From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 886C7C433EF for ; Thu, 17 Feb 2022 12:11:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240253AbiBQMLu (ORCPT ); Thu, 17 Feb 2022 07:11:50 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:44972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232094AbiBQMLs (ORCPT ); Thu, 17 Feb 2022 07:11:48 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3CFBF1116A; Thu, 17 Feb 2022 04:11:33 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F37D6113E; Thu, 17 Feb 2022 04:11:32 -0800 (PST) Received: from [10.57.17.240] (unknown [10.57.17.240]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D6EB33F66F; Thu, 17 Feb 2022 04:11:29 -0800 (PST) Subject: Re: [PATCH 1/2] thermal: cooling: Check Energy Model type in cpufreq_cooling and devfreq_cooling To: Daniel Lezcano Cc: LKML , Linux PM , amit daniel kachhap , Viresh Kumar , "Rafael J. Wysocki" , Amit Kucheria , Zhang Rui , Dietmar Eggemann , Pierre.Gondois@arm.com, Stephen Boyd , Rajendra Nayak , Bjorn Andersson , Doug Anderson , Matthias Kaehlcke References: <20220207073036.14901-1-lukasz.luba@arm.com> <20220207073036.14901-2-lukasz.luba@arm.com> <4a7d4e94-1461-5bac-5798-29998af9793a@arm.com> <7c059f4f-7439-0cad-c398-96dbde4e49c1@linaro.org> <5b8ca53e-3595-85fd-5ae9-a5e8285e8513@arm.com> <53bc13ca-998f-ff83-d9f7-9a83d35b24fd@linaro.org> From: Lukasz Luba Message-ID: <97ecc29b-13a9-fa15-4e88-21c8612ebb7f@arm.com> Date: Thu, 17 Feb 2022 12:11:27 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <53bc13ca-998f-ff83-d9f7-9a83d35b24fd@linaro.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/17/22 11:28 AM, Daniel Lezcano wrote: > On 17/02/2022 11:47, Lukasz Luba wrote: >> Hi Daniel, >> >> On 2/17/22 10:10 AM, Daniel Lezcano wrote: >>> On 16/02/2022 18:33, Doug Anderson wrote: >>>> Hi, >>>> >>>> On Wed, Feb 16, 2022 at 7:35 AM Lukasz Luba >>>> wrote: >>>>> >>>>> Hi Matthias, >>>>> >>>>> On 2/9/22 10:17 PM, Matthias Kaehlcke wrote: >>>>>> On Wed, Feb 09, 2022 at 11:16:36AM +0000, Lukasz Luba wrote: >>>>>>> >>>>>>> >>>>>>> On 2/8/22 5:25 PM, Matthias Kaehlcke wrote: >>>>>>>> On Tue, Feb 08, 2022 at 09:32:28AM +0000, Lukasz Luba wrote: >>>>>>>>> >>>>>>>>> >>>>> >>>>> [snip] >>>>> >>>>>>>>> Could you point me to those devices please? >>>>>>>> >>>>>>>> arch/arm64/boot/dts/qcom/sc7180-trogdor-* >>>>>>>> >>>>>>>> Though as per above they shouldn't be impacted by your change, >>>>>>>> since the >>>>>>>> CPUs always pretend to use milli-Watts. >>>>>>>> >>>>>>>> [skipped some questions/answers since sc7180 isn't actually >>>>>>>> impacted by >>>>>>>>     the change] >>>>>>> >>>>>>> Thank you Matthias. I will investigate your setup to get better >>>>>>> understanding. >>>>>> >>>>>> Thanks! >>>>>> >>>>> >>>>> I've checked those DT files and related code. >>>>> As you already said, this patch is safe for them. >>>>> So we can apply it IMO. >>>>> >>>>> >>>>> -------------Off-topic------------------ >>>>> Not in $subject comments: >>>>> >>>>> AFAICS based on two files which define thermal zones: >>>>> sc7180-trogdor-homestar.dtsi >>>>> sc7180-trogdor-coachz.dtsi >>>>> >>>>> only the 'big' cores are used as cooling devices in the >>>>> 'skin_temp_thermal' - the CPU6 and CPU7. >>>>> >>>>> I assume you don't want to model at all the power usage >>>>> from the Little cluster (which is quite big: 6 CPUs), do you? >>>>> I can see that the Little CPUs have small dyn-power-coeff >>>>> ~30% of the big and lower max freq, but still might be worth >>>>> to add them to IPA. You might give them more 'weight', to >>>>> make sure they receive more power during power split. >>>>> >>>>> You also don't have GPU cooling device in that thermal zone. >>>>> Based on my experience if your GPU is a power hungry one, >>>>> e.g. 2-4Watts, you might get better results when you model >>>>> this 'hot' device (which impacts your temp sensor reported value). >>>> >>>> I think the two boards you point at (homestar and coachz) are just the >>>> two that override the default defined in the SoC dtsi file. If you >>>> look in sc7180.dtsi you'll see 'gpuss1-thermal' which has a cooling >>>> map. You can also see the cooling maps for the littles. >>>> >>>> I guess we don't have a `dynamic-power-coefficient` for the GPU, >>>> though? Seems like we should, but I haven't dug through all the code >>>> here... >>> >>> The dynamic-power-coefficient is available for OPPs which includes >>> CPUfreq and devfreq. As the GPU is managed by devfreq, setting the >>> dynamic-power-coefficient makes the energy model available for it. >>> >>> However, the OPPs must define the frequency and the voltage. That is >>> the case for most platforms except on QCom platform. >>> >>> That may not be specified as it uses a frequency index and the >>> hardware does the voltage change in our back. The QCom cpufreq >>> backend get the voltage table from a register (or whatever) and >>> completes the voltage values for the OPPs, thus adding the >>> information which is missing in the device tree. The energy model can >>> then initializes itself and allows the usage of the Energy Aware >>> Scheduler. >>> >>> However this piece of code is missing for the GPU part. >>> >> >> Thank you for joining the discussion. I don't know about that Qcom >> GPU voltage information is missing. >> >> If the voltage is not available (only the frequencies), there is >> another way. There is an 'advanced' EM which uses registration function: >> em_dev_register_perf_domain(). It uses a local driver callback to get >> power for each found frequency. It has benefit because there is no >> restriction to 'fit' into the math formula, instead just avg power >> values can be feed into EM. It's called 'advanced' EM [1]. >> >> Now we hit (again) the DT & EM issue (it's an old one, IIRC Morten >> was proposing from ~2014 this upstream, but EAS wasn't merged back >> then): >> where to store these power-freq values, which are then used by the >> callback. > > Why not make it more generic and replace the frequency by a performance > index, so it can be used by any kind of perf limiter? For that DT array, yes, it can be an index, so effectively it could be a simple 1d array. something like: msm_gpu_energy_model: msm-gpu-energy-model { compatible = "energy-model" /* Values are sorted micro-Watts which correspond to each OPP or performance state. The total amount of them must match number of OPPs. */ power-microwatt = <100000>, <230000>, <380000>, <600000>; }; then in gpu node instead of having 'dynamic-power-coefficient', which is useless because voltage is missing, we would have 'energy-model', like: energy-model = <&msm_gpu_energy_model>; If you agree to continue this topic. I will send an RFC so we could further discuss this idea. This $subject doesn't fit well. Thank you again for your feedback Daniel!