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

On 11/05/2013 03:11 PM, Jan Beulich wrote:
On 05.11.13 at 16:03, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
On 11/05/2013 02:52 PM, Jan Beulich wrote:
On 05.11.13 at 15:35, Dario Faggioli <dario.faggioli@xxxxxxxxxx> wrote:
@@ -197,6 +199,13 @@ struct vcpu
       /* Used to restore affinity across S3. */
       cpumask_var_t    cpu_affinity_saved;

+    /*
+     * Bitmask of CPUs on which this VCPU prefers to run. For both this
+     * and auto_node_affinity access is serialized against
+     * v->domain->node_affinity_lock.
+     */
+    cpumask_var_t    node_affinity;

This all looks quite sensible, except for the naming here: We
already have a node_affinity field in struct domain, having a
meaning that one can expect with this name. So you break
both consistency and the rule of least surprise here. How
about just "preferred_cpus"?

Actually, would it make more sense to remove node_affinity from the
domain struct, and have the tools manually set the node_affinity for the
various vcpus if the user attempts to set the "domain numa affinity"?

Quite likely, yes. But that doesn't mean that the name can be kept
as is.

Right, I see what you're saying -- in the domain struct, node_affinity is a mask of nodes, but here it's being used as a mask of cpus. Yes, that needs to change.


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