From: Jeff Moyer <jmoyer@redhat.com>
To: Jan Kara <jack@suse.cz>
Cc: jens.axboe@oracle.com, LKML <linux-kernel@vger.kernel.org>,
       Chris Mason <chris.mason@oracle.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Mike Galbraith <efault@gmx.de>
Subject: Re: Performance regression in IO scheduler still there
References: <20091026172012.GC7233@duck.suse.cz>
Date: Mon, 26 Oct 2009 13:26:54 -0400
In-Reply-To: <20091026172012.GC7233@duck.suse.cz> (Jan Kara's message of "Mon,
	26 Oct 2009 18:20:12 +0100")
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Jan Kara <jack@suse.cz> writes:

>   Hi,
>
>   I took time and remeasured tiobench results on recent kernel. A short
> conclusion is that there is still a performance regression which I reported
> few months ago. The machine is Intel 2 CPU with 2 GB RAM and plain SATA
> drive. tiobench sequential write performance numbers with 16 threads:
> 2.6.29:              AVG       STDERR
> 37.80 38.54 39.48 -> 38.606667 0.687475
>
> 2.6.32-rc5:
> 37.36 36.41 36.61 -> 36.793333 0.408928 
>
> So about 5% regression. The regression happened sometime between 2.6.29 and
> 2.6.30 and stays the same since then... With deadline scheduler, there's
> no regression. Shouldn't we do something about it?

Background:
  http://lkml.org/lkml/2009/5/28/415

Thanks for bringing this up again.  I'll try to make some time to look
into it if others don't beat me to it.

Cheers,
Jeff
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