I have a server with E7-4870 *4 processors and it's OS is SLES 11.2.
On it I create 288 virtual machines via KVM, which are used to distribute my spec virt business.
When all the VMs are opened but the spec virt is not running , I can use pcm to monitor the system in SLES11.2
But after all the VMs are running spec virt , the pcm is not working, and show the following:
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)
Even after I input "y" and start pcm again the problem is still exist as above.
So I read the source code of pcm, and know that 176 means "someone has installed pmi handler on counter overflow."
Is this mean the spect virt will make some core's counter overflow?
virtualized environments are not oficially supported by Intel PCM. It seems that KVM and Intel PCM contend on performance monitoring unit (PMU) in the hardware. I don't know if KVM is required to use PMU and if there is an option to avoid its usage.