Re: [Xen-devel] [PATCH RESEND 05/12] xen: numa-sched: make space for per-vcpu node-affinity

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.11.13 at 18:16, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> This would mean the toolstack either assuming, when someone calls 
> vcpu_set_node_affinity, that soft_affinity == numa_affinity, or keeping 
> its own copy of numa_affinity for each vcpu around somewhere.

Question is how reasonable it is for the tool stack to keep such
information around and up-to-date, in particular considering
node/CPU/memory hotplug. If that's reasonable, then your
proposal below seems to be the right one architecturally, i.e.
keeping policy entirely at the tools level.

Jan

> Alternately, we could punt on the NUMA interface altogether for this 
> patch series, and wait until we can implement a full-featured vNUMA 
> interface.  That is, for this patch series, make an interface just do 
> NUMA affinity for memory, and "soft" and "hard" affinities for vcpus. 
> Then in another series (perhaps one shortly after that), implement a 
> full vNUMA interface, with vcpus mapped to vNUMA nodes, and vNUMA nodes 
> mapped to pNUMA nodes -- with the toolstack implementing all of this 
> just using the soft affinities.
> 
> Thoughts?
> 
>   -George




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