Software Tuning, Performance Optimization & Platform Monitoring
Discussion regarding monitoring and software tuning methodologies, Performance Monitoring Unit (PMU) of Intel microprocessors, and platform updating.

[PCM] PCM not restarting after ctrl-c


I have a problem when using pcm on Linux.
After I have compiled pcm sucessfully, I launch pcm.x and it can show the right information. Then I terminated it by Ctrl+C command.
But when I try to run pcm.x again, it show the PMU is busy all time. The output is like below:
WARNING: Core 0 fixed ctrl:176
Access to Intel(r) Performance Counter Monitor has denied (Performance Monitoring Unit is occupied by other application). Try to stop the application that uses PMU.
Alternatively you can try to reset PMU configuration at your own risk. Try to reset? (y/n)

So, what happend to my pcm?

Something must have been gone wrong during shutdown of Intel PCM, which is surprising to me as I usually end PCM with Ctrl-C. What then happens at the next start-up is that Intel PCM finds that the registers are already programmed, which might indicate that some other program is accessing the performance monitoring units (PMUs). PCM therefore bails off, but offers you the option to reprogram them. Since you know that no other program like Linux perf, VTune, or Liquid is using the PMUs, you can safely press "y". PCM will then reset the PMUs and you should be able to start PCM afterwards.

Kind regards


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