perf_record_header_attr_id
ids = perf_record_header_attr_id(event);
size -= perf_record_header_attr_id(event) - (void *)event;
mem_bswap_64(perf_record_header_attr_id(event), size);
memcpy(perf_record_header_attr_id(ev), id, ids * sizeof(u64));