The following commit has been merged into the sched/core branch of tip: Commit-ID: 7b419f47facd286c6723daca6ad69ec355473f78 Gitweb: https://git.kernel.org/tip/7b419f47facd286c6723daca6ad69ec355473f78 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Tue, 25 May 2021 08:53:28 +02:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Tue, 01 Jun 2021 16:00:10 +02:00 sched: Add CONFIG_SCHED_CORE help text Hugh noted that the SCHED_CORE Kconfig option could do with a help text. Requested-by: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> Link: https://lkml.kernel.org/r/YKyhtwhEgvtUDOyl@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx --- kernel/Kconfig.preempt | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index ea1e333..bd7c414 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -104,4 +104,18 @@ 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 + selection across SMT siblings. When enabled -- see + prctl(PR_SCHED_CORE) -- task selection ensures that all SMT siblings + will execute a task from the same 'core group', forcing idle when no + matching task is found. + + Use of this feature includes: + - 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. +
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