From patchwork Tue Sep 29 20:54:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ionela Voinescu X-Patchwork-Id: 11806929 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 71781618 for ; Tue, 29 Sep 2020 20:55:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B27A20773 for ; Tue, 29 Sep 2020 20:55:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729058AbgI2UzV (ORCPT ); Tue, 29 Sep 2020 16:55:21 -0400 Received: from foss.arm.com ([217.140.110.172]:51310 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728729AbgI2UzV (ORCPT ); Tue, 29 Sep 2020 16:55:21 -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 94AF431B; Tue, 29 Sep 2020 13:55:20 -0700 (PDT) Received: from e108754-lin.cambridge.arm.com (unknown [10.1.199.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CED1D3F73B; Tue, 29 Sep 2020 13:55:18 -0700 (PDT) From: Ionela Voinescu To: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, catalin.marinas@arm.com, will@kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org Cc: dietmar.eggemann@arm.com, qperret@google.com, valentin.schneider@arm.com, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ionela.voinescu@arm.com Subject: [PATCH v2 1/3] sched/topology,schedutil: wrap sched domains rebuild Date: Tue, 29 Sep 2020 21:54:40 +0100 Message-Id: <20200929205442.24792-2-ionela.voinescu@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200929205442.24792-1-ionela.voinescu@arm.com> References: <20200929205442.24792-1-ionela.voinescu@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Add the rebuild_sched_domains_energy() function to wrap the functionality that rebuilds the scheduling domains if any of the Energy Aware Scheduling (EAS) initialisation conditions change. This functionality is used when schedutil is added or removed or when EAS is enabled or disabled through the sched_energy_aware sysctl. Therefore, create a single function that is used in both these cases and that can be later reused. Signed-off-by: Ionela Voinescu Acked-by: Quentin Perret Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Viresh Kumar --- include/linux/sched/topology.h | 8 ++++++++ kernel/sched/cpufreq_schedutil.c | 9 +-------- kernel/sched/topology.c | 18 +++++++++++------- 3 files changed, 20 insertions(+), 15 deletions(-) diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index 9ef7bf686a9f..8f0f778b7c91 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -225,6 +225,14 @@ static inline bool cpus_share_cache(int this_cpu, int that_cpu) #endif /* !CONFIG_SMP */ +#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) +extern void rebuild_sched_domains_energy(void); +#else +static inline void rebuild_sched_domains_energy(void) +{ +} +#endif + #ifndef arch_scale_cpu_capacity /** * arch_scale_cpu_capacity - get the capacity scale factor of a given CPU. diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index e39008242cf4..0337a9b025e1 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -912,16 +912,9 @@ struct cpufreq_governor *cpufreq_default_governor(void) cpufreq_governor_init(schedutil_gov); #ifdef CONFIG_ENERGY_MODEL -extern bool sched_energy_update; -extern struct mutex sched_energy_mutex; - static void rebuild_sd_workfn(struct work_struct *work) { - mutex_lock(&sched_energy_mutex); - sched_energy_update = true; - rebuild_sched_domains(); - sched_energy_update = false; - mutex_unlock(&sched_energy_mutex); + rebuild_sched_domains_energy(); } static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn); diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 55c453d140e9..e0a8e55e7df0 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -211,6 +211,15 @@ unsigned int sysctl_sched_energy_aware = 1; DEFINE_MUTEX(sched_energy_mutex); bool sched_energy_update; +void rebuild_sched_domains_energy(void) +{ + mutex_lock(&sched_energy_mutex); + sched_energy_update = true; + rebuild_sched_domains(); + sched_energy_update = false; + mutex_unlock(&sched_energy_mutex); +} + #ifdef CONFIG_PROC_SYSCTL int sched_energy_aware_handler(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) @@ -223,13 +232,8 @@ int sched_energy_aware_handler(struct ctl_table *table, int write, ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (!ret && write) { state = static_branch_unlikely(&sched_energy_present); - if (state != sysctl_sched_energy_aware) { - mutex_lock(&sched_energy_mutex); - sched_energy_update = 1; - rebuild_sched_domains(); - sched_energy_update = 0; - mutex_unlock(&sched_energy_mutex); - } + if (state != sysctl_sched_energy_aware) + rebuild_sched_domains_energy(); } return ret; From patchwork Tue Sep 29 20:54:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ionela Voinescu X-Patchwork-Id: 11806933 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 B84B2618 for ; Tue, 29 Sep 2020 20:55:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A219D208B8 for ; Tue, 29 Sep 2020 20:55:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729504AbgI2Uzb (ORCPT ); Tue, 29 Sep 2020 16:55:31 -0400 Received: from foss.arm.com ([217.140.110.172]:51354 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729491AbgI2Uz3 (ORCPT ); Tue, 29 Sep 2020 16:55:29 -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 5450031B; Tue, 29 Sep 2020 13:55:28 -0700 (PDT) Received: from e108754-lin.cambridge.arm.com (unknown [10.1.199.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8E1353F73B; Tue, 29 Sep 2020 13:55:21 -0700 (PDT) From: Ionela Voinescu To: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, catalin.marinas@arm.com, will@kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org Cc: dietmar.eggemann@arm.com, qperret@google.com, valentin.schneider@arm.com, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ionela.voinescu@arm.com Subject: [PATCH v2 2/3] arm64: rebuild sched domains on invariance status changes Date: Tue, 29 Sep 2020 21:54:41 +0100 Message-Id: <20200929205442.24792-3-ionela.voinescu@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200929205442.24792-1-ionela.voinescu@arm.com> References: <20200929205442.24792-1-ionela.voinescu@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Task scheduler behavior depends on frequency invariance (FI) support and the resulting invariant load tracking signals. For example, in order to make accurate predictions across CPUs for all performance states, Energy Aware Scheduling (EAS) needs frequency-invariant load tracking signals and therefore it has a direct dependency on FI. This dependency is known, but EAS enablement is not yet conditioned on the presence of FI during the built of the scheduling domain hierarchy. Before this is done, the following must be considered: while arch_scale_freq_invariant() will see changes in FI support and could be used to condition the use of EAS, it could return different values during system initialisation. For arm64, such a scenario will happen for a system that does not support cpufreq driven FI, but does support counter-driven FI. For such a system, arch_scale_freq_invariant() will return false if called before counter based FI initialisation, but change its status to true after it. If EAS becomes explicitly dependent on FI this would affect the task scheduler behavior which builds its scheduling domain hierarchy well before the late counter-based FI init. During that process, EAS would be disabled due to its dependency on FI. Two points of future early calls to arch_scale_freq_invariant() which would determine EAS enablement are: - (1) drivers/base/arch_topology.c:126 <> rebuild_sched_domains(); This will happen after CPU capacity initialisation. - (2) kernel/sched/cpufreq_schedutil.c:917 <> rebuild_sched_domains_energy(); -->rebuild_sched_domains(); This will happen during sched_cpufreq_governor_change() for the schedutil cpufreq governor. Therefore, before enforcing the presence of FI support for the use of EAS, ensure the following: if there is a change in FI support status after counter init, use the existing rebuild_sched_domains_energy() function to trigger a rebuild of the scheduling and performance domains that in turn will determine the enablement of EAS. Signed-off-by: Ionela Voinescu Cc: Catalin Marinas Cc: Will Deacon --- arch/arm64/kernel/topology.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 543c67cae02f..2a9b69fdabc9 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -213,6 +213,7 @@ static DEFINE_STATIC_KEY_FALSE(amu_fie_key); static int __init init_amu_fie(void) { + bool invariance_status = topology_scale_freq_invariant(); cpumask_var_t valid_cpus; bool have_policy = false; int ret = 0; @@ -255,6 +256,15 @@ static int __init init_amu_fie(void) if (!topology_scale_freq_invariant()) static_branch_disable(&amu_fie_key); + /* + * Task scheduler behavior depends on frequency invariance support, + * either cpufreq or counter driven. If the support status changes as + * a result of counter initialisation and use, retrigger the build of + * scheduling domains to ensure the information is propagated properly. + */ + if (invariance_status != topology_scale_freq_invariant()) + rebuild_sched_domains_energy(); + free_valid_mask: free_cpumask_var(valid_cpus); From patchwork Tue Sep 29 20:54:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ionela Voinescu X-Patchwork-Id: 11806931 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 758C6112C for ; Tue, 29 Sep 2020 20:55:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F09D208B8 for ; Tue, 29 Sep 2020 20:55:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728729AbgI2Uz1 (ORCPT ); Tue, 29 Sep 2020 16:55:27 -0400 Received: from foss.arm.com ([217.140.110.172]:51334 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729293AbgI2Uz1 (ORCPT ); Tue, 29 Sep 2020 16:55:27 -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 A8AC612FC; Tue, 29 Sep 2020 13:55:26 -0700 (PDT) Received: from e108754-lin.cambridge.arm.com (unknown [10.1.199.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E2F313F85F; Tue, 29 Sep 2020 13:55:24 -0700 (PDT) From: Ionela Voinescu To: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, catalin.marinas@arm.com, will@kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org Cc: dietmar.eggemann@arm.com, qperret@google.com, valentin.schneider@arm.com, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ionela.voinescu@arm.com Subject: [PATCH v2 3/3] sched/topology: condition EAS enablement on FIE support Date: Tue, 29 Sep 2020 21:54:42 +0100 Message-Id: <20200929205442.24792-4-ionela.voinescu@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200929205442.24792-1-ionela.voinescu@arm.com> References: <20200929205442.24792-1-ionela.voinescu@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org In order to make accurate predictions across CPUs and for all performance states, Energy Aware Scheduling (EAS) needs frequency-invariant load tracking signals. EAS task placement aims to minimize energy consumption, and does so in part by limiting the search space to only CPUs with the highest spare capacity (CPU capacity - CPU utilization) in their performance domain. Those candidates are the placement choices that will keep frequency at its lowest possible and therefore save the most energy. But without frequency invariance, a CPU's utilization is relative to the CPU's current performance level, and not relative to its maximum performance level, which determines its capacity. As a result, it will fail to correctly indicate any potential spare capacity obtained by an increase in a CPU's performance level. Therefore, a non-invariant utilization signal would render the EAS task placement logic invalid. Now that we properly report support for the Frequency Invariance Engine (FIE) through arch_scale_freq_invariant() for arm and arm64 systems, while also ensuring a re-evaluation of the EAS use conditions for possible invariance status change, we can assert this is the case when initializing EAS. Warn and bail out otherwise. Signed-off-by: Ionela Voinescu Suggested-by: Quentin Perret Cc: Ingo Molnar Cc: Peter Zijlstra --- kernel/sched/topology.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index e0a8e55e7df0..cbe88b896f93 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -328,6 +328,7 @@ static void sched_energy_set(bool has_eas) * 3. no SMT is detected. * 4. the EM complexity is low enough to keep scheduling overheads low; * 5. schedutil is driving the frequency of all CPUs of the rd; + * 6. frequency invariance support is present; * * The complexity of the Energy Model is defined as: * @@ -376,6 +377,14 @@ static bool build_perf_domains(const struct cpumask *cpu_map) goto free; } + if (!arch_scale_freq_invariant()) { + if (sched_debug()) { + pr_warn("rd %*pbl: Disabling EAS: frequency-invariant load tracking not yet supported", + cpumask_pr_args(cpu_map)); + } + goto free; + } + for_each_cpu(i, cpu_map) { /* Skip already covered CPUs. */ if (find_pd(pd, i))