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Havana Windows 2008 vcpu topology workaround?

asked 2014-12-15 06:33:17 -0500

Apshai gravatar image

updated 2014-12-16 12:15:13 -0500

smaffulli gravatar image

Hello, I've been working on a Havana cloud, and I realize that the solution for my problem is to upgrade to Juno, but that's several months away and I'm hoping that there is a workaround for my problem.

Like many others, I am trying to create some large Windows VMs with up to 32 vCPUs, but the default topology is allocating one core with one thread to each virtual socket, which is causing a conflict with the version of Windows Server 2008 Enterprise, which only allows 8 sockets.

I have tried manually editing the XML files in the qemu directory in order to add the topology, but the XML file gets overwritten whenever I reboot the instance. Is there a way to make the changes permanent and allow a workaround to enable multiple cores per vCPU? Thanks!

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answered 2015-01-22 11:32:51 -0500

I have added the three lines below to /usr/share/pyshared/nova/virt/libvirt/driver.py file, now when Nova generates libvirt.xml it adds a topology line. Now the VM sees all the virtual CPUs as multiple cores on a single socket. The change needs to be applied on all compute nodes where you need it.

--- /usr/share/pyshared/nova/virt/libvirt/driver.py.old 2014-04-03 14:49:46.000000000 -0400
+++ /usr/share/pyshared/nova/virt/libvirt/driver.py     2015-01-22 10:21:37.000000000 -0500
@@ -2850,6 +2850,10 @@

         guest.cpu = self.get_guest_cpu_config()

+        guest.cpu.sockets = 1
+        guest.cpu.threads = 1
+        guest.cpu.cores = inst_type['vcpus']
+
         if 'root' in disk_mapping:
             root_device_name = block_device.prepend_dev(
                 disk_mapping['root']['dev'])
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Asked: 2014-12-15 06:33:17 -0500

Seen: 376 times

Last updated: Dec 15 '14