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Message-ID: <6e0cfd1d0607270416g1248e93fi123b6ada852ff242@mail.gmail.com>
Date: Thu, 27 Jul 2006 13:16:45 +0200
From: "Martin Schwidefsky" <schwidefsky@googlemail.com>
To: "Peter Zijlstra" <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH] mm: inactive-clean list
Cc: "Rik van Riel" <riel@redhat.com>, linux-mm <linux-mm@kvack.org>,
       "Linus Torvalds" <torvalds@osdl.org>, "Andrew Morton" <akpm@osdl.org>,
       linux-kernel <linux-kernel@vger.kernel.org>
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On 7/26/06, Peter Zijlstra <a.p.zijlstra@chello.nl> 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,
  Martin