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SubjectRe: [RFC PATCH v1 0/3] Saving power by cpu evacuation using sched_mc=n

* 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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