Re: cfq-iosched: a regression

From: Shaohua Li
Date: Thu Aug 18 2011 - 20:20:37 EST


On Fri, 2011-08-19 at 04:22 +0800, Justin TerAvest wrote:
> Hi Shaohua,
>
> What was the workload you were running to find this regression?
kernel build as I declared below.

Thanks,
Shaohua

> On Mon, Aug 15, 2011 at 7:47 PM, Shaohua Li <shaohua.li@xxxxxxxxx> wrote:
> > We have a kernel build regression since 3.1-rc1, which is about 10%
> > regression. The kernel source is in an ext3 filesystem.
> > Alex Shi bisect it to commit:
> > commit a07405b7802691d29ab3b23bdc76ee6d006aad0b
> > Author: Justin TerAvest <teravest@xxxxxxxxxx>
> > Date: Sun Jul 10 22:09:19 2011 +0200
> >
> > cfq: Remove special treatment for metadata rqs.
> >
> > Apparently this is caused by lack metadata preemption, where ext3/ext4
> > do use READ_META. I didn't see a way to fix the issue, so suggest
> > reverting the patch.
> >
> > Reported-by: Alex Shi<alex.shi@xxxxxxxxx>
> > Reported-by: Shaohua Li<shaohua.li@xxxxxxxxx>
> >
> >


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