[Speed] Analysis of a Python performance issue

Kevin Modzelewski kmod at dropbox.com
Sat Nov 19 20:58:19 EST 2016


I think it's safe to not reinvent the wheel here.  Some searching gives:
http://perso.ensta-paristech.fr/~bmonsuez/Cours/B6-4/Articles/papers15.pdf
http://www.cs.utexas.edu/users/mckinley/papers/dcm-vee-2006.pdf
https://github.com/facebook/hhvm/tree/master/hphp/tools/hfsort

Pyston takes a different approach where we pull the list of hot functions
from the PGO build, ie defer all the hard work to the C compiler.

On Sat, Nov 19, 2016 at 12:29 PM, serge guelton <sguelton at quarkslab.com>
wrote:

> On Sat, Nov 19, 2016 at 02:32:26AM +0100, Victor Stinner wrote:
> > Hi,
> >
> > I'm happy because I just finished an article putting the most
> > important things that I learnt this year on the most silly issue with
> > Python performance: code placement.
> >
> > https://haypo.github.io/analysis-python-performance-issue.html
> >
> > I explain how to debug such issue and my attempt to fix it in CPython.
> >
> > I hate code placement issues :-) I hate performance slowdowns caused
> > by random unrelated changes...
> >
> > Victor
>
> Thanks *a lot* victor for this great article. You not only very
> accurately describe the method you used to track the performance bug,
> but also give very convincing results.
>
> I still wonder what the conclusion should be:
>
> - (this) Micro benchmarks are not relevant at all, they are sensible to
> minor
>   factors that are not relevant to bigger applications
>
> - There is a generally good code layout that favors most applications?
>   Maybe some core function from the interpreter ? Why does PGO fails to
>   ``find'' them?
>
> Serge
>
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