Red Hat Bugzilla – Bug 1278324
CPU limitation for VM does not work when balloon device is not present
Last modified: 2016-06-15 04:51:33 EDT
Created attachment 1089995 [details]
Description of problem:
CPU limitation not works on vm, it does not matter what cpu profile use vm.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Create CPU QoS with 10% limitation
2. Create CPU profile with CPU QoS above
3. Attach CPU profile above to vm(have number of cpu equal to half of hosts cpu's)
4. Load vm CPU to 100%
Host CPU loaded to 50%
Host CPU must be loaded only on 10%
I do not really sure if problem in MoM of in VDSM
Also I do not see at all parameters of period and quota under <cputune> parameter
<maxMemory slots='16' unit='KiB'>4294967296</maxMemory>
<vcpu placement='static' current='12'>16</vcpu>
I do not see the ready status for the VM in mom.log. That usually means some data is missing for mom to start the policy evaluation.
Can you run the test with DEBUG logging enabled please?
Created attachment 1091225 [details]
So the issue is that balloon info is missing:
test_cpu_profile: Incomplete data: missing set(['balloon_max', 'balloon_cur', 'balloon_min'])
The balloonInfo should always be reported by VDSM. Can you attach the getVmStats output for the VM please?
Ok so we found out what is wrong. This whole issue is caused by a missing memory balloon device which is currently required for any QoS to work properly.
Can you please check whether your VM had a memory ballon device enabled checkbox set in the VM edit / Resource allocation subtab?
You right, balloon device under vm disabled, if I enabled it I can see that period and quota appear under dumpxml:
But I first time hear that QoS need balloon device to work, we just add vm to some cgroup with specific parameters on host, how it connect to balloon device?
MOM requires the balloon device to be able to do the load computations based on memory. It might not be necessary in this case though so the bug might still be valid with a different title.
And btw, balloon was always required. I am lowering the severity and removing the regression keyword.
Moving from 4.0 alpha to 4.0 beta since 4.0 alpha has been already released and bug is not ON_QA.
oVirt 4.0 beta has been released, moving to RC milestone.
*** This bug has been marked as a duplicate of bug 1337834 ***