Date: Mon, 26 Jul 2010 09:54:11 -0400
From: Vivek Goyal <vgoyal@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Heinz Diehl <htd@fancy-poultry.org>, linux-kernel@vger.kernel.org,
        jaxboe@fusionio.com, nauman@google.com, dpshah@google.com,
        guijianfeng@cn.fujitsu.com, jmoyer@redhat.com, czoccolo@gmail.com
Subject: Re: [RFC PATCH] cfq-iosched: IOPS mode for group scheduling and new
 group_idle tunable
Message-ID: <20100726135410.GD12449@redhat.com>
References: <1279834172-4227-1-git-send-email-vgoyal@redhat.com>
 <20100723140343.GA8478@fancy-poultry.org>
 <20100723141303.GB13104@redhat.com>
 <20100723145631.GA8844@fancy-poultry.org>
 <20100723183720.GD13104@redhat.com>
 <20100724080613.GA6554@fancy-poultry.org>
 <20100726134329.GB12449@redhat.com>
 <20100726134818.GA26544@infradead.org>
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On Mon, Jul 26, 2010 at 09:48:18AM -0400, Christoph Hellwig wrote:
> On Mon, Jul 26, 2010 at 09:43:29AM -0400, Vivek Goyal wrote:
> > > Don't know if this is related, but I'm not quite shure if XFS (which I use
> > > exclusively) uses the jbd/jbd2 journaling layer at all.
> > 
> > I also don't know. But because this patch is making a difference with your
> > XFS file system performance, may be it does use.
> > 
> > CCing Christoph, he can tell us.
> 
> No, of course XFS doesn't use jbd.

Hmm.., interesting. So somewhere WRITE_SYNC idling in CFQ is hurting XFS
performance also. This time for some other reason and not jbd/jbd2.

Vivek


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