perf_sample_event_took
perf_sample_event_took(sched_clock() - start_clock);
perf_sample_event_took(finish_clock - start_clock);
perf_sample_event_took(sched_clock() - stamp);
perf_sample_event_took(finish_clock - start_clock);
perf_sample_event_took(finish_clock - start_clock);
perf_sample_event_took(sched_clock() - start_clock);
extern void perf_sample_event_took(u64 sample_len_ns);