Python very slow on the Sharp Zaurus - any idea why?

Dilton McGowan II diltonm at pacbell.net
Mon Aug 12 00:29:08 CEST 2002


"Alexandre Courbot" <alexandrecourbot at linuxgames.com> wrote in message
news:mailman.1029072258.16494.python-list at python.org...
> Okay, sorry for having been so long to reply - most of you probably
> don't remember this thread, I have been unable to find it back on my
> machine myself! :)
>
> The issue was that I had great trouble running our game (which uses
> Python for events and NPCs control) at a decent speed on the Zaurus, and
> that disabling all Python scripting was enough to make it smooth. I
> suspected some floating point stuff to be done internally by Python,
> what the Z doesn't like at all (having no floating point unit, floating
> point operations are done in software). I said that I would come with
> some profiling.
>
> Actually, I was totally wrong since the beginning. Running the same game
> on a P200 (roughly equivalent to the Z's StrongArm) is as slow as
> running it on the Zaurus. The bottleneck was very easy to find out
> however:
>
> We handle 15 characters in the game, each one having its own Python
> schedule run every game cycle. There are 70 game cycles per second,
> which makes at least 15 * 70 = 1050 calls to Python methods per second.
> Most of the time, it is just to decrement a counter. So you can imagine
> that the overhead caused by the Python calls is disproportionated
> compared to what is actually performed. Recent processors were able to
> support it, but older or weaker ones can't, obviously.
>
> We have redone our schedule system, so that all the obvious stuff is
> moved to C++ and it is not necessary to call Python schedules all the
> time. Well, you got it - it's working flawlessly now, even on the
> Zaurus. So Python is fine. Python is great! :) It was just an obvious
> design problem that would have been avoided if we used more modest
> machines. Sorry for all the useless brain work my initial post
> triggered!
>
> See you all,
> Alex.
> --
> http://www.gnurou.org
>

I'm new to Python so your statement is interesting.

So it is a lot of work for Python to increment a counter 1050 times per
second and this is only detectable on slower machines? Does that mean that
Python is not scalable doing simple operations?

Dilton





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