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Re: [PATCH v2 5/7] block: check bio_mergeable() early before merging

From Jeff Moyer <jmoyer@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 5/7] block: check bio_mergeable() early before merging
Date 2015-10-20 17:30 +0200
Message-ID <qlH1o-7IO-17@gated-at.bofh.it> (permalink)
References <qlGRI-7xO-17@gated-at.bofh.it> <qlGRI-7xO-31@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Ming Lei <ming.lei@canonical.com> writes:

> After bio splitting is introduced, one bio can be splitted
> and it is marked as NOMERGE because it is too fat to be merged,
> so check bio_mergeable() earlier to avoid to try to merge it
> unnecessarily.
>
> Signed-off-by: Ming Lei <ming.lei@canonical.com>

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>

> ---
>  block/elevator.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/elevator.c b/block/elevator.c
> index 84d6394..c3555c9 100644
> --- a/block/elevator.c
> +++ b/block/elevator.c
> @@ -420,7 +420,7 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
>  	 * 	noxmerges: Only simple one-hit cache try
>  	 * 	merges:	   All merge tries attempted
>  	 */
> -	if (blk_queue_nomerges(q))
> +	if (blk_queue_nomerges(q) || !bio_mergeable(bio))
>  		return ELEVATOR_NO_MERGE;
>  
>  	/*
--
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Thread

[PATCH v2 0/7] block: some misc changes Ming Lei <ming.lei@canonical.com> - 2015-10-20 17:20 +0200
  [PATCH v2 2/7] block: setup bi_phys_segments after splitting Ming Lei <ming.lei@canonical.com> - 2015-10-20 17:20 +0200
  [PATCH v2 5/7] block: check bio_mergeable() early before merging Ming Lei <ming.lei@canonical.com> - 2015-10-20 17:20 +0200
    Re: [PATCH v2 5/7] block: check bio_mergeable() early before merging Jeff Moyer <jmoyer@redhat.com> - 2015-10-20 17:30 +0200
  [PATCH v2 7/7] blk-mq: mark ctx as pending at batch in flush plug path Ming Lei <ming.lei@canonical.com> - 2015-10-20 17:20 +0200
  [PATCH v2 6/7] blk-mq: fix for trace_block_plug() Ming Lei <ming.lei@canonical.com> - 2015-10-20 17:20 +0200
    Re: [PATCH v2 6/7] blk-mq: fix for trace_block_plug() Jeff Moyer <jmoyer@redhat.com> - 2015-10-20 17:30 +0200
  [PATCH v2 1/7] block: fix plug list flushing for nomerge queues Ming Lei <ming.lei@canonical.com> - 2015-10-20 17:20 +0200
  [PATCH v2 4/7] blk-mq: check bio_mergeable() early before merging Ming Lei <ming.lei@canonical.com> - 2015-10-20 17:20 +0200
  Re: [PATCH v2 0/7] block: some misc changes Jens Axboe <axboe@kernel.dk> - 2015-10-21 23:10 +0200

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