Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!rpi!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.arch
Subject: Re: 64 bits for times....
Message-ID: <2470@crdos1.crd.ge.COM>
Date: 28 Aug 90 18:19:36 GMT
References: <11187@alice.UUCP> <3300165@m.cs.uiuc.edu>
Reply-To: davidsen@crdos1.crd.ge.com (bill davidsen)
Organization: GE Corp R&D Center, Schenectady NY
Lines: 27

In article <3300165@m.cs.uiuc.edu> gillies@m.cs.uiuc.edu writes:

  [ strong statement on stupidity of ns dating ]

| Also, tell me when it will be possible to synchronize all the computer
| clocks with a nano-second accuracy atomic clock.  How will such a
| clock be reset later?

  I guess the first question is when will there be a benefit from doing
so? And how long will it stay in sync?
| 
| My conclusion:  ISO should specify a nanosecond relative timer, and a
| much coaser absolute timer (like milliseconds).

  The timer should not be more accurate than the accuracy of the
setting. Unless there's a good way to set such a timer within a ms
*repeatably* then why worry about how accurately you can measure it? The
relative timer is important, the absolute timer leads people to believe
they have accuracy they don't.

  Yes I know about using phone lines and radio to distribute time, with
and without hardware ping and delay compensation. It is still hard to be
sure you're within a ms. Fortunately getting within 50 ms seems to be
adequate for most things, which is easy to do.
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
    VMS is a text-only adventure game. If you win you can use unix.