partitioning HD for use of swap & for booting

Bogdan Costescu bogdan.costescu at iwr.uni-heidelberg.de
Fri Jun 1 11:59:00 EDT 2001


On Fri, 1 Jun 2001, Robert G. Brown wrote:

> I've heard that 2x memory is the MINIMUM recommended for the
> 2.4 kernels for performance reasons.

This was specifically mentioned when 2.4.0 was launched as it's an
important difference w.r.t. 2.2 line.

> I'd even speculate that a 2.4 kernel
> with lots of memory but small swapspace is a better performer than a 2.4
> kernel with barely enough memory but plenty of swapspace.

No, a 2.4 kernel with small swap space will perform poorly especially with
latest (2.4.4, 2.4.5) kernels. There was/is a discussion on lkml about
that; some people say that from 2.4.0, with every new release, the
behaviour got worse. Some even say that 2.4.x should not be considered
"stable series" because of the VM problems.

> Linux has a very decent memory management system, and generally ...

I guess the more appropiate form is "should have".

Please don't take me as a VM expert. I'm subscribed to lkml and read most
of the messages, that's the source for all the above info. However, as
Linux workstation user, I've noticed a clear degradation between 2.2 and
2.4, even some stability problems.
(To get back on the beowulf track) Until 2.4 behaves at least as good as
2.2 in all aspects, I'm only running 2.2 on the clusters that I administer.

Back on the swap track: we're on the beowulf list and this question should
be in fact related to usage of swap in clusters. I always found a bad
ideea running a parallel application that doesn't fit in RAM (well,
probably a very coarse grained one might work OK). So I'd second Robert's
suggestion to buy more RAM if possible.

Sincerely,

Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu at IWR.Uni-Heidelberg.De




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