linux-kernel - Re: [RFC] respect the referenced bit of KVM guest pages?

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Date:	Fri,  7 Aug 2009 12:17:22 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	Andrea Arcangeli <aarcange@...hat.com>,
	Wu Fengguang <fengguang.wu@...el.com>,
	"Dike, Jeffrey G" <jeffrey.g.dike@...el.com>,
	"Yu, Wilfred" <wilfred.yu@...el.com>,
	"Kleen, Andi" <andi.kleen@...el.com>, Avi Kivity <avi@...hat.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>
Subject: Re: [RFC] respect the referenced bit of KVM guest pages?

> Andrea Arcangeli wrote:
> 
> > Likely we need a cut-off point, if we detect it takes more than X
> > seconds to scan the whole active list, we start ignoring young bits,
> 
> We could just make this depend on the calculated inactive_ratio,
> which depends on the size of the list.
> 
> For small systems, it may make sense to make every accessed bit
> count, because the working set will often approach the size of
> memory.
> 
> On very large systems, the working set may also approach the
> size of memory, but the inactive list only contains a small
> percentage of the pages, so there is enough space for everything.
> 
> Say, if the inactive_ratio is 3 or less, make the accessed bit
> on the active lists count.

Sound reasonable. How do we confirm the idea correctness?
Wu, your X focus switching benchmark is sufficient test?



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