Re: [PATCH] strict VM overcommit accounting for 2.4.32/2.4.33-pre1

From: Willy Tarreau
Date: Sat Dec 31 2005 - 10:00:42 EST


On Sat, Dec 31, 2005 at 03:26:18PM +0100, Arjan van de Ven wrote:
> On Sat, 2005-12-31 at 17:02 +0300, Al Boldi wrote:
>
> > Shouldn't it be possible to disable overcommit completely, thus giving kswapd
> > a break from running wild trying to find something to swap/page, which is
> > the reason why the system gets unstable going over 95% in your example.
>
> shared mappings make this impractical. To disable overcommit completely,
> each process would need to account for all its own shared libraries, eg
> each process gets glibc added etc. You'll find that on any
> non-extremely-stripped system you then end up with much more memory
> needed than you have ram.

Arjan, is this true even for read-only mappings such as shared libs ?
It seems to me that those ones can precisely be mapped once because
they are areas the process cannot extend. Am I wrong ?

Willy

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