From patchwork Mon Oct 19 14:05:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 11844433 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 5A052C433E7 for ; Mon, 19 Oct 2020 14:08:06 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DA83922263 for ; Mon, 19 Oct 2020 14:08:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="cmyjDUqm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA83922263 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:References:In-Reply-To:Message-Id:Date:Subject:To: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hVDx0YehNFGfTzcLtXIcKuWDXcY6KlHx6GshcQmXn/k=; b=cmyjDUqmF8JL8RaybMwcWRlzIM P1ijuEf0N+cKWjmAB9ud2TUu/4KqDWYpjN++hgeXUktMAnFg2UXT6eE4D4f8vpkCDc+Y1Yb5uAu69 iV2Jgk3ruRnmNFHjzKotTZd079mbKE5cGQ3Ex3QoBBmWq9no9bzRBsjJx7ELU6bWZa5rnaBZHhkoj O8/gSORnKDRhsnv4kRuJuhp8bYzSrRsokrPMZKsTZmS0TJR10gKXgQgoZhQ6lZ2dPbsOtdsiO21Gr rtIWctQoK5keEb73PQlLhK9N5Z1ctHWmD6RjNM1AE/KXrJyX7rzVQ3tXrXDnHvQFnasQyCqj9N/bY 89YmFoNQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kUVnw-0003x1-VS; Mon, 19 Oct 2020 14:06:29 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kUVnu-0003wG-QL for linux-arm-kernel@lists.infradead.org; Mon, 19 Oct 2020 14:06:27 +0000 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 22469D6E; Mon, 19 Oct 2020 07:06:25 -0700 (PDT) Received: from e123648.arm.com (unknown [10.57.15.200]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 97A4A3F66E; Mon, 19 Oct 2020 07:06:20 -0700 (PDT) From: Lukasz Luba To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 1/4] PM / EM: Add a flag indicating units of power values in Energy Model Date: Mon, 19 Oct 2020 15:05:58 +0100 Message-Id: <20201019140601.3047-2-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201019140601.3047-1-lukasz.luba@arm.com> References: <20201019140601.3047-1-lukasz.luba@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201019_100626_960493_BC4756AC X-CRM114-Status: GOOD ( 21.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nm@ti.com, rafael@kernel.org, daniel.lezcano@linaro.org, rnayak@codeaurora.org, corbet@lwn.net, sboyd@kernel.org, viresh.kumar@linaro.org, mka@chromium.org, amitk@kernel.org, dianders@chromium.org, morten.rasmussen@arm.com, robh+dt@kernel.org, sudeep.holla@arm.com, qperret@google.com, Dietmar.Eggemann@arm.com, lukasz.luba@arm.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org There are different platforms and devices which might use different scale for the power values. Kernel sub-systems might need to check if all Energy Model (EM) devices are using the same scale. Address that issue and store the information inside EM for each device. Thanks to that they can be easily compared and proper action triggered. Suggested-by: Daniel Lezcano Signed-off-by: Lukasz Luba Reviewed-by: Quentin Perret --- drivers/cpufreq/scmi-cpufreq.c | 3 ++- drivers/opp/of.c | 2 +- include/linux/energy_model.h | 9 +++++++-- kernel/power/energy_model.c | 24 +++++++++++++++++++++++- 4 files changed, 33 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c index e855e8612a67..3714a4cd07fa 100644 --- a/drivers/cpufreq/scmi-cpufreq.c +++ b/drivers/cpufreq/scmi-cpufreq.c @@ -188,7 +188,8 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy) policy->fast_switch_possible = handle->perf_ops->fast_switch_possible(handle, cpu_dev); - em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus); + em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus, + false); return 0; diff --git a/drivers/opp/of.c b/drivers/opp/of.c index 874b58756220..9e1307061de5 100644 --- a/drivers/opp/of.c +++ b/drivers/opp/of.c @@ -1333,7 +1333,7 @@ int dev_pm_opp_of_register_em(struct device *dev, struct cpumask *cpus) goto failed; } - ret = em_dev_register_perf_domain(dev, nr_opp, &em_cb, cpus); + ret = em_dev_register_perf_domain(dev, nr_opp, &em_cb, cpus, true); if (ret) goto failed; diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h index b67a51c574b9..2c31d79bb922 100644 --- a/include/linux/energy_model.h +++ b/include/linux/energy_model.h @@ -29,6 +29,8 @@ struct em_perf_state { * em_perf_domain - Performance domain * @table: List of performance states, in ascending order * @nr_perf_states: Number of performance states + * @milliwatts: Flag indicating the power values are in milli-Watts + * or some other scale. * @cpus: Cpumask covering the CPUs of the domain. It's here * for performance reasons to avoid potential cache * misses during energy calculations in the scheduler @@ -43,6 +45,7 @@ struct em_perf_state { struct em_perf_domain { struct em_perf_state *table; int nr_perf_states; + bool milliwatts; unsigned long cpus[]; }; @@ -79,7 +82,8 @@ struct em_data_callback { struct em_perf_domain *em_cpu_get(int cpu); struct em_perf_domain *em_pd_get(struct device *dev); int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, - struct em_data_callback *cb, cpumask_t *span); + struct em_data_callback *cb, cpumask_t *spani, + bool milliwatts); void em_dev_unregister_perf_domain(struct device *dev); /** @@ -186,7 +190,8 @@ struct em_data_callback {}; static inline int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, - struct em_data_callback *cb, cpumask_t *span) + struct em_data_callback *cb, cpumask_t *span, + bool milliwatts) { return -EINVAL; } diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index c1ff7fa030ab..efe2a595988e 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -52,6 +52,17 @@ static int em_debug_cpus_show(struct seq_file *s, void *unused) } DEFINE_SHOW_ATTRIBUTE(em_debug_cpus); +static int em_debug_units_show(struct seq_file *s, void *unused) +{ + struct em_perf_domain *pd = s->private; + char *units = pd->milliwatts ? "milliWatts" : "bogoWatts"; + + seq_printf(s, "%s\n", units); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(em_debug_units); + static void em_debug_create_pd(struct device *dev) { struct dentry *d; @@ -64,6 +75,8 @@ static void em_debug_create_pd(struct device *dev) debugfs_create_file("cpus", 0444, d, dev->em_pd->cpus, &em_debug_cpus_fops); + debugfs_create_file("units", 0444, d, dev->em_pd, &em_debug_units_fops); + /* Create a sub-directory for each performance state */ for (i = 0; i < dev->em_pd->nr_perf_states; i++) em_debug_create_ps(&dev->em_pd->table[i], d); @@ -250,17 +263,24 @@ EXPORT_SYMBOL_GPL(em_cpu_get); * @cpus : Pointer to cpumask_t, which in case of a CPU device is * obligatory. It can be taken from i.e. 'policy->cpus'. For other * type of devices this should be set to NULL. + * @milliwatts : Flag indicating that the power values are in milliWatts or + * in some other scale. It must be set properly. * * Create Energy Model tables for a performance domain using the callbacks * defined in cb. * + * The @milliwatts is important to set with correct value. Some kernel + * sub-systems might rely on this flag and check if all devices in the EM are + * using the same scale. + * * If multiple clients register the same performance domain, all but the first * registration will be ignored. * * Return 0 on success */ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, - struct em_data_callback *cb, cpumask_t *cpus) + struct em_data_callback *cb, cpumask_t *cpus, + bool milliwatts) { unsigned long cap, prev_cap = 0; int cpu, ret; @@ -313,6 +333,8 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, if (ret) goto unlock; + dev->em_pd->milliwatts = milliwatts; + em_debug_create_pd(dev); dev_info(dev, "EM: created perf domain\n"); From patchwork Mon Oct 19 14:05:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 11844435 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 E1B62C43457 for ; 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Mon, 19 Oct 2020 07:06:25 -0700 (PDT) From: Lukasz Luba To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 2/4] docs: Clarify abstract scale usage for power values in Energy Model Date: Mon, 19 Oct 2020 15:05:59 +0100 Message-Id: <20201019140601.3047-3-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201019140601.3047-1-lukasz.luba@arm.com> References: <20201019140601.3047-1-lukasz.luba@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201019_100631_210055_7BD2DC1E X-CRM114-Status: GOOD ( 16.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nm@ti.com, rafael@kernel.org, daniel.lezcano@linaro.org, rnayak@codeaurora.org, corbet@lwn.net, sboyd@kernel.org, viresh.kumar@linaro.org, mka@chromium.org, amitk@kernel.org, dianders@chromium.org, morten.rasmussen@arm.com, robh+dt@kernel.org, sudeep.holla@arm.com, qperret@google.com, Dietmar.Eggemann@arm.com, lukasz.luba@arm.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The Energy Model (EM) can store power values in milli-Watts or in abstract scale. This might cause issues in the subsystems which use the EM for estimating the device power, such as: - mixing of different scales in a subsystem which uses multiple (cooling) devices (e.g. thermal Intelligent Power Allocation (IPA)) - assuming that energy [milli-Joules] can be derived from the EM power values which might not be possible since the power scale doesn't have to be in milli-Watts To avoid misconfiguration add the needed documentation to the EM and related subsystems: EAS and IPA. Signed-off-by: Lukasz Luba --- .../driver-api/thermal/power_allocator.rst | 13 ++++++++++++- Documentation/power/energy-model.rst | 13 +++++++++++++ Documentation/scheduler/sched-energy.rst | 5 +++++ 3 files changed, 30 insertions(+), 1 deletion(-) diff --git a/Documentation/driver-api/thermal/power_allocator.rst b/Documentation/driver-api/thermal/power_allocator.rst index 67b6a3297238..b7992ae84fef 100644 --- a/Documentation/driver-api/thermal/power_allocator.rst +++ b/Documentation/driver-api/thermal/power_allocator.rst @@ -71,7 +71,10 @@ to the speed-grade of the silicon. `sustainable_power` is therefore simply an estimate, and may be tuned to affect the aggressiveness of the thermal ramp. For reference, the sustainable power of a 4" phone is typically 2000mW, while on a 10" tablet is around 4500mW (may vary -depending on screen size). +depending on screen size). It is possible to have the power value +expressed in an abstract scale. This is the case when the Energy Model +provides the power values in an abstract scale. The sustained power +should be aligned to the scale used by the related cooling devices. If you are using device tree, do add it as a property of the thermal-zone. For example:: @@ -269,3 +272,11 @@ won't be very good. Note that this is not particular to this governor, step-wise will also misbehave if you call its throttle() faster than the normal thermal framework tick (due to interrupts for example) as it will overreact. + +Energy Model requirements +========================= + +Another important thing is the consistent scale of the power values +provided by the cooling devices. All of the cooling devices in a single +thermal zone should have power values reported either in milli-Watts +or scaled to the same 'abstract scale'. diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst index a6fb986abe3c..ba7aa581b307 100644 --- a/Documentation/power/energy-model.rst +++ b/Documentation/power/energy-model.rst @@ -20,6 +20,19 @@ possible source of information on its own, the EM framework intervenes as an abstraction layer which standardizes the format of power cost tables in the kernel, hence enabling to avoid redundant work. +The power values might be expressed in milli-Watts or in an 'abstract scale'. +Multiple subsystems might use the EM and it is up to the system integrator to +check that the requirements for the power value scale types are met. An example +can be found in the Energy-Aware Scheduler documentation +Documentation/scheduler/sched-energy.rst. For some subsystems like thermal or +powercap power values expressed in an 'abstract scale' might cause issues. +These subsystems are more interested in estimation of power used in the past, +thus the real milli-Watts might be needed. An example of these requirements can +be found in the Intelligent Power Allocation in +Documentation/driver-api/thermal/power_allocator.rst. +Important thing to keep in mind is that when the power values are expressed in +an 'abstract scale' deriving real energy in milli-Joules would not be possible. + The figure below depicts an example of drivers (Arm-specific here, but the approach is applicable to any architecture) providing power costs to the EM framework, and interested clients reading the data from it:: diff --git a/Documentation/scheduler/sched-energy.rst b/Documentation/scheduler/sched-energy.rst index 001e09c95e1d..afe02d394402 100644 --- a/Documentation/scheduler/sched-energy.rst +++ b/Documentation/scheduler/sched-energy.rst @@ -350,6 +350,11 @@ independent EM framework in Documentation/power/energy-model.rst. Please also note that the scheduling domains need to be re-built after the EM has been registered in order to start EAS. +EAS uses the EM to make a forecasting decision on energy usage and thus it is +more focused on the difference when checking possible options for task +placement. For EAS it doesn't matter whether the EM power values are expressed +in milli-Watts or in an 'abstract scale'. + 6.3 - Energy Model complexity ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ From patchwork Mon Oct 19 14:06:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 11844439 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 21C7BC433E7 for ; Mon, 19 Oct 2020 14:08:23 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9E35322263 for ; Mon, 19 Oct 2020 14:08:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="izYC5iOt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E35322263 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:References:In-Reply-To:Message-Id:Date:Subject:To: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=YDbHe2/gM3LawyqdpTbVUISJuepGT1NRFnWWfs167+8=; b=izYC5iOtdPixX20S1bc4tzVcMq Kga7lp92iFEgJH+3hq9RFJdwMSnRW1WblVMy9IrSMCU9dUZYqgwn2zB+TNbUyqTrkJ5SNv/FH72D8 c5++e/BzDagWLi02gGrzrW9wz05x8+WTj1uxw/dMWBVKnWng0cuAwV7Bs5WEWCzKRNOBC8dTgXofb 9/6YZN//1zNMHB7SF6lMU+dNelMiBrfWCTLXEyfZAtG7X92H/9VvUMx0kPdI60Zqq4uoQFiZy3cSM OuPFF14wC4/qC9PkV8WyKCtYmYiug50h0LBOdxZMHf8vDW60AUtKxAP1nggtfYSlxmFblDCFyqYDM FrlTDWdg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kUVo9-00040t-Qt; Mon, 19 Oct 2020 14:06:41 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kUVo4-0003zI-1i for linux-arm-kernel@lists.infradead.org; Mon, 19 Oct 2020 14:06:37 +0000 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 1328BD6E; Mon, 19 Oct 2020 07:06:35 -0700 (PDT) Received: from e123648.arm.com (unknown [10.57.15.200]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 85BBA3F66E; Mon, 19 Oct 2020 07:06:30 -0700 (PDT) From: Lukasz Luba To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 3/4] PM / EM: update the comments related to power scale Date: Mon, 19 Oct 2020 15:06:00 +0100 Message-Id: <20201019140601.3047-4-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201019140601.3047-1-lukasz.luba@arm.com> References: <20201019140601.3047-1-lukasz.luba@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201019_100636_187957_4EEC5602 X-CRM114-Status: GOOD ( 16.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nm@ti.com, rafael@kernel.org, daniel.lezcano@linaro.org, rnayak@codeaurora.org, corbet@lwn.net, sboyd@kernel.org, viresh.kumar@linaro.org, mka@chromium.org, amitk@kernel.org, dianders@chromium.org, morten.rasmussen@arm.com, robh+dt@kernel.org, sudeep.holla@arm.com, qperret@google.com, Dietmar.Eggemann@arm.com, lukasz.luba@arm.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The Energy Model supports power values expressed in milli-Watts or in an 'abstract scale'. Update the related comments is the code to reflect that state. Signed-off-by: Lukasz Luba Reviewed-by: Quentin Perret --- include/linux/energy_model.h | 11 +++++------ kernel/power/energy_model.c | 2 +- 2 files changed, 6 insertions(+), 7 deletions(-) diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h index 2c31d79bb922..a900b335dd61 100644 --- a/include/linux/energy_model.h +++ b/include/linux/energy_model.h @@ -13,9 +13,8 @@ /** * em_perf_state - Performance state of a performance domain * @frequency: The frequency in KHz, for consistency with CPUFreq - * @power: The power consumed at this level, in milli-watts (by 1 CPU or - by a registered device). It can be a total power: static and - dynamic. + * @power: The power consumed at this level (by 1 CPU or by a registered + * device). It can be a total power: static and dynamic. * @cost: The cost coefficient associated with this level, used during * energy calculation. Equal to: power * max_frequency / frequency */ @@ -58,7 +57,7 @@ struct em_data_callback { /** * active_power() - Provide power at the next performance state of * a device - * @power : Active power at the performance state in mW + * @power : Active power at the performance state * (modified) * @freq : Frequency at the performance state in kHz * (modified) @@ -69,8 +68,8 @@ struct em_data_callback { * and frequency. * * In case of CPUs, the power is the one of a single CPU in the domain, - * expressed in milli-watts. It is expected to fit in the - * [0, EM_MAX_POWER] range. + * expressed in milli-Watts or an abstract scale. It is expected to + * fit in the [0, EM_MAX_POWER] range. * * Return 0 on success. */ diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index efe2a595988e..1358fa4abfa8 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -143,7 +143,7 @@ static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd, /* * The power returned by active_state() is expected to be - * positive, in milli-watts and to fit into 16 bits. + * positive and to fit into 16 bits. */ if (!power || power > EM_MAX_POWER) { dev_err(dev, "EM: invalid power: %lu\n", From patchwork Mon Oct 19 14:06:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 11844431 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 93734C433DF for ; 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Mon, 19 Oct 2020 07:06:35 -0700 (PDT) From: Lukasz Luba To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 4/4] docs: power: Update Energy Model with new flag indicating power scale Date: Mon, 19 Oct 2020 15:06:01 +0100 Message-Id: <20201019140601.3047-5-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201019140601.3047-1-lukasz.luba@arm.com> References: <20201019140601.3047-1-lukasz.luba@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201019_100640_836970_66F5770F X-CRM114-Status: GOOD ( 14.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nm@ti.com, rafael@kernel.org, daniel.lezcano@linaro.org, rnayak@codeaurora.org, corbet@lwn.net, sboyd@kernel.org, viresh.kumar@linaro.org, mka@chromium.org, amitk@kernel.org, dianders@chromium.org, morten.rasmussen@arm.com, robh+dt@kernel.org, sudeep.holla@arm.com, qperret@google.com, Dietmar.Eggemann@arm.com, lukasz.luba@arm.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Update description and meaning of a new flag, which indicates the type of power scale used for a registered Energy Model (EM) device. Signed-off-by: Lukasz Luba Reviewed-by: Quentin Perret --- Documentation/power/energy-model.rst | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst index ba7aa581b307..60ac091d3b0d 100644 --- a/Documentation/power/energy-model.rst +++ b/Documentation/power/energy-model.rst @@ -30,6 +30,8 @@ These subsystems are more interested in estimation of power used in the past, thus the real milli-Watts might be needed. An example of these requirements can be found in the Intelligent Power Allocation in Documentation/driver-api/thermal/power_allocator.rst. +Kernel subsystems might implement automatic detection to check whether EM +registered devices have inconsistent scale (based on EM internal flag). Important thing to keep in mind is that when the power values are expressed in an 'abstract scale' deriving real energy in milli-Joules would not be possible. @@ -86,7 +88,7 @@ Drivers are expected to register performance domains into the EM framework by calling the following API:: int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, - struct em_data_callback *cb, cpumask_t *cpus); + struct em_data_callback *cb, cpumask_t *cpus, bool milliwatts); Drivers must provide a callback function returning tuples for each performance state. The callback function provided by the driver is free @@ -94,6 +96,10 @@ to fetch data from any relevant location (DT, firmware, ...), and by any mean deemed necessary. Only for CPU devices, drivers must specify the CPUs of the performance domains using cpumask. For other devices than CPUs the last argument must be set to NULL. +The last argument 'milliwatts' is important to set with correct value. Kernel +subsystems which use EM might rely on this flag to check if all EM devices use +the same scale. If there are different scales, these subsystems might decide +to: return warning/error, stop working or panic. See Section 3. for an example of driver implementing this callback, and kernel/power/energy_model.c for further documentation on this API. @@ -169,7 +175,8 @@ EM framework:: 37 nr_opp = foo_get_nr_opp(policy); 38 39 /* And register the new performance domain */ - 40 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus); - 41 - 42 return 0; - 43 } + 40 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus, + 41 true); + 42 + 43 return 0; + 44 }