Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!rice!uw-beaver!ubc-cs!alberta!calgary!cpsc!gintera
From: gintera@cpsc.ucalgary.ca (Andrew Ginter)
Newsgroups: comp.lang.lisp
Subject: Re: LISP compiler? (really future of MACL)
Summary: not as cheap as you seem to think...
Message-ID: <2203@cs-spool.calgary.UUCP>
Date: 5 Dec 89 23:09:18 GMT
References: <5130@internal.Apple.COM> <5149@internal.Apple.COM> <616@pyuxf.UUCP> <5117@tekcrl.LABS.TEK.COM>
Sender: news@calgary.UUCP
Lines: 17

In article <5117@tekcrl.LABS.TEK.COM>, Ken Dickey writes:
> > A real time (parallel or incremental) garbage collector is roughly
> > twice as costly as a comparable stop-and-collect collector ...
>
> This is not the case if you use your VM hardware.  See "Real-time
> Concurrent Collection on Stock Multiprocessors" by Appel, Ellis, &
> Lee; Princeton U. tech. report: CS-TR-133-88.

Appel, Ellis & Li's technique reduces the cost of checking for
forwarding pointers.  It does nothing to address the performance
penalty associated with the increased frequency of garbage collection
in a real time or incremental system (Philip L. Waldler, CACM, Sept/76).
Waldler concludes that parallel collectors consume twice the resources
of serial collectors, almost all of the time, even when using algorithms
without any forwarding pointers.

Andrew Ginter, 403-282-2984, gintera@CPSC.UCALGARY.CA, Ginter@UNCAMULT.BITNET