calcru: negative time of...

[Roman Yashin]

I guess this probably came up before, but I could find any helpful info 
in the list's archive...
I am getting a lot of "calcru: negative time of...". I am on 5.1 
RELEASE.
I have tried troubleshooting hints but without luck.

"sysctl -w kern.timecounter.method=1" gives me "sysctl: unknown oid 
'kern.timecounter.method'"

Could somebody point me to the right direction? Please!

Thanks a lot.

-Roman