[PATCH 0/3] sched,numa: reduce page migrations with pseudo-interleaving

From: riel
Date: Fri Apr 11 2014 - 13:24:40 EST


The pseudo-interleaving code deals fairly well with the placement
of tasks that are part of workloads that span multiple NUMA nodes,
but the code has a number of corner cases left that can result in
higher than desired overhead.

This patch series reduces the overhead slightly, mostly visible
through a lower number of page migrations, while leaving the
throughput of the workload essentially unchanged.

On smaller NUMA systems, these patches should have little or no
effect. On a 4 node test system, I did see a reduction in the
number of page migrations running SPECjbb2005; autonuma-benchmark
appears to be unaffected.

NUMA page migrations on an 8 node system running SPECjbb2005,
courtesy of Vinod:

vanilla with patch
8 - 1 socket wide: 9138324 8918971
4 - 2 socket wide: 8239914 7315148
2 - 4 socket wide: 5732744 3849624
1 - 8 socket wide: 3348475 2660347

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