From: James Bottomley <James.Bottomley@HansenPartnership.com>
Subject: Re: [BUG] fatal hang untarring 90GB file, possibly writeback
 related.
Date: Thu, 28 Apr 2011 10:57:42 -0500
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Cc: Chris Mason <chris.mason@oracle.com>, linux-fsdevel
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 linux-kernel <linux-kernel@vger.kernel.org>, linux-ext4
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To: Colin Ian King <colin.king@ubuntu.com>
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On Wed, 2011-04-27 at 19:25 +0100, Colin Ian King wrote:
> Just like to add that I've seen almost identical issues with 2.6.38
> copying large amounts of data to an ext4 filesystem with systems with
> small amounts of memory.
> 
> I found that increasing /sys/fs/ext4/sdaX/max_writeback_mb_bump worked
> around the issue.

With the PREEMPT kernel, values of 256 and 512 don't prevent kswapd
spinning up to 99% and staying there.

James


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