pointless musings on performance

Paul Boddie paul at boddie.org.uk
Wed Nov 25 01:09:10 CET 2009

On 24 Nov, 19:25, Antoine Pitrou <solip... at pitrou.net> wrote:
> Sorry, I have trouble parsing your sentence. Do you mean bytecode
> interpretation overhead is minimal compared to the cost of actual useful
> work, or the contrary?
> (IMO both are wrong by the way)

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.

> > I imagine that someone (or a number of people) must have profiled the
> > Python interpreter and shown how much time goes on the individual
> > bytecode implementations and how much goes on the interpreter's own
> > housekeeping activities.
> Well the one problem is that it's not easy to draw a line. Another
> problem is that it depends on the workload. If you are compressing large
> data or running expensive regular expressions the answer won't be the
> same as if you compute a Mandelbrot set in pure Python.

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.
Certainly, without such actual cost estimations, a simple counting of
bytecodes should hardly give an indication of how optimal some Python
code might be.


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