[gclist] Re: finding object prefix from infix pointer

Hans Boehm boehm@hoh.engr.sgi.com
Fri, 9 Jul 1999 12:14:15 -0700

On Jul 9,  1:56pm, David Chase wrote:
> [ Replying semi-redundantly ... ].  The conservative
> collector uses BIBOP, or Big Bag of Pages, so the page containing
> an object determines its size.  (See earlier messages on this subject).
> At one time, power-of-two sizes were used, but I am not sure if that
> is still the case.

It now uses a somewhat adaptive technique.  If an allocation request is of a
size that's no smaller than, or not sufficiently close to (say within 20%), an
existing size class, it tries to create a size class corresponding exactly to
that allocation request, enforcing some minimum spacing from the next smaller

I know that integral powers of 2 are not a good idea.  But I have no idea
whether this semi-adaptive technique actually helps.


Hans-J. Boehm