[PATCH] md: use REQ_NOIDLE flag in md_super_write()

[PATCH] md: use REQ_NOIDLE flag in md_super_write()

[Namhyung Kim]

Queue idling is used for the anticipation of immediate
sequencial I/O's but md_super_write() is a kind of one-
shot operation, coupled with md_super_wait(), so the
idling in this case will be just a waste of time.

Specifying REQ_NOIDLE prevents it. Instead of adding
the flag to submit_bio() directly, use pre-defined
macro WRITE_FLUSH_FUA.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
---
 drivers/md/md.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index d97a62534798..8650e9a0ce7c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -848,7 +848,7 @@ void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 	bio->bi_end_io = super_written;
 
 	atomic_inc(&mddev->pending_writes);
-	submit_bio(REQ_WRITE | REQ_SYNC | REQ_FLUSH | REQ_FUA, bio);
+	submit_bio(WRITE_FLUSH_FUA, bio);
 }
 
 void md_super_wait(mddev_t *mddev)
-- 
1.7.6

Re: [PATCH] md: use REQ_NOIDLE flag in md_super_write()

[NeilBrown]

On Thu,  4 Aug 2011 00:57:57 +0900 Namhyung Kim <namhyung@gmail.com> wrote:

> Queue idling is used for the anticipation of immediate
> sequencial I/O's but md_super_write() is a kind of one-
> shot operation, coupled with md_super_wait(), so the
> idling in this case will be just a waste of time.
> 
> Specifying REQ_NOIDLE prevents it. Instead of adding
> the flag to submit_bio() directly, use pre-defined
> macro WRITE_FLUSH_FUA.
> 
> Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> ---
>  drivers/md/md.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index d97a62534798..8650e9a0ce7c 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -848,7 +848,7 @@ void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
>  	bio->bi_end_io = super_written;
>  
>  	atomic_inc(&mddev->pending_writes);
> -	submit_bio(REQ_WRITE | REQ_SYNC | REQ_FLUSH | REQ_FUA, bio);
> +	submit_bio(WRITE_FLUSH_FUA, bio);
>  }
>  
>  void md_super_wait(mddev_t *mddev)

Applied, thanks.

NeilBrown