linux-kernel - Re: [PATCH V2 0/3] Introduce Thermal Pressure

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Date:   Tue, 30 Apr 2019 12:02:47 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Ionela Voinescu <ionela.voinescu@....com>, mingo@...hat.com,
        peterz@...radead.org, rui.zhang@...el.com
Cc:     linux-kernel@...r.kernel.org, amit.kachhap@...il.com,
        viresh.kumar@...aro.org, javi.merino@...nel.org,
        edubezval@...il.com, daniel.lezcano@...aro.org,
        vincent.guittot@...aro.org, nicolas.dechesne@...aro.org,
        bjorn.andersson@...aro.org, dietmar.eggemann@....com
Subject: Re: [PATCH V2 0/3] Introduce Thermal Pressure

On 04/30/2019 11:57 AM, Thara Gopinath wrote:
> On 04/29/2019 09:29 AM, Ionela Voinescu wrote:
>> Hi Thara,
>>
>>>
>>> 			Hackbench: (1 group , 30000 loops, 10 runs)
>>> 				Result            Standard Deviation
>>> 				(Time Secs)        (% of mean)
>>>
>>> No Thermal Pressure             10.21                   7.99%
>>>
>>> Instantaneous thermal pressure  10.16                   5.36%
>>>
>>> Thermal Pressure Averaging
>>> using PELT fmwk                 9.88                    3.94%
>>>
>>> Thermal Pressure Averaging
>>> non-PELT Algo. Decay : 500 ms   9.94                    4.59%
>>>
>>> Thermal Pressure Averaging
>>> non-PELT Algo. Decay : 250 ms   7.52                    5.42%
>>>
>>> Thermal Pressure Averaging
>>> non-PELT Algo. Decay : 125 ms   9.87                    3.94%
>>>
>>>
>>
>> I'm trying your patches on my Hikey960 and I'm getting different results
>> than the ones here.
>>
>> I'm running with the step-wise governor, enabled only on the big cores.
>> The decay period is set to 250ms.
>>
>> The result for hackbench is:
>>
>> # ./hackbench -g 1 -l 30000
>> Running in process mode with 1 groups using 40 file descriptors each (== 40 tasks)
>> Each sender will pass 30000 messages of 100 bytes
>> Time: 20.756
>>
>> During the run I see the little cores running at maximum frequency
>> (1.84GHz) while the big cores run mostly at 1.8GHz, only sometimes capped
>> at 1.42GHz. There should not be any capacity inversion.
>> The temperature is kept around 75 degrees (73 to 77 degrees).
>>
>> I don't have any kind of active cooling (no fans on the board), only a
>> heatsink on the SoC.
>>
>> But as you see my results(~20s) are very far from the 7-10s in your
>> results.
>>
>> Do you see anything wrong with this process? Can you give me more
>> details on your setup that I can use to test on my board? 
> 
> Hi Ionela,
> 
> I used the latest mainline kernel with sched/ tip merged in for my
> testing. My hikey960 did not have any fan or heat sink during testing. I
> disabled cpu cooling for little cores in the dts files.
> Also I have to warn you that I have managed to blow up my hikey960. So I
> no longer have a functional board for past two weeks or so.
> 
> I don't have my test scripts to send you, but I have some of the results
> files downloaded which I can send you in a separate email.
> I did run the test 10 rounds.

Hi Ionela,

I failed to mention that I drop the first run for averaging.

> 
> Also I think 20s is too much of variation for the test results. Like I
> mentioned in my previous emails I think the 7.52 is an anomaly but the
> results should be around the range of 8-9 s.

Also since we are more interested in comparison rather than absolute
numbers did you run tests in a system with no thermal pressure( to see
if there are any improvements)?

Regards
Thara

> 
> Regards
> Thara
> 
>>
>> Thank you,
>> Ionela.
>>
> 
> 


-- 
Regards
Thara