Re: [Xen-devel] [PATCH 04 of 11 v4] xen: sched_credit: let the scheduler know about node-affinity

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 15/03/13 02:30, Dario Faggioli wrote:
> As vcpu-affinity tells where VCPUs must run, node-affinity tells
> where they prefer to. While respecting vcpu-affinity remains mandatory,
> node-affinity is not that strict, it only expresses a preference,
> although honouring it will bring significant performance benefits
> (especially as compared to not having any affinity at all).
>
> This change modifies the VCPUs load balancing algorithm (for the
> credit scheduler only), introducing a two steps logic. During the
> first step, we use both the vcpu-affinity and the node-affinity
> masks (by looking at their intersection). The aim is giving precedence
> to the PCPUs where the domain prefers to run, as expressed by its
> node-affinity (with the intersection with the vcpu-afinity being
> necessary in order to avoid running a VCPU where it never should).
> If that fails in finding a valid PCPU, the node-affinity is just
> ignored and, in the second step, we fall back to using cpu-affinity
> only.
>
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> Acked-by: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>


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