Just Another IT Blog

It's time to share some of my experiences, crazy ideas, tips and tricks !!!

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This week my client faced a weird situation, the CPU utilization of theirs ESXi host were over 100% !!!

Just as informational, the high utilization on their VMs, which caused the hosts to have a high CPU utilization, was not VMware related ; )

We know the hosts were in a high utilization period, but how was be over 100% possible ?

I started looking at vSphere Monitoring andPerformance, on page 49 I found a nice description of the CPU utilization.

The note on that description gave me the first clue

NOTE If a PCPU is running at frequency that is higher than its nominal (rated) frequency, then PCPU USED(%) can be greater than 100%.
Now that I confirmed that it’s possible, I decided to look for what could be allowing that.
Very soon I figured out that it’s a feature on Intel processors called Intel® Turbo Boost Technology.
When it’s enabled it allows the processor to transition to a higher frequency in order to give more horsepower during peak periods.
 I hope you don’t have to face extreme situations like this, but if you do that’s how you explain it to your boss.

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