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OpenCloudOS-Kernel/drivers/block/cfq-iosched.c

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/*
* linux/drivers/block/cfq-iosched.c
*
* 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/kernel.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/bio.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/hash.h>
#include <linux/rbtree.h>
#include <linux/mempool.h>
#include <linux/ioprio.h>
#include <linux/writeback.h>
/*
* tunables
*/
static int cfq_quantum = 4; /* max queue in one round of service */
static int cfq_queued = 8; /* minimum rq allocate limit per-queue*/
static int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
static int cfq_back_penalty = 2; /* penalty of a backwards seek */
static int cfq_slice_sync = HZ / 10;
static int cfq_slice_async = HZ / 25;
static int cfq_slice_async_rq = 2;
static int cfq_slice_idle = HZ / 100;
#define CFQ_IDLE_GRACE (HZ / 10)
#define CFQ_SLICE_SCALE (5)
#define CFQ_KEY_ASYNC (0)
#define CFQ_KEY_ANY (0xffff)
/*
* disable queueing at the driver/hardware level
*/
static int cfq_max_depth = 1;
/*
* 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 ON_RB(node) ((node)->rb_color != RB_NONE)
#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;
#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])
/*
* Per block device queue structure
*/
struct cfq_data {
atomic_t ref;
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;
unsigned int cfq_max_depth;
};
/*
* 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,
CFQ_CFQQ_FLAG_expired,
};
#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);
CFQ_CFQQ_FNS(expired);
#undef CFQ_CFQQ_FNS
enum cfq_rq_state_flags {
CFQ_CRQ_FLAG_in_flight = 0,
CFQ_CRQ_FLAG_in_driver,
CFQ_CRQ_FLAG_is_sync,
CFQ_CRQ_FLAG_requeued,
};
#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(in_flight);
CFQ_CRQ_FNS(in_driver);
CFQ_CRQ_FNS(is_sync);
CFQ_CRQ_FNS(requeued);
#undef CFQ_CRQ_FNS
static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
static void cfq_dispatch_sort(request_queue_t *, struct cfq_rq *);
static void cfq_put_cfqd(struct cfq_data *cfqd);
static inline int cfq_pending_requests(struct cfq_data *cfqd);
#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 void cfq_remove_merge_hints(request_queue_t *q, struct cfq_rq *crq)
{
cfq_del_crq_hash(crq);
if (q->last_merge == crq->request)
q->last_merge = NULL;
}
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;
}
/*
* 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 are 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;
int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */
unsigned long back_max;
if (crq1 == NULL || crq1 == crq2)
return crq2;
if (crq2 == NULL)
return crq1;
if (cfq_crq_requeued(crq1))
return crq1;
if (cfq_crq_requeued(crq2))
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
r1_wrap = 1;
if (s2 >= last)
d2 = s2 - last;
else if (s2 + back_max >= last)
d2 = (last - s2) * cfqd->cfq_back_penalty;
else
r2_wrap = 1;
/* Found required data */
if (!r1_wrap && r2_wrap)
return crq1;
else if (!r2_wrap && r1_wrap)
return crq2;
else if (r1_wrap && r2_wrap) {
/* both behind the head */
if (s1 <= s2)
return crq1;
else
return crq2;
}
/* Both requests in front of the head */
if (d1 < d2)
return crq1;
else if (d2 < d1)
return crq2;
else {
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;
rbnext = NULL;
if (ON_RB(&last->rb_node))
rbnext = rb_next(&last->rb_node);
if (!rbnext) {
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, int requeue)
{
BUG_ON(cfq_cfqq_on_rr(cfqq));
cfq_mark_cfqq_on_rr(cfqq);
cfqd->busy_queues++;
cfq_resort_rr_list(cfqq, requeue);
}
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;
if (ON_RB(&crq->rb_node)) {
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_sort(cfqd->queue, __alias);
rb_insert_color(&crq->rb_node, &cfqq->sort_list);
if (!cfq_cfqq_on_rr(cfqq))
cfq_add_cfqq_rr(cfqd, cfqq, cfq_crq_requeued(crq));
/*
* 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)
{
if (ON_RB(&crq->rb_node)) {
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_rb(struct cfq_data *cfqd, sector_t sector)
{
struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid, CFQ_KEY_ANY);
struct rb_node *n;
if (!cfqq)
goto out;
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_deactivate_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;
if (cfq_crq_in_driver(crq)) {
cfq_clear_crq_in_driver(crq);
WARN_ON(!cfqd->rq_in_driver);
cfqd->rq_in_driver--;
}
if (cfq_crq_in_flight(crq)) {
const int sync = cfq_crq_is_sync(crq);
cfq_clear_crq_in_flight(crq);
WARN_ON(!cfqq->on_dispatch[sync]);
cfqq->on_dispatch[sync]--;
}
cfq_mark_crq_requeued(crq);
}
}
/*
* make sure the service time gets corrected on reissue of this request
*/
static void cfq_requeue_request(request_queue_t *q, struct request *rq)
{
cfq_deactivate_request(q, rq);
list_add(&rq->queuelist, &q->queue_head);
}
static void cfq_remove_request(request_queue_t *q, struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
if (crq) {
list_del_init(&rq->queuelist);
cfq_del_crq_rb(crq);
cfq_remove_merge_hints(q, 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;
ret = elv_try_last_merge(q, bio);
if (ret != ELEVATOR_NO_MERGE) {
__rq = q->last_merge;
goto out_insert;
}
__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_rb(cfqd, bio->bi_sector + bio_sectors(bio));
if (__rq && elv_rq_merge_ok(__rq, bio)) {
ret = ELEVATOR_FRONT_MERGE;
goto out;
}
return ELEVATOR_NO_MERGE;
out:
q->last_merge = __rq;
out_insert:
*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 (ON_RB(&crq->rb_node) && (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);
}
q->last_merge = req;
}
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(q, 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);
cfq_clear_cfqq_expired(cfqq);
}
cfqd->active_queue = cfqq;
}
/*
* 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;
/*
* if current queue is expired but not done with its requests yet,
* wait for that to happen
*/
if ((cfqq = cfqd->active_queue) != NULL) {
if (cfq_cfqq_expired(cfqq) && cfq_cfqq_dispatched(cfqq))
return 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;
}
/*
* 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_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(now, cfqq->slice_end))
cfqq->slice_left = now - cfqq->slice_end;
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) {
/*
* use deferred expiry, if there are requests in progress as
* not to disturb the slice of the next queue
*/
if (cfq_cfqq_dispatched(cfqq))
cfq_mark_cfqq_expired(cfqq);
else
__cfq_slice_expired(cfqd, cfqq, preempted);
}
}
static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
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
*/
if (cfqd->active_cic && !cfqd->active_cic->ioc->task)
return 0;
cfq_mark_cfqq_must_dispatch(cfqq);
cfq_mark_cfqq_wait_request(cfqq);
if (!timer_pending(&cfqd->idle_slice_timer)) {
unsigned long slice_left = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle);
cfqd->idle_slice_timer.expires = jiffies + slice_left;
add_timer(&cfqd->idle_slice_timer);
}
return 1;
}
/*
* we dispatch cfqd->cfq_quantum requests in total from the rr_list queues,
* this function sector sorts the selected request to minimize seeks. we start
* at cfqd->last_sector, not 0.
*/
static void cfq_dispatch_sort(request_queue_t *q, struct cfq_rq *crq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq = crq->cfq_queue;
struct list_head *head = &q->queue_head, *entry = head;
struct request *__rq;
sector_t last;
list_del(&crq->request->queuelist);
last = cfqd->last_sector;
list_for_each_entry_reverse(__rq, head, queuelist) {
struct cfq_rq *__crq = RQ_DATA(__rq);
if (blk_barrier_rq(__rq))
break;
if (!blk_fs_request(__rq))
break;
if (cfq_crq_requeued(__crq))
break;
if (__rq->sector <= crq->request->sector)
break;
if (__rq->sector > last && crq->request->sector < last) {
last = crq->request->sector + crq->request->nr_sectors;
break;
}
entry = &__rq->queuelist;
}
cfqd->last_sector = last;
cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq);
cfq_del_crq_rb(crq);
cfq_remove_merge_hints(q, crq);
cfq_mark_crq_in_flight(crq);
cfq_clear_crq_requeued(crq);
cfqq->on_dispatch[cfq_crq_is_sync(crq)]++;
list_add_tail(&crq->request->queuelist, entry);
}
/*
* 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));
}
/*
* 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->rq_in_driver && cfq_pending_requests(cfqd))
kblockd_schedule_work(&cfqd->unplug_work);
}
/*
* get next queue for service
*/
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd, int force)
{
unsigned long now = jiffies;
struct cfq_queue *cfqq;
cfqq = cfqd->active_queue;
if (!cfqq)
goto new_queue;
if (cfq_cfqq_expired(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 (!force && 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_sort(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_dispatch_requests(request_queue_t *q, int max_dispatch, int force)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq;
if (!cfqd->busy_queues)
return 0;
cfqq = cfq_select_queue(cfqd, force);
if (cfqq) {
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_wait_request(cfqq);
del_timer(&cfqd->idle_slice_timer);
if (cfq_class_idle(cfqq))
max_dispatch = 1;
return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
}
return 0;
}
static inline void cfq_account_dispatch(struct cfq_rq *crq)
{
struct cfq_queue *cfqq = crq->cfq_queue;
struct cfq_data *cfqd = cfqq->cfqd;
if (unlikely(!blk_fs_request(crq->request)))
return;
/*
* accounted bit is necessary since some drivers will call
* elv_next_request() many times for the same request (eg ide)
*/
if (cfq_crq_in_driver(crq))
return;
cfq_mark_crq_in_driver(crq);
cfqd->rq_in_driver++;
}
static inline void
cfq_account_completion(struct cfq_queue *cfqq, struct cfq_rq *crq)
{
struct cfq_data *cfqd = cfqq->cfqd;
unsigned long now;
if (!cfq_crq_in_driver(crq))
return;
now = jiffies;
WARN_ON(!cfqd->rq_in_driver);
cfqd->rq_in_driver--;
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);
}
if (cfq_cfqq_expired(cfqq)) {
__cfq_slice_expired(cfqd, cfqq, 0);
cfq_schedule_dispatch(cfqd);
}
}
if (cfq_crq_is_sync(crq))
crq->io_context->last_end_request = now;
}
static struct request *cfq_next_request(request_queue_t *q)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct request *rq;
if (!list_empty(&q->queue_head)) {
struct cfq_rq *crq;
dispatch:
rq = list_entry_rq(q->queue_head.next);
crq = RQ_DATA(rq);
if (crq) {
struct cfq_queue *cfqq = crq->cfq_queue;
/*
* if idle window is disabled, allow queue buildup
*/
if (!cfq_crq_in_driver(crq) &&
!cfq_cfqq_idle_window(cfqq) &&
cfqd->rq_in_driver >= cfqd->cfq_max_depth)
return NULL;
cfq_remove_merge_hints(q, crq);
cfq_account_dispatch(crq);
}
return rq;
}
if (cfq_dispatch_requests(q, cfqd->cfq_quantum, 0))
goto dispatch;
return NULL;
}
/*
* 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);
cfq_schedule_dispatch(cfqd);
}
cfq_put_cfqd(cfqq->cfqd);
/*
* 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, *next;
hlist_for_each_safe(entry, next, hash_list) {
struct cfq_queue *__cfqq = list_entry_qhash(entry);
const unsigned short __p = IOPRIO_PRIO_VALUE(__cfqq->ioprio_class, __cfqq->ioprio);
if (__cfqq->key == key && (__p == prio || prio == CFQ_KEY_ANY))
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 cfq_io_context *cic)
{
struct cfq_io_context *__cic;
struct list_head *entry, *next;
list_for_each_safe(entry, next, &cic->list) {
__cic = list_entry(entry, struct cfq_io_context, list);
kmem_cache_free(cfq_ioc_pool, __cic);
}
kmem_cache_free(cfq_ioc_pool, cic);
}
/*
* Called with interrupts disabled
*/
static void cfq_exit_single_io_context(struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->cfqq->cfqd;
request_queue_t *q = cfqd->queue;
WARN_ON(!irqs_disabled());
spin_lock(q->queue_lock);
if (unlikely(cic->cfqq == cfqd->active_queue)) {
__cfq_slice_expired(cfqd, cic->cfqq, 0);
cfq_schedule_dispatch(cfqd);
}
cfq_put_queue(cic->cfqq);
cic->cfqq = NULL;
spin_unlock(q->queue_lock);
}
/*
* Another task may update the task cic list, if it is doing a queue lookup
* on its behalf. cfq_cic_lock excludes such concurrent updates
*/
static void cfq_exit_io_context(struct cfq_io_context *cic)
{
struct cfq_io_context *__cic;
struct list_head *entry;
unsigned long flags;
local_irq_save(flags);
/*
* put the reference this task is holding to the various queues
*/
list_for_each(entry, &cic->list) {
__cic = list_entry(entry, struct cfq_io_context, list);
cfq_exit_single_io_context(__cic);
}
cfq_exit_single_io_context(cic);
local_irq_restore(flags);
}
static struct cfq_io_context *
cfq_alloc_io_context(struct cfq_data *cfqd, int gfp_mask)
{
struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_mask);
if (cic) {
INIT_LIST_HEAD(&cic->list);
cic->cfqq = NULL;
cic->key = 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;
}
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_queue *cfqq)
{
if (cfqq) {
struct cfq_data *cfqd = cfqq->cfqd;
spin_lock(cfqd->queue->queue_lock);
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 = ioc->cic;
changed_ioprio(cic->cfqq);
list_for_each_entry(cic, &cic->list, list)
changed_ioprio(cic->cfqq);
return 0;
}
static struct cfq_queue *
cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio,
int gfp_mask)
{
const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
struct cfq_queue *cfqq, *new_cfqq = NULL;
retry:
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;
atomic_inc(&cfqd->ref);
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;
}
/*
* 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. Note that caller is holding a reference to
* cfqq, so we don't need to worry about it disappearing
*/
static struct cfq_io_context *
cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, int 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;
if ((cic = ioc->cic) == NULL) {
cic = cfq_alloc_io_context(cfqd, gfp_mask);
if (cic == NULL)
goto err;
/*
* manually increment generic io_context usage count, it
* cannot go away since we are already holding one ref to it
*/
ioc->cic = cic;
ioc->set_ioprio = cfq_ioc_set_ioprio;
cic->ioc = ioc;
cic->key = cfqd;
atomic_inc(&cfqd->ref);
} else {
struct cfq_io_context *__cic;
/*
* the first cic on the list is actually the head itself
*/
if (cic->key == cfqd)
goto out;
/*
* cic exists, check if we already are there. linear search
* should be ok here, the list will usually not be more than
* 1 or a few entries long
*/
list_for_each_entry(__cic, &cic->list, list) {
/*
* this process is already holding a reference to
* this queue, so no need to get one more
*/
if (__cic->key == cfqd) {
cic = __cic;
goto out;
}
}
/*
* nope, process doesn't have a cic assoicated with this
* cfqq yet. get a new one and add to list
*/
__cic = cfq_alloc_io_context(cfqd, gfp_mask);
if (__cic == NULL)
goto err;
__cic->ioc = ioc;
__cic->key = cfqd;
atomic_inc(&cfqd->ref);
list_add(&__cic->list, &cic->list);
cic = __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;
}
#define sample_valid(samples) ((samples) > 80)
/*
* 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)
{
const int sync = cfq_crq_is_sync(crq);
cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq);
if (sync) {
struct cfq_io_context *cic = crq->io_context;
cfq_update_io_thinktime(cfqd, cic);
cfq_update_idle_window(cfqd, cfqq, cic);
cic->last_queue = jiffies;
}
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_enqueue(struct cfq_data *cfqd, struct request *rq)
{
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);
if (!cfqd->queue->last_merge)
cfqd->queue->last_merge = rq;
}
cfq_crq_enqueued(cfqd, cfqq, crq);
}
static void
cfq_insert_request(request_queue_t *q, struct request *rq, int where)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
switch (where) {
case ELEVATOR_INSERT_BACK:
while (cfq_dispatch_requests(q, INT_MAX, 1))
;
list_add_tail(&rq->queuelist, &q->queue_head);
/*
* If we were idling with pending requests on
* inactive cfqqs, force dispatching will
* remove the idle timer and the queue won't
* be kicked by __make_request() afterward.
* Kick it here.
*/
cfq_schedule_dispatch(cfqd);
break;
case ELEVATOR_INSERT_FRONT:
list_add(&rq->queuelist, &q->queue_head);
break;
case ELEVATOR_INSERT_SORT:
BUG_ON(!blk_fs_request(rq));
cfq_enqueue(cfqd, rq);
break;
default:
printk("%s: bad insert point %d\n", __FUNCTION__,where);
return;
}
}
static inline int cfq_pending_requests(struct cfq_data *cfqd)
{
return !list_empty(&cfqd->queue->queue_head) || cfqd->busy_queues;
}
static int cfq_queue_empty(request_queue_t *q)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
return !cfq_pending_requests(cfqd);
}
static void cfq_completed_request(request_queue_t *q, struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
struct cfq_queue *cfqq;
if (unlikely(!blk_fs_request(rq)))
return;
cfqq = crq->cfq_queue;
if (cfq_crq_in_flight(crq)) {
const int sync = cfq_crq_is_sync(crq);
WARN_ON(!cfqq->on_dispatch[sync]);
cfqq->on_dispatch[sync]--;
}
cfq_account_completion(cfqq, crq);
}
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 pid_t cfq_queue_pid(struct task_struct *task, int rw)
{
if (rw == READ || process_sync(task))
return task->pid;
return CFQ_KEY_ASYNC;
}
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) {
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) {
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,
int 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;
might_sleep_if(gfp_mask & __GFP_WAIT);
cic = cfq_get_io_context(cfqd, key, gfp_mask);
spin_lock_irqsave(q->queue_lock, flags);
if (!cic)
goto queue_fail;
if (!cic->cfqq) {
cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask);
if (!cfqq)
goto queue_fail;
cic->cfqq = cfqq;
} else
cfqq = cic->cfqq;
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;
cfq_clear_crq_in_flight(crq);
cfq_clear_crq_in_driver(crq);
cfq_clear_crq_requeued(crq);
if (rw == READ || process_sync(tsk))
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 (!cfq_pending_requests(cfqd)) {
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_put_cfqd(struct cfq_data *cfqd)
{
request_queue_t *q = cfqd->queue;
if (!atomic_dec_and_test(&cfqd->ref))
return;
blk_put_queue(q);
cfq_shutdown_timer_wq(cfqd);
q->elevator->elevator_data = NULL;
mempool_destroy(cfqd->crq_pool);
kfree(cfqd->crq_hash);
kfree(cfqd->cfq_hash);
kfree(cfqd);
}
static void cfq_exit_queue(elevator_t *e)
{
struct cfq_data *cfqd = e->elevator_data;
cfq_shutdown_timer_wq(cfqd);
cfq_put_cfqd(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);
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(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, 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;
atomic_inc(&q->refcnt);
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);
atomic_set(&cfqd->ref, 1);
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;
cfqd->cfq_max_depth = cfq_max_depth;
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 -->
*/
struct cfq_fs_entry {
struct attribute attr;
ssize_t (*show)(struct cfq_data *, char *);
ssize_t (*store)(struct cfq_data *, const char *, size_t);
};
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(struct cfq_data *cfqd, char *page) \
{ \
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_max_show, cfqd->cfq_back_max, 0);
SHOW_FUNCTION(cfq_back_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);
SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0);
#undef SHOW_FUNCTION
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \
{ \
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_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
STORE_FUNCTION(cfq_back_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);
STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 1, UINT_MAX, 0);
#undef STORE_FUNCTION
static struct cfq_fs_entry cfq_quantum_entry = {
.attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR },
.show = cfq_quantum_show,
.store = cfq_quantum_store,
};
static struct cfq_fs_entry cfq_queued_entry = {
.attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR },
.show = cfq_queued_show,
.store = cfq_queued_store,
};
static struct cfq_fs_entry cfq_fifo_expire_sync_entry = {
.attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR },
.show = cfq_fifo_expire_sync_show,
.store = cfq_fifo_expire_sync_store,
};
static struct cfq_fs_entry cfq_fifo_expire_async_entry = {
.attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR },
.show = cfq_fifo_expire_async_show,
.store = cfq_fifo_expire_async_store,
};
static struct cfq_fs_entry cfq_back_max_entry = {
.attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR },
.show = cfq_back_max_show,
.store = cfq_back_max_store,
};
static struct cfq_fs_entry cfq_back_penalty_entry = {
.attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR },
.show = cfq_back_penalty_show,
.store = cfq_back_penalty_store,
};
static struct cfq_fs_entry cfq_slice_sync_entry = {
.attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR },
.show = cfq_slice_sync_show,
.store = cfq_slice_sync_store,
};
static struct cfq_fs_entry cfq_slice_async_entry = {
.attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR },
.show = cfq_slice_async_show,
.store = cfq_slice_async_store,
};
static struct cfq_fs_entry cfq_slice_async_rq_entry = {
.attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR },
.show = cfq_slice_async_rq_show,
.store = cfq_slice_async_rq_store,
};
static struct cfq_fs_entry cfq_slice_idle_entry = {
.attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR },
.show = cfq_slice_idle_show,
.store = cfq_slice_idle_store,
};
static struct cfq_fs_entry cfq_max_depth_entry = {
.attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR },
.show = cfq_max_depth_show,
.store = cfq_max_depth_store,
};
static struct attribute *default_attrs[] = {
&cfq_quantum_entry.attr,
&cfq_queued_entry.attr,
&cfq_fifo_expire_sync_entry.attr,
&cfq_fifo_expire_async_entry.attr,
&cfq_back_max_entry.attr,
&cfq_back_penalty_entry.attr,
&cfq_slice_sync_entry.attr,
&cfq_slice_async_entry.attr,
&cfq_slice_async_rq_entry.attr,
&cfq_slice_idle_entry.attr,
&cfq_max_depth_entry.attr,
NULL,
};
#define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr)
static ssize_t
cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
elevator_t *e = container_of(kobj, elevator_t, kobj);
struct cfq_fs_entry *entry = to_cfq(attr);
if (!entry->show)
return -EIO;
return entry->show(e->elevator_data, page);
}
static ssize_t
cfq_attr_store(struct kobject *kobj, struct attribute *attr,
const char *page, size_t length)
{
elevator_t *e = container_of(kobj, elevator_t, kobj);
struct cfq_fs_entry *entry = to_cfq(attr);
if (!entry->store)
return -EIO;
return entry->store(e->elevator_data, page, length);
}
static struct sysfs_ops cfq_sysfs_ops = {
.show = cfq_attr_show,
.store = cfq_attr_store,
};
static struct kobj_type cfq_ktype = {
.sysfs_ops = &cfq_sysfs_ops,
.default_attrs = default_attrs,
};
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_next_req_fn = cfq_next_request,
.elevator_add_req_fn = cfq_insert_request,
.elevator_remove_req_fn = cfq_remove_request,
.elevator_requeue_req_fn = cfq_requeue_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,
},
.elevator_ktype = &cfq_ktype,
.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)
{
struct task_struct *g, *p;
unsigned long flags;
read_lock_irqsave(&tasklist_lock, flags);
/*
* iterate each process in the system, removing our io_context
*/
do_each_thread(g, p) {
struct io_context *ioc = p->io_context;
if (ioc && ioc->cic) {
ioc->cic->exit(ioc->cic);
cfq_free_io_context(ioc->cic);
ioc->cic = NULL;
}
} while_each_thread(g, p);
read_unlock_irqrestore(&tasklist_lock, flags);
cfq_slab_kill();
elv_unregister(&iosched_cfq);
}
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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