linux-kernel - Re: [PATCH 0/4 v4] ext3/4: enhance fsync performance when using CFQ

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Date:	Wed, 19 May 2010 11:05:20 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Jeff Moyer <jmoyer@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com, linux-kernel@...r.kernel.org,
	linux-ext4@...r.kernel.org, jens.axboe@...cle.com,
	vgoyal@...hat.com
Subject: Re: [PATCH 0/4 v4] ext3/4: enhance fsync performance when using CFQ

Hi Jeff,

> This patch series addresses a performance problem experienced when running
> io_zone with small file sizes (from 4KB up to 8MB) and including fsync in
> the timings.  A good example of this would be the following command line:
>   iozone -s 64 -e -f /mnt/test/iozone.0 -i 0
> As the file sizes get larger, the performance improves.  By the time the
> file size is 16MB, there is no difference in performance between runs
> using CFQ and runs using deadline.  The storage in my testing was a NetApp
> array connected via a single fibre channel link.  When testing against a
> single SATA disk, the performance difference is not apparent.

offtopic:

Can this patch help to reduce a pain of following much small files issue?

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=578635

Now, userland folks think sync() is faster than fsync() on ext4. I don't 
hope spread this unrecommended habit widely.



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