CPU utilization shown by mpstat command or sar command on guest after live migration does not correspond to actual CPU utilization

Issue

• CPU utilization shown by mpstat command or sar command on guest after live migration does not correspond to actual CPU utilization. Although guest CPU quota is set 50%, mpstat command or sar command on guest shows 92%. mpstat command on host seems to show actual CPU utilization.

- Before live migration

   hyperA# virsh schedinfo --config rhel64
   Scheduler      : posix
   cpu_shares     : 0
   vcpu_period    : 100000
   vcpu_quota     : 50000

   hyperA#
   hyperA# virsh schedinfo --current rhel64
   Scheduler      : posix
   cpu_shares     : 0
   vcpu_period    : 100000
   vcpu_quota     : 50000

   hyperA# virsh vcpupin rhel64
   VCPU: CPU Affinity
   ----------------------------------
      0: 15


   hyperA# mpstat -P ALL 5 4
   Linux 2.6.32-358.el6.x86_64 (rhel64-sv1)         12/27/2012      _x86_64_        (16 CPU)

   03:08:43 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
   03:08:48 PM   15    0.00    0.00    0.00    0.00    0.00    0.00    0.00   50.60   49.60


   guest# mpstat -P ALL 5 4
   Linux 2.6.32-358.el6.x86_64 (rhel64)  12/27/2012      _x86_64_        (1 CPU)

   03:09:37 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
   03:09:42 PM  all   48.01    0.00    2.39    0.00    0.00    0.00   49.60    0.00    0.00
   03:09:42 PM    0   48.01    0.00    2.39    0.00    0.00    0.00   49.60    0.00    0.00


   guest# sar -u 5 4
   Linux 2.6.32-358.el6.x86_64 (rhel64)  12/27/2012      _x86_64_        (1 CPU)

   03:09:59 PM     CPU     %user     %nice   %system   %iowait    %steal     %idle
   03:10:04 PM     all     47.81      0.00      2.59      0.00     49.60      0.00

- After live migration

   hyperB# virsh schedinfo --config rhel64
   Scheduler      : posix
   cpu_shares     : 0
   vcpu_period    : 100000
   vcpu_quota     : 50000

   hyperB# virsh schedinfo --current rhel64
   Scheduler      : posix
   cpu_shares     : 1024
   vcpu_period    : 100000
   vcpu_quota     : 50000

   hyperB# virsh schedinfo --live rhel64
   Scheduler      : posix
   cpu_shares     : 1024
   vcpu_period    : 100000
   vcpu_quota     : 50000

   hyperB# virsh vcpupin rhel64
   VCPU: CPU Affinity
   ----------------------------------
      0: 15


   hyperB# mpstat -P ALL 5 4
   Linux 2.6.32-358.el6.x86_64 (rhel64-sv2)         12/27/2012      _x86_64_        (16 CPU)

   03:12:27 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
   03:12:32 PM   15    0.00    0.00    0.00    0.00    0.00    0.00    0.00   50.40   49.60


   guest# mpstat -P ALL 5 4
   Linux 2.6.32-358.el6.x86_64 (rhel64)  12/27/2012      _x86_64_        (1 CPU)

   03:13:23 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
   03:13:28 PM  all   92.22    0.00    7.78    0.00    0.00    0.00    0.00    0.00    0.00
   03:13:28 PM    0   92.22    0.00    7.78    0.00    0.00    0.00    0.00    0.00    0.00


   guest# sar -u 5 4
   Linux 2.6.32-358.el6.x86_64 (rhel64)  12/27/2012      _x86_64_        (1 CPU)

   03:13:48 PM     CPU     %user     %nice   %system   %iowait    %steal     %idle
   03:13:53 PM     all     92.09      0.00      7.91      0.00      0.00      0.00