From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 542F61DDC37; Fri, 5 Sep 2025 07:31:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757057504; cv=none; b=OfQcMvauc+Sz9U5K5YB8F6xlq/19iGol1tjg1MJtSC4y9QQuuPwMDIOdKw4NwOvzaYOgwyZ0wzfdXjwRriqHa00QOr9sULFURHdZgOSs47Q5R2pQxtplROXzZ5Jol+tMRGIQ/CR0mRMoYrYZn8ll6VFy2YFnhSkeCFKGSoqlc6c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757057504; c=relaxed/simple; bh=SIar4/Kvq+I3ow73z4ohTECl2lfAyH8RFhr48ecQQaE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tkGX06O0w2qMhTOJkKKaZJLR/uh2qqME1xtyfb6DyV2ZYp88dKHTfr+HdpmaXl9eM4YsR4Z6Z0dmR+gI2RTPjAiPA0w7kEpdQNLt0+JjyQLWaAAlBxidNyL5Q4/UomredSXzcWJAuebNeuQ9vX4yhncoTnOAD42sTLcRWHUKZu0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 E5207153B; Fri, 5 Sep 2025 00:31:32 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1747E3F694; Fri, 5 Sep 2025 00:31:36 -0700 (PDT) Date: Fri, 5 Sep 2025 09:31:03 +0200 From: Beata Michalska To: Ionela Voinescu Cc: Lifeng Zheng , catalin.marinas@arm.com, will@kernel.org, rafael@kernel.org, viresh.kumar@linaro.org, sudeep.holla@arm.com, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com, jonathan.cameron@huawei.com, vincent.guittot@linaro.org, yangyicong@hisilicon.com, zhanjie9@hisilicon.com, lihuisong@huawei.com, yubowen8@huawei.com, zhangpengjie2@huawei.com, linhongye@h-partners.com Subject: Re: [PATCH v5 3/3] arm64: topology: Setup AMU FIE for online CPUs only Message-ID: References: <20250819072931.1647431-1-zhenglifeng1@huawei.com> <20250819072931.1647431-4-zhenglifeng1@huawei.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Ionela, On Mon, Sep 01, 2025 at 08:29:26AM +0100, Ionela Voinescu wrote: > Hi, > > On Tuesday 19 Aug 2025 at 15:29:31 (+0800), Lifeng Zheng wrote: > > When boot with maxcpu=1 restrict, and LPI(Low Power Idle States) is on, > > only CPU0 will go online. The support AMU flag of CPU0 will be set but the > > flags of other CPUs will not. This will cause AMU FIE set up fail for CPU0 > > when it shares a cpufreq policy with other CPU(s). After that, when other > > CPUs are finally online and the support AMU flags of them are set, they'll > > never have a chance to set up AMU FIE, even though they're eligible. > > > > To solve this problem, the process of setting up AMU FIE needs to be > > modified as follows: > > > > 1. Set up AMU FIE only for the online CPUs. > > > > 2. Try to set up AMU FIE each time a CPU goes online and do the > > freq_counters_valid() check. If this check fails, clear scale freq source > > of all the CPUs related to the same policy, in case they use different > > source of the freq scale. > > > > At the same time, this change also be applied to cpufreq when calling > > arch_set_freq_scale. > > > > Signed-off-by: Lifeng Zheng > > --- > > arch/arm64/kernel/topology.c | 54 ++++++++++++++++++++++++++++++++++-- > > drivers/cpufreq/cpufreq.c | 4 +-- > > 2 files changed, 54 insertions(+), 4 deletions(-) > > > [..] > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index 78ca68ea754d..d1890a2af1af 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -417,7 +417,7 @@ void cpufreq_freq_transition_end(struct cpufreq_policy *policy, > > > > cpufreq_notify_post_transition(policy, freqs, transition_failed); > > > > - arch_set_freq_scale(policy->related_cpus, > > + arch_set_freq_scale(policy->cpus, > > policy->cur, > > arch_scale_freq_ref(policy->cpu)); > > > > @@ -2219,7 +2219,7 @@ unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy, > > return 0; > > > > policy->cur = freq; > > - arch_set_freq_scale(policy->related_cpus, freq, > > + arch_set_freq_scale(policy->cpus, freq, > > arch_scale_freq_ref(policy->cpu)); > > I think it might be good to keep these calls to arch_set_freq_scale() for > all related CPUs and not only online ones. This can result in CPUs coming > out of hotplug with a wrong scale factor, because while they were out, any > frequency transitions of the policy only modified the scale factor of > online CPUs. When they come out of hotplug, arch_set_freq_scale() will not > be called for them until there's a new frequency transition. > > I understand that if this is not changed to only pass online CPUs, > supports_scale_freq_counters() will now fail when called in > topology_set_freq_scale() for scenarios when only some CPUs in a policy > are online - e.g. the scenario in your commit message. But I think a > simple change in supports_scale_freq_counters() that instead checks that > at least one CPU in the policy supports AMU-based FIE, instead of all, > is a better fix that does not break the cpufreq-based FIE. If at least > one CPU is marked as supporting AMUs for FIE we know that the AMU setup > path is in progress and we should bail out of > topology_set_freq_scale()/arch_set_freq_scale(). > Thank you for pointing that out - that indeed might be an issue, and the solution you have suggested should do the trick. --- BR Beata > Hope it helps, > Ionela. > > > cpufreq_stats_record_transition(policy, freq); > > > > -- > > 2.33.0 > > > >