This is a note to let you know that I've just added the patch titled
sched/numa: Override part of migrate_degrades_locality() when idle balancing
to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-numa-override-part-of-migrate_degrades_locality-when-idle-balancing.patch
and it can be found in the queue-4.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 739294fb03f590401bbd7faa6d31a507e3ffada5 Mon Sep 17 00:00:00 2001
From: Rik van Riel <riel@xxxxxxxxxx>
Date: Fri, 23 Jun 2017 12:55:27 -0400
Subject: sched/numa: Override part of migrate_degrades_locality() when idle balancing
From: Rik van Riel <riel@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20170623165530.22514-2-riel@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
Patches currently in stable-queue which might be from riel@xxxxxxxxxx are
queue-4.12/sched-numa-hide-numa_wake_affine-from-up-build.patch
queue-4.12/sched-numa-use-down_read_trylock-for-the-mmap_sem.patch
queue-4.12/sched-core-implement-new-approach-to-scale-select_idle_cpu.patch
queue-4.12/sched-fair-remove-effective_load.patch
queue-4.12/sched-numa-implement-numa-node-level-wake_affine.patch
queue-4.12/sched-fair-simplify-wake_affine-for-the-single-socket-case.patch
queue-4.12/sched-fair-cpumask-export-for_each_cpu_wrap.patch
queue-4.12/sched-numa-override-part-of-migrate_degrades_locality-when-idle-balancing.patch