Showing posts from February, 2013

Polling CPU Ready Metrics

A customer recently asked me how to easily check their environment for high CPU Ready metrics.  Given that I don't know of an easy way to quickly look through the whole environment by the GUI, I decided to pull out PowerCLI and see what I could put together.

For those who don't know, CPU Ready records the time that a VM spends (during a given interval) ready for CPU time, but no physical CPU is available.  Basically, it reports on CPU contention.  There will always be small amounts of CPU Ready - that just reflects the time that it takes a CPU to react to an OS's request to compute.  In general, CPU Ready times averaging below 5% of your polling interval should be completely unnoticeable.  Between 5% and 10%, delays become noticeable, and beyond 10% they are seriously problematic.

Those rules for interpreting CPU ready are all based on percentage of a time interval, but the metric that is actually recorded is the number of milliseconds spent in a Ready state.  When looking…