Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!cornell!rochester!udel!mmdf
From: escd!es56!karl@decwrl.dec.com (Karl Rowley)
Newsgroups: comp.os.minix
Subject: Re: fork
Message-ID: <10585@louie.udel.EDU>
Date: 10 Mar 89 20:07:38 GMT
Sender: mmdf@udel.EDU
Lines: 15


fork() is expensive if you have to copy the entire process to
do it.  Some operating systems with virtual memory implement
'copy on write' for virtual memory pages.  When a fork() is 
done, no memory is actually copied.  A page is copied when
the parent or child writes to it.  This makes fork() a whole
lot cheaper.

The fork()/exec() combination may not always be efficient,
but it is very flexible.

			Karl Rowley
			Evans and Sutherland Computer Division
			escd!karl@decwrl.dec.com
			...!decwrl!escd!karl