Description of problem:
After upgrading to vdsm-4.16.8.1-8.el6ev the customer is experiencing high performance degradation of his VMs once started there, showing high %steal time and vdsm logs errors for each VM continously:

~~~
PolicyEngine::ERROR::2015-03-28 20:54:56,016::vm::5104::vm.Vm::(_reportException) vmId=`f989786c-9245-40b7-ba5d-be059364216b`::Operation failed
Traceback (most recent call last):
  File "/usr/share/vdsm/virt/vm.py", line 5080, in setCpuTunePeriod
    self._dom.setSchedulerParameters({'vcpu_period': int(period)})
  File "/usr/share/vdsm/virt/vm.py", line 689, in f
    ret = attr(*args, **kwargs)
  File "/usr/lib/python2.6/site-packages/vdsm/libvirtconnection.py", line 111, in wrapper
    ret = f(*args, **kwargs)
  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 2039, in setSchedulerParameters
    if ret == -1: raise libvirtError ('virDomainSetSchedulerParameters() failed', dom=self)
libvirtError: invalid argument: value of 'vcpu_period' is out of range [1000, 1000000]
~~~

Version-Release number of selected component (if applicable):
vdsm-4.16.8.1-8.el6ev

How reproducible:
always at customer site.

Steps to Reproduce:
1. Have RHEV 3.4 with vdsm-4.14 running
2. Upgrade Hypervisors to latest release (yum update -y)
3. Start a VM on that hypervisor which has some load
4. Experience top and /var/log/vdsm/vdsm.log from hypervisor

Actual results:
The VM shows high %steal times (although running alone on the hypervisor):

~~~
Linux 2.6.32-504.8.1.el6.x86_64 (myhost)   03/30/2015      _x86_64_        (5 CPU)

11:21:21 AM     CPU     %user     %nice   %system   %iowait    %steal     %idle
11:21:23 AM     all      7.21      1.33      1.23      0.19     33.87     56.17
11:21:25 AM     all     13.10      0.83      2.31      3.23     64.02     16.51
11:21:27 AM     all     14.41      1.78      1.78      0.89     67.32     13.82
11:21:29 AM     all     12.00      1.94      1.84      1.74     57.79     24.69
11:21:31 AM     all     14.66      1.40      1.89      1.79     70.39      9.87
11:21:33 AM     all     15.53      1.98      1.29      0.00     75.17      6.03
11:21:35 AM     all     15.85      1.81      1.15      0.76     78.61      1.81
11:21:37 AM     all     14.04      1.94      1.26      1.45     66.12     15.20
11:21:39 AM     all     14.95      1.36      1.55      3.69     67.86     10.58
11:21:41 AM     all     14.00      1.19      1.19      0.99     60.77     21.85
11:21:43 AM     all     14.23      2.19      1.29      1.69     68.86     11.74
11:21:45 AM     all     16.63      1.41      1.21      0.00     80.75      0.00
Average:        all     13.86      1.59      1.50      1.38     65.84     15.83

Additionally /var/log/vdsm/vdsm.log as well as /var/log/messages throws the following errors:

vdsm.log:
PolicyEngine::ERROR::2015-03-28 20:54:56,016::vm::5104::vm.Vm::(_reportException) vmId=`f989786c-9245-40b7-ba5d-be059364216b`::Operation failed
Traceback (most recent call last):
  File "/usr/share/vdsm/virt/vm.py", line 5080, in setCpuTunePeriod
    self._dom.setSchedulerParameters({'vcpu_period': int(period)})
  File "/usr/share/vdsm/virt/vm.py", line 689, in f
    ret = attr(*args, **kwargs)
  File "/usr/lib/python2.6/site-packages/vdsm/libvirtconnection.py", line 111, in wrapper
    ret = f(*args, **kwargs)
  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 2039, in setSchedulerParameters
    if ret == -1: raise libvirtError ('virDomainSetSchedulerParameters() failed', dom=self)
libvirtError: invalid argument: value of 'vcpu_period' is out of range [1000, 1000000]

messages:
Mar 29 10:20:32 myhost vdsm vm.Vm ERROR vmId=`2bc56270-2dfe-46bf-97f1-0399cb9390b1`::Operation failed#012Traceback (most recent call last):#012  File "/usr/share/vdsm/virt/vm.py", line 5080, in setCpuTunePeriod#012    self._dom.setSchedulerParameters({'vcpu_period': int(period)})#012  File "/usr/share/vdsm/virt/vm.py", line 689, in f#012    ret = attr(*args, **kwargs)#012  File "/usr/lib/python2.6/site-packages/vdsm/libvirtconnection.py", line 111, in wrapper#012    ret = f(*args, **kwargs)#012  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 2039, in setSchedulerParameters#012    if ret == -1: raise libvirtError ('virDomainSetSchedulerParameters() failed', dom=self)#012libvirtError: invalid argument: value of 'vcpu_period' is out of range [1000, 1000000]

Expected results:
* VM should show no %steal 
* Performance of the VM should not increase dramatically after updating to vdsm-4.16
* The errors logged in vdsm.log/messages should not occur

Additional info:
After downgrading to vdsm-4.14.18-6.el6ev and restarting the VM no further errors could be observed as well as the %steal being back to normal.

On top of that:
Some VMs can't even be started (that was also true for vdsm-4.14.18-7.el6ev) as the VM BIOS never kicked in.
They could be started again after applying version vdsm-4.14.18-6.el6ev as well
(Specs: 10*10 Cores (100 vCPUs) and 386GB of Memory).