RE: Fragmentation was RE: [GD-General] Compile times

[Mick W. <mi...@ne...>]

> -----Original Message-----
> From: Thatcher Ulrich
> Sent: Wednesday, December 18, 2002 8:37 PM
> To: gam...@li...
> Subject: Re: Fragmentation was RE: [GD-General] Compile times
> 
> On Dec 18, 2002 at 12:38 -0600, brian hook wrote:
> > > The reason I ask is because I *know* fragmentation is a 
> problem if 
> > > malloc sucks, and sucky mallocs have been ubiquitous 
> until recently, 
> > > but the only empirical study I'm aware of suggests that if malloc 
> > > doesn't suck, then fragmentation is not a problem.
> > > 
> > > http://www.cs.utexas.edu/users/wilson/papers/fragsolved.pdf
> > 
> > Okay, went back and browsed that paper, and I don't think 
> it applies.
> > The datasets and object sizes they are looking at aren't 
> representative 
> > of what I consider to be normal game. For example, they make the 
> > observation that most programs average allocating objects 
> of about 6-7 
> > different sizes.  Any game that loads models, textures or 
> sound will 
> > almost definitely not fit into this area.
> 
> Possibly; it would be interesting to see numbers on some actual games.
> 

In Tony Hawk's Pro Skater 4 on the PS2, I just did a few tests, and on
the main heap, there are 474 different sizes of memory allocation in
18,000 blocks  (Taking the most frequent 6 sizes accounts for 12,000 of
these).  Script heap (our next biggest heap) has 202 different sizes in
7800 blocks (5000 of them in the most frequent 6 block sizes). We have
about seven distinct heaps using around 30,000 blocks, and 6 "pools" for
various fixed size allocations, using around 100,000 blocks

Mick.