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  1. #1
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    Hyper-V and Windows Task Manager

    Hello,

    I have Windows Server 2012 R2 running on a 4 core machine. I have Hyper-V enabled and I created a VM with 2 CPU's. This VM is now running a video conversion, which (of course) uses 100% CPU on this VM. So I think it is reasonable to expect that the host is running at least 50% CPU load.

    However, Task Manager on the host only shows a load of 2%! It seems that Task manager ignores the load from VM's. I find this misleading, to say the least.

    Has anybody seen this too?

    TIA,

    Bart

  2. #2
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    The host controls how much CPU it allocates to the VM. You should be able to adjust it in the config of the VM.

    cheers, Paul

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    Thanks. But the problem is not that I am or am not able to control the CPU allocation.

    The problem is that Task Manager on the host seems to ignore or hide the CPU usage by VM's. It says 2% CPU load while I am sure that one VM takes at least 50%.

    Bart

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    How can you be sure if Windows doesn't tell you?

    cheers, Paul

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    Quote Originally Posted by Paul T View Post
    How can you be sure if Windows doesn't tell you?

    cheers, Paul
    Well, my reasoning is the following:

    - I am pretty sure that the VM is running on this very same host, not on another system in my network
    - It is doing some real work. I can see the results: converted video files.
    - On the VM, Task Manager reports 99% CPU utilization, using 2 virtual CPU's

    Still, the host Task Manager reports only 2% utilization, which corresponds to sitting idle.

    Bart

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    I suggest trying Process Explorer from Sysinternals. This is as a way of trying to validate that Task Manager data (or validate your thesis that the VMs are excluded).

    The other possibility is that these Hyper-V VMs are not just fractional cores, but are only getting a tiny percentage of those cores maximum capacity (i.e. ~2%). This too would explain your current result, though these would not seem to be sensible defaults for a VM setup.

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    Quote Originally Posted by BHarder View Post
    I suggest trying Process Explorer from Sysinternals. This is as a way of trying to validate that Task Manager data (or validate your thesis that the VMs are excluded).

    The other possibility is that these Hyper-V VMs are not just fractional cores, but are only getting a tiny percentage of those cores maximum capacity (i.e. ~2%). This too would explain your current result, though these would not seem to be sensible defaults for a VM setup.
    Thanks, but no. Process explorere also reports 98% idle, in other words, it does not see the load of the VM. This VM is still happily pounding on the video conversion, and it does produce output, so I do not believe it gets only a tiny fraction of the available resources.

    When I run a video conversion at the same time at the host itself, it says that it takes 100% CPU, but I do not know if the performance would be the same if the VM were not running. Difficult to say, because one video conversion pass takes several hours.

    TANSTAAFL(*), so where do the resources come and go?

    Bart

    (*) There ain't no such thing as a free lunch.

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