linux-kernel - Re: Poor interactive performance with I/O loads with fsync()ing

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Date:	Sat, 27 Mar 2010 20:42:33 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Ben Gamari <bgamari.foss@...il.com>
Cc:	linux-kernel@...r.kernel.org, tytso@....edu, npiggin@...e.de,
	mingo@...e.hu, Ruald Andreae <ruald.a@...il.com>,
	Jens Axboe <jens.axboe@...cle.com>,
	Olly Betts <olly@...vex.com>,
	martin f krafft <madduck@...duck.net>
Subject: Re: Poor interactive performance with I/O loads with fsync()ing

On Sat, 27 Mar 2010 18:20:37 -0700 (PDT)
Ben Gamari <bgamari.foss@...il.com> wrote:

> Hey all,
> 
> I have posted another profile[1] from an incident yesterday. As you
> can see, both swapper and init (strange?) show up prominently in the
> profile. Moreover, most processes seem to be in blk_peek_request a
> disturbingly large percentage of the time. Both of these profiles
> were taken with 2.6.34-rc kernels.
> 
> Anyone have any ideas on how to proceed? Is more profile data
> necessary? Are the existing profiles at all useful? Thanks,


profiles tend to be about cpu usage... and are rather poor to deal with
anything IO related.

latencytop might get closer in giving useful information....

(btw some general suggestion.. make sure you're using noatime or
relatime as mount option) 
-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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