Date: Tue, 5 Feb 2002 10:51:37 -0800 (PST) From: John Polstra <jdp@polstra.com> To: hackers@freebsd.org Cc: phk@critter.freebsd.dk Subject: Re: A question about timecounters Message-ID: <200202051851.g15IpbU04184@vashon.polstra.com> 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 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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