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Commit 3eaf840e authored by Jun'ichi "Nick" Nomura's avatar Jun'ichi "Nick" Nomura Committed by Linus Torvalds
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[PATCH] device-mapper disk statistics: timing 



Record I/O timing statistics

The start time is added to struct dm_io, an existing structure allocated
privately internally within dm and attached to each incoming bio.

We export disk_round_stats() from block/ll_rw_blk.c instead of creating a
private clone.

Signed-off-by: default avatarJun'ichi "Nick" Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 12f03a49

block/ll_rw_blk.c

+2 −0
Original line number Diff line number Diff line
@@ -2579,6 +2579,8 @@ void disk_round_stats(struct gendisk *disk) 
	disk->stamp = now;

}



EXPORT_SYMBOL_GPL(disk_round_stats);



/*

 * queue lock must be held

 */

drivers/md/dm.c

+33 −2
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ struct dm_io { 
	int error;

	struct bio *bio;

	atomic_t io_count;

	unsigned long start_time;

};



/*
@@ -244,6 +245,36 @@ static inline void free_tio(struct mapped_device *md, struct target_io *tio) 
	mempool_free(tio, md->tio_pool);

}



static void start_io_acct(struct dm_io *io)

{

	struct mapped_device *md = io->md;



	io->start_time = jiffies;



	preempt_disable();

	disk_round_stats(dm_disk(md));

	preempt_enable();

	dm_disk(md)->in_flight = atomic_inc_return(&md->pending);

}



static int end_io_acct(struct dm_io *io)

{

	struct mapped_device *md = io->md;

	struct bio *bio = io->bio;

	unsigned long duration = jiffies - io->start_time;

	int pending;

	int rw = bio_data_dir(bio);



	preempt_disable();

	disk_round_stats(dm_disk(md));

	preempt_enable();

	dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending);



	disk_stat_add(dm_disk(md), ticks[rw], duration);



	return !pending;

}



/*

 * Add the bio to the list of deferred io.

 */
@@ -299,7 +330,7 @@ static void dec_pending(struct dm_io *io, int error) 
		io->error = error;



	if (atomic_dec_and_test(&io->io_count)) {

		if (atomic_dec_and_test(&io->md->pending))

		if (end_io_acct(io))

			/* nudge anyone waiting on suspend queue */

			wake_up(&io->md->wait);
@@ -554,7 +585,7 @@ static void __split_bio(struct mapped_device *md, struct bio *bio) 
	ci.sector_count = bio_sectors(bio);

	ci.idx = bio->bi_idx;



	atomic_inc(&md->pending);

	start_io_acct(ci.io);

	while (ci.sector_count)

		__clone_and_map(&ci);