linux-kernel - Re: [PATCH] vmscan: evict use-once pages first (v2)

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Message-ID: <20090502232403.3ca10b97@riellaptop.surriel.com>
Date:	Sat, 2 May 2009 23:24:03 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Wu Fengguang <fengguang.wu@...el.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, elladan@...imo.com,
	peterz@...radead.org, linux-kernel@...r.kernel.org, tytso@....edu,
	kosaki.motohiro@...fujitsu.com, linux-mm@...ck.org
Subject: Re: [PATCH] vmscan: evict use-once pages first (v2)

On Sun, 3 May 2009 11:15:39 +0800
Wu Fengguang <fengguang.wu@...el.com> wrote:

> Commit 7e9cd484204f(vmscan: fix pagecache reclaim referenced bit
> check) tries to address scalability problem when every page get
> mapped and referenced, so that logic(which lowed the priority of
> mapped pages) could be enabled only on conditions like (priority <
> DEF_PRIORITY).
> 
> Or preferably we can explicitly protect the mapped executables,
> as illustrated by this patch (a quick prototype).

Over time, given enough streaming IO and idle applications,
executables will still be evicted with just this patch.

However, a combination of your patch and mine might do the
trick.  I suspect that executables are never a very big
part of memory, except on small memory systems, so protecting
just the mapped executables should not be a scalability
problem.

My patch in combination with your patch should make sure
that if something gets evicted from the active list, it's
not executables - meanwhile, lots of the time streaming
IO will completely leave the active file list alone.

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