Message-ID: <4CD696B4.6070002@kernel.dk>
Date: Sun, 07 Nov 2010 13:08:20 +0100
From: Jens Axboe <axboe@kernel.dk>
MIME-Version: 1.0
To: dave b <db.pub.mail@gmail.com>
CC: Sanjoy Mahajan <sanjoy@olin.edu>, Dave Chinner <david@fromorbit.com>,
        Jesper Juhl <jj@chaosbits.net>, Chris Mason <chris.mason@oracle.com>,
        Ingo Molnar <mingo@elte.hu>, Pekka Enberg <penberg@kernel.org>,
        Aidar Kultayev <the.aidar@gmail.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, Nick Piggin <npiggin@suse.de>,
        Arjan van de Ven <arjan@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>, "Ted Ts'o" <tytso@mit.edu>,
        Corrado Zoccolo <czoccolo@gmail.com>,
        Shaohua Li <shaohua.li@intel.com>, Steven Barrett <damentz@gmail.com>
Subject: Re: 2.6.36 io bring the system to its knees
References: <20101105014334.GF13830@dastard> <E1PELiI-0001Pj-8g@approx.mit.edu> <AANLkTimON_GL6vRF9=_U6oRFQ30EYssx3wv5xdNsU9JM@mail.gmail.com>
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On 2010-11-06 15:10, dave b wrote:
> I now personally have thought that this problem is the kernel not
> keeping track of reads vs writers properly  or not providing enough
> time to reading processes as writing ones which look like they are
> blocking the system....
> 
> If you want to do a simple test do an unlimited dd  (or two dd's of a
> limited size, say 10gb) and a find /
> Tell me how it goes :) ( the system will stall)
> (obviously stop the dd after some time :) ).
> 
> http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/4561
> iirc can reproduce this on plain ext3.

As already mentioned, ext3 is just not a good choice for this sort of
thing. Did you have atimes enabled?

-- 
Jens Axboe

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