linux-kernel - Re: [PATCH v1] cpufreq: Add policy

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Message-ID: <hslbhy6btkbpsgriafvdq4ligq7vorwcpffaakinqoieroopur@beyq5ouauscf>
Date: Thu, 13 Nov 2025 12:14:56 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Samuel Wu <wusamuel@...gle.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, 
	Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, kernel-team@...roid.com, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH v1] cpufreq: Add policy_frequency trace event

On 12-11-25, 15:51, Samuel Wu wrote:
> The existing cpu_frequency trace_event can be verbose, emitting an event
> for every CPU in the policy even when their frequencies are identical.
> 
> This patch adds a new policy_frequency trace event, which provides a
> more efficient alternative to cpu_frequency trace event. This option
> allows users who only need frequency at a policy level more concise logs
> with simpler analysis.
> 
> Signed-off-by: Samuel Wu <wusamuel@...gle.com>
> ---
>  drivers/cpufreq/cpufreq.c    |  2 ++
>  include/trace/events/power.h | 21 +++++++++++++++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 4472bb1ec83c..b65534a4fd9a 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -345,6 +345,7 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy,
>  		pr_debug("FREQ: %u - CPUs: %*pbl\n", freqs->new,
>  			 cpumask_pr_args(policy->cpus));
>  
> +		trace_policy_frequency(freqs->new, policy->cpu);
>  		for_each_cpu(cpu, policy->cpus)
>  			trace_cpu_frequency(freqs->new, cpu);

I don't see much value in almost duplicate trace events. If we feel that a
per-policy event is a better fit (which makes sens), then we can just drop the
trace_cpu_frequency() events and print policy->cpus (or related_cpus)
information along with the per-policy events.

-- 
viresh