Some VM's on Hyper-V show very high loads even without indexing. In the kern.log following messages are shown:



UDEV [1293.877229] add /devices/virtual/misc/vmbus!hv_vss (misc)
UDEV [1293.877432] remove /devices/virtual/misc/vmbus!hv_vss (misc)
UDEV [1293.877724] remove /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:07/VMBUS:01/vmbus_1004160 (vmbus)
UDEV [1293.877880] add /devices/virtual/misc/vmbus!hv_vss (misc)
UDEV [1293.878213] remove /devices/virtual/misc/vmbus!hv_vss (misc)
KERNEL[1293.878323] add /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:07/VMBUS:01/vmbus_1018806 (vmbus)
KERNEL[1293.878370] add /devices/virtual/misc/vmbus!hv_vss (misc)

This is due to the fact that Hyper-V tries to create snapshot using VSS. Disabling VSS will solve this issue.

  1. Go into the settings of your virtual machine
  2. In the right hand column select "Integrated Services" 
  3. Under the Management heading turn off "Backup (Volume Snapshot)". 

CPU load should go back to normal now.