Any idea why Python calls mmap+munmap more even in a venv? Victor
Le mer. 27 févr. 2019 à 10:00, INADA Naoki <songofaca...@gmail.com> a écrit : > > > > > > Ah, another interesting point, this huge slowdown happens only when > > > bm_pickle.py > > > is executed through pyperformance. When run it directly, slowdown is > > > not so large. > > > > pyperformance runs benchmarks in a virtual environment. I don't know > > if it has any impact on bm_pickle. > > > > Most pyperformance can be run outside a virtual env if required > > modules are installed on the system. (bm_pickle only requires the > > stdlib and perf.) > > > > Bingo! > > Without venv: > > unpickle: Mean +- std dev: 26.9 us +- 0.0 us > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 28.78 0.000438 0 1440 read > 27.33 0.000416 1 440 25 stat > 9.72 0.000148 1 144 mmap > ... > 0.79 0.000012 1 11 munmap > > With venv: > > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 57.12 0.099023 2 61471 munmap > 41.87 0.072580 1 61618 mmap > 0.23 0.000395 1 465 27 stat > > unpickle and unpickle_list creates massive same-sized objects, then all > objects are > removed. If all pools in the arena is freed, munmap is called. > > I think we should save some arenas to reuse. On recent Linux, > we may be able to use MADV_FREE instead of munmap. > -- Night gathers, and now my watch begins. It shall not end until my death. _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
