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 (http://www.cyberciti.biz/faq/debian-rhel-centos-redhat-suse-hotplug-cpu/)
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?