linux-kernel - Re: [PATCH] cfq-iosched: simplify prio-unboost code

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Message-ID: <20091029131944.GN10727@kernel.dk>
Date:	Thu, 29 Oct 2009 14:19:44 +0100
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Corrado Zoccolo <czoccolo@...il.com>
Cc:	Linux-Kernel <linux-kernel@...r.kernel.org>,
	Jeff Moyer <jmoyer@...hat.com>
Subject: Re: [PATCH] cfq-iosched: simplify prio-unboost code

On Mon, Oct 26 2009, Corrado Zoccolo wrote:
> Eliminate redundant checks.
> 
> Signed-off-by: Corrado Zoccolo <czoccolo@...il.com>
> ---
>  block/cfq-iosched.c |    8 +++-----
>  1 files changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 6e9b395..244bc8a 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -2611,12 +2611,10 @@ static void cfq_prio_boost(struct cfq_queue *cfqq)
>  			cfqq->ioprio = IOPRIO_NORM;
>  	} else {
>  		/*
> -		 * check if we need to unboost the queue
> +		 * unboost the queue (if needed)
>  		 */
> -		if (cfqq->ioprio_class != cfqq->org_ioprio_class)
> -			cfqq->ioprio_class = cfqq->org_ioprio_class;
> -		if (cfqq->ioprio != cfqq->org_ioprio)
> -			cfqq->ioprio = cfqq->org_ioprio;
> +		cfqq->ioprio_class = cfqq->org_ioprio_class;
> +		cfqq->ioprio = cfqq->org_ioprio;
>  	}

Not sure I see much gain in that, the previous code makes it explicit
that it may not be different and avoid dirtying cfqq if it isn't.

-- 
Jens Axboe

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