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How does VTune collect HPC data?

Baljit_S_
Beginner
476 Views

Hi,

I am new to VTune and was interested in knowing how does VTune collect the performance counter data? Does vTune capture counters while the OS code is executing? Are the counters being updated in user space or in kernel space?

Thanks.

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4 Replies
Peter_W_Intel
Employee
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VTune uses hardware PMU to measure. The general formula is -

MFLOPS Formula = A-specific-event counters / 1,000,000 / Elapsed Time
Elapsed time = CPU_CLK_UNHALTED.THREAD / Processor-Frequency / Number-of-Cores

Please see this blog to know examples in detail.

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Dmitry_P_Intel1
Employee
476 Views

Hello,

It is worth also to look at https://software.intel.com/en-us/node/544067 to understand the sampling collection method that VTune use for hardware (driver) based collections.

BTW - what particular HPC data are you interested in?

Thanks & Regards, Dmitry 

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David_A_Intel1
Employee
476 Views

And, actually, there are two different collection mechanisms: one is software-based and one is hardware-based.  It depends on the analysis type you select.

So, again, what specifically are you asking about?

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Baljit_S_
Beginner
476 Views

Thanks for the reply guys. I am dealing with HPC for branches, cache misses and memory uops.

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