From: Peter Zijlstra <peterz@infradead.org> mainline inclusion from mainline-v5.14-rc1 commit 7b419f47facd286c6723daca6ad69ec355473f78 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5OOWG CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------------------------------------------------- Hugh noted that the SCHED_CORE Kconfig option could do with a help text. Requested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Hugh Dickins <hughd@google.com> Link: https://lkml.kernel.org/r/YKyhtwhEgvtUDOyl@hirez.programming.kicks-ass.net Signed-off-by: Lin Shengwang <linshengwang1@huawei.com> Reviewed-by: lihua <hucool.lihua@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- kernel/Kconfig.preempt | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index ea1e3331c0ba..bd7c4147b9a8 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. + -- 2.20.1