Messages in this thread | | | Date | Thu, 23 Feb 2012 12:26:50 +0100 | From | Ingo Molnar <> | Subject | Re: sched: Avoid SMT siblings in select_idle_sibling() if possible |
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* 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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