Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: galvin-peter@yale-bulldog.arpa (Peter Baer Galvin)
Newsgroups: comp.sys.sun
Subject: Re: sticky bit
Message-ID: <50864@yale-celray.yale.UUCP>
Date: 28 Feb 89 11:46:54 GMT
References: <8902081253.AA06789@ursa-major.SPDCC.COM>
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Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
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Original-Date: 16 Feb 89 16:29:51 GMT
X-Sun-Spots-Digest: Volume 7, Issue 172, message 3 of 15

Under Berkeley Unix an executable program is copied into system swap space
before execution is started.  Paging of the program is done from swap
space rather than from the executable in the file system because
(according to Karels I think) going through the file system would take 3
times longer. When the last processes using the image exits, the image is
removed from swap. The sticky bit tells the OS not to delete the image in
swap space, even if no processes are using that image.  This saves the
overhead of the copy from file system to swap space.  The down side is
that the swap space is then not usable by other programs until the system
in question reboots.  If you always have an emacs running (as I do) then
setting it sticky doesn't do much, one way or the other.

					      --Peter

Peter Baer Galvin       		      (203)432-1254
Senior Systems Programmer, Yale Univ. C.S.    galvin-peter@cs.yale.edu
51 Prospect St, P.O.Box 2158, Yale Station    ucbvax!decvax!yale!galvin-peter
New Haven, Ct   06457			      galvin-peter@yalecs.bitnet