Commit a852d7b8 authored Sep 19, 2012 by NeilBrown

Revert "md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE."



This reverts commit 895e3c5c.

While this patch seemed like a good idea and did help some workloads,
it hurts other workloads.
Large sequential O_DIRECT writes were faster,
Small random O_DIRECT writes were slower.

Other changes (batching RAID5 writes) have improved the sequential
writes using a different mechanism, so the net result of this patch
is definitely negative.  So revert it.

Reported-by: Shaohua Li <shli@kernel.org>
Tested-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

parent 55d512e2

drivers/md/raid5.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4192,7 +4192,7 @@ static void make_request(struct mddev mddev, struct bio bi)
		finish_wait(&conf->wait_for_overlap, &w);
		set_bit(STRIPE_HANDLE, &sh->state);
		clear_bit(STRIPE_DELAYED, &sh->state);
		if ((bi->bi_rw & REQ_NOIDLE) &&
		if ((bi->bi_rw & REQ_SYNC) &&
		!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
		atomic_inc(&conf->preread_active_stripes);
		release_stripe_plug(mddev, sh);

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