raid5 will split bio to proper size internally, there is no point to use underlayer disk's max_hw_sectors. In my qemu system, without the change, the raid5 only receives 128k size bio, which reduces the chance of bio merge sending to underlayer disks. Signed-off-by: Shaohua Li <shli@xxxxxx> --- drivers/md/raid5.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index b95c54c..fc0b600 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -7066,6 +7066,8 @@ static int raid5_run(struct mddev *mddev) else queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue); + + blk_queue_max_hw_sectors(mddev->queue, UINT_MAX); } if (journal_dev) { -- 2.8.0.rc2 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html