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Date: Wed, 25 Jun 2014 15:23:42 +0200
Message-ID: <CABhLV02COaH=qP=Snd7YJtcVOvm9NTmY58QuiTQoPZxH3NemPQ@mail.gmail.com>
Subject: Re: [PATCH] sysctl: Add a feature to drop caches selectively
From: Thomas Knauth <thomas.knauth@gmx.de>
To: Artem Bityutskiy <dedekind1@gmail.com>
Cc: David Rientjes <rientjes@google.com>,
        Maksym Planeta <mcsim.planeta@gmail.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org

On Wed, Jun 25, 2014 at 11:56 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> Thanks for the answer, although you forgot to comment on the question
> about possibly extending the new interface to work with file ranges in
> the future. For example, I have a 2 TiB file, and I am only interested
> in dropping caches for the first couple of gigabytes. Would I extend
> your interface, or would I come up with another one?

Ah, didn't quite understand what was meant with file ranges. Again, we
had not considered this so far. I guess you could make a distinction
between directories and files here. If the path points to a file, you
can have an optional argument indicating the range of bytes you would
like to drop. Something like

echo "my-file 0-1000,8000-1000" > /proc/sys/vm/sdrop_cache

If this is desirable, we can add it to the patch.
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