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When the Guest OS will report a higher usage of CPU's than the hypervisor will, as in the period when the load test was running above, Windows doesn’t know that part of the time, the CPUs are being stolen away from it and given to other guest machines.
As far as it knows, it is using all the CPU it can on 3 of the 4 CPUs, so that must equal 75% load. It doesn’t know that part of the time, it has no access to the CPU’s as they are being used elsewhere, so the real time CPU usage is only about 50%.
Please refer this article which gives some logical explanation.
Hope that helps.
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