Re: Suspected bug in shrink_caches()

[Andrew Morton <akpm@zip.com.au>]

José Luis Domingo López wrote:
> 
> On Wednesday, 02 January 2002, at 22:38:40 -0700,
> Sasha Pachev wrote:
> 
> > I am quite sure there is still a bug in shrink_caches(), at least there was
> > one in 2.4.17-rc2. I have not tried later releases, but there is nothing in
> > the changelog about the fixes anywhere near that area of the code, so I have
> > to assume the problem is still there.
> > [...]
> > When we get to the point where free memory starts running low, even though we
> > may have something like 100 MB of cache, shrink_caches() fails to free up
> > enough memory, which triggers the evil oom killer. Obviously, in the above
> > situation the correct behaviour is to go on cache diet before considering the
> > murders.
> >
> I can confirm this behaviour in my own machine. 128 MB of RAM, swap
> space turned off, machine running KDE 2.2.x, Konqueror, rxvt's, gkrellm,
> xmms and some daemons, and mighty Mozilla :). At this point there are
> still a couple of MB free, a couple buffered and aproximately 40 MB
> in caches.

The current VM gets really unhappy when you push it hard if there's no
swap available.

> ...
> 
> Maybe unrelated, maybe not, is the fact that in 2.4.17 I still see short
> "freezes" in interactive response after doing intensive disk access
> (untarring something, finishing some dd'ing, rebuilding Debian package
> database, etc.). Both on medium-end hardware (128 MB RAM, PIII 600) and
> low-end hardware (64 MB RAM, P166). Vanilla 2.4.17 on both, with ext2 as
> the only filesystem used in mounted partitions.

Please test
http://www.zip.com.au/~akpm/linux/2.4/2.4.18-pre1/read-latency2.patch

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