sample_len_ns    1232 include/linux/perf_event.h extern void perf_sample_event_took(u64 sample_len_ns);
sample_len_ns     510 kernel/events/core.c void perf_sample_event_took(u64 sample_len_ns)
sample_len_ns     523 kernel/events/core.c 	running_len += sample_len_ns;