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Vector instruction set in HPC Perf. Characterization

Smith__John
Beginner
420 Views

Hi,

I am currently profiling a program by using VTune.

 

The attached image shows that there are more than 2 vector instructions.

 

I am wondering if there are more than 2 vector instruction set in the "HPC Performance Characterization", this means that a certain function uses all of the instructions? or they are the possible candidate vector instructions that are used by the function?

 

It would be appreciated if anyone could let me know.

 

Thanks.

 

 

 

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1 Solution
AthiraM_Intel
Moderator
420 Views

Hi,

Usage of instruction set does not depend on which analysis you run – i.e. HPC Performance Characterization or Hotspot analysis. Instruction sets are generated by the compiler and which are analyzed by these profiling tools.

Intel VTune is a profiling tool that analyzes your application, it lists instruction set(s) used  in your application. The vector instruction sets listed by Intel VTune are the ones used by your application and not suitable candidates. Tools like Intel Advisor can list the possible candidates and the performance improvement that can be achieved by using a different instruction set.

Hope this clarifies your query.

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5 Replies
Dmitry_P_Intel1
Employee
420 Views

Hello,t

VTune does static analysis of a function body and lists all vector instruction sets that were recognized.

Could you please specify in more details what you meant under "candidate vector instructions" to give you more precise answer?

Thank you, Regards, Dmitry

 

Smith__John
Beginner
420 Views

Hello, Dmitry

I meant I was wondering whether or not some of those instructions are executed in practice.

 

For example,

If there were three instructions such as AVX, AVX2, SSE in the vector instruction set slot, but only AVX instruction was executed actually.

Is this case possible?

or 

All three instructions above are executed during its execution time?

 

Thank you

 

AthiraM_Intel
Moderator
421 Views

Hi,

Usage of instruction set does not depend on which analysis you run – i.e. HPC Performance Characterization or Hotspot analysis. Instruction sets are generated by the compiler and which are analyzed by these profiling tools.

Intel VTune is a profiling tool that analyzes your application, it lists instruction set(s) used  in your application. The vector instruction sets listed by Intel VTune are the ones used by your application and not suitable candidates. Tools like Intel Advisor can list the possible candidates and the performance improvement that can be achieved by using a different instruction set.

Hope this clarifies your query.

AthiraM_Intel
Moderator
420 Views

Hi,

Could you please confirm whether the solution provided was helpful.

 

AthiraM_Intel
Moderator
420 Views

Hi,

We hope your query is answered. We are closing this thread.

Please feel free to open a new thread if you have any further queries.

 

Thanks

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