Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.12 21/27] sched/numa: Override part of migrate_degrades_locality() when idle balancing | Date | Mon, 10 Jul 2017 19:10:18 +0200 |
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4.12-stable review patch. If anyone has any objections, please let me know.
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From: Rik van Riel <riel@redhat.com>
commit 739294fb03f590401bbd7faa6d31a507e3ffada5 upstream.
Several tests in the NAS benchmark seem to run a lot slower with NUMA balancing enabled, than with NUMA balancing disabled. The slower run time corresponds with increased idle time.
Overriding the final test of migrate_degrades_locality (but still doing the other NUMA tests first) seems to improve performance of those benchmarks.
Reported-by: Jirka Hladky <jhladky@redhat.com> Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20170623165530.22514-2-riel@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6661,6 +6661,10 @@ static int migrate_degrades_locality(str if (dst_nid == p->numa_preferred_nid) return 0; + /* Leaving a core idle is often worse than degrading locality. */ + if (env->idle != CPU_NOT_IDLE) + return -1; + if (numa_group) { src_faults = group_faults(p, src_nid); dst_faults = group_faults(p, dst_nid);
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