RE: question: Embedded scripting language on consol e

The actual memory size is pretty tiny - it's "compiled" to bytecode, and all
the symbol names are referenced, not passed around, so it's fine on that
respects. It was the fragmentation and new/delete performance that was
killing us, but that's all solved with a stack-based allocator.

Speed is the major concern - we'll have to see how we get on with that, and
just how much stuff we'll have to throw over the wall to C. The PS2 is
definately the worst case - the other platforms have bigger caches and
faster CPUs and don't have much of a problem with it.


Tom Forsyth - Muckyfoot bloke and Microsoft MVP.

This email is the product of your deranged imagination,
and does not in any way imply existence of the author.

> -----Original Message-----
> From: Andrew Perella [mailto:[email protected]]
> Sent: 21 February 2003 11:31
> To: [email protected]
> Subject: RE: [GD-Consoles] question: Embedded scripting language on
> console
> 
> 
> Thanks Tom.
> Its good of you to spend the time giving such a detailed reply.
> Given your experience, it is certainly something I will look 
> into here.
> Have you know what sort of memory footprint this takes up?
> Cheers,
> Andrew
> 
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of
> Tom Forsyth
> Sent: 20 February 2003 11:23
> To: [email protected]
> Subject: RE: [GD-Consoles] question: Embedded scripting language on
> console
> 
> 
> Bear in mind that the project is only about a third of the 
> way through, so
> we haven't hit any evil crunch times yet.
> 
> Porting was pretty simple. You need to override the memory 
> handling stuff to
> use your own heaps of course, but that was pretty simple.
> 
> You also probably want to give Python its own heap because it 
> does a lot of
> 12-byte allocations, and if you throw that in the general 
> heap you'll get
> horrible fragmentation. We used a stack-based allocator hard-coded to
> deliver 12-byte entries - nice and fast, no fragmentation.
> 
> Biggest worry is speed on the PS2, because its cache is sooo tiny. But
> Python is hardly a speed demon in the best of times, so you 
> need to make
> sure you're not using a "heartbeat" system (i.e. calling each 
> object each
> frame) - you need a queue-based event system and a C 
> "autonomic" system to
> do the mundane work. This is just good programming practice, whatever
> language you use, but it's especially important when using a 
> slow scripting
> language for your high-level stuff.
> 
> SWIG takes a bit of work to integrate into the toolchain, and 
> it's still not
> great - it doesn't auto-SWIG headers very well, and we do 
> tend to have to
> manually do a "SWIG rebuild" quite often. However, it is 
> pretty fast, so
> that's not a big problem, it's just a bit annoying. I suspect 
> we could fix
> it easily if we just wrote a makefile (rather than trying to 
> use VC.net's
> stuff, which isn't very suited to this sort of stuff).
> 
> Benefits are that Python is incredibly easy to code, and 
> we've got some good
> stuff up and working very quickly. And of course you get a scripting
> language that the designers can use "for free".
> 
> Yes, it's a brave step. But we know that if it does all fall 
> down around our
> ears and speed is a big problem, we can just port the code 
> back to C, and
> only use Python for actual "level scripts" (this switch opens 
> this door,
> stuff like that). SWIG is probably the most important bit of 
> the puzzle,
> because it means that you can freely mix and match Python and 
> C - they can
> access each others members and fucntions quite happily, which 
> means you can
> throw code from one to the other in case of speed 
> emergencies. But we've not
> had to so far.
> 
> Even if the worst happens and no trace of Python survives to 
> the shipped
> game (which I very very much doubt), Python is a great 
> prototyping tool.
> 
> We were inspired by Humungous's work with Python and SWIG - they've
> definately had more experience with this sort of stuff. IIRC, 
> there's a GDC
> talk they did on the pros and cons and gotchas. Definately 
> worth checking
> out.
> 
> 
> Tom Forsyth - Muckyfoot bloke and Microsoft MVP.
> 
> This email is the product of your deranged imagination,
> and does not in any way imply existence of the author.
> 
> > -----Original Message-----
> > From: Andrew Perella [mailto:[email protected]]
> > Sent: 20 February 2003 10:54
> > To: [email protected]
> > Subject: RE: [GD-Consoles] question: Embedded scripting language on
> > console
> >
> >
> > Hi Tom,
> > 	Can you tell us more of your experiences with using
> > python on ps2/xbox/gc?
> > What problems have you had? What unexpected benefits did 
> you get? What
> > worries do you have at the back of your mind? My feeling is
> > that this was a
> > brave step to make at this time.
> > Regards,
> > Andrew
> >
> >
> > Dr Andrew Perella
> > Programming Manager
> > [email protected]
> >
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> 
> 
> 
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