Query on idle VM on a Windows Host.


jimbo45

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Hi folks
Just a query to those more experienced with Windows internals etc. No problem to solve -- just would like some knowlege.

If you have a VM which is in an idle state on a Windows host - you need to gain focus in the VM to be able to use it again.

What I want to know is this purely a hardware interrupt e.g keyboard, mouse, touch screen etc or is there a basic process that cycles continuously checking on any device interrupts. It seems to me that Vmware workstation / player and vbox seem to run at higher cpu load than HYPER-V or KVM / QEMU when the VM doesnt have any activity.

Any ideas. !!!! Just curious as I don't use vmware or oracle's vbox.

cheers
jimbo
 

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Hi folks
Just a query to those more experienced with Windows internals etc. No problem to solve -- just would like some knowlege.

If you have a VM which is in an idle state on a Windows host - you need to gain focus in the VM to be able to use it again.

What I want to know is this purely a hardware interrupt e.g keyboard, mouse, touch screen etc or is there a basic process that cycles continuously checking on any device interrupts. It seems to me that Vmware workstation / player and vbox seem to run at higher cpu load than HYPER-V or KVM / QEMU when the VM doesnt have any activity.

Any ideas. !!!! Just curious as I don't use vmware or oracle's vbox.

cheers
jimbo
I think it all comes down to definition of idle. No pc is ever truly idle - always background tasks going on.

A pc is only ever idle in sleep mode, and even then a very low power state.

If using Hyper-V, as a type 1 hypervisor, it is not always appreciated that the host is in really a virtual machine as well.

The Hypervisor fully segregates each vm and the host.

The hypervisor obviously dynamically assigns shared CPU/hardware resources to each vm.

In essence each vm is being run intermittently - kind of like toggling sleep on or off very fast.

Of course, each vm is assigned resources fast enough so from a human perspective, it looks like it is running continuously.

I may be oversimplying things but obviously you need to have focus to enter data, use mouse etc.
 

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    Yep, Laptop has one.
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I think it all comes down to definition of idle. No pc is ever truly idle - always background tasks going on.

A pc is only ever idle in sleep mode, and even then a very low power state.

If using Hyper-V, as a type 1 hypervisor, it is not always appreciated that the host is in really a virtual machine as well.

The Hypervisor fully segregates each vm and the host.

The hypervisor obviously dynamically assigns shared CPU/hardware resources to each vm.

In essence each vm is being run intermittently - kind of like toggling sleep on or off very fast.

Of course, each vm is assigned resources fast enough so from a human perspective, it looks like it is running continuously.

I may be oversimplying things but obviously you need to have focus to enter data, use mouse etc.
Sounds good -- thanks

but one can also put a computer into total sleep mode where a hardware interrupt wakes it up, restarts the task / dispatch manager etc.

I don't know if you ever worked on the old IBM mainframe series of 1970's e.g MVS/SP but that's how they did it. (You can emulate the old IBM MVS/SP OS on a PC -- use hercules emulator etc) -- amazing though that a modest laptop PC has more processing power and I/O storage than a massive 303X IBM Mainframe with water cooling and huge physical disc drives.

I agree type 1 Hypervisors should be far more efficient which in practice shows they are.

For Windows VM's HYPER-V can be truly excellent however the basic Windows OS doesn't IMHO seem to be geared to running VM's other than grudgingly. Windows server editions particularly the latest 2021/2022 LTSC versions with HYPER-V runs rings around the basic Windows platform whether Home or Pro editions. - Can't say anything about Enterprise or workstation editions as I haven't tested those yet and don't have a license.

Cheers
jimbo
 

My Computer

System One

  • OS
    Windows XP,7,10,11 Linux Arch Linux
    Computer type
    PC/Desktop
    CPU
    2 X Intel i7
Sounds good -- thanks

but one can also put a computer into total sleep mode where a hardware interrupt wakes it up, restarts the task / dispatch manager etc.

I don't know if you ever worked on the old IBM mainframe series of 1970's e.g MVS/SP but that's how they did it. (You can emulate the old IBM MVS/SP OS on a PC -- use hercules emulator etc) -- amazing though that a modest laptop PC has more processing power and I/O storage than a massive 303X IBM Mainframe with water cooling and huge physical disc drives.

I agree type 1 Hypervisors should be far more efficient which in practice shows they are.

For Windows VM's HYPER-V can be truly excellent however the basic Windows OS doesn't IMHO seem to be geared to running VM's other than grudgingly. Windows server editions particularly the latest 2021/2022 LTSC versions with HYPER-V runs rings around the basic Windows platform whether Home or Pro editions. - Can't say anything about Enterprise or workstation editions as I haven't tested those yet and don't have a license.

Cheers
jimbo
It is only Home that can only be run in basic mode as it does not have an rdp server but even that can "be got round".

You cannot put vms into sleep. I was only using that as an analogy.

Re. IBMs - been there, done that, lost the T shirt years ago.
 

My Computer

System One

  • OS
    Windows 10 Pro + others in VHDs
    Computer type
    Laptop
    Manufacturer/Model
    ASUS Vivobook 14
    CPU
    I7
    Motherboard
    Yep, Laptop has one.
    Memory
    16 GB
    Graphics Card(s)
    Integrated Intel Iris XE
    Sound Card
    Realtek built in
    Monitor(s) Displays
    N/A
    Screen Resolution
    1920x1080
    Hard Drives
    1 TB Optane NVME SSD, 1 TB NVME SSD
    PSU
    Yep, got one
    Case
    Yep, got one
    Cooling
    Stella Artois
    Keyboard
    Built in
    Mouse
    Bluetooth , wired
    Internet Speed
    72 Mb/s :-(
    Browser
    Edge mostly
    Antivirus
    Defender
    Other Info
    TPM 2.0
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