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Date:      Tue, 28 Feb 2006 16:34:40 -0800
From:      Nate Lawson <nate@root.org>
To:        Marcus Alves Grando <mnag@FreeBSD.org>
Cc:        FreeBSD Stable <freebsd-stable@FreeBSD.org>
Subject:   Re: sysctl: dev.cpu.0.freq: Device busy (cpufreq p4tcc / RELENG_6)
Message-ID:  <4404EC20.8030500@root.org>
In-Reply-To: <4404E852.80908@FreeBSD.org>
References:  <4404E852.80908@FreeBSD.org>

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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



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