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SubjectRe: sched: Avoid SMT siblings in select_idle_sibling() if possible

* Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> wrote:

> "perf bench sched pipe" was run 10 times and average ops/sec
> score alongwith std. dev is noted as below.
>
>
> SD_BALANCE_WAKE SD_BALANCE_WAKE
> disabled enabled
>
> Avg. score 108984.900 111844.300 (+2.6%)
> std dev 20383.457 21668.604

pro perf tip of the day: did you know that it's possible to run:

perf stat --repeat 10 --null perf bench sched pipe

and get meaningful, normalized stddev calculations for free:

5.486491487 seconds time elapsed ( +- 5.50% )

the percentage at the end shows the level of standard deviation.

You can add "--sync" as well, which will cause perf stat to call
sync() - this gives extra stability of individual iterations and
makes sure all IO cost is accounted to the right run.

Thanks,

Ingo


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