Red Hat Bugzilla – Bug 838490
[RFE] Specify CPU per VM - lower or equal than cluster cpu, or non-migratable
Last modified: 2016-07-13 05:33:16 EDT
Today the CPU type is taken from the cluster level
eg.If the cluster is Westmere then all the VMs are launched with -cpu westmere
We need the ability to specify CPU per virtual machine.
The setting should allow the cluster type or any lower CPU level
Andrew - can you please elaborate on goal/reason here?
we have the -cpu host for performance.
I assume you don't want someone to set a VM to a lower cpu, rather only to a higher one, which may make it impossible to migrate, etc.
is this supposed to be like -cpu host, but "hopefully migrate-able"?
(switching to sla, as main consideration here will be scheduling)
1. Allow a virtual machine to maintain a static CPU configuration.
eg. User is running VM on westmere host and upgrades the host systems to sandybridge.
Just because we are using a SandyBridge based host it doesn't mean we want to expose that to the guest. The guest may need to keep a consistent CPU and hardware profile.
2. Best performance (+ migration and stability)
- 10 node cluster.
- 8 nodes are westmere, 2 are sandybridge
- Cluster level set to "westmere"
Allow admin to run VM with hardcoded "sandybridge" CPU on one of the 2 applicable hosts. Support migration between compatible hosts.
Obviously this brings with it restrictions.
- If no sandbridge system is running (or has capacity) then the VM can't be run
- You can only migrate between the 2 sandybridge machines
- If only one sandybridge machine is running the host won't be able to go into maintenance mode since it can't live migrate to another host so the VM will need to be stopped first.
I've created bug 952238 as a clone of this bug for the more complex 2nd use case.
so 1st use case can cover the simpler modes:
- VM can be set to any cpu model *lower or equal* than cluster model without pinning (for static configuration)
- VM can be set to any cpu model higher than cluster model in non-migratable mode.
Verified with rhevm-3.6.2-0.1.el6.noarch according to attached test plan.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.