Re: [patch 1/4] pcp: zonequeues

[Christoph Lameter <christoph@lameter.com>]

Seems that this also effectively addresses the issues raised with the
pageset localization patches. Great work Nick!

On Sat, 9 Apr 2005, Nick Piggin wrote:

> Hi Jack,
> Was thinking about some problems in this area, and I hacked up
> a possible implementation to improve things.
>
> 1/4 switches the per cpu pagesets in struct zone to a single list
> of zone pagesets for each CPU.
>
> 2/4 changes the per cpu list of pagesets to a list of pointers to
> pagesets, and allocates them dynamically.
>
> 3/4 changes the code to allow NULL pagesets. In that case, a single
> per-zone pageset is used, which is protected by the zone's spinlock.
>
> 4/4 changes setup so non local zones don't have associated pagesets.
>
> It still needs some work - in particular, many NUMA systems probably
> don't want this. I guess benchmarks should be done, and maybe we
> could look at disabling the overhead of 3/4 and functional change of
> 4/4 depending on a CONFIG_ option.
>
> Also, you say you might want "close" remote nodes to have pagesets,
> but 4/4 only does local nodes. I added a comment with patch 4/4
> marked with XXX which should allow you to do this quite easily.
>
> Not tested (only compiled) on a NUMA system, but the NULL pagesets
> logic appears to work OK. Boots on a small UMA SMP system. So just
> be careful with it.
>
> Comments?
>
> --
> SUSE Labs, Novell Inc.
>
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