linux-kernel - Re: Over-eager swapping

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Message-ID: <20100818161346.GA12932@localhost>
Date:	Thu, 19 Aug 2010 00:13:46 +0800
From:	Wu Fengguang <fengguang.wu@...el.com>
To:	Chris Webb <chris@...chsys.com>
Cc:	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Minchan Kim <minchan.kim@...il.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Andi Kleen <andi@...stfloor.org>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: Over-eager swapping

On Wed, Aug 18, 2010 at 11:58:25PM +0800, Chris Webb wrote:
> Lee Schermerhorn <Lee.Schermerhorn@...com> writes:
> 
> > On Wed, 2010-08-18 at 23:21 +0800, Wu Fengguang wrote:
> > > Andi, Christoph and Lee:
> > > 
> > > This looks like an "unbalanced NUMA memory usage leading to premature
> > > swapping" problem.
> > 
> > What is the value of the vm.zone_reclaim_mode sysctl?  If it is !0, the
> > system will go into zone reclaim before allocating off-node pages.
> > However, it shouldn't "swap" in this case unless (zone_reclaim_mode & 4)
> > != 0.  And even then, zone reclaim should only reclaim file pages, not
> > anon.  In theory...
> 
> Hi. This is zero on all our machines:
> 
> # sysctl vm.zone_reclaim_mode
> vm.zone_reclaim_mode = 0

Chris, can you post /proc/vmstat on the problem machines?

Thanks,
Fengguang
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