sysctl: dev.cpu.0.freq: Device busy (cpufreq p4tcc / RELENG_6)

[Nate Lawson]

Marcus Alves Grando wrote:
> I have problems in cpufreq in RELENG_6 (today).
> 
> I try to set another frequency in my laptop and get this error:
> 
> # sysctl dev.cpu.0.freq=250
> dev.cpu.0.freq: 2000
> sysctl: dev.cpu.0.freq: Device busy
> 
> Timecounter "TSC" frequency 1995011972 Hz quality 800
> Timecounters tick every 1.000 msec

Try setting your timecounter to acpi or i8254 (not TSC):

sysctl kern.timecounter.hardware="acpi"

Without complicated recalibration code (which no one has written yet), 
we can't base our system time off the TSC counter when cpufreq is 
changing it.

-- 
Nate