Gregory P. Smith <g...@krypto.org> added the comment:
In my experience, people overthink what needs to go into a CPython profiling run. Sure, our default PROFILE_TASK is rather unfortunate because it takes a very long time by including runs of super slow tests that won't meaningfully contribute profile data (multiprocessing, subprocess, concurrent_futures, heavy I/O, etc). But despite somewhat popular belief, it is not actually a problem that the suite exercises other sides of branches, because by and large just by executing Python code at all and exercising C extension module code, it still acts like most any Python program and spends most of the time on the common critical paths - regardless tests that trigger specific number of executions of other paths. Those executions pale in comparison to the ordinary ones in anywhere critical. I don't recommend making any claim about something "harming" the profile without reliable data to prove it. Feel free to tune what test.regrtest --pgo enables or disables by default. But try to do it in a scientific data based manner rather than guessing. Decreasing the total wall time for a default --enable-optimizations build would be a good thing for everyone, provided the resulting interpreter remains "effectively similar" in speed. If you somehow manage to find something that actually speeds up the resulting interpreter, amazing! https://github.com/python/pyperformance is your friend for real world performance measurement. Patience is key. The builds and benchmark runs are slow. One thing --enable-optimizations does _not_ do today is enable link time optimization by default. Various toolchain+platform versions were having problems successfully generating a working interpreter with LTO enabled. If you want a potential large speed up in the interpreter, figuring out how to get link time optimization on top of the existing PGO working reliably, detecting when toolchains+platform combos where it will be reliable, and enabling it by default on such systems is _likely_ the largest possible gain still to be had. ---------- components: +Build nosy: +gregory.p.smith versions: +Python 3.8, Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue36044> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
