dm table: propagate non rotational flag (4693c966) · Commits · 戴 / test

Allow QUEUE_FLAG_NONROT to propagate up the device stack if all underlying devices are non-rotational. Tools like ureadahead will schedule IOs differently based on the rotational flag. With this patch, I see boot time go from 7.75 s to 7.46 s on my device. Suggested-by:

J. Richard Barnette <jrbarnette@chromium.org> Signed-off-by:

Mandeep Singh Baines <msb@chromium.org> Signed-off-by:

Mike Snitzer <snitzer@redhat.com> Cc: Neil Brown <neilb@suse.de> Cc: Jens Axboe <jaxboe@fusionio.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: dm-devel@redhat.com Signed-off-by:

Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-table.c

+30 −0

Original line number	Diff line number	Diff line
		@@ -1299,6 +1299,31 @@ static bool dm_table_discard_zeroes_data(struct dm_table *t)
		return 1;
		}

		static int device_is_nonrot(struct dm_target ti, struct dm_dev dev,
		sector_t start, sector_t len, void *data)
		{
		struct request_queue *q = bdev_get_queue(dev->bdev);

		return q && blk_queue_nonrot(q);
		}

		static bool dm_table_is_nonrot(struct dm_table *t)
		{
		struct dm_target *ti;
		unsigned i = 0;

		/* Ensure that all underlying device are non-rotational. */
		while (i < dm_table_get_num_targets(t)) {
		ti = dm_table_get_target(t, i++);

		if (!ti->type->iterate_devices \|\|
		!ti->type->iterate_devices(ti, device_is_nonrot, NULL))
		return 0;
		}

		return 1;
		}

		void dm_table_set_restrictions(struct dm_table t, struct request_queue q,
		struct queue_limits *limits)
		{
		@@ -1324,6 +1349,11 @@ void dm_table_set_restrictions(struct dm_table t, struct request_queue q,
		if (!dm_table_discard_zeroes_data(t))
		q->limits.discard_zeroes_data = 0;

		if (dm_table_is_nonrot(t))
		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
		else
		queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);

		dm_table_set_integrity(t);

		/*

Admin message