libvirtError: Requested operation is not valid: cgroup CPUACCT controller is not mounted

Issue

• "libvirtError: Requested operation is not valid: cgroup CPUACCT controller is not mounted" messages are logged into vdsm.log file

                Oct  8 03:34:05 hostname vdsm vm.Vm ERROR vmId=`55343900-fd93-425d-b33a-353cece85a87`::Stats function failed: <AdvancedStatsFunction _sampleCpu at 0x1094c00>#012Traceback (most recent call last):#012  File "/usr/lib64/python2.6/site-packages/vdsm/utils.py", line 412, in collect#012    statsFunction()#012  File "/usr/lib64/python2.6/site-packages/vdsm/utils.py", line 287, in __call__#012    retValue = self._function(*args, **kwargs)#012  File "/usr/share/vdsm/libvirtvm.py", line 154, in _sampleCpu#012    cpuStats = self._vm._dom.getCPUStats(True, 0)#012  File "/usr/share/vdsm/libvirtvm.py", line 531, in f#012    ret = attr(*args, **kwargs)#012  File "/usr/lib64/python2.6/site-packages/vdsm/libvirtconnection.py", line 104, in wrapper#012    ret = f(*args, **kwargs)#012  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 1849, in getCPUStats#012    if ret is None: raise libvirtError ('virDomainGetCPUStats() failed', dom=self)#012libvirtError: Requested operation is not valid: cgroup CPUACCT controller is not mounted
        Oct  8 03:34:05 hostname vdsm vm.Vm ERROR vmId=`431db091-ff95-458e-9749-555a84e50f7c`::Stats function failed: <AdvancedStatsFunction _sampleCpu at 0x1094c00>#012Traceback (most recent call last):#012  File "/usr/lib64/python2.6/site-packages/vdsm/utils.py", line 412, in collect#012    statsFunction()#012  File"/usr/lib64/python2.6/site-packages/vdsm/utils.py", line 287, in __call__#012    retValue = self._function(*args, **kwargs)#012  File "/usr/share/vdsm/libvirtvm.py", line 154, in _sampleCpu#012    cpuStats = self._vm._dom.getCPUStats(True, 0)#012  File "/usr/share/vdsm/libvirtvm.py", line 531, in f#012    ret = attr(*args, **kwargs)#012  File "/usr/lib64/python2.6/site-packages/vdsm/libvirtconnection.py", line 104, in wrapper#012 ret = f(*args, **kwargs)#012  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 1849, in getCPUStats#012    if ret is None: raise libvirtError ('virDomainGetCPUStats() failed', dom=self)#012libvirtError: Requested operation is not valid: cgroup CPUACCT controller is not mounted