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- Fix a small inconsistency (bug) in load tracking, caught by a

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new warning that several people reported.
 
 - Flip CONFIG_SCHED_CORE to default-disabled, and update the
   Kconfig help text.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2021-06-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar:

 - 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.

* tag 'sched-urgent-2021-06-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Disable CONFIG_SCHED_CORE by default
  sched/fair: Ensure _sum and _avg values stay consistent
This commit is contained in:
Linus Torvalds 2021-06-30 15:37:49 -07:00
commit a6eaf3850c
2 changed files with 6 additions and 6 deletions
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6
kernel/Kconfig.preempt
View File

@ -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.

6
kernel/sched/fair.c
View File

@ -3685,15 +3685,15 @@ 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