Messages in this thread | | | Date | Mon, 27 Apr 2009 05:52:16 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH v1 0/3] Saving power by cpu evacuation using sched_mc=n |
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* Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote:
> Test results for ebizzy 8 threads at various sched_mc settings has > been summarised with relative values below. The test platform is > dual socket quad core x86 system (pre-Nehalem). > > -------------------------------------------------------- > sched_mc No Cores Performance AvgPower > used Records/sec (Watts) > -------------------------------------------------------- > 0 8 1.00x 1.00y > 1 8 1.02x 1.01y > 2 8 0.83x 1.01y > 3 7 0.86x 0.97y > 4 6 0.76x 0.92y > 5 4 0.72x 0.82y > --------------------------------------------------------
Looks like we want the kernel default to be sched_mc=1 ?
Regarding the values for 2...5 - is the AvgPower column time normalized or workload normalized?
If it's time normalized then it appears there's no power win here at all: we'd be better off by throttling the workload directly (by injecting sleeps or something like that), right?
Ingo
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