Re: [Xen-devel] [PATCH] xen/sched: Re-position the domain_update_node_affinity() call during vcpu construction

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrew,

On 06/09/18 15:01, Andrew Cooper wrote:
> alloc_vcpu()'s call to domain_update_node_affinity() has existed for a decade,
> but its effort is mostly wasted.
>
> alloc_vcpu() is called in a loop for each vcpu, bringing them into existence.
> The values of the affinity masks are still default, which is allcpus in
> general, or a processor singleton for pinned domains.
>
> Furthermore, domain_update_node_affinity() itself loops over all vcpus
> accumulating the masks, making it a scalability concern with large numbers of
> vcpus.
>
> Move it to be called once after all vcpus are constructed, which has the same
> net effect, but with fewer intermediate memory allocations and less cpumask
> arithmetic.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
For Arm bits:

Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

--
Julien Grall

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