On Mon, 16 Jul 2012 16:33:02 +0800 majianpeng <majianpeng@xxxxxxxxx> wrote:
> Using flag REQ_NOIDLE to difference odirect-write and sync_write.
>
> Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
> ---
> drivers/md/raid5.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 04348d7..29edaf0 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -4113,7 +4113,10 @@ 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_SYNC) &&
> + /* Difference odirect-write between regular file
> + * and block-device
> + */
> + if ((bi->bi_rw & REQ_NOIDLE) &&
> !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
> atomic_inc(&conf->preread_active_stripes);
> mddev_check_plugged(mddev);
Thanks.
I've improved that patch description and remove the code comment and I don't
think it is helpful.
NeilBrown
From c6e353648f062901f435f67b91e9438897d42ddf Mon Sep 17 00:00:00 2001
From: majianpeng <majianpeng@xxxxxxxxx>
Date: Tue, 17 Jul 2012 12:00:35 +1000
Subject: [PATCH] md/raid5: For odirect-write performance, do not set
STRIPE_PREREAD_ACTIVE.
'sync' writes set both REQ_SYNC and REQ_NOIDLE.
O_DIRECT writes set REQ_SYNC but not REQ_NOIDLE.
We currently assume that a REQ_SYNC request will not be followed by
more requests and so set STRIPE_PREREAD_ACTIVE to expedite the
request.
This is appropriate for sync requests, but not for O_DIRECT requests.
So make the setting of STRIPE_PREREAD_ACTIVE conditional on REQ_NOIDLE
rather than REQ_SYNC. This is consistent with the documented meaning
of REQ_NOIDLE:
__REQ_NOIDLE, /* don't anticipate more IO after this one */
Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0e4439e..ee492a8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4187,7 +4187,7 @@ 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_SYNC) &&
+ if ((bi->bi_rw & REQ_NOIDLE) &&
!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
atomic_inc(&conf->preread_active_stripes);
release_stripe_plug(mddev, sh);
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