Negative ping times with FreeBSD 8.1-RELEASE on older Celeron system

[Chuck Swiger]

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