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Nithiyan
Enthusiast
Enthusiast
‎03-10-2010 02:59 AM
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ESX server CPU utilization

Anyone can explain how esx server allocating the CPU resource and how VM utilizing the CPU?

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weinstein5
Immortal
Immortal
‎03-10-2010 05:04 AM
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I am not sure ow deep you want to go but I will keep it at a high level - as a VM runs its virtual cpu is receiving instruction to run from the VMs o.s and applications - these are passed off to the vmkerner, the hypervisor in the esx server, and these instructions are scheduled to a single logical cpu (logical cpu equates to a physical core(or hyperthread if HT is enabled) on the physical cpu - it is a 1:! relationship virtual cpu to logical cpu -

Hope this helps -

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MattG
Expert
Expert
‎03-10-2010 05:06 AM
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Hypervisor is essentially owning and scheduling slices of the underlying CPU resources as per VMs making requests for CPU. VM thinks it has full access to the physcial CPUs, but actually doesnt.

NOTE: If you are running multiple vCPUs per VM, everytime a multi-vCPU VM requests a CPU slice, the hypervisor needs to grab an underlying core/thread for all vCPUs in the VM even if it is a single threaded request.

-MattG

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