On 11/14/25 05:11, Viresh Kumar wrote: > On 13-11-25, 19:41, Samuel Wu wrote: >> 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. > > Fine by me. I have added Scheduler maintainers in the loop to see if they > have a > different view. >
And IIUC your proposal is to fold policy_frequency into cpu_frequency but then only have one cpu_frequency event per policy emitted? I think from a tooling perspective it would be easier to remove cpu_frequency entirely, then tools can probe on the presence of policy_frequency / cpu_frequency.
