Identify CPU contention on a virtual machine in ESXTOP

  • %RUN
  • %READY
  • %CSTP
  • %WAIT
 The percentage of total scheduled time for the world to run.

 The percentage of
time the world was ready to run

 The percentage of time the world spent in ready, co-deschedule state. This co-deschedule state is only meaningful for SMP VMs. Roughly speaking, ESX CPU scheduler deliberately puts a VCPU in this state, if this VCPU advances much farther than other VCPUs.

 The percentage of time the world spent in wait state. This %WAIT is the total wait time. I.e., the world is waiting for some VMKernel resource. This wait time includes I/O wait time, idle time and among other resources. Idle time is presented as %IDLE.

+Q: How do I know CPU resource is under contention?+
+A: %RDY is a main indicator. But, it is not sufficient by itself.+

 +If a "CPU Limit" is set to a VM's resource settings, the VM will be deliberately held from scheduled to a PCPU when it uses up its allocated CPU resource. This may happen even when there is plenty of free CPU cycles. This time deliberately held by scheduler is shown by "%MLMTD", which will be describe next. Note that %RDY includes %MLMTD. For, for CPU contention, we will use "%RDY - %MLMTD". So, if "%RDY - %MLMTD" is high, e.g., larger than 20%, you may experience CPU contention.+

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