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Samuel_M_1
New Contributor I
144 Views

Read Base Clock Frequency

I understand that the frequency of the base clock varies between the nehalem and the sandy/ivy bridge architectures (133.33 MHz vs 100 MHz). Is there a way to read this number from an MSR or some other source? 

0 Kudos
9 Replies
Patrick_F_Intel1
Employee
144 Views

If there is another way, I have not seen it.

In my tools I have to check the cpuid family and model to see on which cpu I'm running and then use the appropriate 100 or 133 MHz speed.

Sorry,

Pat

SergeyKostrov
Valued Contributor II
144 Views

>>...In my tools I have to check the cpuid family and model to see on which cpu I'm running and then use the appropriate 100 or >>133 MHz speed. Patrick, Could you be more specific, please?
Bernard
Black Belt
144 Views

IIRC I saw in the documentation that one of the MSR registers 0xCE reports base frequency.I need to check ISDM to verify this.

Patrick_F_Intel1
Employee
144 Views

Hello Sergey,

It is just the standard, pain-in-the-rear code like:

if ( family == 0x6 && xmodel == 0x3e ) {

    bclock == 100 ;   // so cpu model is ivybridge, bclock is 100 MHz

} else if ( family == 0x6 && xmodel == 0x2a ) { // sandybridge...

the family and xmodel (extended model) is based on the CPUID app note http://www.intel.com/content/www/us/en/processors/processor-identification-cpuid-instruction-note.ht...

There is a discussion of using cpuid to ID cpu type at http://software.intel.com/en-us/articles/intel-architecture-and-processor-identification-with-cpuid-...

Pat

 

SergeyKostrov
Valued Contributor II
144 Views

>>...the family and xmodel (extended model) is based on the CPUID app note... Thanks for the note, Patrick. I didn't see processor-identification-cpuid-instruction-note.pdf document before.
PONRAM
Beginner
144 Views

hope you may interested in the following link

software.intel.com/en-us/platform-monitoring

SergeyKostrov
Valued Contributor II
144 Views

>>hope you may interested in the following link >> >>software.intel.com/en-us/platform-monitoring Thanks for the link.
Samuel_M_1
New Contributor I
144 Views

Great link PONRAM.

My conclusion for the original question is that Patrick's method using cpuid is the only viable option, and I have implemented that in my code. Thank you all for your responses.

Bernard
Black Belt
144 Views

Thank you PONRAM for the link.It contains a great amount of information.

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