Intel PCM and CPU hotplug Issue

Intel PCM and CPU hotplug Issue

Hi all,

I was using the Intel PCM in an 8 core (SMT-16thread) Intel server and it was doing fine. Recently, I needed to run my experiments while diableing some cores using CPU hotplug capability of Linux (

But when I try to run the PCM while some of the cores are disabled I get the following error:

Can not access CPUs Model Specific Registers (MSRs).
Try to execute 'modprobe msr' as root user and then
you also must have read and write permissions for /dev/cpu/*/msr devices (the 'chown' command can help).

Nothing has changed in the system in terms of permission and the msr module is added using modprobe. So I guess PCM tries to access the folders for diabled cores in /dev/cpu/* and since hotplug removes the folder for the diabled cores, this error is generated.

I was wondering if there is a way to solve this problem? or if the developers are aware of this issue?


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thanks for reporting this. So far we did not look at the systems with cores disabled by OS. We shouldfind outhow we can prioritize this requestto find a simple solution for such configurations.


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