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Date: Sun, 16 Aug 2009 11:29:57 +0530
From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Rik van Riel <riel@redhat.com>, Avi Kivity <avi@redhat.com>,
       Andrea Arcangeli <aarcange@redhat.com>,
       "Dike, Jeffrey G" <jeffrey.g.dike@intel.com>,
       "Yu, Wilfred" <wilfred.yu@intel.com>,
       "Kleen, Andi" <andi.kleen@intel.com>,
       Hugh Dickins <hugh.dickins@tiscali.co.uk>,
       Andrew Morton <akpm@linux-foundation.org>,
       Christoph Lameter <cl@linux-foundation.org>,
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       Mel Gorman <mel@csn.ul.ie>, LKML <linux-kernel@vger.kernel.org>,
       linux-mm <linux-mm@kvack.org>
Subject: Re: [RFC] respect the referenced bit of KVM guest pages?
Message-ID: <20090816055957.GS5087@balbir.in.ibm.com>
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* Wu Fengguang <fengguang.wu@intel.com> [2009-08-16 12:55:22]:

> On Sun, Aug 16, 2009 at 11:56:39AM +0800, Rik van Riel wrote:
> > Wu Fengguang wrote:
> > 
> > > Right, but I meant busty page allocations and accesses on them, which
> > > can make a large continuous segment of referenced pages in LRU list,
> > > say 50MB.  They may or may not be valuable as a whole, however a local
> > > algorithm may keep the first 4MB and drop the remaining 46MB.
> > 
> > I wonder if the problem is that we simply do not keep a large
> > enough inactive list in Jeff's test.  If we do not, pages do
> > not have a chance to be referenced again before the reclaim
> > code comes in.
> 
> Exactly, that's the case I call the list FIFO.
> 
> > The cgroup stats should show how many active anon and inactive
> > anon pages there are in the cgroup.
> 
> Jeff, can you have a look at these stats? Thanks!

Another experiment would be to toy with memory.swappiness (although
defaults should work well). Could you compare the in-guest values of
nr_*active* with the cgroup values as seen by the host?

-- 
	Balbir