kern/140361: [cpufreq] speed-stepping broken on PhenomII (acpi?)

[Bruce Cran]

The following reply was made to PR kern/140361; it has been noted by GNATS.

From: Bruce Cran <bruce at cran.org.uk>
To: bug-followup at FreeBSD.org, freebsd at soulrebel.in-berlin.de
Cc:  
Subject: Re: kern/140361: [cpufreq] speed-stepping broken on PhenomII
 (acpi?)
Date: Sun, 12 Sep 2010 09:59:39 +0100

 Hannes,
 
 It looks like powerd is doing its job: the line "dev.cpu.0.freq: 800"
 shows that your CPU is running at 800MHz which is far below its
 maximum. By checking the value of dev.cpu.0.freq every so often you
 should see it reduce when the system is idle and increase when doing
 CPU-intensive work like running a build etc.
 
 The cx_usage lines (e.g. dev.cpu.0.cx_usage: 100.00% last 500us) are
 just reporting the amount of time the CPU was in a certain power state.
 Since your CPU doesn't support C2 and C3 all the time is spent in C1 -
 hence the "100%". That's normal, and would only be less than 100% if
 you had C2 or C3 and you'd set hw.acpi.cpu.cx_lowest.
 
 I don't think this is a bug in FreeBSD if you can confirm that the
 dev.cpu.0.freq value is changing. If so, I'd like to close this PR.
 
 -- 
 Bruce Cran