On Wed, Nov 12, 2025 at 10:45 PM Viresh Kumar <[email protected]> wrote: > > 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 <[email protected]> > > --- > > 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.
Thank you for the feedback Viresh. Fair enough, I've done some testing and a single trace event should work and would be cleaner. Please let me know what you think of this proposal for v2. We can append a bitmask of policy->cpus field to trace_cpu_frequency(). This way we maintain backwards compatibility: trace_cpu_frequency() is not removed, and its pre-existing fields are not disturbed. Call flow wise, we can delete all the for_each_cpu() loops, and we still retain the benefits of the trace emitting once per policy instead of once per cpu.
