[Query] VM CPU scheduling

[Query] VM CPU scheduling

[Ramesh B]

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Hi All,

I started recently using QEMU for OS virtualization.
Want to know/understand about scheduling.

Environment:
Host OS: Ubuntu 18.4 + KVM enable
QEMU: 4.2
Workstation/Desktop: x86_64

Would like to understand,

1. How CPU scheduling works.
2. Tools/commands to monitor.
3. Tuning parameter/API

Could you please suggest good reference or books or pointers.

Thanks,
Babu

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Re: [Query] VM CPU scheduling

[Stefan Hajnoczi]

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On Sun, May 03, 2020 at 05:04:10PM +0530, Ramesh B wrote:
> Hi All,
> 
> I started recently using QEMU for OS virtualization.
> Want to know/understand about scheduling.
> 
> Environment:
> Host OS: Ubuntu 18.4 + KVM enable
> QEMU: 4.2
> Workstation/Desktop: x86_64
> 
> Would like to understand,
> 
> 1. How CPU scheduling works.
> 2. Tools/commands to monitor.
> 3. Tuning parameter/API
> 
> Could you please suggest good reference or books or pointers.

Each guest CPU (vCPU) is a QEMU thread. The host scheduler decides when
and where it runs.

You can various features that influence scheduling like cgroups, CPU
affinity, etc to control vCPU scheduling. But the main thing to
understand is that vCPUs are just threads running on the host Linux
scheduler. All the usual tools are at your disposal.

Libvirt also provides support for configuring CPU scheduling/resource
control.

Stefan

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Re: [Query] VM CPU scheduling

[Lukas Straub]

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On Sun, 3 May 2020 17:04:10 +0530
Ramesh B <rmsh.b4@gmail.com> wrote:

> Hi All,
> 
> I started recently using QEMU for OS virtualization.
> Want to know/understand about scheduling.
> 
> Environment:
> Host OS: Ubuntu 18.4 + KVM enable
> QEMU: 4.2
> Workstation/Desktop: x86_64
> 
> Would like to understand,
> 
> 1. How CPU scheduling works.
> 2. Tools/commands to monitor.
> 3. Tuning parameter/API
> 
> Could you please suggest good reference or books or pointers.
> 
> Thanks,
> Babu

Hi,
With qemu/KVM the VM just runs as a normal process under linux, so you can use all the tools and interfaces to manage processes for qemu as well.
Keywords: top, nice, cgroups, cpuset, numactl

Regards,
Lukas Straub

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