[Beowulf] Turboboost/IDA on Nehalem

George Wm Turner turnerg at indiana.edu
Sat Jun 19 12:37:48 EDT 2010


cat /proc/cpuinfo
Look for a clock rate higher then the chip's rated clock speed.
You must have cpuspeed enabled (re: redhat:  service cpuspeed start)

On multi core chips, turbomode comes into play when the chip is lighty  
loaded and the idle cores can be clocked down and that power divereted  
to the core(s) actually running code.  On an idle system,  you may  
notice that all the cpus in /proc/cpuinfo" say they're running at the  
higher clock speeds;  it's an illusion; they ain't doin' nuttin.

george wm turner
high performance systems
812 855 5156



On Jun 19, 2010, at 11:24 AM, Rahul Nabar wrote:

> On Fri, Jun 18, 2010 at 7:27 AM, Douglas Guptill <douglas.guptill at dal.ca 
> > wrote:
>> On Fri, Jun 18, 2010 at 12:30:12PM +0100, Hearns, John wrote:
>>> Does anyone know much about Turboboost on Nehalem?
>>> I would like to have some indication that this is working, and  
>>> perhaps
>>> measure what effect it has.
>>> I have enabled Turboboost in the BIOS, however when I modprobe
>>> acpi_cpufreq I get
>
> What's a good way to confirm if  my procs are actually in a turbo
> state at a given point of time. It doesn't get reported back through
> the usual BIOS channels does it?
>
> -- 
> Rahul
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