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Re: [RFC PATCH] sched/numa: do load balance between remote nodes

To: Alex Shi <>
Subject: Re: [RFC PATCH] sched/numa: do load balance between remote nodes
From: Sergei Shtylyov <>
Date: Wed, 06 Jun 2012 14:53:08 +0400
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On 06-06-2012 10:52, Alex Shi wrote:

commit cb83b629b

   Please also specify that commit's summary in parens.

remove the NODE sched domain and check if the node
distance in SLIT table is farther than REMOTE_DISTANCE, if so, it will
lose the load balance chance at exec/fork/wake_affine points.

But actually, even the node distance is farther than REMOTE_DISTANCE,
Modern CPUs also has QPI like connections, that make memory access is

   "Is" not needed here.

not too slow between nodes.  So above losing on NUMA machine make a
huge performance regression on benchmark: hackbench, tbench, netperf
and oltp etc.

This patch will recover the scheduler behavior to old mode on all my
Intel platforms: NHM EP/EX, WSM EP, SNB EP/EP4S, and so remove the
perfromance regressions. (all of them just has 2 kinds distance, 10 21)

Signed-off-by: Alex Shi<>

WBR, Sergei

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