From nobody Fri Feb 13 14:11:05 2026 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 03910CE7A8C for ; Mon, 25 Sep 2023 08:12:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232882AbjIYIMI (ORCPT ); Mon, 25 Sep 2023 04:12:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232712AbjIYILo (ORCPT ); Mon, 25 Sep 2023 04:11:44 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8E17611F; Mon, 25 Sep 2023 01:11:37 -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 206901424; Mon, 25 Sep 2023 01:12:15 -0700 (PDT) Received: from e129166.arm.com (unknown [10.57.93.139]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 798103F5A1; Mon, 25 Sep 2023 01:11:34 -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, mhiramat@kernel.org, qyousef@layalina.io, wvw@google.com Subject: [PATCH v4 09/18] PM: EM: Introduce runtime modifiable table Date: Mon, 25 Sep 2023 09:11:30 +0100 Message-Id: <20230925081139.1305766-10-lukasz.luba@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230925081139.1305766-1-lukasz.luba@arm.com> References: <20230925081139.1305766-1-lukasz.luba@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The new runtime table would be populated with a new power data to better reflect the actual power. The power can vary over time e.g. due to the SoC temperature change. Higher temperature can increase power values. For longer running scenarios, such as game or camera, when also other devices are used (e.g. GPU, ISP) the CPU power can change. The new EM framework is able to addresses this issue and change the data at runtime safely. The runtime modifiable EM data is used by the Energy Aware Scheduler (EAS) for the task placement. All the other users (thermal, etc.) are still using the default (basic) EM. This fact drove the design of this feature. Signed-off-by: Lukasz Luba --- include/linux/energy_model.h | 4 +++- kernel/power/energy_model.c | 12 +++++++++++- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h index 546dee90f716..740e7c25cfff 100644 --- a/include/linux/energy_model.h +++ b/include/linux/energy_model.h @@ -39,7 +39,7 @@ struct em_perf_state { /** * struct em_perf_table - Performance states table * @state: List of performance states, in ascending order - * @rcu: RCU used for safe access and destruction + * @rcu: RCU used only for runtime modifiable table */ struct em_perf_table { struct em_perf_state *state; @@ -49,6 +49,7 @@ struct em_perf_table { /** * struct em_perf_domain - Performance domain * @default_table: Pointer to the default em_perf_table + * @runtime_table: Pointer to the runtime modifiable em_perf_table * @nr_perf_states: Number of performance states * @flags: See "em_perf_domain flags" * @cpus: Cpumask covering the CPUs of the domain. It's here @@ -64,6 +65,7 @@ struct em_perf_table { */ struct em_perf_domain { struct em_perf_table *default_table; + struct em_perf_table __rcu *runtime_table; int nr_perf_states; unsigned long flags; unsigned long cpus[]; diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index 797141638b29..5b40db38b745 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -251,6 +251,9 @@ static int em_create_pd(struct device *dev, int nr_stat= es, return ret; } =20 + /* Initialize runtime table as default table. */ + rcu_assign_pointer(pd->runtime_table, default_table); + if (_is_cpu_device(dev)) for_each_cpu(cpu, cpus) { cpu_dev =3D get_cpu_device(cpu); @@ -448,6 +451,7 @@ EXPORT_SYMBOL_GPL(em_dev_register_perf_domain); */ void em_dev_unregister_perf_domain(struct device *dev) { + struct em_perf_table __rcu *runtime_table; struct em_perf_domain *pd; =20 if (IS_ERR_OR_NULL(dev) || !dev->em_pd) @@ -457,18 +461,24 @@ void em_dev_unregister_perf_domain(struct device *dev) return; =20 pd =3D dev->em_pd; - /* * The mutex separates all register/unregister requests and protects * from potential clean-up/setup issues in the debugfs directories. * The debugfs directory name is the same as device's name. */ mutex_lock(&em_pd_mutex); + em_debug_remove_pd(dev); =20 + runtime_table =3D pd->runtime_table; + + rcu_assign_pointer(pd->runtime_table, NULL); + synchronize_rcu(); + kfree(pd->default_table->state); kfree(pd->default_table); kfree(dev->em_pd); + dev->em_pd =3D NULL; mutex_unlock(&em_pd_mutex); } --=20 2.25.1