From owner-freebsd-current  Tue Oct 31 10:03:53 1995
Return-Path: owner-current
Received: (from root@localhost)
          by freefall.freebsd.org (8.6.12/8.6.6) id KAA12510
          for current-outgoing; Tue, 31 Oct 1995 10:03:53 -0800
Received: from aslan.cdrom.com (aslan.cdrom.com [192.216.223.142])
          by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id KAA12493
          ; Tue, 31 Oct 1995 10:03:49 -0800
Received: from localhost.cdrom.com (localhost.cdrom.com [127.0.0.1]) by aslan.cdrom.com (8.6.12/8.6.9) with SMTP id KAA08628; Tue, 31 Oct 1995 10:05:22 -0800
Message-Id: <199510311805.KAA08628@aslan.cdrom.com>
X-Authentication-Warning: aslan.cdrom.com: Host localhost.cdrom.com didn't use HELO protocol
To: "Garrett A. Wollman" <wollman@lcs.mit.edu>
cc: "Justin T. Gibbs" <gibbs@freefall.FreeBSD.org>, current@FreeBSD.org,
        wollman@FreeBSD.org
Subject: Re: Time problems 
In-reply-to: Your message of "Tue, 31 Oct 1995 12:47:55 EST."
             <9510311747.AA29686@halloran-eldar.lcs.mit.edu> 
Date: Tue, 31 Oct 1995 10:05:22 -0800
From: "Justin T. Gibbs" <gibbs@freefall.FreeBSD.org>
Sender: owner-current@FreeBSD.org
Precedence: bulk

>If that doesn't work, then just #ifdef out the body of
>the function, which will cause the 8254-alike to act as the reference
>for timekeeping.

Can we do occasional 8254 based sanity checking of the system time to
either automatically revert to the 8254 on systems that the new code
yields poor results, or simply to fix up the time occasionally?  I
thought the main reason for using this approach was to remove the
overhead of going out to the 8254, so doing so only every once in
a while gives the same type of reduction we have know, but should
work on all systems that have a working 8254.

>Needless to say, on the three different motherboards we have here
>(60, 100, and 120-MHz CPUs), we have never seen this problem, so it's
>a bit hard to diagnose.  For those machines on which the results are
>reasonable, I expect timekeeping to be rather better than it was.
>According to xntpd, my machine is within about 3 seconds per day,
>which is about the same as it was before.  (It's the precision, rather
>than the accuracy, where this technique gives a benefit.)
>
>-GAWollman

Precision and overhead right?  Why is it that xntpd doesn't either
complain about my large offset (I started it just after using ntpdate),
or keep my time in sync?

>--
>Garrett A. Wollman   | Shashish is simple, it's discreet, it's brief. ... 
>wollman@lcs.mit.edu  | Shashish is the bonding of hearts in spite of distance.
>Opinions not those of| It is a bond more powerful than absence.  We like peopl
>e
>MIT, LCS, ANA, or NSA| who like Shashish.  - Claude McKenzie + Florent Vollant

--
Justin T. Gibbs
===========================================
  Software Developer - Walnut Creek CDROM
  FreeBSD: Turning PCs into workstations
===========================================