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From: barmar@kulla (Barry Margolin)
Newsgroups: comp.lang.lisp
Subject: Re: Allegro: loading into oldspace
Message-ID: <31203@news.Think.COM>
Date: 29 Oct 89 04:55:46 GMT
References: <33647@cornell.UUCP>
Sender: news@Think.COM
Organization: Thinking Machines Corporation, Cambridge MA, USA
Lines: 18

By definition, objects can't be created in oldspace.  New objects are
always created in newspace.  When a copying garbage collector runs,
newspace is renamed to oldspace and non-garbage objects are then copied
from oldspace to newspace (in the case of a real-time GC, actually to a
subspace called "copyspace").

In general, a copying GC requires that you have enough VM for two copies of
every non-garbage object.  In some systems, the Lisp environment is broken
up into "areas", and areas can be GCed individually, which may reduce the
memory requirements; however, some garbage in those areas may not be
reclaimed because it is referenced by garbage in the non-GCed areas (during
a by-area GC, other areas are considered to contain only non-garbage).
Some Lisps also have "static" areas, which are not GCed by default (such
areas only have newspace).
Barry Margolin, Thinking Machines Corp.

barmar@think.com
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