Date: Mon, 12 Sep 2011 17:15:02 -0700 From: Chuck Swiger <cswiger@mac.com> To: Brett Glass <brett@lariat.net> Cc: questions@freebsd.org Subject: Re: Negative ping times with FreeBSD 8.1-RELEASE on older Celeron system Message-ID: <F06D137D-F364-46B2-9458-6882B543B3A6@mac.com> In-Reply-To: <201109122350.RAA21916@lariat.net> References: <201109122350.RAA21916@lariat.net>
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On Sep 12, 2011, at 4:50 PM, Brett Glass wrote: > What's more, it appears that the negative ping times being shown for pings of > localhost are off by about -687 ms, consistently. Any ideas? Your system's timekeeping appears to be busted. Are you running ntpd with "tinker step 0.0" or some home-grown mechanism which might be forcibly stepping the clock rather than skewing it, by any chance? Anyway, the output of: sysctl -a kern.timecounter ...is likely to be informative. Try switching to another clock type, especially ACPI-safe if it hasn't been chosen by default. Your CPU is probably too old to have a power-state invariant TSC, but if you disable SpeedStep, powerd and similar which might change the processor frequency, TSC might work OK also. Regards, -- -Chuck
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