[ODE] Re: Capped Cylinder - trimesh collider - FIXED!!!

[Mark Wayland]

There's a great paper from Christer Ericson "Memory Optimization" from GDC2003 that y'all should check out.
I think you can find it at www.gdconf.com in the archives.

Mark

> -----Original Message-----
> From: Russ Smith [mailto:russ at q12.org]
> Sent: Friday, 16 April 2004 1:56 PM
> To: Nguyen Binh
> Cc: adam at gimp.org; aspirin at ntlworld.com; ODE at q12.org
> Subject: Re: [ODE] Re: Capped Cylinder - trimesh collider - FIXED!!!
> 
> 
> 
> hi nguyen,
> 
> > Hmm...! Could you please explain? I do think that inline
> > is good for small function.
> 
> inline functions should be treated as optimizations, for all but the
> smallest and most trivial functions. in other words, you should
> determine that a function should be inlined only after performance
> testing, profiling etc - typically when the code is stable, not during
> development. the trouble with inline functions is that they 
> can make the
> code bigger, which in itself can greatly hurt performance because it
> causes other code to be deleted from the I-cache. i have seen even
> small, simple code grow to hundreds of k in size just by 
> indiscriminate
> use of inline functions.
> 
> > ADM> 3) Stylistically it hurts to see so many globals... I don't
> > ADM> really know what to say about that.
> >      Yes, I don't like it either. But I don't see any other 
> way to get
> >      through though. Moreover, I just focus on the 
> performance side of
> >      the code and globals don't hurt performance...
> 
> globals are bad for two reasons. first, they usually prevent the code
> from being thread-safe. i don't know of anyone using ODE in multiple
> threads, but there shouldn't be anything in the library that precludes
> this. second, globals DO hurt performance, in two ways: (1) they are
> harder for the compiler to optimize with because less can be
> determined about aliasing to globals, and (2) globals are 
> typically not
> stored anywhere near the stack, so you get less locality of reference
> (remember that the stack is a hot area of the D-cache, so changing a
> global to a stack variable can often save cache-load cycles).
> if you have a bunch of state that must be passed between 
> functions, just
> put it all in a stack (if not too large) or heap structure 
> and pass the
> pointer around.
> 
> BTW, thanks for all the hard work!
> 
> russ.
> 
> -- 
> Russell Smith
> http://www.q12.org
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