From patchwork Mon Dec 2 20:28:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 180642 Delivered-To: patch@linaro.org Received: by 2002:a92:3001:0:0:0:0:0 with SMTP id x1csp500779ile; Mon, 2 Dec 2019 12:28:26 -0800 (PST) X-Google-Smtp-Source: APXvYqwFyYJBIJ/A3mmGq+5csAsE1NSkm1v5LrhL+B2qgS80sX+0VxkluQUvOi8LQPfBSo1DoDnc X-Received: by 2002:a17:906:5251:: with SMTP id y17mr1344482ejm.108.1575318505945; Mon, 02 Dec 2019 12:28:25 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1575318505; cv=none; d=google.com; s=arc-20160816; b=IevTyAl+9gPZaj0CzAW95X2Iq1QsZVZZ466t+fca9PfqmjOPlEyHGSbE4V9wXb5ZU9 ysB29XgKv2B7VCqimjQhRCw74N0lnNOe2zoWCqTtTrsLPIltpaq6zbtc88SH0nkHL+JZ G/qPrD095zRx9OiDFKeXbB1arwOqwJ5y6GPd5oHodAVwSjCCGHiDBZMFnrKUYZaBcoJN D9mYZQpkOMXKAoc/t8w+fF7I9LR0yWpWMEB9gSUuFP/er7ZZDesMmztJ/5l3ou1qTSKe t0HGg2McFKuSCRJlBVh9xBuBl7TeeggPLD3h4cL/SBRzmAspiZBY5U4+K5tDg4txvpCU Vpdg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:message-id:date:subject:cc:to:from :dkim-signature; bh=Ov3qfLDesJCRBNnguqXtY2vyu5jCndpMMvqcZHjaUgY=; b=zeHxLAKHA6getOsenxxECHeKfZbOxZ1Fr5oCGlU1lQg2ZoNH+hWZYuSRD3YjrVyFeh 6/lDkQa1rz84kZy1AOD6BXxfX3F/Nl4AhuL6GQSuRWthiYmGN1lYGSV67tU1l4d0TiD2 lSnSFoW1zfbZdLw3njvhGbbPsm35d5UaX2972gemlg4Pztvjo+PlkM+76K7gHTmSQg9V 2ddutMOxvt13hiUb9fynB1TDd81/a84Rx/r8XzIjLegLH2L9IFMvAjcAtEQZaOBMKtR9 r9nN1u/GuFU8whg06/k3Axj0txr5x3QCu5N45QpsV54vZYZK9bNUw9imYFmvTEIb/MKt D51Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=lqyHGeUt; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id a19si492394eje.396.2019.12.02.12.28.25; Mon, 02 Dec 2019 12:28:25 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=lqyHGeUt; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727455AbfLBU2Y (ORCPT + 10 others); Mon, 2 Dec 2019 15:28:24 -0500 Received: from mail-wm1-f66.google.com ([209.85.128.66]:52059 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727418AbfLBU2Y (ORCPT ); Mon, 2 Dec 2019 15:28:24 -0500 Received: by mail-wm1-f66.google.com with SMTP id g206so736498wme.1 for ; Mon, 02 Dec 2019 12:28:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=Ov3qfLDesJCRBNnguqXtY2vyu5jCndpMMvqcZHjaUgY=; b=lqyHGeUtxxdEEaCZVDqaXCr/pN6fZMpBRfNUzEhXj+5xICpr9jadEu9V232RlhlB1e UjFB0HMG9tr+1MdpnoJ2BcQB3+kImfPnZ8rLfsHhxH1PKRq1T5Tva0cYy5ec+3QerPKG aTvXFiab7LC/ZZt8tGMIVmyAsp8t5FeA1hFTMTD71DjII7MZ3YXlIh7i7ZuU4Cq6xbaJ IiByzw1YteII1wNhyYuzhorxJkoAW5/OxUXp6SB9xs8qxddQAmXLULhLBJNmutDdHk9v t0Xh3RSe7r3T9bC4jTlfme2jsY3Vlm3Hdvi4ahj9n2pyGF7BFOlbSnIQ/wbiooCIbP9z gZNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=Ov3qfLDesJCRBNnguqXtY2vyu5jCndpMMvqcZHjaUgY=; b=bCoq6r0ha+PhGN1okvrmZd3jwXHrNhIxtkGptc8qGUI2xTNTsAe1R9qliYba6zaiuC rTHcxuM+4G+WEMkoEuwzOSmmH/LIDFPXH73G1SvUqExH3OovqpqKTvOsQC7aoUZGgjsK wRzoxPlMYRPy9OCY7C/8YmxgSpb8TA9kq/q7adgaJaxn2g+Y7rk4SrpLqup9aEs/BElA E0B22oUAX7lrpqDewcuy1csVsFUWPOc+vWqTB48ZU9/PuXxKg8/sBdrVrMG7ehAsfpRs BIriOMGxFVc7cdGme6qTuVMhUr8WUgKyv5559jIvt3fxAxzb/IeXGR6yPPu9GFWM+Ona OKzQ== X-Gm-Message-State: APjAAAXgxkqEiNUsqaNilpDfZ+Q8EQNpLJzJRjri097SYV4uFz5Tb41L nEgYZ+6aUXLX5F3/0PTsgxAVWj18qwE= X-Received: by 2002:a1c:4b03:: with SMTP id y3mr19930816wma.91.1575318501716; Mon, 02 Dec 2019 12:28:21 -0800 (PST) Received: from localhost.localdomain ([2a01:e34:ed2f:f020:8196:cbcc:fb2c:4975]) by smtp.gmail.com with ESMTPSA id k20sm556456wmj.10.2019.12.02.12.28.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Dec 2019 12:28:21 -0800 (PST) From: Daniel Lezcano To: viresh.kumar@linaro.org, rui.zhang@intel.com Cc: rjw@rjwysocki.net, edubezval@gmail.com, linux-pm@vger.kernel.org, amit.kucheria@linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V2 1/4] thermal/drivers/Kconfig: Convert the CPU cooling device to a choice Date: Mon, 2 Dec 2019 21:28:12 +0100 Message-Id: <20191202202815.22731-1-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.17.1 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org The next changes will add a new way to cool down a CPU by injecting idle cycles. With the current configuration, a CPU cooling device is the cpufreq cooling device. As we want to add a new CPU cooling device, let's convert the CPU cooling to a choice giving a list of CPU cooling devices. At this point, there is obviously only one CPU cooling device. There is no functional changes. Signed-off-by: Daniel Lezcano --- V2: - Default CPU_FREQ_COOLING when CPU_THERMAL is set (Viresh Kumar) --- drivers/thermal/Kconfig | 14 ++++++++++++-- drivers/thermal/Makefile | 2 +- include/linux/cpu_cooling.h | 6 +++--- 3 files changed, 16 insertions(+), 6 deletions(-) -- 2.17.1 Acked-by: Viresh Kumar Acked-by: Viresh Kumar diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig index 001a21abcc28..4e3ee036938b 100644 --- a/drivers/thermal/Kconfig +++ b/drivers/thermal/Kconfig @@ -150,8 +150,18 @@ config THERMAL_GOV_POWER_ALLOCATOR config CPU_THERMAL bool "Generic cpu cooling support" - depends on CPU_FREQ depends on THERMAL_OF + help + Enable the CPU cooling features. If the system has no active + cooling device available, this option allows to use the CPU + as a cooling device. + +if CPU_THERMAL + +config CPU_FREQ_THERMAL + bool "CPU frequency cooling device" + depends on CPU_FREQ + default y help This implements the generic cpu cooling mechanism through frequency reduction. An ACPI version of this already exists @@ -159,7 +169,7 @@ config CPU_THERMAL This will be useful for platforms using the generic thermal interface and not the ACPI interface. - If you want this support, you should say Y here. +endif config CLOCK_THERMAL bool "Generic clock cooling support" diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile index 74a37c7f847a..d3b01cc96981 100644 --- a/drivers/thermal/Makefile +++ b/drivers/thermal/Makefile @@ -19,7 +19,7 @@ thermal_sys-$(CONFIG_THERMAL_GOV_USER_SPACE) += user_space.o thermal_sys-$(CONFIG_THERMAL_GOV_POWER_ALLOCATOR) += power_allocator.o # cpufreq cooling -thermal_sys-$(CONFIG_CPU_THERMAL) += cpu_cooling.o +thermal_sys-$(CONFIG_CPU_FREQ_THERMAL) += cpu_cooling.o # clock cooling thermal_sys-$(CONFIG_CLOCK_THERMAL) += clock_cooling.o diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h index b74732535e4b..3cdd85f987d7 100644 --- a/include/linux/cpu_cooling.h +++ b/include/linux/cpu_cooling.h @@ -19,7 +19,7 @@ struct cpufreq_policy; -#ifdef CONFIG_CPU_THERMAL +#ifdef CONFIG_CPU_FREQ_THERMAL /** * cpufreq_cooling_register - function to create cpufreq cooling device. * @policy: cpufreq policy. @@ -40,7 +40,7 @@ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev); struct thermal_cooling_device * of_cpufreq_cooling_register(struct cpufreq_policy *policy); -#else /* !CONFIG_CPU_THERMAL */ +#else /* !CONFIG_CPU_FREQ_THERMAL */ static inline struct thermal_cooling_device * cpufreq_cooling_register(struct cpufreq_policy *policy) { @@ -58,6 +58,6 @@ of_cpufreq_cooling_register(struct cpufreq_policy *policy) { return NULL; } -#endif /* CONFIG_CPU_THERMAL */ +#endif /* CONFIG_CPU_FREQ_THERMAL */ #endif /* __CPU_COOLING_H__ */ From patchwork Mon Dec 2 20:28:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 180643 Delivered-To: patch@linaro.org Received: by 2002:a92:3001:0:0:0:0:0 with SMTP id x1csp500804ile; Mon, 2 Dec 2019 12:28:27 -0800 (PST) X-Google-Smtp-Source: APXvYqxQLAlTrH0VA+LryMTW7Gx+gQLaaMOk7ODiWgXK/f10bXG0WxC1NDYCW2a91PlzkQPZxGTD X-Received: by 2002:a17:906:d790:: with SMTP id pj16mr1282623ejb.19.1575318507597; Mon, 02 Dec 2019 12:28:27 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1575318507; cv=none; d=google.com; s=arc-20160816; b=P1Xt0YTJ6e3vJts3ktTSmMxUG2aj4p9s5IPhm32xqMZo4wH2IlZpauZAR/p1lCXLYK rHppTSSxRZx5CoZOcMlZ1XzacPmbke3zBplfKvHE8gdjusq2ldQb5k9x6COg+XITmBV5 LIvusn5n/In6szkS9a1dRQLdU2Xqn/xB2RpbgpdQudA/DbV1YwVRxQTyqzashAfzTVAb AgWnvqWwlgW3r8DilgJPcdkRdsQhB1G0WW98oz8OZtzLmS84pA6njOu3CRsZB8K03CSG C6q+cWf5QOQt3qCp2FW/+MuvPCVRc6LmqRUPQl20gn4K6MEaeFG7K3kGijeDKdMRiJKg 26YQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=J6TOUAUpf290Soz5pSkfNzyRRTkHTSc9qnKiA/fCb8o=; b=RK0j6hEUMHrrJaWUlEeenDG3TuRulYQC1daI5gLvjOMRv/MK2stt8CQWcZoLXGcnpg 9iisJkyn2Uoeqva6ogC2i9tllhh13eLrU9V2S2DDGc06FQAxSedDIxlMEd+tFK6qFnIn eOtqFv4BnAqZpe9/NTrMvAh166MgX/oFJ7s0ZPoLnG79YYybQcuI5ekhBkwKn8N8by6k WIoIdsZdtN9ECLGaoKOdyM/BAWrYeLAidXKbi4PzyobKVZBxLBX0Tbi8ADTsPdaYU4nG EG2JUx5UdYhTWWFhIAZrme9jYpVTLJ9hyA3qpbMw1muurEgQOZ0fO/ZHsfMC/qZBSY9P sD+A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=UYf3GhON; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id a19si492394eje.396.2019.12.02.12.28.27; Mon, 02 Dec 2019 12:28:27 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=UYf3GhON; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727533AbfLBU20 (ORCPT + 10 others); Mon, 2 Dec 2019 15:28:26 -0500 Received: from mail-wm1-f65.google.com ([209.85.128.65]:54314 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727420AbfLBU2Z (ORCPT ); Mon, 2 Dec 2019 15:28:25 -0500 Received: by mail-wm1-f65.google.com with SMTP id b11so705549wmj.4 for ; Mon, 02 Dec 2019 12:28:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=J6TOUAUpf290Soz5pSkfNzyRRTkHTSc9qnKiA/fCb8o=; b=UYf3GhONDa27GK7l36RzzSk2ThG/2hBAsQ3uSAgaUtS0a/aCkVlsGJ97hM/ZKjOfdX XMpbYOHSnMGHOEy0cJQeUk4A3avr87X9HodGDQqyce3kL8BdFvb6oH2v01Gs6z66QlmP JF8FEISgylcS58SpyZET8BYfLxvKAF0kQu34NqnGGUXYsG9wUf5TFK/OWUjckerfskiw i0nmkCHGYlhIZ1jUQyV8apDMVB4iJGii3ypjJE4Sc4NYoJRsDClRTh/CahaXiQe9j9MP wG8unBQL2dw+CrS/AMTTolWDo98+qU/f3T6c81Bb1E2uKp3dUM5yPeSncXZUwqn43aMj /AIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=J6TOUAUpf290Soz5pSkfNzyRRTkHTSc9qnKiA/fCb8o=; b=SeIeHjvEz/zu3cGC9U9kznGRHJ6NeX6ldgjz6WU2fuc0MCRmUJtcMp3acPeI1j3qJ2 83gArOCZZycA9GUuANgnatAZ6rvxD7+WwEjtmCQp3eoUxb6HH0xMLz8bjICnMeR0iVSd Z/skRqVIs0Ks6ppobcgXmS0rv2rCpjB8X1xTwnMMxXYMtJDfWvnuUGrWRddJHmmP5whG 873oz0qWns/xfLsMlzJMpsFJV3EzYCX44SigsPbcMwkrJaPaWKidBKkSdGV+WwePciw0 r2ulr5XHuK6m7Q+vroqw7sHh+qPdnDXoUwJF316eClqfym7sH5QIdkpoSYb1urk15wjw 30dg== X-Gm-Message-State: APjAAAUTgSNfbS3PFi49w5dyJNTo3y6qeQL+xGTcjaMIi0+T85Gri59U kSDtmJvE4yuXvsqLFFT6uv3XTQ== X-Received: by 2002:a1c:2395:: with SMTP id j143mr29746361wmj.128.1575318503203; Mon, 02 Dec 2019 12:28:23 -0800 (PST) Received: from localhost.localdomain ([2a01:e34:ed2f:f020:8196:cbcc:fb2c:4975]) by smtp.gmail.com with ESMTPSA id k20sm556456wmj.10.2019.12.02.12.28.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Dec 2019 12:28:22 -0800 (PST) From: Daniel Lezcano To: viresh.kumar@linaro.org, rui.zhang@intel.com Cc: rjw@rjwysocki.net, edubezval@gmail.com, linux-pm@vger.kernel.org, amit.kucheria@linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V2 2/4] thermal/drivers/cpu_cooling: Add idle cooling device documentation Date: Mon, 2 Dec 2019 21:28:13 +0100 Message-Id: <20191202202815.22731-2-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191202202815.22731-1-daniel.lezcano@linaro.org> References: <20191202202815.22731-1-daniel.lezcano@linaro.org> MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Provide some documentation for the idle injection cooling effect in order to let people to understand the rational of the approach for the idle injection CPU cooling device. Signed-off-by: Daniel Lezcano --- .../driver-api/thermal/cpu-idle-cooling.rst | 166 ++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 Documentation/driver-api/thermal/cpu-idle-cooling.rst -- 2.17.1 Acked-by: Viresh Kumar diff --git a/Documentation/driver-api/thermal/cpu-idle-cooling.rst b/Documentation/driver-api/thermal/cpu-idle-cooling.rst new file mode 100644 index 000000000000..457cd9979ddb --- /dev/null +++ b/Documentation/driver-api/thermal/cpu-idle-cooling.rst @@ -0,0 +1,166 @@ + +Situation: +---------- + +Under certain circumstances a SoC can reach the maximum temperature +limit or is unable to stabilize the temperature around a temperature +control. When the SoC has to stabilize the temperature, the kernel can +act on a cooling device to mitigate the dissipated power. When the +maximum temperature is reached and to prevent a reboot or a shutdown, +a decision must be taken to reduce the temperature under the critical +threshold, that impacts the performance. + +Another situation is when the silicon reaches a certain temperature +which continues to increase even if the dynamic leakage is reduced to +its minimum by clock gating the component. The runaway phenomena will +continue with the static leakage and only powering down the component, +thus dropping the dynamic and static leakage will allow the component +to cool down. + +Last but not least, the system can ask for a specific power budget but +because of the OPP density, we can only choose an OPP with a power +budget lower than the requested one and underuse the CPU, thus losing +performances. In other words, one OPP under uses the CPU with a power +lesser than the power budget and the next OPP exceed the power budget, +an intermediate OPP could have been used if it were present. + +Solutions: +---------- + +If we can remove the static and the dynamic leakage for a specific +duration in a controlled period, the SoC temperature will +decrease. Acting at the idle state duration or the idle cycle +injection period, we can mitigate the temperature by modulating the +power budget. + +The Operating Performance Point (OPP) density has a great influence on +the control precision of cpufreq, however different vendors have a +plethora of OPP density, and some have large power gap between OPPs, +that will result in loss of performance during thermal control and +loss of power in other scenes. + +At a specific OPP, we can assume injecting idle cycle on all CPUs, +belonging to the same cluster, with a duration greater than the +cluster idle state target residency, we drop the static and the +dynamic leakage for this period (modulo the energy needed to enter +this state). So the sustainable power with idle cycles has a linear +relation with the OPP’s sustainable power and can be computed with a +coefficient similar to: + + Power(IdleCycle) = Coef x Power(OPP) + +Idle Injection: +--------------- + +The base concept of the idle injection is to force the CPU to go to an +idle state for a specified time each control cycle, it provides +another way to control CPU power and heat in addition to +cpufreq. Ideally, if all CPUs belonging to the same cluster, inject +their idle cycle synchronously, the cluster can reach its power down +state with a minimum power consumption and static leakage +drop. However, these idle cycles injection will add extra latencies as +the CPUs will have to wakeup from a deep sleep state. + + ^ + | + | + |------- ------- ------- + |_______|_____|_______|_____|_______|___________ + + <-----> + idle <----> + running + +With the fixed idle injection duration, we can give a value which is +an acceptable performance drop off or latency when we reach a specific +temperature and we begin to mitigate by varying the Idle injection +period. + +The mitigation begins with a maximum period value which decrease when +more cooling effect is requested. When the period duration is equal to +the idle duration, then we are in a situation the platform can’t +dissipate the heat enough and the mitigation fails. In this case the +situation is considered critical and there is nothing to do. The idle +injection duration must be changed by configuration and until we reach +the cooling effect, otherwise an additionnal cooling device must be +used or ultimately decrease the SoC performance by dropping the +highest OPP point of the SoC. + +The idle injection duration value must comply with the constraints: + +- It is lesser or equal to the latency we tolerate when the mitigation + begins. It is platform dependent and will depend on the user + experience, reactivity vs performance trade off we want. This value + should be specified. + +- It is greater than the idle state’s target residency we want to go + for thermal mitigation, otherwise we end up consuming more energy. + +Minimum period +-------------- + +The idle injection duration being fixed, it is obvious the minimum +period can’t be lesser than that, otherwise we will be scheduling the +idle injection task right before the idle injection duration is +complete, so waking up the CPU to put it asleep again. + +Maximum period +-------------- + +The maximum period is the initial period when the mitigation +begins. Theoretically when we reach the thermal trip point, we have to +sustain a specified power for specific temperature but at this time we +consume: + + Power = Capacitance x Voltage^2 x Frequency x Utilisation + +... which is more than the sustainable power (or there is something +wrong on the system setup). The ‘Capacitance’ and ‘Utilisation’ are a +fixed value, ‘Voltage’ and the ‘Frequency’ are fixed artificially +because we don’t want to change the OPP. We can group the +‘Capacitance’ and the ‘Utilisation’ into a single term which is the +‘Dynamic Power Coefficient (Cdyn)’ Simplifying the above, we have: + + Pdyn = Cdyn x Voltage^2 x Frequency + +The IPA will ask us somehow to reduce our power in order to target the +sustainable power defined in the device tree. So with the idle +injection mechanism, we want an average power (Ptarget) resulting on +an amount of time running at full power on a specific OPP and idle +another amount of time. That could be put in a equation: + + P(opp)target = ((trunning x (P(opp)running) + (tidle P(opp)idle)) / + (trunning + tidle) + ... + + tidle = trunning x ((P(opp)running / P(opp)target) - 1) + +At this point if we know the running period for the CPU, that gives us +the idle injection, we need. Alternatively if we have the idle +injection duration, we can compute the running duration with: + + trunning = tidle / ((P(opp)running / P(opp)target) - 1) + +Practically, if the running power is lesses than the targeted power, +we end up with a negative time value, so obviously the equation usage +is bound to a power reduction, hence a higher OPP is needed to have +the running power greater than the targeted power. + +However, in this demonstration we ignore three aspects: + + * The static leakage is not defined here, we can introduce it in the + equation but assuming it will be zero most of the time as it is + difficult to get the values from the SoC vendors + + * The idle state wake up latency (or entry + exit latency) is not + taken into account, it must be added in the equation in order to + rigorously compute the idle injection + + * The injected idle duration must be greater than the idle state + target residency, otherwise we end up consuming more energy and + potentially invert the mitigation effect + +So the final equation is: + + trunning = (tidle - twakeup ) x + (((P(opp)dyn + P(opp)static ) - P(opp)target) / P(opp)target ) From patchwork Mon Dec 2 20:28:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 180644 Delivered-To: patch@linaro.org Received: by 2002:a92:3001:0:0:0:0:0 with SMTP id x1csp500908ile; Mon, 2 Dec 2019 12:28:32 -0800 (PST) X-Google-Smtp-Source: APXvYqwPq2AVfUaAi3T2JedFlMcwTOjP+9UzQTPPow5nvU0PEUPjHVnuXgHclvzkp6VeyLFDUHA1 X-Received: by 2002:a50:dacd:: with SMTP id s13mr1072045edj.194.1575318512168; Mon, 02 Dec 2019 12:28:32 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1575318512; cv=none; d=google.com; s=arc-20160816; b=B1SS0J6w8Rnc4RFZWb3Ou0ZguIb8D4c/YykyZX5Bq5CbxXeCBk7uWX9B675J3k5R3f OoBqwdPoauHc7etFgaHG8ENGK27KtlGPrtLk5GsYc16fiIfBEDrdVDJt29REus55Exmk PBEUGl7E1lk4oiFJiJ6bFLfYZ+Z4dluBO5yrVQFLCa5p/Av5BytRFggBcYBSonQGG9RW MfEyjkRu7ebvpNR/bB4CIPMxdtMd48vZqEd2/Ua0gr4/vMaibanMmYvSD22ksHAa2zXW nYauOeCsp0tJr2/KOLj4er2ekOmQXCARxuGhzV0qUhGQqVg6/kCvxiKYnpsalNABrFQy kvpA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature; bh=1somXtkHoxvC/VbspBH5qSIskfATKri+DPQIL3Oev+8=; b=nCZV64ruTT40VBUcxgXgL1UZB4AIRQFMUbjI2itZ/oRhXcqFPj3QAPGEZOedLRZmhn xu13daG06BaRHNLVIdRSPQ0zHaJOFJXfXvjUV1/AGzhqvzLWCUWnwU7gvUKduv5REK1q lLyfkHnbBO/Uwe8d6y8+P3w0eMheH3ScB4tLWqKKCHac75y7HfKxjADIUdyD552v+L+E ovsDf1bfQX/q6bSv2PNrjoTJ2gM4b/p/SBwnykV4heLXbcKpY+ltlZ+/XJ211jTTG+UM bSvfwGmZJ+/nm3CCnlW6glAUvFkRbtNUnLfBz5T4nl3QagrVlfCJl8+8UqQ/tk0itIwU 4MAA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=giCE0LR4; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id f14si436478edm.137.2019.12.02.12.28.32; Mon, 02 Dec 2019 12:28:32 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=giCE0LR4; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727638AbfLBU23 (ORCPT + 10 others); Mon, 2 Dec 2019 15:28:29 -0500 Received: from mail-wr1-f65.google.com ([209.85.221.65]:46328 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727600AbfLBU22 (ORCPT ); Mon, 2 Dec 2019 15:28:28 -0500 Received: by mail-wr1-f65.google.com with SMTP id z7so792573wrl.13 for ; Mon, 02 Dec 2019 12:28:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=1somXtkHoxvC/VbspBH5qSIskfATKri+DPQIL3Oev+8=; b=giCE0LR4sDAsP3tAyxL+P7S3VCqgq4mJ5kRNNuKHc+i6sXaaPgntzv/F3DTBjX1TqX 2CYDqVXBCpMrIbiOjElu2WiB+UVgK0iYUDnDAAboH607ksuVqLuJKfYfiVFxBPO/qB+f QYIz64fP3O3SJbB4F0r+QGj67bEwFB8H9a8iDt++UGDF8JvSsAzNKl86guiYx9xtxWhJ RLbA8F98G6G7yUIC797GERJG0wNSbVEYCui6361m2p1XOxxnm+9Yboq/uDF1ZfRLIeWj LRySFtB7c5iI2w7j+tM7d+URYkOhx9ROVsp8zT+FUtedNiEogHzy8WGEVw/n9RNagnvS K4rQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=1somXtkHoxvC/VbspBH5qSIskfATKri+DPQIL3Oev+8=; b=fyt9eiP4UwED5kCZXGA9egPnWsq4AXZXIDiFtrQgh2mfr/6XlU0JnoTeLVIBginARf hoLduTxGn+5j3D10fPMDR+k23goOOcTYP8ZvK1g37itAL6W50ufjtpQxHHKZRm2ZhGqE q4EXpANKG3yjX5TdnVOdprP+4u+tBGVD1fvzsfnxX/gMJZlgvdDBfDL+MQcAtIlmgzF9 8B8weF8vTSUhm1KIOpsgFxv63tQlCva3h74hQ/p13LLiJExnvBqRNaOh4CGW2+oNak0S gD9NRUcweslYYQc78yCh0ViWuj+Ij0pyYkFuejPaNc06nwW2emglGIbfvG85kOEmtNWw 29vg== X-Gm-Message-State: APjAAAWdiEyF1+Oa4WhabUeSgmxhU4I6jSOAIxGh8u+IWWfFYQ0Rdizl zgttmblSPtgiN+5ZxDBGUXdoAQ== X-Received: by 2002:adf:90e7:: with SMTP id i94mr900848wri.47.1575318506359; Mon, 02 Dec 2019 12:28:26 -0800 (PST) Received: from localhost.localdomain ([2a01:e34:ed2f:f020:8196:cbcc:fb2c:4975]) by smtp.gmail.com with ESMTPSA id k20sm556456wmj.10.2019.12.02.12.28.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Dec 2019 12:28:25 -0800 (PST) From: Daniel Lezcano To: viresh.kumar@linaro.org, rui.zhang@intel.com Cc: rjw@rjwysocki.net, edubezval@gmail.com, linux-pm@vger.kernel.org, amit.kucheria@linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V2 4/4] thermal/drivers/cpu_cooling: Rename to cpufreq_cooling Date: Mon, 2 Dec 2019 21:28:15 +0100 Message-Id: <20191202202815.22731-4-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191202202815.22731-1-daniel.lezcano@linaro.org> References: <20191202202815.22731-1-daniel.lezcano@linaro.org> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org As we introduced the idle injection cooling device called cpuidle_cooling, let's be consistent and rename the cpu_cooling to cpufreq_cooling as this one mitigates with OPPs changes. Signed-off-by: Daniel Lezcano --- drivers/thermal/Makefile | 2 +- drivers/thermal/{cpu_cooling.c => cpufreq_cooling.c} | 0 2 files changed, 1 insertion(+), 1 deletion(-) rename drivers/thermal/{cpu_cooling.c => cpufreq_cooling.c} (100%) -- 2.17.1 diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile index 9c8aa2d4bd28..5c98472ffd8b 100644 --- a/drivers/thermal/Makefile +++ b/drivers/thermal/Makefile @@ -19,7 +19,7 @@ thermal_sys-$(CONFIG_THERMAL_GOV_USER_SPACE) += user_space.o thermal_sys-$(CONFIG_THERMAL_GOV_POWER_ALLOCATOR) += power_allocator.o # cpufreq cooling -thermal_sys-$(CONFIG_CPU_FREQ_THERMAL) += cpu_cooling.o +thermal_sys-$(CONFIG_CPU_FREQ_THERMAL) += cpufreq_cooling.o thermal_sys-$(CONFIG_CPU_IDLE_THERMAL) += cpuidle_cooling.o # clock cooling diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpufreq_cooling.c similarity index 100% rename from drivers/thermal/cpu_cooling.c rename to drivers/thermal/cpufreq_cooling.c