pointless musings on performance

[Antoine Pitrou]

Le Tue, 24 Nov 2009 16:09:10 -0800, Paul Boddie a écrit :
> 
> I'm referring to what you're talking about at the end. The enhancements
> in Python 3 presumably came about after discussion of "threaded
> interpreters", confirming that the evaluation loop in Python 2 was not
> exactly optimal.

An optimal evaluation loop is a evaluation loop which doesn't get 
executed at all :-)
(which is what unladen-swallow, cython and pypy are trying to do)

> You need to draw the line between work done by system and external
> libraries and that done by Python, but a breakdown of the time spent
> executing each kind of bytecode instruction could be interesting.

When you say "executing each kind of bytecode instruction", are you 
talking about the overhead of bytecode dispatch and operand gathering, or 
the total cost including doing the useful work?

Regardless, it probably isn't easy to do such measurements. I once tried 
using AMD's CodeAnalyst (I have an AMD CPU) but I didn't manage to get 
any useful data out of it; the software felt very clumsy and it wasn't 
obvious how to make it take into account the source code of the Python 
interpreter.

Regards

Antoine.