From patchwork Wed Dec 4 15:39:27 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 180803 Delivered-To: patch@linaro.org Received: by 2002:ac9:3d8b:0:0:0:0:0 with SMTP id u11csp785383oce; Wed, 4 Dec 2019 07:39:46 -0800 (PST) X-Google-Smtp-Source: APXvYqzvywpw5nEmCKzGgLv+E9gxRZAp0IslA9HFb4+kIAlUSH0yEkzTJ2VA3KowVc9VPDDiBQ2S X-Received: by 2002:a05:6808:64d:: with SMTP id z13mr3215950oih.104.1575473986626; Wed, 04 Dec 2019 07:39:46 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1575473986; cv=none; d=google.com; s=arc-20160816; b=1CSLqMIG7t9Oei7DQx2fIQRTYKJOJtF2d47wA9aubMLqbAc97DbGMr8Yt0MxLhp4Ig K314qlNRtN+8ozELfgk5GeWMwtCQs2Z1PZgQLXDfgXRCXLd2ZdSGRdfNLclo2TBP+YrU nbGo9WLKOEoj7ybdbSwCZ++DpJqKPasndV4vulUPu1fgbzIbXoq0/D5x8Pi2DF1i95GU /TwCYnFsahvOSlv2lROZa3ie5kOMzzOy+nxz0SJsI1LHcT5hB9iBfdeq1P61ij2LuHK+ nUmmBtwsn7fiS0sA40cw3cQVTfQOsDFOW98/y9YsqfPjIXvZ7ewJTaA/2M+tFY8yZRQl /Oqw== 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=v9aPs/wpi2L5/d1FqkD06cZ03HNvyIimtXPANJEaaic=; b=vn7oDgCADW1Fg7PAqfk435C9XlUbjBEvFHlYR73PeiAyumi+PYuAHWgt0zyVev/+6w iUofp44V93wY6eL5CQOc/dcKGuglt3LJIwGS3oLAkGH9ugOQX6XmxAUVGKce593VhROy kgL3MjVVCyT6T9nNPjkVqnPFxHDN9Z5nPjw83g5FV/eTJV28qTNoUIhk2mLUJv48q3Yg ZMIoNmBzvNzCj8l7OR6fDhDjIalOuF8RlJnvod7Hl7DFEoDKwms84JJ2LYL+WMMbZDzW +cjC7ocvVEF/mrCWyEyDFi/940VPWXaMQ/4Pc7oHxCR7bUtLSzsPRr2zh0lV11s/dpO5 5pIw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=Yv73NxI2; 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 x21si3421923oif.250.2019.12.04.07.39.46; Wed, 04 Dec 2019 07:39:46 -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=Yv73NxI2; 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 S1728390AbfLDPjo (ORCPT + 10 others); Wed, 4 Dec 2019 10:39:44 -0500 Received: from mail-wm1-f66.google.com ([209.85.128.66]:38247 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728324AbfLDPjo (ORCPT ); Wed, 4 Dec 2019 10:39:44 -0500 Received: by mail-wm1-f66.google.com with SMTP id p17so199133wmi.3 for ; Wed, 04 Dec 2019 07:39:43 -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=v9aPs/wpi2L5/d1FqkD06cZ03HNvyIimtXPANJEaaic=; b=Yv73NxI2i/49vDu9InO7rsocVrEzs/pBK32Etx2/SRVL8T0kjo8vJhE68rp0tiWbhR TN8smksr1qo5jOSXE0ktqPNSd1/1dRMfTE8+SS8Bpi6KTZiRYN30m4WydmYSJamc2lRa h7Q72QkNuo+V1taaUC0pltB9ygR1YXD9vcnVa9DsgK+5AkoSGpjoBUSSSb4Msde00w3r 9bLseDoQ7cRk3pYamuekA9GBoLgpn/1m+9JfY5RTnzalwp7L5fRiSrOQyjsz0lt0Kv/a 29yZVw5lyWcz+KydY3Bj9fo5ANJKePNhagEJ4ZKA5elxZfZU8tNWzwcQNWbRfazvixSJ P2sg== 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=v9aPs/wpi2L5/d1FqkD06cZ03HNvyIimtXPANJEaaic=; b=S6YDudRxqiTYQrHfxJ2gmHdT7/8LlQFBa7Dv4co/ewqUrroCaxGvpvw3upIRoQ0MqD hYmltKUwiwH2CM2hwZIxc7CRR1tIIfP6PyCwcfwwDfpDq1uS9KI1OF8l0gAbKR/6XHdu jWWRsztGzWZIfR6QVbzMVMjryViOsb9j2YJu5ySLT9Pm6UVifHhjUqHAue4R8TyLiQnN H79lFjxnzxd2Y0lqZqwzJo6hpFqec8qBeaMZdY6Kt3GiG8DpIqxsySucYKfTtuPmNVvi s/vEeJNWmNe2EtwEKKLVdINAG8iL1XGqhb6PzKliJnlCxg9Dt5BbN6AOnQpL5g1HYpTO 5VwA== X-Gm-Message-State: APjAAAU18Btv0QMlk96X7ANRcipZa9XPkAUPt/DouzGy/6apLWqPUJTM zMaCt3q1dOeqTieFIj3bXOoWwuLifwk= X-Received: by 2002:a1c:a98e:: with SMTP id s136mr112577wme.140.1575473981990; Wed, 04 Dec 2019 07:39:41 -0800 (PST) Received: from localhost.localdomain ([2a01:e34:ed2f:f020:a551:321a:c21f:1f92]) by smtp.gmail.com with ESMTPSA id f1sm8631311wrp.93.2019.12.04.07.39.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Dec 2019 07:39:41 -0800 (PST) From: Daniel Lezcano To: edubezval@gmail.com, rui.zhang@intel.com Cc: rjw@rjwysocki.net, linux-pm@vger.kernel.org, viresh.kumar@linaro.org, amit.kucheria@linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 1/4] thermal/drivers/Kconfig: Convert the CPU cooling device to a choice Date: Wed, 4 Dec 2019 16:39:27 +0100 Message-Id: <20191204153930.9128-1-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 Acked-by: Viresh Kumar --- 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 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 Wed Dec 4 15:39:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 180804 Delivered-To: patch@linaro.org Received: by 2002:ac9:3d8b:0:0:0:0:0 with SMTP id u11csp785419oce; Wed, 4 Dec 2019 07:39:49 -0800 (PST) X-Google-Smtp-Source: APXvYqzjWD57135kJR3j7CGCy9ixoOyIqNwQ/38C9aLisXYABHYJLql091KoC2rM2aFi2n4j+Th2 X-Received: by 2002:a05:6830:1715:: with SMTP id 21mr3016344otk.67.1575473988883; Wed, 04 Dec 2019 07:39:48 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1575473988; cv=none; d=google.com; s=arc-20160816; b=IipsbA9Y4uaMPo/8zhx8tIVryErxBVI74RsXsISUbGtYh642eQZ+RXPK2AJtHXO5jM nk0rCLU5zcPKhp/fYOQKik/E6bF6figtLaaZvAw1iyYPl/9iJ2spqgJHUmNNR7pUGHy0 GAn4wVtelvhVOVRTR88236F8l3G0orET/ugFf8kKlVSwyrdZDJB2uojNKJGO1nWX2VgK AeB8ejhrPEwJ7t94b1pgNcQCjhDfH52PGfS9Sm25SxDah7aP1gk16gpXawuSlQ5+Vxmc xPPKgEbg3FlTJ8wdTdrGsa/alJYlspIqGa3FOdLpDJRwPSmTt7Ru5ICmcgdEFf/9uhwZ L1LA== 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=eHar8caGVk2CHYCleN7lzgXckcrdAjaPRcEzE+leMkc=; b=XlZPyshKgaBxD60e2Tz6uh2fKVM8meAOoX7lDGeKEk30HbH6Irhwsf8AyQeII5fQo1 VGlaieV70fI09tH3/rfnQolhjhEUhV/A3//Jsb8E1+8zoN0Z+BGDmdKzsOtS/iX8rW+0 JauFk9I7b56OuuEQ3PAbhKmoCJQztV4Su9b2iptb49uIeZoeopJFkwwvifuhx9tQ2WFF I54muLY/yzZnLM6vUwzpN1PTCPONW1ZaMzOwLMltkmojzo1rGhda/zvX6fpJaZeHNuCf WI3Xiq0piOiv3BkNUWZQH11u4QWVKyuVzzZha7wDyY+ODTqPzxbYsmcJzdt5FWDMfflc NTwg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=qsESq1Zl; 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 x21si3421923oif.250.2019.12.04.07.39.48; Wed, 04 Dec 2019 07:39:48 -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=qsESq1Zl; 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 S1728396AbfLDPjs (ORCPT + 10 others); Wed, 4 Dec 2019 10:39:48 -0500 Received: from mail-wm1-f66.google.com ([209.85.128.66]:33489 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728324AbfLDPjr (ORCPT ); Wed, 4 Dec 2019 10:39:47 -0500 Received: by mail-wm1-f66.google.com with SMTP id y23so5135275wma.0 for ; Wed, 04 Dec 2019 07:39:46 -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=eHar8caGVk2CHYCleN7lzgXckcrdAjaPRcEzE+leMkc=; b=qsESq1ZlfGlT7CaPQkcDkqRCPhUkYAp1MvgB6WHuCAtK2sLShsuWQSKYsRZfUbBjDu Aa34HDxy7CO9PAE+CqsIwkYOlE6g1R+xCTygjCW6/FRra8CoMU13b6h1CN807oeWvz1P X4bv54JEPFFcIaCTz1s9fGbZFjSL7TNxQJBFxSldkK9opfBZqWtK0+4w/NNqDLA3SYwb vjaCX9GUrosUFAdqnlqA3nEUzvg8gFhF1Vne6UC9bkeTo6yQv9BXQG8/LS1+wy9ztJ9K neH8DCaRsy421eJKTwbslQObGAG6+xHvBOGn8N0BQfFaC5oh6jjNpI+B3zE2FyiGHH49 XAKg== 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=eHar8caGVk2CHYCleN7lzgXckcrdAjaPRcEzE+leMkc=; b=c+3dFhOtlU6g2z5dWAApst9wOprf/4Xj25MlRvkR88by0p18P11UT/+iCyBJumAG1L URFOyDkAX07oCGkBUTiDbwHiNx6gy+Vfc8jrSHoLRuZsjHwZLBFUbhzEbcqEq0lDy80q G6k+CyP6srkWgmiyw49Jb/LIpCvUEvDMggtfZAHAFmzeJIwOi0vg+PcqFQ5BGK0YFvz+ w3TRLl2Q9FCPE30MmKOXmFL/owfqZXIliGqP8z3U1bQDFZ799vBClIGr+GyomgkfWoSE BA8EiLSYqA4FAici3x4XBxjc4RSHVAwCpxztR/XDZ++D6Aj5/6m4abhcs+10IuV7aE/i LFbw== X-Gm-Message-State: APjAAAU1Y9tJAypwHUea/fF1LIuchuXufBnzrthOALAydWBiu6IVfYvl 8VWPv9b8SV1SV4ztOwG+jwbHsA== X-Received: by 2002:a1c:a906:: with SMTP id s6mr180759wme.125.1575473985220; Wed, 04 Dec 2019 07:39:45 -0800 (PST) Received: from localhost.localdomain ([2a01:e34:ed2f:f020:a551:321a:c21f:1f92]) by smtp.gmail.com with ESMTPSA id f1sm8631311wrp.93.2019.12.04.07.39.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Dec 2019 07:39:44 -0800 (PST) From: Daniel Lezcano To: edubezval@gmail.com, rui.zhang@intel.com Cc: rjw@rjwysocki.net, linux-pm@vger.kernel.org, viresh.kumar@linaro.org, amit.kucheria@linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 2/4] thermal/drivers/cpu_cooling: Add idle cooling device documentation Date: Wed, 4 Dec 2019 16:39:28 +0100 Message-Id: <20191204153930.9128-2-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191204153930.9128-1-daniel.lezcano@linaro.org> References: <20191204153930.9128-1-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 Acked-by: Viresh Kumar --- V4: - Fixed typos, replaced 'period' per 'duty cycles', clarified some wording (Amit Kucheria) --- .../driver-api/thermal/cpu-idle-cooling.rst | 189 ++++++++++++++++++ 1 file changed, 189 insertions(+) create mode 100644 Documentation/driver-api/thermal/cpu-idle-cooling.rst -- 2.17.1 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..13d7fe4e8de8 --- /dev/null +++ b/Documentation/driver-api/thermal/cpu-idle-cooling.rst @@ -0,0 +1,189 @@ + +Situation: +---------- + +Under certain circumstances a SoC can reach a critical temperature +limit and 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 +critical temperature is reached, a decision must be taken to reduce +the temperature, that, in turn impacts performance. + +Another situation is when the silicon temperature continues to +increase even after the dynamic leakage is reduced to its minimum by +clock gating the component. This runaway phenomenon can continue due +to the static leakage. The only solution is to power down the +component, thus dropping the dynamic and static leakage that 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 under-utilize the CPU, thus +losing performance. In other words, one OPP under-utilizes the CPU +with a power less than the requested power budget and the next OPP +exceeds 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 on 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 scenarios. + +At a specific OPP, we can assume that injecting idle cycle on all CPUs +belong to the same cluster, with a duration greater than the cluster +idle state target residency, we lead to dropping 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 cycles synchronously, the cluster can reach its power down +state with a minimum power consumption and reduce the static leakage +to almost zero. However, these idle cycles injection will add extra +latencies as the CPUs will have to wakeup from a deep sleep state. + +We use a fixed duration of idle injection that gives an acceptable +performance penalty and a fixed latency. Mitigation can be increased +or decreased by modulating the duty cycle of the idle injection. + + ^ + | + | + |------- ------- + |_______|_______________________|_______|___________ + + <------> + idle <----------------------> + running + + <-----------------------------> + duty cycle 25% + + +The implementation of the cooling device bases the number of states on +the duty cycle percentage. When no mitigation is happening the cooling +device state is zero, meaning the duty cycle is 0%. + +When the mitigation begins, depending on the governor's policy, a +starting state is selected. With a fixed idle duration and the duty +cycle (aka the cooling device state), the running duration can be +computed. + +The governor will change the cooling device state thus the duty cycle +and this variation will modulate the cooling effect. + + ^ + | + | + |------- ------- + |_______|_______________|_______|___________ + + <------> + idle <--------------> + running + + <-----------------------------> + duty cycle 33% + + + ^ + | + | + |------- ------- + |_______|_______|_______|___________ + + <------> + idle <------> + running + + <-------------> + duty cycle 50% + +The idle injection duration value must comply with the constraints: + +- It is less than 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. + +Power considerations +-------------------- + +When we reach the thermal trip point, we have to sustain a specified +power for a 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 in 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 power allocator governor 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 in 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 x 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 less 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 Wed Dec 4 15:39:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 180806 Delivered-To: patch@linaro.org Received: by 2002:ac9:3d8b:0:0:0:0:0 with SMTP id u11csp785539oce; Wed, 4 Dec 2019 07:39:54 -0800 (PST) X-Google-Smtp-Source: APXvYqw8w9EZH5dmkW8JvlgJQreBus6yYKBfgwc1MCK+6p3Yd/B0Qfar8kHnG3F2SAcDC1mOf9o0 X-Received: by 2002:aca:3846:: with SMTP id f67mr3027105oia.61.1575473994766; Wed, 04 Dec 2019 07:39:54 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1575473994; cv=none; d=google.com; s=arc-20160816; b=RXEuLIYW3pj+pYYQ6R8ioz0OIjsdafThm1UV24bFFSCcyZLof4a6Gmh5tSamYgwCfr PzYWduORVA5Khd0zQ6PMggvK28rgR/K/UL8y9IklEsUds16IC73r+KWNobBbKUrIxXLM CABD+JOSIUefUOAqS2/HnudKSEviJSLKBWUBfuNYQWhVJ/jCmjgNHOwS1hzVEb2AGv02 Yhgh8IwsINmobQx0Myd18yjwOz45cyMWBMFFp0Q0y9qBlHFJipvEKm182fiq8tGW6A/h FoCuSZ1dNMAWeJT4H9cHGQNLRyw66ZXIq8rxV7F+UYltguf/ykImP8jp9Xv3dF2AJNIJ GpEQ== 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=1niKCMXXnmGnzZRABJx3hRarOaikbE/OwsjmxwSrkNE=; b=QO/VnCsEUOR8kxGLG8Cxwwt63sC/fAhxFBRuBbSsuiQVdDg/g3Se646/NjfRFsuh0p wunw+Z/5ffISIHJLK3TCgtm9Lf+dUaea3PH3WTyvvFtzmf2HEgSFad1NGddqT+qqHYYI BALpkszLu7qRTImxgkbs9R5xL9/4aBo3TgrnpMtz5lcL1m57PjvxK60CRb5CFDJ8+hax ij3Scz1jlesrVLdS6xLIE1MbDwIIsRMOXy9pmpfvklYMmLZwC95CYj8n9nJA8X9cFZHU kaEgKGOrjG4vLJ7KMrJvbEcumSeKYLn+Ma39QUEg5Gf1n0a2JK2OWs348MxumdEzAsqR T+PQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b="c0n/xZi+"; 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 u130si3459092oib.211.2019.12.04.07.39.54; Wed, 04 Dec 2019 07:39:54 -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="c0n/xZi+"; 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 S1728311AbfLDPjx (ORCPT + 10 others); Wed, 4 Dec 2019 10:39:53 -0500 Received: from mail-wm1-f65.google.com ([209.85.128.65]:33912 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728471AbfLDPjw (ORCPT ); Wed, 4 Dec 2019 10:39:52 -0500 Received: by mail-wm1-f65.google.com with SMTP id f4so5122437wmj.1 for ; Wed, 04 Dec 2019 07:39:51 -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=1niKCMXXnmGnzZRABJx3hRarOaikbE/OwsjmxwSrkNE=; b=c0n/xZi+mCTzNlQRlLCYjL7pSvvKCB2mFzQHqcD21Rl2yMihwatj4fu8MSQQephKYM a53jHtNdVOTYqPaU2OTmrxTns5ls+7huxMeLT3DF6hgUepdwGGF+jS0dLiaXZ+apjioK O6sCTN1jtZFL4PnYdDcsMiYukIKh36htiy9e2m5GzxW+GzrlyV3Fe+okrXsjG4vwpshO He65muV6t5s792gfmkrfXiBfyEtlVjzecqV/9lrd6qTEiP95sdeLmpHFh6tNENFOrVqu Fpz5JPkPK+doI9Ejk9P3ITy0Gz19Drwy5yrhavCIeo547Rnlrb9P8xDm0qEkJ/ut8xBm NG5A== 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=1niKCMXXnmGnzZRABJx3hRarOaikbE/OwsjmxwSrkNE=; b=uXEGaXwIvsOqnL8MlSz6ntPAbqIU/jTL3+Yb/0If0Z5OjGAWhfsZvUCkxDZebq63xW 5AK1UZ95p70iD2FQ+HcbOd1/+UC1i5wxyAe5jgVgtP2VRpprTeCjB6Pr9Azt/PsDxHAQ KhH9FdVYECNgTQtLBgTNAkkVMXxx914wM5bntXBwxsF/h7AM2NcdIuoKH0Phk/Lonfgr VZUzpfWQ5Rb+AiPx4+SzVwglOQjj20NiqhukuQ82YI2too+mXidonfKmlA80bH8SCoQQ zpTC0jj7INtkCqqaLLft4LQgKWdPK/5tICqGRtG3ekWFk2zYj5Va0OdxMH1ktlF6QapQ 2swg== X-Gm-Message-State: APjAAAVzMkYN8tFlSdMuaYEzNx9JIHNIGc9jdC9BMvm6kTWtfFiB+hwJ PLPzXDZ4FoX4j9Hn+iV1Mxqqrg== X-Received: by 2002:a1c:9d4a:: with SMTP id g71mr239894wme.50.1575473990613; Wed, 04 Dec 2019 07:39:50 -0800 (PST) Received: from localhost.localdomain ([2a01:e34:ed2f:f020:a551:321a:c21f:1f92]) by smtp.gmail.com with ESMTPSA id f1sm8631311wrp.93.2019.12.04.07.39.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Dec 2019 07:39:50 -0800 (PST) From: Daniel Lezcano To: edubezval@gmail.com, rui.zhang@intel.com Cc: rjw@rjwysocki.net, linux-pm@vger.kernel.org, viresh.kumar@linaro.org, amit.kucheria@linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 4/4] thermal/drivers/cpu_cooling: Rename to cpufreq_cooling Date: Wed, 4 Dec 2019 16:39:30 +0100 Message-Id: <20191204153930.9128-4-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191204153930.9128-1-daniel.lezcano@linaro.org> References: <20191204153930.9128-1-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 Acked-by: Viresh Kumar Reviewed-by: Amit Kucheria --- V4: - Added Acked-by and Reviewed-by V3: - Fix missing name conversion (Viresh Kumar) --- Documentation/driver-api/thermal/exynos_thermal.rst | 2 +- MAINTAINERS | 2 +- drivers/thermal/Makefile | 2 +- drivers/thermal/clock_cooling.c | 2 +- drivers/thermal/{cpu_cooling.c => cpufreq_cooling.c} | 6 +++--- include/linux/clock_cooling.h | 2 +- 6 files changed, 8 insertions(+), 8 deletions(-) rename drivers/thermal/{cpu_cooling.c => cpufreq_cooling.c} (99%) -- 2.17.1 diff --git a/Documentation/driver-api/thermal/exynos_thermal.rst b/Documentation/driver-api/thermal/exynos_thermal.rst index 5bd556566c70..d4e4a5b75805 100644 --- a/Documentation/driver-api/thermal/exynos_thermal.rst +++ b/Documentation/driver-api/thermal/exynos_thermal.rst @@ -67,7 +67,7 @@ TMU driver description: The exynos thermal driver is structured as:: Kernel Core thermal framework - (thermal_core.c, step_wise.c, cpu_cooling.c) + (thermal_core.c, step_wise.c, cpufreq_cooling.c) ^ | | diff --git a/MAINTAINERS b/MAINTAINERS index d2e92a0360f2..26e4be914765 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -16194,7 +16194,7 @@ L: linux-pm@vger.kernel.org S: Supported F: Documentation/driver-api/thermal/cpu-cooling-api.rst F: Documentation/driver-api/thermal/cpu-idle-cooling.rst -F: drivers/thermal/cpu_cooling.c +F: drivers/thermal/cpufreq_cooling.c F: drivers/thermal/cpuidle_cooling.c F: include/linux/cpu_cooling.h 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/clock_cooling.c b/drivers/thermal/clock_cooling.c index 3ad3256c48fd..7cb3ae4b44ee 100644 --- a/drivers/thermal/clock_cooling.c +++ b/drivers/thermal/clock_cooling.c @@ -7,7 +7,7 @@ * Copyright (C) 2013 Texas Instruments Inc. * Contact: Eduardo Valentin * - * Highly based on cpu_cooling.c. + * Highly based on cpufreq_cooling.c. * Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com) * Copyright (C) 2012 Amit Daniel */ diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpufreq_cooling.c similarity index 99% rename from drivers/thermal/cpu_cooling.c rename to drivers/thermal/cpufreq_cooling.c index 6b9865c786ba..3a3f9cf94b6d 100644 --- a/drivers/thermal/cpu_cooling.c +++ b/drivers/thermal/cpufreq_cooling.c @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 /* - * linux/drivers/thermal/cpu_cooling.c + * linux/drivers/thermal/cpufreq_cooling.c * * Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com) * @@ -694,7 +694,7 @@ of_cpufreq_cooling_register(struct cpufreq_policy *policy) u32 capacitance = 0; if (!np) { - pr_err("cpu_cooling: OF node not available for cpu%d\n", + pr_err("cpufreq_cooling: OF node not available for cpu%d\n", policy->cpu); return NULL; } @@ -705,7 +705,7 @@ of_cpufreq_cooling_register(struct cpufreq_policy *policy) cdev = __cpufreq_cooling_register(np, policy, capacitance); if (IS_ERR(cdev)) { - pr_err("cpu_cooling: cpu%d failed to register as cooling device: %ld\n", + pr_err("cpufreq_cooling: cpu%d failed to register as cooling device: %ld\n", policy->cpu, PTR_ERR(cdev)); cdev = NULL; } diff --git a/include/linux/clock_cooling.h b/include/linux/clock_cooling.h index b5cebf766e02..4b0a69863656 100644 --- a/include/linux/clock_cooling.h +++ b/include/linux/clock_cooling.h @@ -7,7 +7,7 @@ * Copyright (C) 2013 Texas Instruments Inc. * Contact: Eduardo Valentin * - * Highly based on cpu_cooling.c. + * Highly based on cpufreq_cooling.c. * Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com) * Copyright (C) 2012 Amit Daniel */