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

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Message-ID: <8eed9601-8bbb-9f62-f786-f08bd4a72907@arm.com>
Date:   Mon, 29 Apr 2019 14:29:03 +0100
From:   Ionela Voinescu <ionela.voinescu@....com>
To:     Thara Gopinath <thara.gopinath@...aro.org>, 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

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?

Thank you,
Ionela.