The block layer defaults the maximum segments to 128, which means requests tend to get split around the 512KB depending on how many pages can be merged. There's no such restriction in the raid5 code so increase the limit to USHRT_MAX so that larger requests can be sent as one. Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> --- drivers/md/raid5.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index e48c16bfe657..5723a497108a 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -8005,6 +8005,9 @@ static int raid5_run(struct mddev *mddev) */ blk_queue_max_hw_sectors(mddev->queue, RAID5_MAX_REQ_STRIPES << RAID5_STRIPE_SHIFT(conf)); + + /* No restrictions on the number of segments in the request */ + blk_queue_max_segments(mddev->queue, USHRT_MAX); } if (log_init(conf, journal_dev, raid5_has_ppl(conf))) -- 2.30.2
