From 739c89319601b303d523d14a1b6858d3bea8789c Mon Sep 17 00:00:00 2001
From: Matt Fleming <mfleming@suse.de>
Date: Tue, 31 Oct 2017 13:57:03 +0000
Subject: [PATCH] sched/fair: Enable SIS_AVG_CPU by default
Patch-mainline: Not yet, pending
References: bsc#1061593,bsc#1148030
This scheduler knob was introduced to limit scans of the LLC domain in
situations where the cost of scanning isn't worth it.
Turning it on results in a decent improvement to tbench's throughput
for all machines on the performance test grid.
Here's a typical result:
tbench4
4.12.14 4.12.14
sles15 sles15-sis-avg-cpu
Hmean mb/sec-1 568.89 ( 0.00%) 581.57 ( 2.23%)
Hmean mb/sec-2 1136.19 ( 0.00%) 1126.80 ( -0.83%)
Hmean mb/sec-4 2114.17 ( 0.00%) 2155.82 ( 1.97%)
Hmean mb/sec-8 3868.19 ( 0.00%) 3900.22 ( 0.83%)
Hmean mb/sec-16 7355.25 ( 0.00%) 7378.81 ( 0.32%)
Hmean mb/sec-32 12610.86 ( 0.00%) 12633.55 ( 0.18%)
Hmean mb/sec-64 16523.71 ( 0.00%) 21391.61 ( 29.46%)
Hmean mb/sec-128 31329.89 ( 0.00%) 31723.43 ( 1.26%)
Hmean mb/sec-256 31611.06 ( 0.00%) 31977.63 ( 1.16%)
Hmean mb/sec-320 31773.01 ( 0.00%) 31836.25 ( 0.20%)
See
http://laplace.suse.de/pt-master/SLE-15-SP2/0005-mgorman-sisavgcpu/dashboard.html
for a more general comparison.
Signed-off-by: Matt Fleming <mfleming@suse.de>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
kernel/sched/features.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 319ed0e8a347..01125351736e 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -54,7 +54,7 @@ SCHED_FEAT(TTWU_QUEUE, true)
/*
* When doing wakeups, attempt to limit superfluous scans of the LLC domain.
*/
-SCHED_FEAT(SIS_AVG_CPU, false)
+SCHED_FEAT(SIS_AVG_CPU, true)
SCHED_FEAT(SIS_PROP, true)
/*
--
2.14.2