FreeBSD 5 clock run at double speed - Solution!

I have been having an issue with my FreeBSD 5.1 RELEASE box. The clock was running fast, at exactly twice the speed it should be running at. Each time I reset the box the time would come good again so it wasnt a BIOS issue.

Now FreeBSD doesn't do via the BIOS clock while running, it does its own time keeping. In version 4 I did not have this issue, in version 5 I did. I found out in version 4 they used TSC for clocking, in 5 they updated it to use ACPI. ACPI is a better choice but they have been having issues with certain motherboards (mine is one of them) where it runs at double speed. To fix this problem you need to make the system go back to using TSC.

Edit your /etc/sysctl.conf and add kern.timecounter.hardware=TSC. This will make the clock run correctly after a reboot. To enforce this setting without rebooting type sysctl kern.timecounter.hardware="TSC"

That will fix the issue.

EDIT: Removed quotes as per notice below

whoa, sweet, this is exactly what I was looking for...

the only thing I noticed, is that in /etc/sysctl.conf it wants kern.timecounter.hardware=TSC that is, without the quotes.

thanks a million !!

Thanks for that correction, the other day we had to cut the power to house while doing some electical work. When we turned it back on I noticed my server was running clock at double speed again, because I had to quotes in the config file

My install chose TSC by default, running sysctl -w kern.timecounter.hardware=i8254
fixed this on a AMD64.. thanks for this.. took 3 days to find this solution..