From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [Bug #12809] iozone regression with 2.6.29-rc6
Date: Sat, 7 Mar 2009 22:35:52 +0100
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Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Kernel Testers List <kernel-testers@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       "Lin, Ming M" <ming.m.lin@intel.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Nick Piggin <npiggin@suse.de>, Peter Zijlstra <a.p.zijlstra@chello.nl>
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On Thursday 05 March 2009, Wu Fengguang wrote:
> On Tue, Mar 03, 2009 at 09:25:59PM +0200, Rafael J. Wysocki wrote:
> > This message has been generated automatically as a part of a report
> > of recent regressions.
> > 
> > The following bug entry is on the current list of known regressions
> > from 2.6.28.  Please verify if it still should be listed and let me know
> > (either way).
> > 
> > 
> > Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=12809
> > Subject		: iozone regression with 2.6.29-rc6
> > Submitter	: Lin Ming <ming.m.lin@intel.com>
> > Date		: 2009-02-27 9:13 (5 days old)
> > First-Bad-Commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=1cf6e7d83bf334cc5916137862c920a97aabc018
> > References	: http://marc.info/?l=linux-kernel&m=123572630504360&w=4
> > Handled-By	: Wu Fengguang <fengguang.wu@intel.com>
> 
> Following Peter's idea of relaxing writeback throttling, Lin Ming
> and I tried the idea of totally disabling writeback throttling by
> doing benchmarks with the following parameters:
> 
>         echo 60 > /proc/sys/vm/dirty_ratio
>         echo 50 > /proc/sys/vm/dirty_background_ratio
> 
> The result is encouraging: the iozone performance is restored to the
> level of 2.6.29-rc5!
> 
> We'll continue to evaluate the dirty/throttling numbers with Nick's patch.

Thanks for the update.

Rafael
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