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 EDBAE54664; Mon, 8 Jan 2024 16:35:16 +0000 (UTC) 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 3C484FEC; Mon, 8 Jan 2024 08:36:02 -0800 (PST) Received: from [192.168.178.6] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A9D683F64C; Mon, 8 Jan 2024 08:35:10 -0800 (PST) Message-ID: <158a8c60-cb54-43c1-8232-6a0a46cc6d42@arm.com> Date: Mon, 8 Jan 2024 17:35:08 +0100 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/5] cpufreq: Add a cpufreq pressure feedback for the scheduler Content-Language: en-US To: Vincent Guittot , linux@armlinux.org.uk, catalin.marinas@arm.com, will@kernel.org, sudeep.holla@arm.com, rafael@kernel.org, viresh.kumar@linaro.org, agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, lukasz.luba@arm.com, rui.zhang@intel.com, mhiramat@kernel.org, daniel.lezcano@linaro.org, amit.kachhap@gmail.com, corbet@lwn.net, gregkh@linuxfoundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: qyousef@layalina.io References: <20240108134843.429769-1-vincent.guittot@linaro.org> <20240108134843.429769-2-vincent.guittot@linaro.org> From: Dietmar Eggemann In-Reply-To: <20240108134843.429769-2-vincent.guittot@linaro.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 08/01/2024 14:48, Vincent Guittot wrote: > Provide to the scheduler a feedback about the temporary max available > capacity. Unlike arch_update_thermal_pressure, this doesn't need to be > filtered as the pressure will happen for dozens ms or more. Is this then related to the 'medium pace system pressure' you mentioned in your OSPM '23 talk? > > Signed-off-by: Vincent Guittot > --- > drivers/cpufreq/cpufreq.c | 36 ++++++++++++++++++++++++++++++++++++ > include/linux/cpufreq.h | 10 ++++++++++ > 2 files changed, 46 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 44db4f59c4cc..fa2e2ea26f7f 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -2563,6 +2563,40 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu) > } > EXPORT_SYMBOL(cpufreq_get_policy); > > +DEFINE_PER_CPU(unsigned long, cpufreq_pressure); > + > +/** > + * cpufreq_update_pressure() - Update cpufreq pressure for CPUs > + * @policy: cpufreq policy of the CPUs. > + * > + * Update the value of cpufreq pressure for all @cpus in the policy. > + */ > +static void cpufreq_update_pressure(struct cpufreq_policy *policy) > +{ > + unsigned long max_capacity, capped_freq, pressure; > + u32 max_freq; > + int cpu; > + > + /* > + * Handle properly the boost frequencies, which should simply clean > + * the thermal pressure value. ^^^^^^^ IMHO, this is a copy & paste error from topology_update_thermal_pressure()? > + */ > + if (max_freq <= capped_freq) { max_freq seems to be uninitialized. > + pressure = 0; Is this x86 (turbo boost) specific? IMHO at arm we follow this max freq (including boost) relates to 1024 in capacity? Or haven't we made this discussion yet? > + } else { > + cpu = cpumask_first(policy->related_cpus); > + max_capacity = arch_scale_cpu_capacity(cpu); > + capped_freq = policy->max; > + max_freq = arch_scale_freq_ref(cpu); > + > + pressure = max_capacity - > + mult_frac(max_capacity, capped_freq, max_freq); > + } > + > + for_each_cpu(cpu, policy->related_cpus) > + WRITE_ONCE(per_cpu(cpufreq_pressure, cpu), pressure); > +} > + [...]