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SubjectRe: [PATCH 09/10] sched: task_sched_runtime introduce micro optimization
> Stronger:
>
> +#ifdef CONFIG_64BIT
> + if (!p->on_cpu)
> + return p->se.sum_exec_runtime;
> +#endif
>
> [ Or !p->on_cpu || !add_delta ].
>
> We can take the racy read versus p->on_cpu since:
> If we race with it leaving cpu: we take lock, we're correct
> If we race with it entering cpu: unaccounted time ---> 0, this is
> indistinguishable from the read occurring a few cycles earlier.

OK, agreed. That's nice.




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