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); -- 2.52.0.107.ga0afd4fd5b-goog
