Commit 06eed768 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: avoid needless dm_io access if all IO accounting is disabled 



Update dm_io_acct() to eliminate most dm_io struct accesses if both
block core's IO stats and dm-stats are disabled.

Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 526d1006

drivers/md/dm.c

+21 −22
Original line number Diff line number Diff line
@@ -487,51 +487,50 @@ u64 dm_start_time_ns_from_clone(struct bio *bio) 
}

EXPORT_SYMBOL_GPL(dm_start_time_ns_from_clone);



static bool bio_is_flush_with_data(struct bio *bio)

static inline bool bio_is_flush_with_data(struct bio *bio)

{

	return ((bio->bi_opf & REQ_PREFLUSH) && bio->bi_iter.bi_size);

}



static void dm_io_acct(struct dm_io *io, bool end)

static inline unsigned int dm_io_sectors(struct dm_io *io, struct bio *bio)

{

	struct dm_stats_aux *stats_aux = &io->stats_aux;

	unsigned long start_time = io->start_time;

	struct mapped_device *md = io->md;

	struct bio *bio = io->orig_bio;

	unsigned int sectors;



	/*

	 * If REQ_PREFLUSH set, don't account payload, it will be

	 * submitted (and accounted) after this flush completes.

	 */

	if (bio_is_flush_with_data(bio))

		sectors = 0;

	else if (likely(!(dm_io_flagged(io, DM_IO_WAS_SPLIT))))

		sectors = bio_sectors(bio);

	else

		sectors = io->sectors;

		return 0;

	if (unlikely(dm_io_flagged(io, DM_IO_WAS_SPLIT)))

		return io->sectors;

	return bio_sectors(bio);

}



static void dm_io_acct(struct dm_io *io, bool end)

{

	struct bio *bio = io->orig_bio;



	if (dm_io_flagged(io, DM_IO_BLK_STAT)) {

		if (!end)

			bdev_start_io_acct(bio->bi_bdev, bio_op(bio),

					   start_time);

					   io->start_time);

		else

			bdev_end_io_acct(bio->bi_bdev, bio_op(bio),

					 sectors, start_time);

					 dm_io_sectors(io, bio),

					 io->start_time);

	}



	if (static_branch_unlikely(&stats_enabled) &&

	    unlikely(dm_stats_used(&md->stats))) {

	    unlikely(dm_stats_used(&io->md->stats))) {

		sector_t sector;



		if (likely(!dm_io_flagged(io, DM_IO_WAS_SPLIT)))

			sector = bio->bi_iter.bi_sector;

		else

		if (unlikely(dm_io_flagged(io, DM_IO_WAS_SPLIT)))

			sector = bio_end_sector(bio) - io->sector_offset;

		else

			sector = bio->bi_iter.bi_sector;



		dm_stats_account_io(&md->stats, bio_data_dir(bio),

				    sector, sectors,

				    end, start_time, stats_aux);

		dm_stats_account_io(&io->md->stats, bio_data_dir(bio),

				    sector, dm_io_sectors(io, bio),

				    end, io->start_time, &io->stats_aux);

	}

}