Commit 0e4aac73 authored by Artur Paszkiewicz's avatar Artur Paszkiewicz Committed by Song Liu
Browse files

md/raid5: only add to wq if reshape is in progress 



Now that actual overlaps are not handled on the wait_for_overlap wq
anymore, the remaining cases when we wait on this wq are limited to
reshape. If reshape is not in progress, don't add to the wq in
raid5_make_request() because add_wait_queue() / remove_wait_queue()
operations take a spinlock and cause noticeable contention when multiple
threads are submitting requests to the mddev.

Signed-off-by: default avatarArtur Paszkiewicz <artur.paszkiewicz@intel.com>
Link: https://lore.kernel.org/r/20240827153536.6743-3-artur.paszkiewicz@intel.com


Signed-off-by: default avatarSong Liu <song@kernel.org>
parent e6a03207

drivers/md/raid5.c

+10 −3
Original line number Diff line number Diff line
@@ -6070,6 +6070,7 @@ static sector_t raid5_bio_lowest_chunk_sector(struct r5conf *conf, 
static bool raid5_make_request(struct mddev *mddev, struct bio * bi)

{

	DEFINE_WAIT_FUNC(wait, woken_wake_function);

	bool on_wq;

	struct r5conf *conf = mddev->private;

	sector_t logical_sector;

	struct stripe_request_ctx ctx = {};
@@ -6143,11 +6144,15 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) 
	 * sequential IO pattern. We don't bother with the optimization when

	 * reshaping as the performance benefit is not worth the complexity.

	 */

	if (likely(conf->reshape_progress == MaxSector))

	if (likely(conf->reshape_progress == MaxSector)) {

		logical_sector = raid5_bio_lowest_chunk_sector(conf, bi);

		on_wq = false;

	} else {

		add_wait_queue(&conf->wait_for_overlap, &wait);

		on_wq = true;

	}

	s = (logical_sector - ctx.first_sector) >> RAID5_STRIPE_SHIFT(conf);



	add_wait_queue(&conf->wait_for_overlap, &wait);

	while (1) {

		res = make_stripe_request(mddev, conf, &ctx, logical_sector,

					  bi);
@@ -6158,6 +6163,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) 
			continue;



		if (res == STRIPE_SCHEDULE_AND_RETRY) {

			WARN_ON_ONCE(!on_wq);

			/*

			 * Must release the reference to batch_last before

			 * scheduling and waiting for work to be done,
@@ -6182,6 +6188,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) 
		logical_sector = ctx.first_sector +

			(s << RAID5_STRIPE_SHIFT(conf));

	}

	if (unlikely(on_wq))

		remove_wait_queue(&conf->wait_for_overlap, &wait);



	if (ctx.batch_last)