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Beginner
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which intel processor has best performance monitoring support

Dear all,

we are investigating performance monitoring on intel processors. We noticed differences in their capabilities for doing this for two intel processors we currently test.

Which intel processors currently have the best support/capability for performance monitoring (e.g number of hardware performance counters)?

Thanks in advance and best,
Habb 

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Hello haab, 

 

Thank you for posting on the Intel® communities.   

 

I would like to confirm some information, can you please provide the following? 

 

  1. Are you looking to know what processors are the better ones for use/development using the Intel® Performance Counter Monitor? Tool shown here: https://software.intel.com/content/www/us/en/develop/articles/intel-performance-counter-monitor.html  
  2. Are you developing any application, software, API, or something similar? 
  3. What are the processors that you have tested already? Please provide the full model number.  

 

Regards, 

 

Sebastian M  

Intel Customer Support Technician  


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Beginner
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Dear Sebastian,

thanks a lot for your reply.

Yes, we are aware of intel pcm and actually we have tested that.

The purpose of our investigation is to profile and tune applications on intel processors, for which we need good intel processors that allow us to do this monitoring/profiling in an efficient way, i.e. it should be low overhead and it should support optimal amount of events to be monitored. We understand that this boils down to a large extent to the number of hardware performance counters. So a directly related question is that which intel processor has the best PMU (number of performance counters)?

Currently we are using two mainstream processors (we are open to any other type as long as the PMU support is good):

  1. intel core i7-2640m, 10 hardware counters and 384 max multiplex counters, with fast rdpmc
  2. intel core i7-7800x, 10 hardware counters and 384 max multiplex counters, without fast rdpmc

We would highly appreciate it if you could point to some good (even best) intel processors when talking about profiling capbilities.

Thanks a lot in advance,
Pengcheng

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Hello haab,  

 

Thank you for your clarification. 

 

Based on what you are reporting, we are moving your thread for better assistance to: 

 

Software Development Topics > Software Tuning, Performance Optimization & Platform Monitoring 

 

Please kindly wait for a response.  

 

Regards,  

  

Sebastian M  

Intel Customer Support Technician   


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Black Belt
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it should be low overhead and it should support optimal amount of events to be monitored. We understand that this boils down to a large extent to the number of hardware performance counters. So a directly related question is that which intel processor has the best PMU (number of performance counters)?

You can only achieve low overhead access for fixed counters which are readable from the user space by calling the RDPMC machine code instruction.

For low overhead access of programmable counters you may use libpfc library and I presume (have not measure yet) , that overhead will be at least hundreds of cycles if not more for each PMC access. You would not have a multiplexing and thread-following on context switch and there is a need to set an affinity to specific thread.

There is a lot performance events (up to 400-500 on server SKU's) and very few performance counters (usually 8-10). So may use VTune or perf profiler and program it to measure either 4 events or 8 events per session, this way you will eliminate the counter multiplexing access overhead (at least hundreds of cycles), but you will need to run more session.

It is hard to say which CPU is the "best"  as everything must be analyzed and some counter will undercount or overcount (you may ask Dr. Bandwidth).

 

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Hello haab,  

 

I would like to inform you that after checking internally with higher levels and engineering department, they advised they don't think there are “better” or “more” PMUs. Sometimes they can be present and sometimes cannot and this is because all processor segments will have different numbers. For example, there’s a PMU for each core so CPUs with different numbers of cores will have different numbers of PMUs for them. Additionally, newer processors have more advanced feature sets.  

  

Documentation on Intel® Performance Counter Monitor (Intel® PCM) which is discontinued:  

https://software.intel.com/content/www/us/en/develop/articles/intel-performance-counter-monitor.html 

  

The open PCM fork Intel contributes to now:  

https://github.com/opcm/pcm

 

Regards,   

   

Sebastian M   

Intel Customer Support Technician  


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