Date: Tue, 05 Feb 2002 19:44:38 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: John Polstra <jdp@polstra.com> Cc: hackers@FreeBSD.ORG Subject: Re: A question about timecounters Message-ID: <91477.1012934678@critter.freebsd.dk> In-Reply-To: Your message of "Tue, 05 Feb 2002 10:30:52 PST." <200202051830.g15IUq004143@vashon.polstra.com>
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In message <200202051830.g15IUq004143@vashon.polstra.com>, John Polstra writes: >In article <200202051826.g15IQDt04095@vashon.polstra.com>, >John Polstra <jdp@polstra.com> wrote: >> In article <90498.1012930272@critter.freebsd.dk>, >> Poul-Henning Kamp <phk@critter.freebsd.dk> wrote: >> > In message <200202051723.g15HNH603801@vashon.polstra.com>, John Polstra writes: >> > >> > Can you try to MFC rev 1.111 and see if that changes anything ? >> >> That produced some interesting results. I am still testing under >> very heavy network interrupt load. With the change from 1.111, I >> still get the microuptime messages about as often. But look how >> much larger the reported backwards jumps are: >> >> microuptime() went backwards (896.225603 -> 888.463636) >> microuptime() went backwards (896.225603 -> 888.494440) >> microuptime() went backwards (896.225603 -> 888.500875) >> microuptime() went backwards (1184.392277 -> 1176.603001) >> microuptime() went backwards (1184.392277 -> 1176.603749) > >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. This points to an arithmetic overflow (ie: point 3 in my previous email) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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