Linux / Unix / VMware

VMware ESX: High CPU Usage on CPU0

Details

Published on Monday, 24 August 2009 14:33

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A VMware ESX host's CPU0 is hovering at around 100% utilization while the rest of the CPU's have no, less or normal load.  

Cause
VMware ESX usually assigns CPU0 to the Service Console and/or any other services including third party software (SAN management, monitoring, backup agent). An extensive usage of CPU0 is could be caused by such a software service. There are several possible reasons and therefore many possible solutions.

Solution 1: Restart ESX Host

• Hot-migrate all running Virtual Machines from the affected ESX host using Vmotion.
• Enter "Maintenance Mode".
• Logon to ESX Service Console and type "shutdown -r now".
• Check whether the problem is solved. If not, follow the instructions in solution 2 below.

Solution 2: Identify the Causer

• Use the commands "top" and "esxtop" to identify the processes with the highest CPU time.
• Try to stop/restart the appropriate service:
  service <Name of the Service> restart
• Or kill hung processes using:
  kill -9 “Process ID”
  
  Note that the server may lose connection with Virtual Center.

Solution 3: Reconfigure HA

• There is a known issue with High Availability (HA) Agents. Use the commands "top" and "esxtop" to determine the CPU intensive processes.
• If the processes ftPerl and/or ftAgent are responsible for the excessive CPU usage, we have to "Reconfigure HA" in Virtual Center.
  
  Note that this actions have no impact on running VMs.