linux/drivers/block/cfq-iosched.c

1857 lines
43 KiB
C

/*
* 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>
static unsigned long max_elapsed_crq;
static unsigned long max_elapsed_dispatch;
/*
* 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_service = HZ; /* period over which service is avg */
static int cfq_fifo_expire_r = HZ / 2; /* fifo timeout for sync requests */
static int cfq_fifo_expire_w = 5 * HZ; /* fifo timeout for async requests */
static int cfq_fifo_rate = HZ / 8; /* fifo expiry rate */
static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
static int cfq_back_penalty = 2; /* penalty of a backwards seek */
/*
* 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 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
/*
* threshold for switching off non-tag accounting
*/
#define CFQ_MAX_TAG (4)
/*
* sort key types and names
*/
enum {
CFQ_KEY_PGID,
CFQ_KEY_TGID,
CFQ_KEY_UID,
CFQ_KEY_GID,
CFQ_KEY_LAST,
};
static char *cfq_key_types[] = { "pgid", "tgid", "uid", "gid", NULL };
static kmem_cache_t *crq_pool;
static kmem_cache_t *cfq_pool;
static kmem_cache_t *cfq_ioc_pool;
struct cfq_data {
struct list_head rr_list;
struct list_head empty_list;
struct hlist_head *cfq_hash;
struct hlist_head *crq_hash;
/* queues on rr_list (ie they have pending requests */
unsigned int busy_queues;
unsigned int max_queued;
atomic_t ref;
int key_type;
mempool_t *crq_pool;
request_queue_t *queue;
sector_t last_sector;
int rq_in_driver;
/*
* tunables, see top of file
*/
unsigned int cfq_quantum;
unsigned int cfq_queued;
unsigned int cfq_fifo_expire_r;
unsigned int cfq_fifo_expire_w;
unsigned int cfq_fifo_batch_expire;
unsigned int cfq_back_penalty;
unsigned int cfq_back_max;
unsigned int find_best_crq;
unsigned int cfq_tagged;
};
struct cfq_queue {
/* reference count */
atomic_t ref;
/* parent cfq_data */
struct cfq_data *cfqd;
/* hash of mergeable requests */
struct hlist_node cfq_hash;
/* hash key */
unsigned long key;
/* whether queue is on rr (or empty) list */
int on_rr;
/* 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[2];
/* last time fifo expired */
unsigned long last_fifo_expire;
int key_type;
unsigned long service_start;
unsigned long service_used;
unsigned int max_rate;
/* number of requests that have been handed to the driver */
int in_flight;
/* number of currently allocated requests */
int alloc_limit[2];
};
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 long service_start;
unsigned long queue_start;
unsigned int in_flight : 1;
unsigned int accounted : 1;
unsigned int is_sync : 1;
unsigned int is_write : 1;
};
static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned long);
static void cfq_dispatch_sort(request_queue_t *, struct cfq_rq *);
static void cfq_update_next_crq(struct cfq_rq *);
static void cfq_put_cfqd(struct cfq_data *cfqd);
/*
* what the fairness is based on (ie how processes are grouped and
* differentiated)
*/
static inline unsigned long
cfq_hash_key(struct cfq_data *cfqd, struct task_struct *tsk)
{
/*
* optimize this so that ->key_type is the offset into the struct
*/
switch (cfqd->key_type) {
case CFQ_KEY_PGID:
return process_group(tsk);
default:
case CFQ_KEY_TGID:
return tsk->tgid;
case CFQ_KEY_UID:
return tsk->uid;
case CFQ_KEY_GID:
return tsk->gid;
}
}
/*
* 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;
cfq_update_next_crq(crq);
}
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));
BUG_ON(!hlist_unhashed(&crq->hash));
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;
BUG_ON(hlist_unhashed(&crq->hash));
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;
s1 = crq1->request->sector;
s2 = crq2->request->sector;
last = cfqd->last_sector;
#if 0
if (!list_empty(&cfqd->queue->queue_head)) {
struct list_head *entry = &cfqd->queue->queue_head;
unsigned long distance = ~0UL;
struct request *rq;
while ((entry = entry->prev) != &cfqd->queue->queue_head) {
rq = list_entry_rq(entry);
if (blk_barrier_rq(rq))
break;
if (distance < abs(s1 - rq->sector + rq->nr_sectors)) {
distance = abs(s1 - rq->sector +rq->nr_sectors);
last = rq->sector + rq->nr_sectors;
}
if (distance < abs(s2 - rq->sector + rq->nr_sectors)) {
distance = abs(s2 - rq->sector +rq->nr_sectors);
last = rq->sector + rq->nr_sectors;
}
}
}
#endif
/*
* 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;
if (!ON_RB(&last->rb_node))
return NULL;
if ((rbnext = rb_next(&last->rb_node)) == NULL)
rbnext = rb_first(&cfqq->sort_list);
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 int cfq_check_sort_rr_list(struct cfq_queue *cfqq)
{
struct list_head *head = &cfqq->cfqd->rr_list;
struct list_head *next, *prev;
/*
* list might still be ordered
*/
next = cfqq->cfq_list.next;
if (next != head) {
struct cfq_queue *cnext = list_entry_cfqq(next);
if (cfqq->service_used > cnext->service_used)
return 1;
}
prev = cfqq->cfq_list.prev;
if (prev != head) {
struct cfq_queue *cprev = list_entry_cfqq(prev);
if (cfqq->service_used < cprev->service_used)
return 1;
}
return 0;
}
static void cfq_sort_rr_list(struct cfq_queue *cfqq, int new_queue)
{
struct list_head *entry = &cfqq->cfqd->rr_list;
if (!cfqq->on_rr)
return;
if (!new_queue && !cfq_check_sort_rr_list(cfqq))
return;
list_del(&cfqq->cfq_list);
/*
* sort by our mean service_used, sub-sort by in-flight requests
*/
while ((entry = entry->prev) != &cfqq->cfqd->rr_list) {
struct cfq_queue *__cfqq = list_entry_cfqq(entry);
if (cfqq->service_used > __cfqq->service_used)
break;
else if (cfqq->service_used == __cfqq->service_used) {
struct list_head *prv;
while ((prv = entry->prev) != &cfqq->cfqd->rr_list) {
__cfqq = list_entry_cfqq(prv);
WARN_ON(__cfqq->service_used > cfqq->service_used);
if (cfqq->service_used != __cfqq->service_used)
break;
if (cfqq->in_flight > __cfqq->in_flight)
break;
entry = prv;
}
}
}
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 requests serviced
*/
static inline void
cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
/*
* it's currently on the empty list
*/
cfqq->on_rr = 1;
cfqd->busy_queues++;
if (time_after(jiffies, cfqq->service_start + cfq_service))
cfqq->service_used >>= 3;
cfq_sort_rr_list(cfqq, 1);
}
static inline void
cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
list_move(&cfqq->cfq_list, &cfqd->empty_list);
cfqq->on_rr = 0;
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;
BUG_ON(!cfqq->queued[crq->is_sync]);
cfq_update_next_crq(crq);
cfqq->queued[crq->is_sync]--;
rb_erase(&crq->rb_node, &cfqq->sort_list);
RB_CLEAR_COLOR(&crq->rb_node);
if (RB_EMPTY(&cfqq->sort_list) && cfqq->on_rr)
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[crq->is_sync]++;
/*
* 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 (!cfqq->on_rr)
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)
{
if (ON_RB(&crq->rb_node)) {
rb_erase(&crq->rb_node, &cfqq->sort_list);
cfqq->queued[crq->is_sync]--;
}
cfq_add_crq_rb(crq);
}
static struct request *
cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
{
const unsigned long key = cfq_hash_key(cfqd, current);
struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, key);
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_rq *crq = RQ_DATA(rq);
if (crq) {
struct cfq_queue *cfqq = crq->cfq_queue;
if (cfqq->cfqd->cfq_tagged) {
cfqq->service_used--;
cfq_sort_rr_list(cfqq, 0);
}
if (crq->accounted) {
crq->accounted = 0;
cfqq->cfqd->rq_in_driver--;
}
}
}
/*
* 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) {
cfq_remove_merge_hints(q, crq);
list_del_init(&rq->queuelist);
if (crq->cfq_queue)
cfq_del_crq_rb(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) {
BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
if (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) {
if (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)
{
struct cfq_rq *crq = RQ_DATA(rq);
struct cfq_rq *cnext = RQ_DATA(next);
cfq_merged_request(q, rq);
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
if (time_before(cnext->queue_start, crq->queue_start)) {
list_move(&rq->queuelist, &next->queuelist);
crq->queue_start = cnext->queue_start;
}
}
cfq_update_next_crq(cnext);
cfq_remove_request(q, next);
}
/*
* 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;
cfq_del_crq_rb(crq);
cfq_remove_merge_hints(q, crq);
list_del(&crq->request->queuelist);
last = cfqd->last_sector;
while ((entry = entry->prev) != head) {
__rq = list_entry_rq(entry);
if (blk_barrier_rq(crq->request))
break;
if (!blk_fs_request(crq->request))
break;
if (crq->request->sector > __rq->sector)
break;
if (__rq->sector > last && crq->request->sector < last) {
last = crq->request->sector;
break;
}
}
cfqd->last_sector = last;
crq->in_flight = 1;
cfqq->in_flight++;
list_add(&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;
const int reads = !list_empty(&cfqq->fifo[0]);
const int writes = !list_empty(&cfqq->fifo[1]);
unsigned long now = jiffies;
struct cfq_rq *crq;
if (time_before(now, cfqq->last_fifo_expire + cfqd->cfq_fifo_batch_expire))
return NULL;
crq = RQ_DATA(list_entry(cfqq->fifo[0].next, struct request, queuelist));
if (reads && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_r)) {
cfqq->last_fifo_expire = now;
return crq;
}
crq = RQ_DATA(list_entry(cfqq->fifo[1].next, struct request, queuelist));
if (writes && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_w)) {
cfqq->last_fifo_expire = now;
return crq;
}
return NULL;
}
/*
* dispatch a single request from given queue
*/
static inline void
cfq_dispatch_request(request_queue_t *q, struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
struct cfq_rq *crq;
/*
* follow expired path, else get first next available
*/
if ((crq = cfq_check_fifo(cfqq)) == NULL) {
if (cfqd->find_best_crq)
crq = cfqq->next_crq;
else
crq = rb_entry_crq(rb_first(&cfqq->sort_list));
}
cfqd->last_sector = crq->request->sector + crq->request->nr_sectors;
/*
* finally, insert request into driver list
*/
cfq_dispatch_sort(q, crq);
}
static int cfq_dispatch_requests(request_queue_t *q, int max_dispatch)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq;
struct list_head *entry, *tmp;
int queued, busy_queues, first_round;
if (list_empty(&cfqd->rr_list))
return 0;
queued = 0;
first_round = 1;
restart:
busy_queues = 0;
list_for_each_safe(entry, tmp, &cfqd->rr_list) {
cfqq = list_entry_cfqq(entry);
BUG_ON(RB_EMPTY(&cfqq->sort_list));
/*
* first round of queueing, only select from queues that
* don't already have io in-flight
*/
if (first_round && cfqq->in_flight)
continue;
cfq_dispatch_request(q, cfqd, cfqq);
if (!RB_EMPTY(&cfqq->sort_list))
busy_queues++;
queued++;
}
if ((queued < max_dispatch) && (busy_queues || first_round)) {
first_round = 0;
goto restart;
}
return queued;
}
static inline void cfq_account_dispatch(struct cfq_rq *crq)
{
struct cfq_queue *cfqq = crq->cfq_queue;
struct cfq_data *cfqd = cfqq->cfqd;
unsigned long now, elapsed;
if (!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 (crq->accounted)
return;
now = jiffies;
if (cfqq->service_start == ~0UL)
cfqq->service_start = now;
/*
* on drives with tagged command queueing, command turn-around time
* doesn't necessarily reflect the time spent processing this very
* command inside the drive. so do the accounting differently there,
* by just sorting on the number of requests
*/
if (cfqd->cfq_tagged) {
if (time_after(now, cfqq->service_start + cfq_service)) {
cfqq->service_start = now;
cfqq->service_used /= 10;
}
cfqq->service_used++;
cfq_sort_rr_list(cfqq, 0);
}
elapsed = now - crq->queue_start;
if (elapsed > max_elapsed_dispatch)
max_elapsed_dispatch = elapsed;
crq->accounted = 1;
crq->service_start = now;
if (++cfqd->rq_in_driver >= CFQ_MAX_TAG && !cfqd->cfq_tagged) {
cfqq->cfqd->cfq_tagged = 1;
printk("cfq: depth %d reached, tagging now on\n", CFQ_MAX_TAG);
}
}
static inline void
cfq_account_completion(struct cfq_queue *cfqq, struct cfq_rq *crq)
{
struct cfq_data *cfqd = cfqq->cfqd;
if (!crq->accounted)
return;
WARN_ON(!cfqd->rq_in_driver);
cfqd->rq_in_driver--;
if (!cfqd->cfq_tagged) {
unsigned long now = jiffies;
unsigned long duration = now - crq->service_start;
if (time_after(now, cfqq->service_start + cfq_service)) {
cfqq->service_start = now;
cfqq->service_used >>= 3;
}
cfqq->service_used += duration;
cfq_sort_rr_list(cfqq, 0);
if (duration > max_elapsed_crq)
max_elapsed_crq = duration;
}
}
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);
if ((crq = RQ_DATA(rq)) != NULL) {
cfq_remove_merge_hints(q, crq);
cfq_account_dispatch(crq);
}
return rq;
}
if (cfq_dispatch_requests(q, cfqd->cfq_quantum))
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)
{
BUG_ON(!atomic_read(&cfqq->ref));
if (!atomic_dec_and_test(&cfqq->ref))
return;
BUG_ON(rb_first(&cfqq->sort_list));
BUG_ON(cfqq->on_rr);
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 long key, 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);
if (__cfqq->key == key)
return __cfqq;
}
return NULL;
}
static struct cfq_queue *
cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned long key)
{
return __cfq_find_cfq_hash(cfqd, key, hash_long(key, CFQ_QHASH_SHIFT));
}
static inline void
cfq_rehash_cfqq(struct cfq_data *cfqd, struct cfq_queue **cfqq,
struct cfq_io_context *cic)
{
unsigned long hashkey = cfq_hash_key(cfqd, current);
unsigned long hashval = hash_long(hashkey, CFQ_QHASH_SHIFT);
struct cfq_queue *__cfqq;
unsigned long flags;
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
hlist_del(&(*cfqq)->cfq_hash);
__cfqq = __cfq_find_cfq_hash(cfqd, hashkey, hashval);
if (!__cfqq || __cfqq == *cfqq) {
__cfqq = *cfqq;
hlist_add_head(&__cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
__cfqq->key_type = cfqd->key_type;
} else {
atomic_inc(&__cfqq->ref);
cic->cfqq = __cfqq;
cfq_put_queue(*cfqq);
*cfqq = __cfqq;
}
cic->cfqq = __cfqq;
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
}
static void cfq_free_io_context(struct cfq_io_context *cic)
{
kmem_cache_free(cfq_ioc_pool, cic);
}
/*
* locking hierarchy is: io_context lock -> queue locks
*/
static void cfq_exit_io_context(struct cfq_io_context *cic)
{
struct cfq_queue *cfqq = cic->cfqq;
struct list_head *entry = &cic->list;
request_queue_t *q;
unsigned long flags;
/*
* put the reference this task is holding to the various queues
*/
spin_lock_irqsave(&cic->ioc->lock, flags);
while ((entry = cic->list.next) != &cic->list) {
struct cfq_io_context *__cic;
__cic = list_entry(entry, struct cfq_io_context, list);
list_del(entry);
q = __cic->cfqq->cfqd->queue;
spin_lock(q->queue_lock);
cfq_put_queue(__cic->cfqq);
spin_unlock(q->queue_lock);
}
q = cfqq->cfqd->queue;
spin_lock(q->queue_lock);
cfq_put_queue(cfqq);
spin_unlock(q->queue_lock);
cic->cfqq = NULL;
spin_unlock_irqrestore(&cic->ioc->lock, flags);
}
static struct cfq_io_context *cfq_alloc_io_context(int gfp_flags)
{
struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_flags);
if (cic) {
cic->dtor = cfq_free_io_context;
cic->exit = cfq_exit_io_context;
INIT_LIST_HEAD(&cic->list);
cic->cfqq = NULL;
}
return cic;
}
/*
* 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_queue **cfqq, int gfp_flags)
{
struct cfq_data *cfqd = (*cfqq)->cfqd;
struct cfq_queue *__cfqq = *cfqq;
struct cfq_io_context *cic;
struct io_context *ioc;
might_sleep_if(gfp_flags & __GFP_WAIT);
ioc = get_io_context(gfp_flags);
if (!ioc)
return NULL;
if ((cic = ioc->cic) == NULL) {
cic = cfq_alloc_io_context(gfp_flags);
if (cic == NULL)
goto err;
ioc->cic = cic;
cic->ioc = ioc;
cic->cfqq = __cfqq;
atomic_inc(&__cfqq->ref);
} else {
struct cfq_io_context *__cic;
unsigned long flags;
/*
* since the first cic on the list is actually the head
* itself, need to check this here or we'll duplicate an
* cic per ioc for no reason
*/
if (cic->cfqq == __cfqq)
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
*/
spin_lock_irqsave(&ioc->lock, flags);
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->cfqq == __cfqq) {
cic = __cic;
spin_unlock_irqrestore(&ioc->lock, flags);
goto out;
}
}
spin_unlock_irqrestore(&ioc->lock, flags);
/*
* 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(gfp_flags);
if (__cic == NULL)
goto err;
__cic->ioc = ioc;
__cic->cfqq = __cfqq;
atomic_inc(&__cfqq->ref);
spin_lock_irqsave(&ioc->lock, flags);
list_add(&__cic->list, &cic->list);
spin_unlock_irqrestore(&ioc->lock, flags);
cic = __cic;
*cfqq = __cfqq;
}
out:
/*
* if key_type has been changed on the fly, we lazily rehash
* each queue at lookup time
*/
if ((*cfqq)->key_type != cfqd->key_type)
cfq_rehash_cfqq(cfqd, cfqq, cic);
return cic;
err:
put_io_context(ioc);
return NULL;
}
static struct cfq_queue *
__cfq_get_queue(struct cfq_data *cfqd, unsigned long key, 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, 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
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[0]);
INIT_LIST_HEAD(&cfqq->fifo[1]);
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->key_type = cfqd->key_type;
cfqq->service_start = ~0UL;
}
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 void cfq_enqueue(struct cfq_data *cfqd, struct cfq_rq *crq)
{
crq->is_sync = 0;
if (rq_data_dir(crq->request) == READ || current->flags & PF_SYNCWRITE)
crq->is_sync = 1;
cfq_add_crq_rb(crq);
crq->queue_start = jiffies;
list_add_tail(&crq->request->queuelist, &crq->cfq_queue->fifo[crq->is_sync]);
}
static void
cfq_insert_request(request_queue_t *q, struct request *rq, int where)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_rq *crq = RQ_DATA(rq);
switch (where) {
case ELEVATOR_INSERT_BACK:
while (cfq_dispatch_requests(q, cfqd->cfq_quantum))
;
list_add_tail(&rq->queuelist, &q->queue_head);
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, crq);
break;
default:
printk("%s: bad insert point %d\n", __FUNCTION__,where);
return;
}
if (rq_mergeable(rq)) {
cfq_add_crq_hash(cfqd, crq);
if (!q->last_merge)
q->last_merge = rq;
}
}
static int cfq_queue_empty(request_queue_t *q)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
return list_empty(&q->queue_head) && list_empty(&cfqd->rr_list);
}
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 (crq->in_flight) {
WARN_ON(!cfqq->in_flight);
cfqq->in_flight--;
}
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;
}
static int cfq_may_queue(request_queue_t *q, int rw)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq;
int ret = ELV_MQUEUE_MAY;
if (current->flags & PF_MEMALLOC)
return ELV_MQUEUE_MAY;
cfqq = cfq_find_cfq_hash(cfqd, cfq_hash_key(cfqd, current));
if (cfqq) {
int limit = cfqd->max_queued;
if (cfqq->allocated[rw] < cfqd->cfq_queued)
return ELV_MQUEUE_MUST;
if (cfqd->busy_queues)
limit = q->nr_requests / cfqd->busy_queues;
if (limit < cfqd->cfq_queued)
limit = cfqd->cfq_queued;
else if (limit > cfqd->max_queued)
limit = cfqd->max_queued;
if (cfqq->allocated[rw] >= limit) {
if (limit > cfqq->alloc_limit[rw])
cfqq->alloc_limit[rw] = limit;
ret = ELV_MQUEUE_NO;
}
}
return ret;
}
static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
{
struct request_list *rl = &q->rq;
const int write = waitqueue_active(&rl->wait[WRITE]);
const int read = waitqueue_active(&rl->wait[READ]);
if (read && cfqq->allocated[READ] < cfqq->alloc_limit[READ])
wake_up(&rl->wait[READ]);
if (write && cfqq->allocated[WRITE] < cfqq->alloc_limit[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;
BUG_ON(q->last_merge == rq);
BUG_ON(!hlist_unhashed(&crq->hash));
if (crq->io_context)
put_io_context(crq->io_context->ioc);
BUG_ON(!cfqq->allocated[crq->is_write]);
cfqq->allocated[crq->is_write]--;
mempool_free(crq, cfqd->crq_pool);
rq->elevator_private = NULL;
smp_mb();
cfq_check_waiters(q, cfqq);
cfq_put_queue(cfqq);
}
}
/*
* Allocate cfq data structures associated with this request. A queue and
*/
static int cfq_set_request(request_queue_t *q, struct request *rq, int gfp_mask)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_io_context *cic;
const int rw = rq_data_dir(rq);
struct cfq_queue *cfqq, *saved_cfqq;
struct cfq_rq *crq;
unsigned long flags;
might_sleep_if(gfp_mask & __GFP_WAIT);
spin_lock_irqsave(q->queue_lock, flags);
cfqq = __cfq_get_queue(cfqd, cfq_hash_key(cfqd, current), gfp_mask);
if (!cfqq)
goto out_lock;
repeat:
if (cfqq->allocated[rw] >= cfqd->max_queued)
goto out_lock;
cfqq->allocated[rw]++;
spin_unlock_irqrestore(q->queue_lock, flags);
/*
* if hashing type has changed, the cfq_queue might change here.
*/
saved_cfqq = cfqq;
cic = cfq_get_io_context(&cfqq, gfp_mask);
if (!cic)
goto err;
/*
* repeat allocation checks on queue change
*/
if (unlikely(saved_cfqq != cfqq)) {
spin_lock_irqsave(q->queue_lock, flags);
saved_cfqq->allocated[rw]--;
goto repeat;
}
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;
crq->service_start = crq->queue_start = 0;
crq->in_flight = crq->accounted = crq->is_sync = 0;
crq->is_write = rw;
rq->elevator_private = crq;
cfqq->alloc_limit[rw] = 0;
return 0;
}
put_io_context(cic->ioc);
err:
spin_lock_irqsave(q->queue_lock, flags);
cfqq->allocated[rw]--;
cfq_put_queue(cfqq);
out_lock:
spin_unlock_irqrestore(q->queue_lock, flags);
return 1;
}
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);
mempool_destroy(cfqd->crq_pool);
kfree(cfqd->crq_hash);
kfree(cfqd->cfq_hash);
kfree(cfqd);
}
static void cfq_exit_queue(elevator_t *e)
{
cfq_put_cfqd(e->elevator_data);
}
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));
INIT_LIST_HEAD(&cfqd->rr_list);
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);
/*
* just set it to some high value, we want anyone to be able to queue
* some requests. fairness is handled differently
*/
q->nr_requests = 1024;
cfqd->max_queued = q->nr_requests / 16;
q->nr_batching = cfq_queued;
cfqd->key_type = CFQ_KEY_TGID;
cfqd->find_best_crq = 1;
atomic_set(&cfqd->ref, 1);
cfqd->cfq_queued = cfq_queued;
cfqd->cfq_quantum = cfq_quantum;
cfqd->cfq_fifo_expire_r = cfq_fifo_expire_r;
cfqd->cfq_fifo_expire_w = cfq_fifo_expire_w;
cfqd->cfq_fifo_batch_expire = cfq_fifo_rate;
cfqd->cfq_back_max = cfq_back_max;
cfqd->cfq_back_penalty = cfq_back_penalty;
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;
}
static ssize_t
cfq_clear_elapsed(struct cfq_data *cfqd, const char *page, size_t count)
{
max_elapsed_dispatch = max_elapsed_crq = 0;
return count;
}
static ssize_t
cfq_set_key_type(struct cfq_data *cfqd, const char *page, size_t count)
{
spin_lock_irq(cfqd->queue->queue_lock);
if (!strncmp(page, "pgid", 4))
cfqd->key_type = CFQ_KEY_PGID;
else if (!strncmp(page, "tgid", 4))
cfqd->key_type = CFQ_KEY_TGID;
else if (!strncmp(page, "uid", 3))
cfqd->key_type = CFQ_KEY_UID;
else if (!strncmp(page, "gid", 3))
cfqd->key_type = CFQ_KEY_GID;
spin_unlock_irq(cfqd->queue->queue_lock);
return count;
}
static ssize_t
cfq_read_key_type(struct cfq_data *cfqd, char *page)
{
ssize_t len = 0;
int i;
for (i = CFQ_KEY_PGID; i < CFQ_KEY_LAST; i++) {
if (cfqd->key_type == i)
len += sprintf(page+len, "[%s] ", cfq_key_types[i]);
else
len += sprintf(page+len, "%s ", cfq_key_types[i]);
}
len += sprintf(page+len, "\n");
return len;
}
#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_r_show, cfqd->cfq_fifo_expire_r, 1);
SHOW_FUNCTION(cfq_fifo_expire_w_show, cfqd->cfq_fifo_expire_w, 1);
SHOW_FUNCTION(cfq_fifo_batch_expire_show, cfqd->cfq_fifo_batch_expire, 1);
SHOW_FUNCTION(cfq_find_best_show, cfqd->find_best_crq, 0);
SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0);
SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 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_r_store, &cfqd->cfq_fifo_expire_r, 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_fifo_expire_w_store, &cfqd->cfq_fifo_expire_w, 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_fifo_batch_expire_store, &cfqd->cfq_fifo_batch_expire, 0, UINT_MAX, 1);
STORE_FUNCTION(cfq_find_best_store, &cfqd->find_best_crq, 0, 1, 0);
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);
#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_r_entry = {
.attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR },
.show = cfq_fifo_expire_r_show,
.store = cfq_fifo_expire_r_store,
};
static struct cfq_fs_entry cfq_fifo_expire_w_entry = {
.attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR },
.show = cfq_fifo_expire_w_show,
.store = cfq_fifo_expire_w_store,
};
static struct cfq_fs_entry cfq_fifo_batch_expire_entry = {
.attr = {.name = "fifo_batch_expire", .mode = S_IRUGO | S_IWUSR },
.show = cfq_fifo_batch_expire_show,
.store = cfq_fifo_batch_expire_store,
};
static struct cfq_fs_entry cfq_find_best_entry = {
.attr = {.name = "find_best_crq", .mode = S_IRUGO | S_IWUSR },
.show = cfq_find_best_show,
.store = cfq_find_best_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_clear_elapsed_entry = {
.attr = {.name = "clear_elapsed", .mode = S_IWUSR },
.store = cfq_clear_elapsed,
};
static struct cfq_fs_entry cfq_key_type_entry = {
.attr = {.name = "key_type", .mode = S_IRUGO | S_IWUSR },
.show = cfq_read_key_type,
.store = cfq_set_key_type,
};
static struct attribute *default_attrs[] = {
&cfq_quantum_entry.attr,
&cfq_queued_entry.attr,
&cfq_fifo_expire_r_entry.attr,
&cfq_fifo_expire_w_entry.attr,
&cfq_fifo_batch_expire_entry.attr,
&cfq_key_type_entry.attr,
&cfq_find_best_entry.attr,
&cfq_back_max_entry.attr,
&cfq_back_penalty_entry.attr,
&cfq_clear_elapsed_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 0;
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 -EINVAL;
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;
if (cfq_slab_setup())
return -ENOMEM;
ret = elv_register(&iosched_cfq);
if (!ret) {
__module_get(THIS_MODULE);
return 0;
}
cfq_slab_kill();
return ret;
}
static void __exit cfq_exit(void)
{
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");