Date: Tue, 1 Jun 2004 09:50:08 +0100
From: John Bradford <john@grabjohn.com>
Message-Id: <200406010850.i518o8PD000134@81-2-122-30.bradfords.org.uk>
To: William Lee Irwin III <wli@holomorphy.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>, Michael Brennan <mbrennan@ezrs.com>,
       linux-kernel@vger.kernel.org
In-Reply-To: <20040601083206.GI2093@holomorphy.com>
References: <40BB88B5.8080300@ezrs.com>
 <200405312029.i4VKTCZ0000596@81-2-122-30.bradfords.org.uk>
 <40BBB5F7.1010407@yahoo.com.au>
 <200406010834.i518Y1cT000414@81-2-122-30.bradfords.org.uk>
 <20040601083206.GI2093@holomorphy.com>
Subject: Re: why swap at all?
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1193
Lines: 27

Quote from William Lee Irwin III <wli@holomorphy.com>:
> On Tue, Jun 01, 2004 at 09:34:01AM +0100, John Bradford wrote:
> > Sure, but tell me, for example, what is the point of having swap on a system
> > like this:
> > $ free
> >              total       used       free     shared    buffers     cached
> > Mem:        516688      19900     496788          0        628      11276
> > -/+ buffers/cache:       7996     508692
> > Swap:            0          0          0
> 
> So you can move userspace pages out of ZONE_DMA as-needed.

But how does that improve performance before untouched RAM, (496788 in this
example), is exhausted?

In normal use, (almost always CPU bound), I've honestly never noticed any
performance gain from having swap configured.  I must admit I haven't put
a lot of effort recently in to looking at this, but I have never been able
to reproduce these 'swap increases performance even with untouched RAM'
claims.

John.
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