From patchwork Fri Oct 2 11:44:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 267496 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=-12.7 required=3.0 tests=BAYES_00, 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 CE633C47423 for ; Fri, 2 Oct 2020 11:44:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4601206FA for ; Fri, 2 Oct 2020 11:44:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387797AbgJBLo6 (ORCPT ); Fri, 2 Oct 2020 07:44:58 -0400 Received: from foss.arm.com ([217.140.110.172]:33368 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725964AbgJBLo6 (ORCPT ); Fri, 2 Oct 2020 07:44:58 -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 48C571063; Fri, 2 Oct 2020 04:44:57 -0700 (PDT) Received: from e123648.arm.com (unknown [10.57.50.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 1AC2E3F73B; Fri, 2 Oct 2020 04:44:53 -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 Cc: robh+dt@kernel.org, amitk@kernel.org, corbet@lwn.net, daniel.lezcano@linaro.org, lukasz.luba@arm.com, Dietmar.Eggemann@arm.com, qperret@google.com, dianders@chromium.org, mka@chromium.org, rnayak@codeaurora.org, rjw@rjwysocki.net Subject: [PATCH v2 1/3] docs: Clarify abstract scale usage for power values in Energy Model Date: Fri, 2 Oct 2020 12:44:24 +0100 Message-Id: <20201002114426.31277-2-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201002114426.31277-1-lukasz.luba@arm.com> References: <20201002114426.31277-1-lukasz.luba@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.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 Fri Oct 2 11:44:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 267495 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=-12.7 required=3.0 tests=BAYES_00, 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 5F8D9C47423 for ; Fri, 2 Oct 2020 11:45:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D03E206FA for ; Fri, 2 Oct 2020 11:45:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387811AbgJBLpE (ORCPT ); Fri, 2 Oct 2020 07:45:04 -0400 Received: from foss.arm.com ([217.140.110.172]:33394 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725964AbgJBLpC (ORCPT ); Fri, 2 Oct 2020 07:45:02 -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 2E99A1063; Fri, 2 Oct 2020 04:45:01 -0700 (PDT) Received: from e123648.arm.com (unknown [10.57.50.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A9D673F73B; Fri, 2 Oct 2020 04:44:57 -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 Cc: robh+dt@kernel.org, amitk@kernel.org, corbet@lwn.net, daniel.lezcano@linaro.org, lukasz.luba@arm.com, Dietmar.Eggemann@arm.com, qperret@google.com, dianders@chromium.org, mka@chromium.org, rnayak@codeaurora.org, rjw@rjwysocki.net Subject: [PATCH v2 2/3] PM / EM: update the comments related to power scale Date: Fri, 2 Oct 2020 12:44:25 +0100 Message-Id: <20201002114426.31277-3-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201002114426.31277-1-lukasz.luba@arm.com> References: <20201002114426.31277-1-lukasz.luba@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.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 --- 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 b67a51c574b9..b19146b31760 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 */ @@ -55,7 +54,7 @@ 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) @@ -66,8 +65,8 @@ 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 c1ff7fa030ab..2bd2afbb83f5 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -130,7 +130,7 @@ 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 Fri Oct 2 11:44:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 267025 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=-12.7 required=3.0 tests=BAYES_00, 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 1B2B3C4741F for ; Fri, 2 Oct 2020 11:45:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ECDCE206FA for ; Fri, 2 Oct 2020 11:45:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725964AbgJBLpI (ORCPT ); Fri, 2 Oct 2020 07:45:08 -0400 Received: from foss.arm.com ([217.140.110.172]:33410 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387817AbgJBLpF (ORCPT ); Fri, 2 Oct 2020 07:45:05 -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 074961063; Fri, 2 Oct 2020 04:45:05 -0700 (PDT) Received: from e123648.arm.com (unknown [10.57.50.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8EF9C3F73B; Fri, 2 Oct 2020 04:45:01 -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 Cc: robh+dt@kernel.org, amitk@kernel.org, corbet@lwn.net, daniel.lezcano@linaro.org, lukasz.luba@arm.com, Dietmar.Eggemann@arm.com, qperret@google.com, dianders@chromium.org, mka@chromium.org, rnayak@codeaurora.org, rjw@rjwysocki.net Subject: [PATCH v2 3/3] dt-bindings: thermal: update sustainable-power with abstract scale Date: Fri, 2 Oct 2020 12:44:26 +0100 Message-Id: <20201002114426.31277-4-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201002114426.31277-1-lukasz.luba@arm.com> References: <20201002114426.31277-1-lukasz.luba@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Update the documentation for the binding 'sustainable-power' and allow to provide values in an abstract scale. It is required when the cooling devices use an abstract scale for their power values. Signed-off-by: Lukasz Luba --- .../devicetree/bindings/thermal/thermal-zones.yaml | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml index 3ec9cc87ec50..4d8f2e37d1e6 100644 --- a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml +++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml @@ -99,10 +99,15 @@ patternProperties: sustainable-power: $ref: /schemas/types.yaml#/definitions/uint32 description: - An estimate of the sustainable power (in mW) that this thermal zone - can dissipate at the desired control temperature. For reference, the - sustainable power of a 4-inch phone is typically 2000mW, while on a - 10-inch tablet is around 4500mW. + An estimate of the sustainable power (in mW or in an abstract scale) + that this thermal zone can dissipate at the desired control + temperature. For reference, the sustainable power of a 4-inch phone + is typically 2000mW, while on a 10-inch tablet is around 4500mW. + + It is possible to express the sustainable power in an abstract + scale. This is the case when the related cooling devices use also + abstract scale to express their power usage. The scale must be + consistent. trips: type: object