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Alex ShiIngo Molnar
Alex Shi
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Ingo Molnar
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sched/numa: Add SD_PERFER_SIBLING to CPU domain
Commit 8e7fbcb ("sched: Remove stale power aware scheduling remnants and dysfunctional knobs") removed SD_PERFER_SIBLING from the CPU domain. On NUMA machines this causes that load_balance() doesn't perfer LCPU in same physical CPU package. It causes some actual performance regressions on our NUMA machines from Core2 to NHM and SNB. Adding this domain flag again recovers the performance drop. This change doesn't have any bad impact on any of my benchmarks: specjbb, kbuild, fio, hackbench .. etc, on all my machines. Signed-off-by: Alex Shi <alex.shi@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1342765190-21540-1-git-send-email-alex.shi@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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‎include/linux/topology.h

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@@ -164,6 +164,7 @@ int arch_update_cpu_topology(void);
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| 0*SD_SHARE_CPUPOWER \
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| 0*SD_SHARE_PKG_RESOURCES \
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| 0*SD_SERIALIZE \
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| 1*SD_PREFER_SIBLING \
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, \
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.last_balance = jiffies, \
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.balance_interval = 1, \

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