How to tell real CPU load in a xen environment

topvirtualizationxen

I have a Debian machine with 4 CPU cores running Xen with two virtual machines, and I'm having trouble determining overall real CPU usage.

Each machine has two VCPUs assigned to it with no cap on CPU use:

Domain-0                             0    256    0
dom01                                1    256    0
dom02                                4    256    0

While logged into each of those machines, top shows 80-90% CPU usage on each CPU (I press '1' to show each core individually). xentop on dom0 agrees with this report.

However, top on dom0 shows all 4 CPU cores spending most of their time idle.

Does xen hide the CPU utilization of the virtual environments from dom0's top? If so, is there any way to display the real utilization of the CPU cores on the machine?

Best Answer

Correct, dom0 doesn't see domU CPU activity.

The answer is in your question: xentop on dom0 shows you the real utilization of the CPUs.

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