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From: lkaplan@bbn.com (Larry Kaplan)
Newsgroups: comp.arch,comp.lang.functional,comp.lang.lisp,comp.lang.prolog
Subject: Re: GC triggering and stack limit checking by MMU hardware
Message-ID: <58338@bbn.BBN.COM>
Date: 20 Jul 90 19:02:44 GMT
References: <1990Jul19.151524.22544@diku.dk> <3260@swi.swi.psy.uva.nl> <Fhtz5421@cs.psu.edu>
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In article <Fhtz5421@cs.psu.edu> schwartz@groucho.cs.psu.edu (Scott E. Schwartz) writes:
>
>In article <3260@swi.swi.psy.uva.nl> 
> jan@swi.psy.uva.nl (Jan Wielemaker) writes:
>| Both schemas are not ideal.  The mmap() requires a file and reads the
>| file into the page as a page is mapped.  This is a waste of resources; I
>| just want a page of uninitialised memory and need no file.
>
>Rather than mapping a file, you can map /dev/zero, which provides zero
>filled copy on write pages.

Ever hear of anonymous mapped memory.  Check out the 4.3BSD Architecture Manual
(PS1:6) for a description of this rarely (or almost never) implemented 
feature.  Using MAP_ANON causes the memory to be zero filled, but not 
necessarily copy on write.  It is more meant for sharing of zero initialized
pages.  The file descriptor is only used for rendezvous.  We've implemented
it here and found it very useful.

#include <std_disclaimer>
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