Messages in this thread | | | Date | Tue, 28 Jun 2022 11:51:01 +0800 | Subject | Re: [PATCH v4 4/7] sched/fair: remove useless check in select_idle_core | From | Abel Wu <> |
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On 6/28/22 7:42 AM, Josh Don Wrote: > On Sun, Jun 19, 2022 at 5:05 AM Abel Wu <wuyun.abel@bytedance.com> wrote: >> >> The function only gets called when sds->has_idle_cores is true which can >> be possible only when sched_smt_present is enabled. >> >> Signed-off-by: Abel Wu <wuyun.abel@bytedance.com> >> --- >> kernel/sched/fair.c | 3 --- >> 1 file changed, 3 deletions(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index aba1dad19574..1cc86e76e38e 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -6256,9 +6256,6 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu >> bool idle = true; >> int cpu; >> >> - if (!static_branch_likely(&sched_smt_present)) >> - return __select_idle_cpu(core, p); >> - > > The static branch is basically free; although you're right that we > currently don't take !smt_present branch direction here, it doesn't > seem harmful to leave this check in case assumptions change about when > we call select_idle_core().
I was thinking that it would be better to align with select_idle_smt that the caller do the check if necessary.
> >> for_each_cpu(cpu, cpu_smt_mask(core)) { >> if (!available_idle_cpu(cpu)) { >> idle = false; >> -- >> 2.31.1 >>
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