Date: Thu, 30 Apr 2009 20:59:36 -0400
From: Rik van Riel <riel@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Elladan <elladan@eskimo.com>, peterz@infradead.org,
       linux-kernel@vger.kernel.org, tytso@mit.edu,
       kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org
Subject: Re: [PATCH] vmscan: evict use-once pages first (v2)
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On Thu, 30 Apr 2009 17:45:36 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> Were you able to tell whether altering /proc/sys/vm/swappiness
> appropriately regulated the rate at which the mapped page count
> decreased?

That should not make a difference at all for mapped file
pages, after the change was merged that makes the VM ignores
the referenced bit of mapped active file pages.

Ever since the split LRU code was merged, all that the
swappiness controls is the aggressiveness of file vs
anonymous LRU scanning.

Currently the kernel has no effective code to protect the 
page cache working set from streaming IO.  Elladan's bug
report shows that we do need some kind of protection...

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