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Re: [Xen-users] Q: CPU usage in Dom0



People have talked about different things in this thread so
I thought I should clarify the options available to set CPU
affinity to various VCPUs for both dom0 and domUs:

The config file variable "cpus" defines a cpu affinity mask
which applies to all VCPUs of a domain. So all VCPUs for that
domain will be assigned the same CPU mask. I suggest you have
at least as many CPUs set in the mask as you have VCPUs.

You can also set this per VCPU after a domU has started using
the "xm vcpu-pin" command. In 3.0.3 and unstable, you can
use vcpu-pin on dom0 as well.

Also in 3.0.3 and unstable, you can use the Xen boot argument
"dom0_vcpus_pin" to pin VCPU N or dom0 on physical CPU N.

Also to note is that the credit scheduler is already moving
things around for you to keep runnable VCPUs running. No
physical CPU will sit idle while there is a runnable VCPU,
dom0 or domU.

Cheers,
Emmanuel

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