Commit a6eaf385 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents f4cc74c9 a22a5cb8

kernel/Kconfig.preempt

+3 −3
Original line number Diff line number Diff line
@@ -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.

kernel/sched/fair.c

+3 −3
Original line number Diff line number Diff line
@@ -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