sched: Fix select_idle_sibling() bouncing cow syndrome

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If the previous CPU is cache affine and idle, select it.

The current implementation simply traverses the sd_llc domain,
taking the first idle CPU encountered, which walks buddy pairs
hand in hand over the package, inflicting excruciating pain.

1 tbench pair (worst case) in a 10 core + SMT package:

  pre   15.22 MB/sec 1 procs
  post 252.01 MB/sec 1 procs

Signed-off-by: Mike Galbraith <bitbucket@online.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1359371965.5783.127.camel@marge.simpson.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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Mike Galbraith 2013-01-28 12:19:25 +01:00 • committed by Ingo Molnar

parent 60334caf37

commit e0a79f529d

1 changed files with 7 additions and 14 deletions

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23

kernel/sched/fair.c

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