perf_event__synthesize_event_update_scale
!perf_event__synthesize_event_update_scale(NULL, evsel, process_event_scale));
err = perf_event__synthesize_event_update_scale(tool, evsel, process);
int perf_event__synthesize_event_update_scale(const struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);