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Path: utzoo!linus!vaxine!ptw
From: ptw@vaxine.UUCP (P. T. Withington)
Newsgroups: net.unix-wizards
Subject: Re: software clock losing time - (nf)
Message-ID: <380@vaxine.UUCP>
Date: Fri, 4-Nov-83 09:53:42 EST
Article-I.D.: vaxine.380
Posted: Fri Nov  4 09:53:42 1983
Date-Received: Sat, 5-Nov-83 18:12:29 EST
References: <2262@hp-pcd.UUCP>
Organization: Automatix Inc., Billerica, MA
Lines: 20

This is a longstanding bug which I have never found any answer to.  I suspect
it has to do with clock ticks getting lost on a heavily loaded VAX.  (There is
no code to deal with interval timer overrun.)  It shows up more on a 750
because it is easier to overload.

My pet peeve is that the VAX has this nifty high-resolution time-of-year
clock that Unix only bothers to look at at boot time, and then maintains its
time using an interval timer to approximate a line frequency clock (at a
significantly poorer resolution).  I understand the history of this
organization, but...

So an immediate solution is to reboot often enough to keep your time
inaccuracy down.  This also gives you an excuse to fsck, clean /tmp, etc.

There is a mention of a long-standing time bug being fixed in 4.2, but I
haven't had a chance to see what they do.  (I'm betting they read the TOY
clock when the interval timer overruns.)

			     't`   --Tucker (ptw@vaxine.UUCP)
			      ~