Re: [Xen-devel] [DOC RFC] Heterogeneous Multi Processing Support in Xen

[Juergen Gross <jgross@xxxxxxxx>]

On 07/12/16 19:29, Dario Faggioli wrote:
> Setting and getting the CPU class of a vCPU will happen via two new
> hypercalls:
> 
> * `XEN_DOMCTL_setvcpuclass`
> * `XEN_DOMCTL_setvcpuclass`

XEN_DOMCTL_getvcpuclass

> ### Phase 2
> 
> Inside Xen, the various schedulers will be modified to deal internally with
> the fact that vCPUs can only run on pCPUs from the class(es) they are
> associated with. This allows for more efficient implementation, and paves
> the way for enabling more intelligent logic (e.g., for minimizing power
> consumption) in *phase 3*.
> 
> Calling `libxl_set_vcpuaffinity()` from `xl` / libxl is therefore no longer
> necessary and will be avoided (i.e., only `libxl_set_vcpuclass()` will be
> called).

Any idea how to avoid problems in the schedulers related to vcpus with
different weights? Remember, weights and pinning don't go well together,
that was the main reason for inventing cpupools. You should at least
name that problem. In case of vcpus being capable to run on pcpus of
more than one class this problem might surface again.


Juergen


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