From owner-freebsd-hackers  Tue Feb  5 10:51:54 2002
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Date: Tue, 5 Feb 2002 10:51:37 -0800 (PST)
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To: hackers@freebsd.org
From: John Polstra <jdp@polstra.com>
Cc: phk@critter.freebsd.dk
Subject: Re: A question about timecounters 
In-Reply-To: <91477.1012934678@critter.freebsd.dk>
References: <91477.1012934678@critter.freebsd.dk>
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In article <91477.1012934678@critter.freebsd.dk>,
Poul-Henning Kamp  <phk@critter.freebsd.dk> wrote:
> In message <200202051830.g15IUq004143@vashon.polstra.com>, John Polstra writes:
> >In article <200202051826.g15IQDt04095@vashon.polstra.com>,
> >John Polstra  <jdp@polstra.com> wrote:
> >
> >Another interesting thing is that the jumps are always 7.7x seconds
> >back -- usually 7.79 seconds.  This is even true with more data points
> >from two different machines.
> 
> Yes, I noticed, but didn't dare draw conclusions based on two data points.

It's pretty consistent -- always 7.7somthing.

> This points to an arithmetic overflow (ie: point 3 in my previous email)

Yes, I think you're onto something now.  It's a 550 MHz. machine, so
the TSC increments every 1.82 nsec.  And 1.82 nsec * 2^32 is 7.81
seconds. :-)

I'll try the things you suggested in your other mail.

John
-- 
  John Polstra
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Disappointment is a good sign of basic intelligence."  -- Chögyam Trungpa


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