From: Juergen Beisert <juergen127@kreuzholzen.de>
Organization: Privat
To: linux-kernel@vger.kernel.org
Subject: Re: speeding up swapoff
Date: Wed, 29 Aug 2007 17:12:35 +0200
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Cc: Daniel Drake <ddrake@brontes3d.com>,
       Arjan van de Ven <arjan@infradead.org>, linux-mm@kvack.org
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On Wednesday 29 August 2007 16:44, Daniel Drake wrote:
> On Wed, 2007-08-29 at 07:30 -0700, Arjan van de Ven wrote:
> > > My experiments show that when there is not much free physical memory,
> > > swapoff moves pages out of swap at a rate of approximately 5mb/sec.
> >
> > sounds like about disk speed (at random-seek IO pattern)
>
> We are only using 'standard' seagate SATA disks, but I would have
> thought much more performance (40+ mb/sec) would be reachable.
>
> > before you go there... is this a "real life" problem? Or just a
> > mostly-artificial corner case? (the answer to that obviously is
> > relevant for the 'should we really care' question)
>
> It's more-or-less a real life problem. We have an interactive
> application which, when triggered by the user, performs rendering tasks
> which must operate in real-time. In attempt to secure performance, we
> want to ensure everything is memory resident and that nothing might be
> swapped out during the process. So, we run swapoff at that time.

Did you play with mlock()?

Juergen
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