Garbage collection

David Gould <>
Fri Aug 27 17:59:32 CEST 1999


On Fri, Aug 27, 1999 at 02:01:47AM +0000, Vlad Dumitrescu wrote:
> Hi!
> 
> I will try to look closer at the existing collector... it is an interesting
> area. Difficult, but worth trying, I think. Only I have the time! :-)
> 
> >Allocating a cons is done as:
> >
> >uint32 *mem = p->htop;
> >p->htop += 2;

And also:

   if (p->htop >= p->maxhtop)
	gc(p);
Or however it gets coded.


> >This is fast, 
> 
> The allocation is fast, but the collection will be slower!
> 
> > if the Boehm collector should be used, we
> >need to replace this with:
> >
> >uint32 *mem = (uint32*) malloc(2);
> >
> >which is slow, extremely slow.

Uh no. The Boehm collector allocation is quite fast. Allocation gets inlined
as approximately:

 if (freelist[size]) {
     /* fast path allocation */
     mem = freelist[size];
     freelist[size] = *mem;
 } else
      /* possibly need to gc */
      gen_malloc(size);

Which is not that slow.

-dg

-- 
David Gould                       510.628.3783 or 510.305.9468 
Informix Software                       300 Lakeside Drive  Oakland, CA 94612
You will cooperate with Microsoft, for the good of Microsoft
and for your own survival.                 -- Navindra Umanee




More information about the erlang-questions mailing list