Re: Swapping in 2.1.103?

Geert Uytterhoeven (
Thu, 21 May 1998 21:49:36 +0200 (CEST)

On Thu, 21 May 1998, Karl GŁnter =?ISO-8859-1?Q?W=FCnsch ?= wrote:
> I have one concern with the latest development kernels and that concern
> is swapping.
> (I am going to check this on a 2.1.88/2.1.40 if this helps, but that
> really depends on time at hand which is a scarce resource at the moment)

That won't matter. It's also true for 2.0.x.

> OK. Lets describe the setup:
> Freshly booted system. 128 Mb of RAM and really only 25 MB used at the
> time of the test (mostly a netscape and X11). The test:
> tar cf - . | cat >/dev/null
> In my opinion this test shouldn't force any applications to be swapped
> (because the only thing really used by this test is the buffer cache,
> which is supposed to take up only free memory). Well the end of the
> story is, that I end up with more than 10 Mb of swap space used, and 11
> Mb of free memory. Why is buffering preferred to keeping applications in
> memory?

This is a generalization of the `least recently used' principle. If an
application didn't use all its pages recently, some of them may be swapped out
when more free memory is needed.

What's wrong with that? Nothing. If a program was idle, it should be swapped
out to make room for more current activities.



Geert Uytterhoeven           
Wavelets, Linux/{m68k~Amiga,PPC~CHRP}
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium

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