Re: More info: 2.1.108 page cache performance on low memory

["Stephen C. Tweedie" <sct@redhat.com>]

Hi,

On 13 Jul 1998 20:29:33 +0200, Zlatko Calusic <Zlatko.Calusic@CARNet.hr>
said:

> I agree that ageing of the page cache has a bad impact on the
> performance.

> Just to mention, I have 64MB of physical memory, and my machine is
> definitely not memory starved, but it also suffers from some of the
> recent VM changes.

Yep.  Has anybody else got observations about what sort of
configurations are helped or hindered by the current 2.1 changes?

> That (removing cache limits) is one of my favorite changes.

> Free memory == unused memory == bad policy!

> There is no reason why any of the caches would not utilize all of the
> free memory at any given moment.

The existing limits don't affect the ability of the cache to grow; they
just give a target bound for the cache when we start trying to get pages
back for something else.

> If anybody want to see, I can provide benchmark results, but I'm not
> prepared to compile another kernel image if nobody's interested. :)

Well, I've been compiling kernels all day for this. :)  Any information
you can give will help, but for now it does look as if backing out the
cache ageing is a necessary first step.

--Stephen
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