[GIT PULL] scheduler fixes for v5.14

From: Ingo Molnar
Date: Wed Jun 30 2021 - 06:53:26 EST


Linus,

Please pull the latest sched/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-2021-06-30

# HEAD: a22a5cb81e20657194fde6c835e07d28c4dfddbe Merge branch 'sched/core' into sched/urgent, to pick up fix

- Fix a small inconsistency (bug) in load tracking, caught by a
new warning that several people reported.

- Flip CONFIG_SCHED_CORE to default-disabled, and update the
Kconfig help text.

Thanks,

Ingo

------------------>
Ingo Molnar (1):
sched/core: Disable CONFIG_SCHED_CORE by default

Odin Ugedal (1):
sched/fair: Ensure _sum and _avg values stay consistent


kernel/Kconfig.preempt | 6 +++---
kernel/sched/fair.c | 6 +++---
2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index bd7c4147b9a8..5876e30c5740 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -102,7 +102,6 @@ config PREEMPT_DYNAMIC

config SCHED_CORE
bool "Core Scheduling for SMT"
- default y
depends on SCHED_SMT
help
This option permits Core Scheduling, a means of coordinated task
@@ -115,7 +114,8 @@ config SCHED_CORE
- mitigation of some (not all) SMT side channels;
- limiting SMT interference to improve determinism and/or performance.

- SCHED_CORE is default enabled when SCHED_SMT is enabled -- when
- unused there should be no impact on performance.
+ SCHED_CORE is default disabled. When it is enabled and unused,
+ which is the likely usage by Linux distributions, there should
+ be no measurable impact on performance.


diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4a3e61a88acc..45edf61eed73 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3657,15 +3657,15 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)

r = removed_load;
sub_positive(&sa->load_avg, r);
- sub_positive(&sa->load_sum, r * divider);
+ sa->load_sum = sa->load_avg * divider;

r = removed_util;
sub_positive(&sa->util_avg, r);
- sub_positive(&sa->util_sum, r * divider);
+ sa->util_sum = sa->util_avg * divider;

r = removed_runnable;
sub_positive(&sa->runnable_avg, r);
- sub_positive(&sa->runnable_sum, r * divider);
+ sa->runnable_sum = sa->runnable_avg * divider;

/*
* removed_runnable is the unweighted version of removed_load so we