Commit 42dad764 authored by Jerome Marchand's avatar Jerome Marchand Committed by Jens Axboe
Browse files

block: simplify I/O stat accounting 



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: default avatarJerome Marchand <jmarchan@redhat.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 097102c2

block/blk-core.c

+4 −2
Original line number Diff line number Diff line
@@ -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);

block/blk-merge.c

+4 −1
Original line number Diff line number Diff line
@@ -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))

block/blk-sysfs.c

+0 −4
Original line number Diff line number Diff line
@@ -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;

block/blk.h

+1 −6
Original line number Diff line number Diff line
@@ -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

include/linux/blkdev.h

+3 −0
Original line number Diff line number Diff line
@@ -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)))

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