On 12/1/25 20:24, Samuel Wu wrote: > The existing cpu_frequency trace_event can be verbose, emitting a nearly > identical trace event for every CPU in the policy even when their > frequencies are identical. > > This patch replaces the cpu_frequency trace event with policy_frequency > trace event, a more efficient alternative. From the kernel's > perspective, emitting a trace event once per policy instead of once per > cpu saves some memory and is less overhead. From the post-processing > perspective, analysis of the trace log is simplified without any loss of > information. > > Signed-off-by: Samuel Wu <[email protected]> > --- > drivers/cpufreq/cpufreq.c | 14 ++------------ > drivers/cpufreq/intel_pstate.c | 6 ++++-- > include/trace/events/power.h | 24 +++++++++++++++++++++--- > kernel/trace/power-traces.c | 2 +- > samples/bpf/cpustat_kern.c | 8 ++++---- > samples/bpf/cpustat_user.c | 6 +++--- > tools/perf/builtin-timechart.c | 12 ++++++------ > 7 files changed, 41 insertions(+), 31 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 4472bb1ec83c..dd3f08f3b958 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -309,8 +309,6 @@ static void cpufreq_notify_transition(struct > cpufreq_policy *policy, > struct cpufreq_freqs *freqs, > unsigned int state) > { > - int cpu; > - > BUG_ON(irqs_disabled()); > > if (cpufreq_disabled()) > @@ -344,10 +342,7 @@ static void cpufreq_notify_transition(struct > cpufreq_policy *policy, > adjust_jiffies(CPUFREQ_POSTCHANGE, freqs); > pr_debug("FREQ: %u - CPUs: %*pbl\n", freqs->new, > cpumask_pr_args(policy->cpus)); > - > - for_each_cpu(cpu, policy->cpus) > - trace_cpu_frequency(freqs->new, cpu); > - > + trace_policy_frequency(freqs->new, policy->cpu, policy->cpus); > srcu_notifier_call_chain(&cpufreq_transition_notifier_list, > CPUFREQ_POSTCHANGE, freqs); > > @@ -2201,7 +2196,6 @@ unsigned int cpufreq_driver_fast_switch(struct > cpufreq_policy *policy, > unsigned int target_freq) > { > unsigned int freq; > - int cpu; > > target_freq = clamp_val(target_freq, policy->min, policy->max); > freq = cpufreq_driver->fast_switch(policy, target_freq); > @@ -2213,11 +2207,7 @@ unsigned int cpufreq_driver_fast_switch(struct > cpufreq_policy *policy, > arch_set_freq_scale(policy->related_cpus, freq, > arch_scale_freq_ref(policy->cpu)); > cpufreq_stats_record_transition(policy, freq); > - > - if (trace_cpu_frequency_enabled()) { > - for_each_cpu(cpu, policy->cpus) > - trace_cpu_frequency(freq, cpu); > - } > + trace_policy_frequency(freq, policy->cpu, policy->cpus); > > return freq; > } > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index ec4abe374573..9724b5d19d83 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -2297,7 +2297,8 @@ static int hwp_get_cpu_scaling(int cpu) > > static void intel_pstate_set_pstate(struct cpudata *cpu, int pstate) > { > - trace_cpu_frequency(pstate * cpu->pstate.scaling, cpu->cpu); > + trace_policy_frequency(pstate * cpu->pstate.scaling, cpu->cpu, > + cpumask_of(cpu->cpu)); > cpu->pstate.current_pstate = pstate; > /* > * Generally, there is no guarantee that this code will always run on > @@ -2587,7 +2588,8 @@ static void intel_pstate_adjust_pstate(struct cpudata > *cpu) > > target_pstate = get_target_pstate(cpu); > target_pstate = intel_pstate_prepare_request(cpu, target_pstate); > - trace_cpu_frequency(target_pstate * cpu->pstate.scaling, cpu->cpu); > + trace_policy_frequency(target_pstate * cpu->pstate.scaling, cpu->cpu, > + cpumask_of(cpu->cpu)); > intel_pstate_update_pstate(cpu, target_pstate); > > sample = &cpu->sample; > diff --git a/include/trace/events/power.h b/include/trace/events/power.h > index 370f8df2fdb4..317098ffdd5f 100644 > --- a/include/trace/events/power.h > +++ b/include/trace/events/power.h > @@ -182,11 +182,29 @@ TRACE_EVENT(pstate_sample, > { PM_EVENT_RECOVER, "recover" }, \ > { PM_EVENT_POWEROFF, "poweroff" }) > > -DEFINE_EVENT(cpu, cpu_frequency, > +TRACE_EVENT(policy_frequency, > > - TP_PROTO(unsigned int frequency, unsigned int cpu_id), > + TP_PROTO(unsigned int frequency, unsigned int cpu_id, > + const struct cpumask *policy_cpus), > > - TP_ARGS(frequency, cpu_id) > + TP_ARGS(frequency, cpu_id, policy_cpus), > + > + TP_STRUCT__entry( > + __field(u32, state) > + __field(u32, cpu_id) > + __cpumask(cpumask) > + ), > + > + TP_fast_assign( > + __entry->state = frequency; > + __entry->cpu_id = cpu_id; > + __assign_cpumask(cpumask, policy_cpus); > + ), > + > + TP_printk("state=%lu cpu_id=%lu policy_cpus=%*pb", > + (unsigned long)__entry->state, > + (unsigned long)__entry->cpu_id, > + cpumask_pr_args((struct cpumask > *)__get_dynamic_array(cpumask))) > ); > > TRACE_EVENT(cpu_frequency_limits, > diff --git a/kernel/trace/power-traces.c b/kernel/trace/power-traces.c > index f2fe33573e54..a537e68a6878 100644 > --- a/kernel/trace/power-traces.c > +++ b/kernel/trace/power-traces.c > @@ -16,5 +16,5 @@ > > EXPORT_TRACEPOINT_SYMBOL_GPL(suspend_resume); > EXPORT_TRACEPOINT_SYMBOL_GPL(cpu_idle); > -EXPORT_TRACEPOINT_SYMBOL_GPL(cpu_frequency); > +EXPORT_TRACEPOINT_SYMBOL_GPL(policy_frequency); > > diff --git a/samples/bpf/cpustat_kern.c b/samples/bpf/cpustat_kern.c > index 7ec7143e2757..f485de0f89b2 100644 > --- a/samples/bpf/cpustat_kern.c > +++ b/samples/bpf/cpustat_kern.c > @@ -75,9 +75,9 @@ struct { > } pstate_duration SEC(".maps"); > > /* > - * The trace events for cpu_idle and cpu_frequency are taken from: > + * The trace events for cpu_idle and policy_frequency are taken from: > * /sys/kernel/tracing/events/power/cpu_idle/format > - * /sys/kernel/tracing/events/power/cpu_frequency/format > + * /sys/kernel/tracing/events/power/policy_frequency/format > * > * These two events have same format, so define one common structure. > */ > @@ -162,7 +162,7 @@ int bpf_prog1(struct cpu_args *ctx) > */ > if (ctx->state != (u32)-1) { > > - /* record pstate after have first cpu_frequency event */ > + /* record pstate after have first policy_frequency event */ > if (!*pts) > return 0; > > @@ -208,7 +208,7 @@ int bpf_prog1(struct cpu_args *ctx) > return 0; > } > > -SEC("tracepoint/power/cpu_frequency") > +SEC("tracepoint/power/policy_frequency") > int bpf_prog2(struct cpu_args *ctx) > { > u64 *pts, *cstate, *pstate, cur_ts, delta; > diff --git a/samples/bpf/cpustat_user.c b/samples/bpf/cpustat_user.c > index 356f756cba0d..f7e81f702358 100644 > --- a/samples/bpf/cpustat_user.c > +++ b/samples/bpf/cpustat_user.c > @@ -143,12 +143,12 @@ static int cpu_stat_inject_cpu_idle_event(void) > > /* > * It's possible to have no any frequency change for long time and cannot > - * get ftrace event 'trace_cpu_frequency' for long period, this introduces > + * get ftrace event 'trace_policy_frequency' for long period, this introduces > * big deviation for pstate statistics. > * > * To solve this issue, below code forces to set 'scaling_max_freq' to 208MHz > - * for triggering ftrace event 'trace_cpu_frequency' and then recovery back > to > - * the maximum frequency value 1.2GHz. > + * for triggering ftrace event 'trace_policy_frequency' and then recovery > back > + * to the maximum frequency value 1.2GHz. > */ > static int cpu_stat_inject_cpu_frequency_event(void) > { > diff --git a/tools/perf/builtin-timechart.c b/tools/perf/builtin-timechart.c > index 22050c640dfa..3ef1a2fd0493 100644 > --- a/tools/perf/builtin-timechart.c > +++ b/tools/perf/builtin-timechart.c > @@ -612,10 +612,10 @@ process_sample_cpu_idle(struct timechart *tchart > __maybe_unused, > } > > static int > -process_sample_cpu_frequency(struct timechart *tchart, > - struct evsel *evsel, > - struct perf_sample *sample, > - const char *backtrace __maybe_unused) > +process_sample_policy_frequency(struct timechart *tchart, > + struct evsel *evsel, > + struct perf_sample *sample, > + const char *backtrace __maybe_unused) > { > u32 state = evsel__intval(evsel, sample, "state"); > u32 cpu_id = evsel__intval(evsel, sample, "cpu_id"); > @@ -1541,7 +1541,7 @@ static int __cmd_timechart(struct timechart *tchart, > const char *output_name) > { > const struct evsel_str_handler power_tracepoints[] = { > { "power:cpu_idle", process_sample_cpu_idle }, > - { "power:cpu_frequency", process_sample_cpu_frequency }, > + { "power:policy_frequency", process_sample_policy_frequency > }, > { "sched:sched_wakeup", process_sample_sched_wakeup }, > { "sched:sched_switch", process_sample_sched_switch }, > #ifdef SUPPORT_OLD_POWER_EVENTS > @@ -1804,7 +1804,7 @@ static int timechart__record(struct timechart *tchart, > int argc, const char **ar > unsigned int backtrace_args_no = ARRAY_SIZE(backtrace_args); > > const char * const power_args[] = { > - "-e", "power:cpu_frequency", > + "-e", "power:policy_frequency", > "-e", "power:cpu_idle", > }; > unsigned int power_args_nr = ARRAY_SIZE(power_args);
perf timechart seem to do per-CPU reporting though? So this is broken by not emitting an event per-CPU? At least with a simple s/cpu_frequency/policy_frequency/ like here. Similar for the bpf samples technically...
