Am 10.06.14 18:30, schrieb Steve Dower: > I ran a quick test with profile-guided optimization (PGO, pronounced > "pogo"), which has supposedly been improved since VC9, and saw a very > unscientific 20% speed improvement on pybench.py and 10% size > reduction in python35.dll. I'm not sure what we used to get from VC9, > but it certainly seems worth enabling provided it doesn't break > anything. (Interestingly, PGO decided that only 1% of functions > needed to be compiled for speed. Not sure if I can find out which > ones those are but if anyone's interested I can give it a shot?)
You probably ran too little Python code. See PCbuild/build_pgo.bat for what used to be part of the release process. It takes quite some time, but it rebuilt more than 1% (IIRC). FWIW, I stopped using PGO for the official releases when it was demonstrated to generate bad code. In my experience, a compiler that generates bad code has lost trust "forever", so it will be hard to justify re-enabling PGO (like "but it really works this time"). I wasn't sad when I found a justification to skip the profiling, since it significantly held up the release process. Regards, Martin _______________________________________________ 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
