Newsgroups: comp.lang.lisp
Path: cantaloupe.srv.cs.cmu.edu!das-news.harvard.edu!news2.near.net!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!pipex!uknet!festival!edcogsci!jeff
From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Subject: Re: C is faster than lisp (lisp vs c++ / Rick Graham...)
Message-ID: <Cvo0zM.HBA@cogsci.ed.ac.uk>
Sender: usenet@cogsci.ed.ac.uk (C News Software)
Nntp-Posting-Host: bute.aiai.ed.ac.uk
Organization: AIAI, University of Edinburgh, Scotland
References: <DAVIS.94Sep1110221@passy.ilog.fr> <345du6$g4h@cantaloupe.srv.cs.cmu.edu> <TMB.94Sep2023108@arolla.idiap.ch>
Date: Mon, 5 Sep 1994 16:40:33 GMT
Lines: 22

In article <TMB.94Sep2023108@arolla.idiap.ch> tmb@idiap.ch writes:
>|In a way, clever implementation makes floats and closure efficiency worse
>|(less predictable), since sometimes the consing will be optimized away, and
>|sometimes it won't.
>|
>|Fortunately, this frivolous consing is easily reclaimed by generational
>|garbage collection.
>
>This "frivolous consing" is absolutely unacceptable in numerical
>code.  Even if collecting the floating point garbage were completely
>free, just the cost of allocating the values and dereferencing them is
>often much too expensive.

But just how expensive is it?  10%  A factor of 3?

>  And, in fact, even systems with excellent
>generational GC become very slow for numerical code whenever there is
>any consing going on in the numerical code.

How slow is "very slow"?

-- jd
