linux-kernel - Re: [RFC PATCH 0/7] Introduce thermal pressure

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Date:   Thu, 11 Oct 2018 10:23:14 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Lukasz Luba <l.luba@...tner.samsung.com>,
        Thara Gopinath <thara.gopinath@...aro.org>,
        linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, rui.zhang@...el.com,
        gregkh@...uxfoundation.org, rafael@...nel.org,
        amit.kachhap@...il.com, viresh.kumar@...aro.org,
        javi.merino@...nel.org, edubezval@...il.com,
        linux-pm@...r.kernel.org, quentin.perret@....com,
        ionela.voinescu@....com, vincent.guittot@...aro.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [RFC PATCH 0/7] Introduce thermal pressure

On 11/10/2018 09:35, Lukasz Luba wrote:
> Hi Daniel,
> 
> On 10/10/2018 06:54 PM, Daniel Lezcano wrote:
>> On 10/10/2018 17:35, Lukasz Luba wrote:
>>> Hi Thara,
>>>
>>> I have run it on Exynos5433 mainline.
>>> When it is enabled with step_wise thermal governor,
>>> some of my tests are showing ~30-50% regression (i.e. hackbench),
>>> dhrystone ~10%.
>>>
>>> Could you tell me which thermal governor was used in your case?
>>> Please also share the name of that benchmark, i will give it a try.
>>> Is it single threaded compute-intensive?
>>
>> aobench AFAICT
>>
>> It would be interesting if you can share the thermal profile of your board.
>>
> Thanks for the benchmark name.
> It was tested on Samsung TM2 device with Exynos 5433 with debian.
> Thermal stuff you can find in mainline:
> arch/arm64/boot/dts/exynos/exynos5433-tmu.dtsi

By thermal profile, I was meaning a figure with the temperature
regulation (temperature idle, then workload, then temperature increase,
mitigated temperature, end of workload, temperature decrease).

The thermal description looks wrong in the DT. I suggest to experiment
the series with the DT fixed.

eg. from hi6220.dtsi


                thermal-zones {

                        cls0: cls0 {
                                polling-delay = <1000>;
                                polling-delay-passive = <100>;
                                sustainable-power = <3326>;

                                /* sensor ID */
                                thermal-sensors = <&tsensor 2>;

                                trips {
                                        threshold: trip-point@0 {
                                                temperature = <65000>;
                                                hysteresis = <0>;
                                                type = "passive";
                                        };

                                        target: trip-point@1 {
                                                temperature = <75000>;
                                                hysteresis = <0>;
                                                type = "passive";
                                        };
                                };

                                cooling-maps {
                                        map0 {
                                                trip = <&target>;
                                                cooling-device = <&cpu0
THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
                                        };
                                };
                        };
                };

Note the cooling devices are *passive*


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