From mboxrd@z Thu Jan 1 00:00:00 1970 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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 07257C10DCE for ; Fri, 6 Mar 2020 14:43:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB5702084E for ; Fri, 6 Mar 2020 14:43:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727498AbgCFOnB (ORCPT ); Fri, 6 Mar 2020 09:43:01 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:53852 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727242AbgCFOmX (ORCPT ); Fri, 6 Mar 2020 09:42:23 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jAEB7-0006Oo-Ft; Fri, 06 Mar 2020 15:42:17 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id C94C01C21D6; Fri, 6 Mar 2020 15:42:10 +0100 (CET) Date: Fri, 06 Mar 2020 14:42:10 -0000 From: "tip-bot2 for Thara Gopinath" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] drivers/base/arch_topology: Add infrastructure to store and update instantaneous thermal pressure Cc: Thara Gopinath , "Peter Zijlstra (Intel)" , Ingo Molnar , x86 , LKML In-Reply-To: <20200222005213.3873-4-thara.gopinath@linaro.org> References: <20200222005213.3873-4-thara.gopinath@linaro.org> MIME-Version: 1.0 Message-ID: <158350573056.28353.8289359977043719899.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: ad58cc5cc50ca8423cf630778594bd38252a0a58 Gitweb: https://git.kernel.org/tip/ad58cc5cc50ca8423cf630778594bd38252a0a58 Author: Thara Gopinath AuthorDate: Fri, 21 Feb 2020 19:52:07 -05:00 Committer: Ingo Molnar CommitterDate: Fri, 06 Mar 2020 12:57:18 +01:00 drivers/base/arch_topology: Add infrastructure to store and update instantaneous thermal pressure Add architecture specific APIs to update and track thermal pressure on a per CPU basis. A per CPU variable thermal_pressure is introduced to keep track of instantaneous per CPU thermal pressure. Thermal pressure is the delta between maximum capacity and capped capacity due to a thermal event. topology_get_thermal_pressure can be hooked into the scheduler specified arch_scale_thermal_pressure to retrieve instantaneous thermal pressure of a CPU. arch_set_thermal_pressure can be used to update the thermal pressure. Considering topology_get_thermal_pressure reads thermal_pressure and arch_set_thermal_pressure writes into thermal_pressure, one can argue for some sort of locking mechanism to avoid a stale value. But considering topology_get_thermal_pressure can be called from a system critical path like scheduler tick function, a locking mechanism is not ideal. This means that it is possible the thermal_pressure value used to calculate average thermal pressure for a CPU can be stale for up to 1 tick period. Signed-off-by: Thara Gopinath Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lkml.kernel.org/r/20200222005213.3873-4-thara.gopinath@linaro.org --- drivers/base/arch_topology.c | 11 +++++++++++ include/linux/arch_topology.h | 10 ++++++++++ 2 files changed, 21 insertions(+) diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index 6119e11..68dfa49 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -42,6 +42,17 @@ void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity) per_cpu(cpu_scale, cpu) = capacity; } +DEFINE_PER_CPU(unsigned long, thermal_pressure); + +void arch_set_thermal_pressure(struct cpumask *cpus, + unsigned long th_pressure) +{ + int cpu; + + for_each_cpu(cpu, cpus) + WRITE_ONCE(per_cpu(thermal_pressure, cpu), th_pressure); +} + static ssize_t cpu_capacity_show(struct device *dev, struct device_attribute *attr, char *buf) diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h index 3015ecb..88a115e 100644 --- a/include/linux/arch_topology.h +++ b/include/linux/arch_topology.h @@ -33,6 +33,16 @@ unsigned long topology_get_freq_scale(int cpu) return per_cpu(freq_scale, cpu); } +DECLARE_PER_CPU(unsigned long, thermal_pressure); + +static inline unsigned long topology_get_thermal_pressure(int cpu) +{ + return per_cpu(thermal_pressure, cpu); +} + +void arch_set_thermal_pressure(struct cpumask *cpus, + unsigned long th_pressure); + struct cpu_topology { int thread_id; int core_id;