linux-kernel - Containers and /proc/sys/vm/drop

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Message-ID: <20101230075901.GA4115@glandium.org>
Date:	Thu, 30 Dec 2010 08:59:01 +0100
From:	Mike Hommey <mh@...ndium.org>
To:	linux-kernel@...r.kernel.org
Subject: Containers and /proc/sys/vm/drop_caches

Hi,

I noticed that from within a lxc container, writing "3" to
/proc/sys/vm/drop_caches would flush the host page cache. That sounds a
little dangerous for VPS offerings that would be based on lxc, as in one
VPS instance root user could impact the overall performance of the host.
I don't know about other containers but I've been told openvz isn't
subject to this problem.
I only tested the current Debian Squeeze kernel, which is based on
2.6.32.27.

Cheers,

Mike
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