Re: [RFC] Limit the size of the pagecache

From: Peter Zijlstra
Date: Wed Jan 24 2007 - 07:58:49 EST


On Wed, 2007-01-24 at 23:50 +1100, Nick Piggin wrote:
> Peter Zijlstra wrote:
> > On Tue, 2007-01-23 at 16:49 -0800, Christoph Lameter wrote:
>
> >>2. Insure rapid turnaround of pages in the cache.
>
> [...]
>
> > The only maybe valid point would be 2, and I'd like to see if we can't
> > solve that differently - a better use-once logic comes to mind.
>
> There must be something I'm missing with that point. The faster
> the turnaround of pagecache pages, the *less* efficiently the
> pagecache is working (assuming a rapid turnaround means a high
> rate of pages brought into, then reclaimed from pagecache).
>
> I can't argue that a smaller pagecache will be subject to a
> higher turnaround given the same workload, but I don't know why
> that would be a good thing.

I interpreted the issue as selecting the wrong pages for the 'working
set'. Like not quickly evicting pages from a large streaming read, which
then pushes out more useful pages.

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