Box293
Enthusiast
Enthusiast

Windows Task Manager CPU usage vs VI Performance Monitors

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This is probably a very obvious question but there is some debate about this with my co-workers.

When I view the Windows Task Manager it shows me the CPU history. Is this scale an accurate representation of the entire CPU on the ESX host or is it a representation of how much MHZ the ESX host is handing the guest at that point in time?

IE I have an Intel Xeon 3.0Ghz CPU in my virtual machine, when it is at 60% in the cpu history of task manager is that an accurate representation of 60% of the 3.0Ghz processor?

VCP3 & VCP4 32846 VSP4 VTSP4
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VirtualNoitall
Virtuoso
Virtuoso

Hello,

I would not use task manager as a definitive source for CPU performance for two reasons:

1) time keeping: http://www.vmware.com/pdf/vmware_timekeeping.pdf

2)each virtual processor, in each vm ,will only get a share of the total CPU available and can even be scheduled onto different processors ( but only one at a time per vcpu ) VI provides tools for tracking CPU usage on vms. I would use those numbers over what you can collect inside a vm.

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kalex
Enthusiast
Enthusiast

Its the representation of how much ESX host assigns to your Guest OS.

spex
Expert
Expert

It's dynamic I would guess - 2 examples:

ESX Host Idle:

CPU belongs nearly exclusive to a vm: 60% of Taskmanager should be equal 60% of phys. CPU

ESX Host heavily loaded and vm has low shares:

VM has a lot of read time, but is not scheduled. Taskmanager shows 100% but VM nearly gets no CPU. (you can make this lost cpu cycles visible with the optional desched process from vmware tools)

Regards Spex

VirtualNoitall
Virtuoso
Virtuoso

Hello,

I would not use task manager as a definitive source for CPU performance for two reasons:

1) time keeping: http://www.vmware.com/pdf/vmware_timekeeping.pdf

2)each virtual processor, in each vm ,will only get a share of the total CPU available and can even be scheduled onto different processors ( but only one at a time per vcpu ) VI provides tools for tracking CPU usage on vms. I would use those numbers over what you can collect inside a vm.

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Box293
Enthusiast
Enthusiast

Thanks for the answers. After reading the time keeping article I'll defiantly go through and disable windows time and configure VMware tools to do the time sync stuff.

I noticed there was some mention of shares, is there any documentation on this as I haven't really grasped this concept yet.

VCP3 & VCP4 32846 VSP4 VTSP4
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kalex
Enthusiast
Enthusiast
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Box293
Enthusiast
Enthusiast

Cheers, lots of good information in here.

Thanks

VCP3 & VCP4 32846 VSP4 VTSP4
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