From Fedora Project Wiki
This test case verifies the CPUs can be dynamically added to and removed from Fedora Xen DomU guests.
How to test
- Shut down the rawhide domU guest.
- Edit the Xen configuration file for the domU guest to make the "vcpus" parameter equal to the number of CPUs you have in your machine. For instance, if you have a system with 2 dual-core processors, set the vcpus parameter in the guest configuration file to 4.
- Start up the rawhide domU guest.
- Once the guest is booted, inside the guest run
$> getconf _NPROCESSORS_ONLNThis number should match what you set in the guest configuration file above.
- Now on the dom0, unplug some vcpus from the guest
$> xm vcpu-set rawhide 2
- Inside the guest, run
$> getconf _NPROCESSORS_ONLNagain. This should now be 2.
- Repeat the above test, varying the number of processors you plug and unplug. Note that you can never plug in more vcpus than you started with, but you can unplug all the way down to a single vcpu.
- Put some load on the guest (for example, a kernel compile), and repeat the above test, varying the number of processors you plug and unplug.
- The guest should not crash while plugging and unplugging vcpus.
- There should be no softlockup or other warnings while plugging and unplugging vcpus.