From patchwork Fri May 12 09:57:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 13238970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 840D3C7EE25 for ; Fri, 12 May 2023 09:58:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240196AbjELJ60 (ORCPT ); Fri, 12 May 2023 05:58:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240588AbjELJ6P (ORCPT ); Fri, 12 May 2023 05:58:15 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0A07A11634; Fri, 12 May 2023 02:57:57 -0700 (PDT) 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 1601CFEC; Fri, 12 May 2023 02:58:42 -0700 (PDT) Received: from e123648.arm.com (unknown [10.57.22.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C95813F5A1; Fri, 12 May 2023 02:57:54 -0700 (PDT) From: Lukasz Luba To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rafael@kernel.org Cc: lukasz.luba@arm.com, dietmar.eggemann@arm.com, rui.zhang@intel.com, amit.kucheria@verdurent.com, amit.kachhap@gmail.com, daniel.lezcano@linaro.org, viresh.kumar@linaro.org, len.brown@intel.com, pavel@ucw.cz, Pierre.Gondois@arm.com, ionela.voinescu@arm.com, rostedt@goodmis.org, mhiramat@kernel.org Subject: [PATCH v2 00/17] Introduce runtime modifiable Energy Model Date: Fri, 12 May 2023 10:57:26 +0100 Message-Id: <20230512095743.3393563-1-lukasz.luba@arm.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Hi all, This patch set adds a new feature which allows to modify Energy Model (EM) power values at runtime. It will allow to better reflect power model of a recent SoCs and silicon. Different characteristics of the power usage can be leveraged and thus better decisions made during task placement in EAS. It's part of feature set know as Dynamic Energy Model. It has been presented and discussed recently at OSPM2023 [3]. This patch set implements the 1st improvement for the EM. The concepts: 1. The CPU power usage can vary due to the workload that it's running or due to the temperature of the SoC. The same workload can use more power when the temperature of the silicon has increased (e.g. due to hot GPU or ISP). In such situation or EM can be adjusted and reflect the fact of increased power usage. That power increase is due to a factor called static power (sometimes called simply: leakage). The CPUs in recent SoCs are different. We have heterogeneous SoCs with 3 (or even 4) different microarchitectures. They are also built differently with High Performance (HP) cells or Low Power (LP) cells. They are affected by the temperature increase differently: HP cells have bigger leakage. The SW model can leverage that knowledge. 2. It is also possible to change the EM to better reflect the currently running workload. Usually the EM is derived from some average power values taken from experiments with benchmark (e.g. Dhrystone). The model derived from such scenario might not represent properly the workloads usually running on the device. Therefore, runtime modification of the EM allows to switch to a different model, when there is a need. 3. The EM can be adjusted after boot, when all the modules are loaded and more information about the SoC is available e.g. chip binning. This would help to better reflect the silicon characteristics. Thus, this EM modification API allows it now. It wasn't possible in the past and the EM had to be 'set in stone'. Some design details: The internal mechanisms for the memory allocation are handled internally in the EM. Kernel modules can just call the new API to update the EM data and the new memory would be provided and owned by the EM. The EM memory is used by EAS, which impacts those design decisions. The EM writers are protected by a mutex. This new runtime modified EM table is protected using RCU mechanism, which fits the current EAS hot path (which already uses RCU read lock). The unregister API handles only non-CPU (e.g. GPU, ISP) devices and uses the same mutex as EM modifiers to make sure the memory is safely freed. More detailed explanation and background can be found in presentations during LPC2022 [1][2] or in the documentation patches. Changelog: v2: - solved build warning of unused variable in patch 13/17 when EM is not compiled in, e.g. on Intel platform for this cpufreq_cooling - re-based on top of v6.4-rc1 v1: - implementation can be found here [4] Regards, Lukasz Luba [1] https://lpc.events/event/16/contributions/1341/attachments/955/1873/Dynamic_Energy_Model_to_handle_leakage_power.pdf [2] https://lpc.events/event/16/contributions/1194/attachments/1114/2139/LPC2022_Energy_model_accuracy.pdf [3] https://www.youtube.com/watch?v=2C-5uikSbtM&list=PL0fKordpLTjKsBOUcZqnzlHShri4YBL1H [4] https://lore.kernel.org/lkml/20230314103357.26010-1-lukasz.luba@arm.com/ Lukasz Luba (17): PM: EM: Refactor em_cpufreq_update_efficiencies() arguments PM: EM: Find first CPU online while updating OPP efficiency PM: EM: Refactor em_pd_get_efficient_state() to be more flexible PM: EM: Create a new function em_compute_costs() trace: energy_model: Add trace event for EM runtime modifications PM: EM: Add update_power() callback for runtime modifications PM: EM: Check if the get_cost() callback is present in em_compute_costs() PM: EM: Introduce runtime modifiable table PM: EM: Add RCU mechanism which safely cleans the old data PM: EM: Add runtime update interface to modify EM power PM: EM: Use runtime modified EM for CPUs energy estimation in EAS PM: EM: Add argument to get_cost() for runtime modification PM: EM: Refactor struct em_perf_domain and add default_table Documentation: EM: Add a new section about the design Documentation: EM: Add a runtime modifiable EM design description Documentation: EM: Add example with driver modifying the EM Documentation: EM: Describe the API of runtime modifications Documentation/power/energy-model.rst | 134 +++++++++++- drivers/cpufreq/cppc_cpufreq.c | 2 +- drivers/powercap/dtpm_cpu.c | 27 ++- drivers/powercap/dtpm_devfreq.c | 23 +- drivers/thermal/cpufreq_cooling.c | 23 +- drivers/thermal/devfreq_cooling.c | 23 +- include/linux/energy_model.h | 93 ++++++-- include/trace/events/energy_model.h | 46 ++++ kernel/power/energy_model.c | 305 +++++++++++++++++++++++---- 9 files changed, 580 insertions(+), 96 deletions(-) create mode 100644 include/trace/events/energy_model.h