linux-kernel - Re: [rfc 3/3] mm: vmscan: revert file list boost on lru addition

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Date:	Mon, 7 Nov 2011 11:45:20 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Johannes Weiner <jweiner@...hat.com>
Cc:	Konstantin Khlebnikov <khlebnikov@...allels.com>,
	Pekka Enberg <penberg@...nel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>,
	Minchan Kim <minchan.kim@...il.com>,
	Gene Heskett <gene.heskett@...il.com>
Subject: Re: [rfc 3/3] mm: vmscan: revert file list boost on lru addition

On Wed, 2 Nov 2011 17:32:47 +0100
Johannes Weiner <jweiner@...hat.com> wrote:

> The idea in 9ff473b 'vmscan: evict streaming IO first' was to steer
> reclaim focus onto file pages with every new file page that hits the
> lru list, so that an influx of used-once file pages does not lead to
> swapping of anonymous pages.
> 
> The problem is that nobody is fixing up the balance if the pages in
> fact become part of the resident set.
> 
> Anonymous page creation is neutral to the inter-lru balance, so even a
> comparably tiny number of heavily used file pages tip the balance in
> favor of the file list.
> 
> In addition, there is no refault detection, and every refault will
> bias the balance even more.  A thrashing file working set will be
> mistaken for a very lucrative source of reclaimable pages.
> 
> As anonymous pages are no longer swapped above a certain priority
> level, this mechanism is no longer needed.  Used-once file pages
> should get reclaimed before the VM even considers swapping.
> 
> Signed-off-by: Johannes Weiner <jweiner@...hat.com>

Do you have some results ?

Thanks,
-Kame

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