Multiple Virtual CPUs are Causing Performance Issues

  1. Open a console prompt on the ESX host or initiate an SSH connection to it.
  2. Type esxtop and press Enter.
  3. In the CPU screen, check the %CSTP value. If this number is higher than 3.00, the performance issues may be caused by the vCPU count. Try lowering the vCPU count of the virtual machine by 1.Note: The %CSTP value represents the amount of time a virtual machine with multiple virtual CPUs is waiting to be scheduled on multiple cores on the physical host. The higher the value, the longer it waits and the worse its performance.  Lowering the number of vCPUs reduces the scheduling wait time.
  4. In vCenter, you can also edit the realtime graphs to show Co-Stop:Co-Stop

As a general rule, I recommend starting with one processor and upgrading to multi-processors if it is really necessary. Case in point: I have a DBA that wanted 8 processors for his Oracle Database, I initially gave it to him, but soon the DB began this power grab on the vHost. Once I convinced him it was his server causing the issues, we rolled the system back several processors and the DB worked much better.

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