william E Davidsen (davidsen@ariel.crd.GE.COM) wrote:
: In article <1992Aug17.065450.28834@colorado.edu>, drew@ophelia.cs.colorado.edu (Drew Eckhardt) writes:
: 
: | Boom.  You've just dirtied that page, and it is no longer 
: | shareable.  So, instead of having > 200K shared between all
: | of your shells, you have closer to 800K (Who has less than
: | 4 shells running at a time).  Not a good thing (tm).
: 
:   Well, no, actually. Since the new version of the page is still valid
: for all processes it would still be sharable. And it would not have to
: be saved somewhere in the unlikely event that it gets paged out, because
: the unmodified varsion is still perfectly valid.

No, it wouldn't be shareable.  When a process writes to a shared page,
it gets its very own copy of it which is no longer shared.  There is a
term for this that you probably already know, but others may not.  It's
called Copy-On-Write.

David
-- 
David Engel                        Optical Data Systems, Inc.
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