Re: New Feature Idea: Compress swap file

Peter T. Waltenberg (peterw@karaka.chch.cri.nz)
Fri, 20 Feb 1998 15:38:15 +1300 (NZDT)

There's also the problem of mapping between swapped pages on disk and in
memory. At the moment it's 4k in mem<->4k on disk, working out where the
pages are going to and coming from is trivial and there's no real chance
of fragmenting the swap space.

If we compress, the pages on disk are variable sized, once you've paged
in and out a few hundred times we could easilly fragment the swap space to
hell :).

Then what ?, stall while we defragment the swap space.

Keep it simple.

Peter

On 20-Feb-98 docwhat@gerf.org ;The Doctor What wrote:
> Telephone Game! Rik van Riel said (on 01:19 AM 2/20/98 +0100):
> ->Sorry Jim and Adam, compressed swap has already been
> ->implemented and tried. The results were:
> ->- more CPU spent on swapping --> slower system
> ->- more I/O spent on swapping because the I/O patterns
> -> became more complex than normal swap --> slower system
>
> Can't optimize this by compressing on a per page basis? I'm not overly
> familiar with the theory, but it seems that there is less to compress
> (yeah, the compression isn't as good) and less for the CPU to worry about.
>
> Hmmm.... If only there was intellegent hardware that could do this for
> us...
>
> Just an Idea
> -=Doc
> --
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E-Mail: P.Waltenberg@irl.cri.nz
Date: 20-Feb-98
Time: 15:34:44
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