I ran the Python test suite to compare macros versus static inline functions (using PR 29728). I built Python with gcc -O3, LTO and PGO optimizations.
=> There is *no* significant performance difference. I understand that static inline functions are inlined by the C compiler (GCC) as expected. * Macros: 361 sec +- 1 sec * Static inline functions: 361 sec +- 1 sec $ python3 -m pyperf compare_to pgo-lto_test_suite_macros.json pgo-lto_test_suite_static_inline.json Benchmark hidden because not significant (1): command I built Python with: $ ./configure --with-lto --enable-optimizations --prefix $PWD/install $ taskset --cpu-list 2,3,6,7 make $ make install And I ran the following benchmark, run the test suite 5 times using pyperf which pin the process to isolated CPUs: $ python3 -m pyperf command -p1 --warmups=0 --loops=1 --values=5 -v -o ../pgo-lto_test_suite_macros.json -- ./bin/python3.11 -m test -j5 I isolated 4 logical CPUs (2, 3, 6 and 7) on 8: physical CPU cores 2 and 3 (cores 0 and 1 are not isolated). -- Right now, I cannot use pyperformance: it fails to create a virtual environment because greenlet fails to build with Python 3.11. On speed.python.org, the benchmark are still running only because... pyperformance uses a cached binary wheel of greenlet. It looks dangerous to use a cached wheel, since the Python ABI (PyThreadState) changed! Help is welcomed to repair pyperformance: https://github.com/python/pyperformance/issues/113 Victor On Wed, Nov 24, 2021 at 12:27 AM Guido van Rossum <gu...@python.org> wrote: > > On Tue, Nov 23, 2021 at 3:15 PM Antoine Pitrou <anto...@python.org> wrote: >> >> On Tue, 23 Nov 2021 18:00:28 +0100 >> Victor Stinner <vstin...@python.org> wrote: >> >> > I didn't run benchmarks on Python built in release mode, since gcc -O3 >> > with LTO and PGO should inline all static inline functions and I don't >> > expect any difference between macros and static inline functions. >> >> That would actually be interesting, since there can be surprises >> sometimes with compilers... (function inlining depends on heuristics, >> for example, and there may be positive or negative interactions with >> other optimizations) > > > Thanks Antoine. We definitely need to push back on such "expectations" and > turn them into facts by performing careful measurements. Surprises lurk > everywhere. See e.g. > https://github.com/faster-cpython/ideas/issues/109#issuecomment-975619113 > (and watch the Emery Berger video linked there if you haven't already). > > -- > --Guido van Rossum (python.org/~guido) > Pronouns: he/him (why is my pronoun here?) > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/TPUARSPZ7MLDHHWZKPO3FLMIEHMOM6SB/ > Code of Conduct: http://python.org/psf/codeofconduct/ -- Night gathers, and now my watch begins. It shall not end until my death. _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/NINSZIW2LU2AEL2FB6FWXV3EA7BA7XMA/ Code of Conduct: http://python.org/psf/codeofconduct/
