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

[Dario Faggioli <dfaggioli@xxxxxxxx>]

On Thu, 2018-09-06 at 15:01 +0100, 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>
>
Reviewed-by: Dario Faggioli <dfaggioli@xxxxxxxx>

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
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Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Software Engineer @ SUSE https://www.suse.com/

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