PERF_EVENT_IOC_PERIOD 458 include/uapi/linux/perf_event.h #define PERF_EVENT_IOC_PERIOD _IOW('$', 4, __u64) PERF_EVENT_IOC_PERIOD 458 tools/include/uapi/linux/perf_event.h #define PERF_EVENT_IOC_PERIOD _IOW('$', 4, __u64)