perf_mmap__mmap_len
size_t perf_mmap__mmap_len(struct perf_mmap *map);
map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
munmap(map->base, perf_mmap__mmap_len(map));
return perf_mmap__mmap_len(&map->core);