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block: simplify I/O stat accounting

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This simplifies I/O stat accounting switching code and separates it
completely from I/O scheduler switch code.

Requests are accounted according to the state of their request queue
at the time of the request allocation. There is no need anymore to
flush the request queue when switching I/O accounting state.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jerome Marchand 2009-04-22 14:01:49 +02:00 committed by Jens Axboe
parent 097102c2d0
commit 42dad7647a
5 changed files with 12 additions and 13 deletions
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6
block/blk-core.c
View file

@ -643,7 +643,7 @@ static inline void blk_free_request(struct request_queue *q, struct request *rq)
}
static struct request *
blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask)
blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask)
{
struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
@ -652,7 +652,7 @@ blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask)
blk_rq_init(q, rq);
rq->cmd_flags = rw | REQ_ALLOCED;
rq->cmd_flags = flags | REQ_ALLOCED;
if (priv) {
if (unlikely(elv_set_request(q, rq, gfp_mask))) {
@ -792,6 +792,8 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
if (priv)
rl->elvpriv++;
if (blk_queue_io_stat(q))
rw_flags |= REQ_IO_STAT;
spin_unlock_irq(q->queue_lock);
rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);

5
block/blk-merge.c
View file

@ -402,7 +402,10 @@ static int attempt_merge(struct request_queue *q, struct request *req,
elv_merge_requests(q, req, next);
blk_account_io_merge(req);
/*
* 'next' is going away, so update stats accordingly
*/
blk_account_io_merge(next);
req->ioprio = ioprio_best(req->ioprio, next->ioprio);
if (blk_rq_cpu_valid(next))

4
block/blk-sysfs.c
View file

@ -209,14 +209,10 @@ static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
ssize_t ret = queue_var_store(&stats, page, count);
spin_lock_irq(q->queue_lock);
elv_quiesce_start(q);
if (stats)
queue_flag_set(QUEUE_FLAG_IO_STAT, q);
else
queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
elv_quiesce_end(q);
spin_unlock_irq(q->queue_lock);
return ret;

7
block/blk.h
View file

@ -114,12 +114,7 @@ static inline int blk_cpu_to_group(int cpu)
static inline int blk_do_io_stat(struct request *rq)
{
struct gendisk *disk = rq->rq_disk;
if (!disk || !disk->queue)
return 0;
return blk_queue_io_stat(disk->queue) && (rq->cmd_flags & REQ_ELVPRIV);
return rq->rq_disk && blk_rq_io_stat(rq);
}
#endif

3
include/linux/blkdev.h
View file

@ -118,6 +118,7 @@ enum rq_flag_bits {
__REQ_COPY_USER, /* contains copies of user pages */
__REQ_INTEGRITY, /* integrity metadata has been remapped */
__REQ_NOIDLE, /* Don't anticipate more IO after this one */
__REQ_IO_STAT, /* account I/O stat */
__REQ_NR_BITS, /* stops here */
};
@ -145,6 +146,7 @@ enum rq_flag_bits {
#define REQ_COPY_USER (1 << __REQ_COPY_USER)
#define REQ_INTEGRITY (1 << __REQ_INTEGRITY)
#define REQ_NOIDLE (1 << __REQ_NOIDLE)
#define REQ_IO_STAT (1 << __REQ_IO_STAT)
#define BLK_MAX_CDB 16
@ -598,6 +600,7 @@ enum {
blk_failfast_transport(rq) || \
blk_failfast_driver(rq))
#define blk_rq_started(rq) ((rq)->cmd_flags & REQ_STARTED)
#define blk_rq_io_stat(rq) ((rq)->cmd_flags & REQ_IO_STAT)
#define blk_account_rq(rq) (blk_rq_started(rq) && (blk_fs_request(rq) || blk_discard_rq(rq)))