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1unix rwho0

    Date: Thu, 17 Sep 87 21:41 EDT
    From: Brad Miller <miller@DOUGHNUT.CS.ROCHESTER.EDU>

1	Date: Mon, 14 Sep 87 12:10 EDT
	From: Eric S. Crawley <Crawley@ALDERAAN.SCRC.Symbolics.COM>

	    Date: Thu, 10 Sep 87 14:48:43 EDT
	    From: royt@pravda.gatech.edu (Roy M Turner)

	    I was looking over the documentation and noticed that the Symbolics
	    supports something called unix-rwho service; however, upon looking it
	    up in the TCP code, I didn't see that it really *did* anything except 
	    intercept rwho packets from unix hosts and store them in a variable.
	    Does anyone have any functions to make use of this information, such
	    as something that will do the equivalent of unix's rwho command?  Or 
	    even better, a replacement server that will send information back to 
	    Unix's rwho server, so that information about the lisp machines show
	    up in rwho's done on unix?



	The Unix RWHO server has been removed in 7.2.  It is still in the files
	but commented out at the moment.  It was removed because it is not a
	standard Internet or lispm protocol and no one complained that it didn't
	work.  The questions were more like "Why is this here?".  If you want a
	hack that will give better information than the Unix RWHO, take a look
	at the server-finger hack in SYS:EXAMPLES;.  

    It may give better info (well, then again, looks pretty much the same to me),
    but it isn't free: it fingers all your machines every n minutes. UNIX machines
    already broadcast RWHO, so the ideal soln, would be to take advantage of
    what's already on the net, and only fingering machines that aren't telling you
    anyway. RWHO may not be an internet standard, but how many sites don't have
    UNIX machines? RWHO is like NFS. It's there, it works, you may as well take
    advantage of it. Plus it's efficient: usually RWHO packets are broadcast.
2(The opinions expressed below are those of my alter-ego Unix-ra, and not
those of me or my current employer)

0Efficient at using up CPU time that is.  Think about a large number of
workstations all waking up at randomly staggered 10 minute intervals to
broadcast their rwho status.  Think about all of those workstations
having to task switch and handle each one of those packets.  I know a
number of sites turn off rwho when they see what percentage of CPU time
(on every machine on their net!) is consumed by /etc/rwhod.  Unless I
misremember, Sun's default to having it off.  The finger hack lets one
machine do the work of rwhod, and doesn't disturb the net with lots of
irrelevant broadcast packets.