EST SpeedStep with E2140 shows wrong frequencies

[John Baldwin]

On Wednesday 25 February 2009 7:45:35 pm Daniel Duerr wrote:
> Hello,
> 
> I have been following the developments (or lack thereof) around EST  
> and the more recent Intel Dual-core CPUs and was very happy to  
> discover some new results with the latest FreeBSD 7.1 versions,  
> specifically Gabriel Lavoie's recent posts about his success with the  
> E5200 CPU.  My CPU is an Intel Pentium Dual 65nm E2140 @ 1.6GHz which  
> is supposed to use under 8W of power when idled down with EST.  Since  
> this server is always on, this power savings would be wonderful.
> 
> Today, I decided to give it another shot and updated my 7.1-STABLE  
> amd64 system to the current sources.  I re-enabled the cpufreq driver  
> in my /boot/loader.conf and now, upon bootup, no longer get the  
> message about EST not recognizing my CPU which seems like a great step  
> forward.  Furthermore, EST is actually attaching to the cpufreq  
> subsystem and populating frequency information as it should.   
> Unfortunately I am experiencing two issues though:
> 1) the resulting frequency information picked up by EST don't seem  
> complete/accurate for my CPU
> 2) the behavior changes further if I disable the multiple cores in my  
> BIOS

We rely on the BIOS to tell us the available speed settings via ACPI.  Also, 
for idle consumption the bigger gain will come from using higher Cx states 
rather than using throttling.

-- 
John Baldwin