[Python-Dev] Python 3.5 on VC14 - update

[Thomas Wouters]

On Tue, Jun 10, 2014 at 9:30 AM, Steve Dower <Steve.Dower at microsoft.com>
wrote:

>
> 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?)
>

For what it's worth, we build Google's internal Python interpreters with
gcc's flavour of PGO and are seeing somewhat more than 20% performance
increase for Python 2.7. (We train using most of the testsuite, not
pybench, and I believe the Debian/Ubuntu packages also do this.) I believe
almost all of that is from speedups to the main eval loop, which is a huge
switch in a bigger loop with complicated jump logic. It wouldn't surprise
me if VS's PGO only decided to optimize that eval loop :)

-- 
Thomas Wouters <thomas at python.org>

Hi! I'm an email virus! Think twice before sending your email to help me
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