From: Mandeep Singh Baines 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 Signed-off-by: Mandeep Singh Baines Signed-off-by: Mike Snitzer Cc: Neil Brown Cc: Jens Axboe Cc: Martin K. Petersen Cc: dm-devel@redhat.com Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) Index: linux-3.0/drivers/md/dm-table.c =================================================================== --- linux-3.0.orig/drivers/md/dm-table.c +++ linux-3.0/drivers/md/dm-table.c @@ -1301,6 +1301,31 @@ static void dm_table_set_integrity(struc blk_get_integrity(template_disk)); } +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) { @@ -1314,6 +1339,11 @@ void dm_table_set_restrictions(struct dm else queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); + 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); /*