calcru: runtime went backwards errors
fbsdlists at gmail.com
Mon Jun 30 14:38:27 UTC 2008
On 6/30/08, David Allen <the.real.david.allen at gmail.com> wrote:
> I've been seeing errors like the following appearing:
> Jun 30 03:13:57 ford kernel: calcru: runtime went backwards from 261
> usec to 258 usec for pid 516 (devd)
> Jun 30 03:13:57 ford kernel: calcru: runtime went backwards from 486
> usec to 481 usec for pid 0 (swapper)
> and narrowed down the cause to openntpd.
> Do these errors fall into the Mostly Harmless category?
It's probably just an annoyance, unless it is happening so often it
causes other problems.
The FreeBSD FAQ used to have a nice explanation of this, but it has
been replaced by a discussion that simply assumes the problem is
caused by the Intel SpeedStep implementation on your motherboard:
But in general, this error can be caused by several things, including
a device that is slow to respond to interrupts. One thing that often
helps on SMP systems is to make sure your timecounter isn't using TSC:
$ sysctl kern.timecounter
kern.timecounter.choice: TSC(-100) HPET(900) ACPI-fast(1000) i8254(0)
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