Davide Rizzo <sor...@gmail.com> added the comment:
munmap() of private maps is usually pretty fast but not negligible (2 ms for 1GB). Shared maps are much slower. For some reason, shared maps explicitly backed by POSIX shared memory stand in between but are still pretty slow. If someone cares about file-backed mmaps I can test those too. I thought this is already significant to justify releasing the GIL. This is on Linux 4.4: shared anon mmap 1048576 bytes mmap time 6,393 ns write time 449,062 ns munmap time 100,205 ns -- private anon mmap 1048576 bytes mmap time 2,168 ns write time 308,966 ns munmap time 36,930 ns -- posix shm + mmap 1048576 bytes mmap time 13,299 ns write time 369,305 ns close time 1,545 ns munmap time 26,759 ns -- shared anon mmap 134217728 bytes mmap time 4,641 ns write time 64,508,536 ns munmap time 13,592,556 ns -- private anon mmap 134217728 bytes mmap time 6,116 ns write time 25,402,084 ns munmap time 388,976 ns -- posix shm + mmap 134217728 bytes mmap time 29,034 ns write time 66,826,645 ns close time 3,707 ns munmap time 3,475,977 ns -- shared anon mmap 1073741824 bytes mmap time 11,127 ns write time 508,227,373 ns munmap time 94,885,306 ns -- private anon mmap 1073741824 bytes mmap time 7,133 ns write time 199,933,903 ns munmap time 2,361,036 ns -- posix shm + mmap 1073741824 bytes mmap time 24,868 ns write time 527,566,819 ns close time 4,015 ns munmap time 21,179,674 ns -- ---------- Added file: https://bugs.python.org/file48177/unmap.c _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue36139> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
