From patchwork Tue Sep 1 20:55:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ionela Voinescu X-Patchwork-Id: 11749465 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 34454138A for ; Tue, 1 Sep 2020 20:57:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26D0D2078B for ; Tue, 1 Sep 2020 20:57:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728141AbgIAU5H (ORCPT ); Tue, 1 Sep 2020 16:57:07 -0400 Received: from foss.arm.com ([217.140.110.172]:50414 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728111AbgIAU47 (ORCPT ); Tue, 1 Sep 2020 16:56:59 -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 A1C75142F; Tue, 1 Sep 2020 13:56:58 -0700 (PDT) Received: from e108754-lin.cambridge.arm.com (e108754-lin.cambridge.arm.com [10.1.199.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 385AD3F66F; Tue, 1 Sep 2020 13:56:57 -0700 (PDT) From: Ionela Voinescu To: rjw@rjwysocki.net, viresh.kumar@linaro.org, dietmar.eggemann@arm.com, catalin.marinas@arm.com, sudeep.holla@arm.com, will@kernel.org, valentin.schneider@arm.com Cc: linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ionela.voinescu@arm.com Subject: [PATCH v5 5/5] arch_topology, arm, arm64: define arch_scale_freq_invariant() Date: Tue, 1 Sep 2020 21:55:49 +0100 Message-Id: <20200901205549.30096-6-ionela.voinescu@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200901205549.30096-1-ionela.voinescu@arm.com> References: <20200901205549.30096-1-ionela.voinescu@arm.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Valentin Schneider arch_scale_freq_invariant() is used by schedutil to determine whether the scheduler's load-tracking signals are frequency invariant. Its definition is overridable, though by default it is hardcoded to 'true' if arch_scale_freq_capacity() is defined ('false' otherwise). This behaviour is not overridden on arm, arm64 and other users of the generic arch topology driver, which is somewhat precarious: arch_scale_freq_capacity() will always be defined, yet not all cpufreq drivers are guaranteed to drive the frequency invariance scale factor setting. In other words, the load-tracking signals may very well *not* be frequency invariant. Now that cpufreq can be queried on whether the current driver is driving the Frequency Invariance (FI) scale setting, the current situation can be improved. This combines the query of whether cpufreq supports the setting of the frequency scale factor, with whether all online CPUs are counter-based FI enabled. While cpufreq FI enablement applies at system level, for all CPUs, counter-based FI support could also be used for only a subset of CPUs to set the invariance scale factor. Therefore, if cpufreq-based FI support is present, we consider the system to be invariant. If missing, we require all online CPUs to be counter-based FI enabled in order for the full system to be considered invariant. If the system ends up not being invariant, a new condition is needed in the counter initialization code that disables all scale factor setting based on counters. Precedence of counters over cpufreq use is not important here. The invariant status is only given to the system if all CPUs have at least one method of setting the frequency scale factor. Signed-off-by: Valentin Schneider Signed-off-by: Ionela Voinescu Acked-by: Catalin Marinas Acked-by: Viresh Kumar Cc: Catalin Marinas Cc: Will Deacon Cc: Sudeep Holla Reviewed-by: Sudeep Holla --- arch/arm/include/asm/topology.h | 1 + arch/arm64/include/asm/topology.h | 1 + arch/arm64/kernel/topology.c | 7 +++++++ drivers/base/arch_topology.c | 6 ++++++ include/linux/arch_topology.h | 2 ++ 5 files changed, 17 insertions(+) diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h index e0593cf095d0..9219e67befbe 100644 --- a/arch/arm/include/asm/topology.h +++ b/arch/arm/include/asm/topology.h @@ -9,6 +9,7 @@ /* Replace task scheduler's default frequency-invariant accounting */ #define arch_scale_freq_capacity topology_get_freq_scale +#define arch_scale_freq_invariant topology_scale_freq_invariant /* Replace task scheduler's default cpu-invariant accounting */ #define arch_scale_cpu_capacity topology_get_cpu_scale diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h index e042f6527981..7cb519473fbd 100644 --- a/arch/arm64/include/asm/topology.h +++ b/arch/arm64/include/asm/topology.h @@ -27,6 +27,7 @@ void topology_scale_freq_tick(void); /* Replace task scheduler's default frequency-invariant accounting */ #define arch_scale_freq_capacity topology_get_freq_scale +#define arch_scale_freq_invariant topology_scale_freq_invariant /* Replace task scheduler's default cpu-invariant accounting */ #define arch_scale_cpu_capacity topology_get_cpu_scale diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 9a9f2b8dedf5..4064d39bb66d 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -246,6 +246,13 @@ static int __init init_amu_fie(void) static_branch_enable(&amu_fie_key); } + /* + * If the system is not fully invariant after AMU init, disable + * partial use of counters for frequency invariance. + */ + if (!topology_scale_freq_invariant()) + static_branch_disable(&amu_fie_key); + free_valid_mask: free_cpumask_var(valid_cpus); diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index 91de5331ac8a..89cae168b076 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -21,6 +21,12 @@ #include #include +bool topology_scale_freq_invariant(void) +{ + return cpufreq_supports_freq_invariance() || + arch_freq_counters_available(cpu_online_mask); +} + __weak bool arch_freq_counters_available(const struct cpumask *cpus) { return false; diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h index 810c83336257..083df331a3c9 100644 --- a/include/linux/arch_topology.h +++ b/include/linux/arch_topology.h @@ -30,6 +30,8 @@ static inline unsigned long topology_get_freq_scale(int cpu) return per_cpu(freq_scale, cpu); } +bool topology_scale_freq_invariant(void); + bool arch_freq_counters_available(const struct cpumask *cpus); DECLARE_PER_CPU(unsigned long, thermal_pressure);