqq->service_last = now;
cfq_resort_rr_list(cfqq, 0);
}
cfq_schedule_dispatch(cfqd);
}
if (cfq_crq_is_sync(crq))
crq->io_context->last_end_request = now;
}
static struct request *
cfq_former_request(request_queue_t *q, struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
struct rb_node *rbprev = rb_prev(&crq->rb_node);
if (rbprev)
return rb_entry_crq(rbprev)->request;
return NULL;
}
static struct request *
cfq_latter_request(request_queue_t *q, struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
struct rb_node *rbnext = rb_next(&crq->rb_node);
if (rbnext)
return rb_entry_crq(rbnext)->request;
return NULL;
}
/*
* we temporarily boost lower priority queues if they are holding fs exclusive
* resources. they are boosted to normal prio (CLASS_BE/4)
*/
static void cfq_prio_boost(struct cfq_queue *cfqq)
{
const int ioprio_class = cfqq->ioprio_class;
const int ioprio = cfqq->ioprio;
if (has_fs_excl()) {
/*
* boost idle prio on transactions that would lock out other
* users of the filesystem
*/
if (cfq_class_idle(cfqq))
cfqq->ioprio_class = IOPRIO_CLASS_BE;
if (cfqq->ioprio > IOPRIO_NORM)
cfqq->ioprio = IOPRIO_NORM;
} else {
/*
* check if we need to unboost the queue
*/
if (cfqq->ioprio_class != cfqq->org_ioprio_class)
cfqq->ioprio_class = cfqq->org_ioprio_class;
if (cfqq->ioprio != cfqq->org_ioprio)
cfqq->ioprio = cfqq->org_ioprio;
}
/*
* refile between round-robin lists if we moved the priority class
*/
if ((ioprio_class != cfqq->ioprio_class || ioprio != cfqq->ioprio) &&
cfq_cfqq_on_rr(cfqq))
cfq_resort_rr_list(cfqq, 0);
}
static inline int
__cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct task_struct *task, int rw)
{
#if 1
if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
!cfq_cfqq_must_alloc_slice(cfqq)) {
cfq_mark_cfqq_must_alloc_slice(cfqq);
return ELV_MQUEUE_MUST;
}
return ELV_MQUEUE_MAY;
#else
if (!cfqq || task->flags & PF_MEMALLOC)
return ELV_MQUEUE_MAY;
if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) {
if (cfq_cfqq_wait_request(cfqq))
return ELV_MQUEUE_MUST;
/*
* only allow 1 ELV_MQUEUE_MUST per slice, otherwise we
* can quickly flood the queue with writes from a single task
*/
if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) {
cfq_mark_cfqq_must_alloc_slice(cfqq);
return ELV_MQUEUE_MUST;
}
return ELV_MQUEUE_MAY;
}
if (cfq_class_idle(cfqq))
return ELV_MQUEUE_NO;
if (cfqq->allocated[rw] >= cfqd->max_queued) {
struct io_context *ioc = get_io_context(GFP_ATOMIC);
int ret = ELV_MQUEUE_NO;
if (ioc && ioc->nr_batch_requests)
ret = ELV_MQUEUE_MAY;
put_io_context(ioc);
return ret;
}
return ELV_MQUEUE_MAY;
#endif
}
static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct task_struct *tsk = current;
struct cfq_queue *cfqq;
/*
* don't force setup of a queue from here, as a call to may_queue
* does not necessarily imply that a request actually will be queued.
* so just lookup a possibly existing queue, or return 'may queue'
* if that fails
*/
cfqq = cfq_find_cfq_hash(cfqd, cfq_queue_pid(tsk, rw), tsk->ioprio);
if (cfqq) {
cfq_init_prio_data(cfqq);
cfq_prio_boost(cfqq);
return __cfq_may_queue(cfqd, cfqq, tsk, rw);
}
return ELV_MQUEUE_MAY;
}
static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct request_list *rl = &q->rq;
if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) {
smp_mb();
if (waitqueue_active(&rl->wait[READ]))
wake_up(&rl->wait[READ]);
}
if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) {
smp_mb();
if (waitqueue_active(&rl->wait[WRITE]))
wake_up(&rl->wait[WRITE]);
}
}
/*
* queue lock held here
*/
static void cfq_put_request(request_queue_t *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_rq *crq = RQ_DATA(rq);
if (crq) {
struct cfq_queue *cfqq = crq->cfq_queue;
const int rw = rq_data_dir(rq);
BUG_ON(!cfqq->allocated[rw]);
cfqq->allocated[rw]--;
put_io_context(crq->io_context->ioc);
mempool_free(crq, cfqd->crq_pool);
rq->elevator_private = NULL;
cfq_check_waiters(q, cfqq);
cfq_put_queue(cfqq);
}
}
/*
* Allocate cfq data structures associated with this request.
*/
static int
cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
gfp_t gfp_mask)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct task_struct *tsk = current;
struct cfq_io_context *cic;
const int rw = rq_data_dir(rq);
pid_t key = cfq_queue_pid(tsk, rw);
struct cfq_queue *cfqq;
struct cfq_rq *crq;
unsigned long flags;
int is_sync = key != CFQ_KEY_ASYNC;
might_sleep_if(gfp_mask & __GFP_WAIT);
cic = cfq_get_io_context(cfqd, gfp_mask);
spin_lock_irqsave(q->queue_lock, flags);
if (!cic)
goto queue_fail;
if (!cic->cfqq[is_sync]) {
cfqq = cfq_get_queue(cfqd, key, tsk, gfp_mask);
if (!cfqq)
goto queue_fail;
cic->cfqq[is_sync] = cfqq;
} else
cfqq = cic->cfqq[is_sync];
cfqq->allocated[rw]++;
cfq_clear_cfqq_must_alloc(cfqq);
cfqd->rq_starved = 0;
atomic_inc(&cfqq->ref);
spin_unlock_irqrestore(q->queue_lock, flags);
crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
if (crq) {
RB_CLEAR(&crq->rb_node);
crq->rb_key = 0;
crq->request = rq;
INIT_HLIST_NODE(&crq->hash);
crq->cfq_queue = cfqq;
crq->io_context = cic;
if (is_sync)
cfq_mark_crq_is_sync(crq);
else
cfq_clear_crq_is_sync(crq);
rq->elevator_private = crq;
return 0;
}
spin_lock_irqsave(q->queue_lock, flags);
cfqq->allocated[rw]--;
if (!(cfqq->allocated[0] + cfqq->allocated[1]))
cfq_mark_cfqq_must_alloc(cfqq);
cfq_put_queue(cfqq);
queue_fail:
if (cic)
put_io_context(cic->ioc);
/*
* mark us rq allocation starved. we need to kickstart the process
* ourselves if there are no pending requests that can do it for us.
* that would be an extremely rare OOM situation
*/
cfqd->rq_starved = 1;
cfq_schedule_dispatch(cfqd);
spin_unlock_irqrestore(q->queue_lock, flags);
return 1;
}
static void cfq_kick_queue(void *data)
{
request_queue_t *q = data;
struct cfq_data *cfqd = q->elevator->elevator_data;
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
if (cfqd->rq_starved) {
struct request_list *rl = &q->rq;
/*
* we aren't guaranteed to get a request after this, but we
* have to be opportunistic
*/
smp_mb();
if (waitqueue_active(&rl->wait[READ]))
wake_up(&rl->wait[READ]);
if (waitqueue_active(&rl->wait[WRITE]))
wake_up(&rl->wait[WRITE]);
}
blk_remove_plug(q);
q->request_fn(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
/*
* Timer running if the active_queue is currently idling inside its time slice
*/
static void cfq_idle_slice_timer(unsigned long data)
{
struct cfq_data *cfqd = (struct cfq_data *) data;
struct cfq_queue *cfqq;
unsigned long flags;
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
if ((cfqq = cfqd->active_queue) != NULL) {
unsigned long now = jiffies;
/*
* expired
*/
if (time_after(now, cfqq->slice_end))
goto expire;
/*
* only expire and reinvoke request handler, if there are
* other queues with pending requests
*/
if (!cfqd->busy_queues) {
cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end);
add_timer(&cfqd->idle_slice_timer);
goto out_cont;
}
/*
* not expired and it has a request pending, let it dispatch
*/
if (!RB_EMPTY(&cfqq->sort_list)) {
cfq_mark_cfqq_must_dispatch(cfqq);
goto out_kick;
}
}
expire:
cfq_slice_expired(cfqd, 0);
out_kick:
cfq_schedule_dispatch(cfqd);
out_cont:
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
}
/*
* Timer running if an idle class queue is waiting for service
*/
static void cfq_idle_class_timer(unsigned long data)
{
struct cfq_data *cfqd = (struct cfq_data *) data;
unsigned long flags, end;
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
/*
* race with a non-idle queue, reset timer
*/
end = cfqd->last_end_request + CFQ_IDLE_GRACE;
if (!time_after_eq(jiffies, end)) {
cfqd->idle_class_timer.expires = end;
add_timer(&cfqd->idle_class_timer);
} else
cfq_schedule_dispatch(cfqd);
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
}
static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
{
del_timer_sync(&cfqd->idle_slice_timer);
del_timer_sync(&cfqd->idle_class_timer);
blk_sync_queue(cfqd->queue);
}
static void cfq_exit_queue(elevator_t *e)
{
struct cfq_data *cfqd = e->elevator_data;
request_queue_t *q = cfqd->queue;
cfq_shutdown_timer_wq(cfqd);
write_lock(&cfq_exit_lock);
spin_lock_irq(q->queue_lock);
if (cfqd->active_queue)
__cfq_slice_expired(cfqd, cfqd->active_queue, 0);
while (!list_empty(&cfqd->cic_list)) {
struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
struct cfq_io_context,
queue_list);
if (cic->cfqq[ASYNC]) {
cfq_put_queue(cic->cfqq[ASYNC]);
cic->cfqq[ASYNC] = NULL;
}
if (cic->cfqq[SYNC]) {
cfq_put_queue(cic->cfqq[SYNC]);
cic->cfqq[SYNC] = NULL;
}
cic->key = NULL;
list_del_init(&cic->queue_list);
}
spin_unlock_irq(q->queue_lock);
write_unlock(&cfq_exit_lock);
cfq_shutdown_timer_wq(cfqd);
mempool_destroy(cfqd->crq_pool);
kfree(cfqd->crq_hash);
kfree(cfqd->cfq_hash);
kfree(cfqd);
}
static int cfq_init_queue(request_queue_t *q, elevator_t *e)
{
struct cfq_data *cfqd;
int i;
cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
if (!cfqd)
return -ENOMEM;
memset(cfqd, 0, sizeof(*cfqd));
for (i = 0; i < CFQ_PRIO_LISTS; i++)
INIT_LIST_HEAD(&cfqd->rr_list[i]);
INIT_LIST_HEAD(&cfqd->busy_rr);
INIT_LIST_HEAD(&cfqd->cur_rr);
INIT_LIST_HEAD(&cfqd->idle_rr);
INIT_LIST_HEAD(&cfqd->empty_list);
INIT_LIST_HEAD(&cfqd->cic_list);
cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
if (!cfqd->crq_hash)
goto out_crqhash;
cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL);
if (!cfqd->cfq_hash)
goto out_cfqhash;
cfqd->crq_pool = mempool_create_slab_pool(BLKDEV_MIN_RQ, crq_pool);
if (!cfqd->crq_pool)
goto out_crqpool;
for (i = 0; i < CFQ_MHASH_ENTRIES; i++)
INIT_HLIST_HEAD(&cfqd->crq_hash[i]);
for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
INIT_HLIST_HEAD(&cfqd->cfq_hash[i]);
e->elevator_data = cfqd;
cfqd->queue = q;
cfqd->max_queued = q->nr_requests / 4;
q->nr_batching = cfq_queued;
init_timer(&cfqd->idle_slice_timer);
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
cfqd->idle_slice_timer.data = (unsigned long) cfqd;
init_timer(&cfqd->idle_class_timer);
cfqd->idle_class_timer.function = cfq_idle_class_timer;
cfqd->idle_class_timer.data = (unsigned long) cfqd;
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q);
cfqd->cfq_queued = cfq_queued;
cfqd->cfq_quantum = cfq_quantum;
cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
cfqd->cfq_back_max = cfq_back_max;
cfqd->cfq_back_penalty = cfq_back_penalty;
cfqd->cfq_slice[0] = cfq_slice_async;
cfqd->cfq_slice[1] = cfq_slice_sync;
cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
cfqd->cfq_slice_idle = cfq_slice_idle;
return 0;
out_crqpool:
kfree(cfqd->cfq_hash);
out_cfqhash:
kfree(cfqd->crq_hash);
out_crqhash:
kfree(cfqd);
return -ENOMEM;
}
static void cfq_slab_kill(void)
{
if (crq_pool)
kmem_cache_destroy(crq_pool);
if (cfq_pool)
kmem_cache_destroy(cfq_pool);
if (cfq_ioc_pool)
kmem_cache_destroy(cfq_ioc_pool);
}
static int __init cfq_slab_setup(void)
{
crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0,
NULL, NULL);
if (!crq_pool)
goto fail;
cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0,
NULL, NULL);
if (!cfq_pool)
goto fail;
cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool",
sizeof(struct cfq_io_context), 0, 0, NULL, NULL);
if (!cfq_ioc_pool)
goto fail;
return 0;
fail:
cfq_slab_kill();
return -ENOMEM;
}
/*
* sysfs parts below -->
*/
static ssize_t
cfq_var_show(unsigned int var, char *page)
{
return sprintf(page, "%d\n", var);
}
static ssize_t
cfq_var_store(unsigned int *var, const char *page, size_t count)
{
char *p = (char *) page;
*var = simple_strtoul(p, &p, 10);
return count;
}
#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
static ssize_t __FUNC(elevator_t *e, char *page) \
{ \
struct cfq_data *cfqd = e->elevator_data; \
unsigned int __data = __VAR; \
if (__CONV) \
__data = jiffies_to_msecs(__data); \
return cfq_var_show(__data, (page)); \
}
SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0);
SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
#undef SHOW_FUNCTION
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \
{ \
struct cfq_data *cfqd = e->elevator_data; \
unsigned int __data; \
int ret = cfq_var_store(&__data, (page), count); \
if (__data < (MIN)) \
__data = (MIN); \
else if (__data > (MAX)) \
__data = (MAX); \
if (__CONV) \
*(__PTR) = msecs_to_jiffies(__data); \
else \
*(__PTR) = __data; \
return ret; \
}
STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0);
STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0);
STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0);
#undef STORE_FUNCTION
#define CFQ_ATTR(name) \
__ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
static struct elv_fs_entry cfq_attrs[] = {
CFQ_ATTR(quantum),
CFQ_ATTR(queued),
CFQ_ATTR(fifo_expire_sync),
CFQ_ATTR(fifo_expire_async),
CFQ_ATTR(back_seek_max),
CFQ_ATTR(back_seek_penalty),
CFQ_ATTR(slice_sync),
CFQ_ATTR(slice_async),
CFQ_ATTR(slice_async_rq),
CFQ_ATTR(slice_idle),
__ATTR_NULL
};
static struct elevator_type iosched_cfq = {
.ops = {
.elevator_merge_fn = cfq_merge,
.elevator_merged_fn = cfq_merged_request,
.elevator_merge_req_fn = cfq_merged_requests,
.elevator_dispatch_fn = cfq_dispatch_requests,
.elevator_add_req_fn = cfq_insert_request,
.elevator_activate_req_fn = cfq_activate_request,
.elevator_deactivate_req_fn = cfq_deactivate_request,
.elevator_queue_empty_fn = cfq_queue_empty,
.elevator_completed_req_fn = cfq_completed_request,
.elevator_former_req_fn = cfq_former_request,
.elevator_latter_req_fn = cfq_latter_request,
.elevator_set_req_fn = cfq_set_request,
.elevator_put_req_fn = cfq_put_request,
.elevator_may_queue_fn = cfq_may_queue,
.elevator_init_fn = cfq_init_queue,
.elevator_exit_fn = cfq_exit_queue,
.trim = cfq_trim,
},
.elevator_attrs = cfq_attrs,
.elevator_name = "cfq",
.elevator_owner = THIS_MODULE,
};
static int __init cfq_init(void)
{
int ret;
/*
* could be 0 on HZ < 1000 setups
*/
if (!cfq_slice_async)
cfq_slice_async = 1;
if (!cfq_slice_idle)
cfq_slice_idle = 1;
if (cfq_slab_setup())
return -ENOMEM;
ret = elv_register(&iosched_cfq);
if (ret)
cfq_slab_kill();
return ret;
}
static void __exit cfq_exit(void)
{
DECLARE_COMPLETION(all_gone);
elv_unregister(&iosched_cfq);
ioc_gone = &all_gone;
barrier();
if (atomic_read(&ioc_count))
complete(ioc_gone);
synchronize_rcu();
cfq_slab_kill();
}
module_init(cfq_init);
module_exit(cfq_exit);
MODULE_AUTHOR("Jens Axboe");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
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