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SubjectRe: [Patch v6 0/7] Introduce Thermal Pressure
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On 12/16/2019 09:56 AM, Peter Zijlstra wrote:
> On Wed, Dec 11, 2019 at 11:11:41PM -0500, Thara Gopinath wrote:
>> Test Results
>>
>> Hackbench: 1 group , 30000 loops, 10 runs
>> Result SD
>> (Secs) (% of mean)
>> No Thermal Pressure 14.03 2.69%
>> Thermal Pressure PELT Algo. Decay : 32 ms 13.29 0.56%
>> Thermal Pressure PELT Algo. Decay : 64 ms 12.57 1.56%
>> Thermal Pressure PELT Algo. Decay : 128 ms 12.71 1.04%
>> Thermal Pressure PELT Algo. Decay : 256 ms 12.29 1.42%
>> Thermal Pressure PELT Algo. Decay : 512 ms 12.42 1.15%
>>
>> Dhrystone Run Time : 20 threads, 3000 MLOOPS
>> Result SD
>> (Secs) (% of mean)
>> No Thermal Pressure 9.452 4.49%
>> Thermal Pressure PELT Algo. Decay : 32 ms 8.793 5.30%
>> Thermal Pressure PELT Algo. Decay : 64 ms 8.981 5.29%
>> Thermal Pressure PELT Algo. Decay : 128 ms 8.647 6.62%
>> Thermal Pressure PELT Algo. Decay : 256 ms 8.774 6.45%
>> Thermal Pressure PELT Algo. Decay : 512 ms 8.603 5.41%
>
> What is the conclusion, if any from these results? Clearly thermal
> pressuse seems to help, but what window? ISTR we default to 32ms, which
> is a wash for drystone, but sub-optimal for hackbench.
Hi Peter,

Thanks for the reviews. IMHO, the conclusion is that thermal pressure is
beneficial but the decay period to be used depends on the architecture
and/or use-cases. Sticking to 32ms should give some improvement but it
can be tuned depending on the system.

>
>
> Anyway, the patches look more or less acceptible, just a bunch of nits,
> the biggest being the fact that even if an architecture does not support
> this there is still the code and runtime overhead.

I am fixing this and sending out a v7.

>


--
Warm Regards
Thara

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