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 X-Spam-Level: X-Spam-Status: No, score=-10.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 249ADC48BE8 for ; Wed, 16 Jun 2021 18:31:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01E32613EF for ; Wed, 16 Jun 2021 18:31:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231868AbhFPSdd (ORCPT ); Wed, 16 Jun 2021 14:33:33 -0400 Received: from foss.arm.com ([217.140.110.172]:43776 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231858AbhFPSdb (ORCPT ); Wed, 16 Jun 2021 14:33:31 -0400 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 0C5CD1042; Wed, 16 Jun 2021 11:31:25 -0700 (PDT) Received: from [10.57.9.31] (unknown [10.57.9.31]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 956763F70D; Wed, 16 Jun 2021 11:31:21 -0700 (PDT) Subject: Re: [PATCH v4 2/3] sched/fair: Take thermal pressure into account while estimating energy To: Dietmar Eggemann Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, peterz@infradead.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, vincent.guittot@linaro.org, qperret@google.com, vincent.donnefort@arm.com, Beata.Michalska@arm.com, mingo@redhat.com, juri.lelli@redhat.com, rostedt@goodmis.org, segall@google.com, mgorman@suse.de, bristot@redhat.com, thara.gopinath@linaro.org, amit.kachhap@gmail.com, amitk@kernel.org, rui.zhang@intel.com, daniel.lezcano@linaro.org References: <20210614185815.15136-1-lukasz.luba@arm.com> <20210614191128.22735-1-lukasz.luba@arm.com> <237ef538-c8ca-a103-b2cc-240fc70298fe@arm.com> <9821712d-be27-a2e7-991c-b0010e23fa70@arm.com> From: Lukasz Luba Message-ID: <813b4ea6-97b0-f98b-5fe1-2ae2c1ff1ab0@arm.com> Date: Wed, 16 Jun 2021 19:31:19 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <9821712d-be27-a2e7-991c-b0010e23fa70@arm.com> 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 6/16/21 6:24 PM, Dietmar Eggemann wrote: > On 15/06/2021 18:09, Lukasz Luba wrote: >> >> On 6/15/21 4:31 PM, Dietmar Eggemann wrote: >>> On 14/06/2021 21:11, Lukasz Luba wrote: > > [...] > >>> It's important to highlight that this will only fix this issue between >>> schedutil and EAS when it's due to `thermal pressure` (today only via >>> CPU cooling). There are other places which could restrict policy->max >>> via freq_qos_update_request() and EAS will be unaware of it. >> >> True, but for this I have some other plans. > > As long as people are aware of the fact that this was developed to be > beneficial for `EAS - IPA` integration, I'm fine with this. Good. I had in mind that I will have to do some re-work on this thermal pressure code in the cpufreq cooling, to satisfy our roadmap goals... > > [...] > >>> IMHO, this means that this is catered for the IPA governor then. I'm not >>> sure if this would be beneficial when another thermal governor is used? >> >> Yes, it will be, the cpufreq_set_cur_state() is called by >> thermal exported function: >> thermal_cdev_update() >>   __thermal_cdev_update() >>     thermal_cdev_set_cur_state() >>       cdev->ops->set_cur_state(cdev, target) >> >> So it can be called not only by IPA. All governors call it, because >> that's the default mechanism. > > True, but I'm still not convinced that it is useful outside `EAS - IPA`. It is. So in mainline thermal there is another governor: fair_share [1], which uses 'weights' to split the cooling effort across cooling devices in the thermal zone. That governor would manage CPUs and GPU and set throttling like IPA. > >>> The mechanical side of the code would allow for such benefits, I just >>> don't know if their CPU cooling device + thermal zone setups would cater >>> for this? >> >> Yes, it's possible. Even for custom vendor governors (modified clones >> of IPA) > > Let's stick to mainline here ;-) It's complicated enough ... I agree, so there isn't only IPA in mainline. > > [...] > >>> Maybe shorter? >>> >>>          struct cpumask *pd_mask = perf_domain_span(pd); >>> -       unsigned long cpu_cap = >>> arch_scale_cpu_capacity(cpumask_first(pd_mask)); >>> +       int cpu = cpumask_first(pd_mask); >>> +       unsigned long cpu_cap = arch_scale_cpu_capacity(cpu); >>> +       unsigned long _cpu_cap = cpu_cap - >>> arch_scale_thermal_pressure(cpu); >>>          unsigned long max_util = 0, sum_util = 0; >>> -       unsigned long _cpu_cap = cpu_cap; >>> -       int cpu; >>> - >>> -       _cpu_cap -= arch_scale_thermal_pressure(cpumask_first(pd_mask)); >> >> Could be, but still, the definitions should be sorted from longest on >> top, to shortest at the bottom. I wanted to avoid modifying too many >> lines with this simple patch. > > Only if there are no dependencies, but here we have already `cpu_cap -> > pd_mask`. OK, not a big deal. True, those dependencies are tricky to sort them properly, so I coded it this way. [snip] >> I see what you mean, but this might cause some issues in the design >> (per-cpu scmi cpu perf control). Let's use this EM pointer gently ;) > > OK, with the requirement that clients see the EM as ro: > > Reviewed-by: Dietmar Eggemann > Thank you Dietmar for the review! Regards, Lukasz [1] https://elixir.bootlin.com/linux/v5.13-rc6/source/drivers/thermal/gov_fair_share.c#L111