Re: [PATCH] mm: inactive-clean list

From: Martin Schwidefsky
Date: Thu Jul 27 2006 - 07:14:39 EST

On 7/26/06, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
Wouldn't we typically have all free pages > min_free in state U?
Also wouldn't all R/O mapped pages not also be V, all R/W mapped pages
and unmapped page-cache pages P like you state in your paper.

Ahh, ok, I misunderstood. You want to keep the state changes for clean
page cache pages, I assumed that you only want to make pages volatile
if the get on the inactive_clean list and leave them stable if they
are on one of the other two lists.

This patch would just increase the number of V pages with the tail end
of the guest LRU, which are typically the pages you would want to evict
(perhaps even add 5th guest state to indicate that these V pages are
preferable over the others?)

Yes, that would help for architectures that cannot implement the
potential-volatile state.

But isn't it so that for the gross over-commit scenario you outline the
host OS will have to swap out S pages eventually?

My point was that you really have to distinguish between host memory
pressure and guest memory pressure.

blue skies,
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