perf_record_id_index
struct perf_record_id_index id_index;
struct perf_record_id_index *ie = &event->id_index;
max_nr = (UINT16_MAX - sizeof(struct perf_record_id_index)) / etot_sz;
sz = sizeof(struct perf_record_id_index) + n * etot_sz;
sz = sizeof(struct perf_record_id_index) + n * e1_sz;
sz = sizeof(struct perf_record_id_index) + nr * e1_sz;