Subject: Re: Sudden and massive page cache eviction
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter =?ISO-8859-1?Q?Sch=FCller?= <scode@spotify.com>,
        linux-kernel@vger.kernel.org,
        Mattias de Zalenski <zalenski@spotify.com>, linux-mm@kvack.org
In-Reply-To: <20101122161158.02699d10.akpm@linux-foundation.org>
References: <AANLkTikg-sR97tkG=ST9kjZcHe6puYSvMGh-eA3cnH7X@mail.gmail.com>
	 <20101122161158.02699d10.akpm@linux-foundation.org>
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Date: Tue, 23 Nov 2010 00:38:22 -0800
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On Mon, 2010-11-22 at 16:11 -0800, Andrew Morton wrote:
> > This latest observation we understand may be due to NUMA related
> > allocation issues, and we should probably try to use numactl to ask
> > for a more even allocation. We have not yet tried this. However, it
> is not clear how any issues having to do with that would cause sudden
> > eviction of data already *in* the page cache (on whichever node). 

You don't have anybody messing with /proc/sys/vm/drop_caches, do you?

That can cause massive, otherwise unprovoked page cache eviction.  

-- Dave

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