"calcru: runtime went backwards" messages

Jansen Gotis jtgotis at gmail.com
Fri Jun 11 06:03:09 UTC 2010

On Fri, Jun 11, 2010 at 7:03 AM, Jilles Tjoelker <jilles at stack.nl> wrote:
> On Fri, Jun 11, 2010 at 12:35:05AM +0800, Jansen Gotis wrote:
>> Hi, for the past couple of months since moving to RELENG_8 I've been
>> receiving "calcru: runtime went backwards" messages on the console.
> This may well be a manifestation of a brokenness (which should not be
> unknown) in how FreeBSD stores CPU time utilization. The time is
> maintained in "CPU ticks" (CPU clock cycles), so if the clock frequency
> changes, the values of existing processes will be wrong (a jump when
> converted to seconds). When calcru detects this, it generates messages
> like the above. If this analysis is right, the messages can be ignored,
> but indicate that CPU time statistics may be inaccurate.

You're probably right, the messages can be ignored. I don't see any issues
other than the messages being printed on the console; I don't experience
freezing, etc. It just struck me as weird because searching the -current and
-stable mailing lists does not show anyone else having the issue as recently
as I have.

Just some more info to add which I forgot about last time...setting kern.hz to
100 did not help.

Thanks for the reply.

Best regards,

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