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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 849ECC4361B for ; Mon, 14 Dec 2020 12:59:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DE6720728 for ; Mon, 14 Dec 2020 12:59:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407883AbgLNM7F (ORCPT ); Mon, 14 Dec 2020 07:59:05 -0500 Received: from foss.arm.com ([217.140.110.172]:47126 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728559AbgLNM6i (ORCPT ); Mon, 14 Dec 2020 07:58:38 -0500 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 B58091FB; Mon, 14 Dec 2020 04:57:52 -0800 (PST) Received: from localhost (unknown [10.1.198.32]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4D7FE3F66B; Mon, 14 Dec 2020 04:57:52 -0800 (PST) Date: Mon, 14 Dec 2020 12:57:50 +0000 From: Ionela Voinescu To: Viresh Kumar Cc: Catalin Marinas , Will Deacon , Vincent Guittot , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 1/2] arm64: topology: Avoid the have_policy check Message-ID: <20201214125750.GA15405@arm.com> References: <5f85c2ddf7aa094d7d2ebebe8426f84fad0a99b7.1607617625.git.viresh.kumar@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5f85c2ddf7aa094d7d2ebebe8426f84fad0a99b7.1607617625.git.viresh.kumar@linaro.org> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 10 Dec 2020 at 21:59:22 (+0530), Viresh Kumar wrote: > Every time I have stumbled upon this routine, I get confused with the > way 'have_policy' is used and I have to dig in to understand why is it > so. Here is an attempt to make it easier to understand, and hopefully it > is an improvement. > > The 'have_policy' check was just an optimization to avoid writing > to amu_fie_cpus in case we don't have to, but that optimization itself > is creating more confusion than the real work. Lets just do that if all > the CPUs support AMUs. It is much cleaner that way. > > Signed-off-by: Viresh Kumar > --- > V2: > - Skip the have_policy check altogether > - Updated subject and log > > arch/arm64/kernel/topology.c | 20 ++++++-------------- > 1 file changed, 6 insertions(+), 14 deletions(-) > > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c > index f6faa697e83e..ebadc73449f9 100644 > --- a/arch/arm64/kernel/topology.c > +++ b/arch/arm64/kernel/topology.c > @@ -199,14 +199,14 @@ static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate) > return 0; > } > > -static inline bool > +static inline void > enable_policy_freq_counters(int cpu, cpumask_var_t valid_cpus) > { > struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); > > if (!policy) { > pr_debug("CPU%d: No cpufreq policy found.\n", cpu); > - return false; > + return; > } > > if (cpumask_subset(policy->related_cpus, valid_cpus)) > @@ -214,8 +214,6 @@ enable_policy_freq_counters(int cpu, cpumask_var_t valid_cpus) > amu_fie_cpus); > > cpufreq_cpu_put(policy); > - > - return true; > } > > static DEFINE_STATIC_KEY_FALSE(amu_fie_key); > @@ -225,7 +223,6 @@ 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; > int cpu; > > @@ -245,17 +242,12 @@ static int __init init_amu_fie(void) > continue; > > cpumask_set_cpu(cpu, valid_cpus); > - have_policy |= enable_policy_freq_counters(cpu, valid_cpus); > + enable_policy_freq_counters(cpu, valid_cpus); > } > > - /* > - * If we are not restricted by cpufreq policies, we only enable > - * the use of the AMU feature for FIE if all CPUs support AMU. > - * Otherwise, enable_policy_freq_counters has already enabled > - * policy cpus. > - */ > - if (!have_policy && cpumask_equal(valid_cpus, cpu_present_mask)) > - cpumask_or(amu_fie_cpus, amu_fie_cpus, valid_cpus); > + /* Overwrite amu_fie_cpus if all CPUs support AMU */ > + if (cpumask_equal(valid_cpus, cpu_present_mask)) > + cpumask_copy(amu_fie_cpus, cpu_present_mask); > > if (!cpumask_empty(amu_fie_cpus)) { > pr_info("CPUs[%*pbl]: counters will be used for FIE.", > -- > 2.25.0.rc1.19.g042ed3e048af > Reviewed-by: Ionela Voinescu Thanks, Ionela.