Re: [PATCH] 2.6.23-rc1-mm1 - fix missing numa_zonelist_order sysctl

From: Mel Gorman
Date: Thu Aug 02 2007 - 12:14:53 EST


On (02/08/07 09:44), KAMEZAWA Hiroyuki didst pronounce:
> On Wed, 01 Aug 2007 15:02:51 -0400
> Lee Schermerhorn <Lee.Schermerhorn@xxxxxx> wrote:
> > [But, maybe reordering the zonelists is not such a good idea
> > when ZONE_MOVABLE is populated?]
> >
>
> It's case-by-case I think. In zone order with ZONE_MOVABLE case,
> user's page cache will not use ZONE_NORMAL until ZONE_MOVABLE in all node
> is exhausted. This is an expected behavior, I think.
>

This is expected behaviour. I see no reason for lower zones to be used
for allocations that use memory from a higher zone with free memory.

> I think the real problem is the scheme for "How to set zone movable size to
> appropriate value for the system". This needs more study and documentation.
> (but maybe depends on system configuration to some extent.)
>

It depends on the system configuration and the workload requirements.
Right now, there isn't exact information available on what size the zone
should be. It'll need to be studied over a period of time.

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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