I'm just trying to understand what overhead ESX (vmkernel and sc) have on the CPU. I have a figure of 5% in my head but i'm not sure where i got this from. I searched through the resource management whitepaper etc but i can only seem to find info on the memory overheads.
Anyone got any ideas?
One white paper says this...
The overhead of ESX Server compared to an operating system running directly on hardware is between 12%-15%.
You might read through these, they have alot of techy info about cpu.
Evaluation of ESX Server under CPU Intensive Workloads - http://www.windley.com/docs/2006/OIT%20Report%20Sept06.pdf
ESX Server 3 Ready Time Observations - http://www.vmware.com/pdf/esx3_ready_time.pdf
A Performance Comparison of Hypervisors - http://www.vmware.com/pdf/hypervisor_performance.pdf
ESX Server CPU Scheduling - http://www.vmware-tsx.com/download.php?asset_id=39
Thanks for the links. But i think i may not have explained myself properly.
I'm not looking to find out the overhead/impact on the VMs performance vs native/physical performance.
But how much CPU resource the SC and vmkernel need to run ESX. I understand that this is going to be dependant on the number and type of VMS running on the box, but is there any equation/info about this.
For example in terms of memory resources used by the ESX it is the amount of memory assigned to SC, plus memory used by the VMkernel (which is dependant on the number and size of drivers loaded and the number, size(mem), type (SMP, 32bit,64bit) of VMs running)
In ESX 2.5 I think the number was somewhere around 92% efficiency...so about 8% overhead for ESX (and possibly 83% efficiency for GSX)
Not sure what ESX 3 is..haven't seen anything like that mentioned in the docs
I am also struggling with the same question that you had posted on how I can measure quantitatively the total amount of platform time that my Hypervisor is consuming. Were you able to find out an answer for this question?