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.