Re: [PATCH] numa: select nodes by cpu affinity

[Andrew Jones <drjones@redhat.com>]

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On 08/04/2010 04:38 PM, Keir Fraser wrote:
> Changeset 21913 in http://xenbits.xen.org/staging/xen-unstable.hg
> 
>  -- Keir
> 
> On 04/08/2010 13:38, "Keir Fraser" <keir.fraser@eu.citrix.com> wrote:
> 
>> Good idea. I will take this and rework it a bit and check it in.
>>
>>  Thanks,
>>  Keir
>>
>> On 04/08/2010 13:04, "Andrew Jones" <drjones@redhat.com> wrote:
>

I also considered managing the nodemask as new domain state, as you do,
as it may come in useful elsewhere, but my principle of least patch
instincts kept me from doing it...

I'm not sure about keeping track of the last_alloc_node and then always
avoiding it (at least when there's more than 1 node) by checking it
last. I liked the way it worked before, favoring the node of the
currently running processor, but I don't have any perf numbers to know
what would be better.

I've attached a patch with a couple minor tweaks. It removes the
unnecessary node clearing from an empty initialized nodemask, and also
moves a couple of domain_update_node_affinity() calls outside
for_each_vcpu loops.

Andrew

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diff --git a/xen/common/domain.c b/xen/common/domain.c
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -358,12 +358,8 @@
         cpus_or(cpumask, cpumask, v->cpu_affinity);
 
     for_each_online_node ( node )
-    {
         if ( cpus_intersects(node_to_cpumask(node), cpumask) )
             node_set(node, nodemask);
-        else
-            node_clear(node, nodemask);
-    }
 
     d->node_affinity = nodemask;
     spin_unlock(&d->node_affinity_lock);
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -270,13 +270,13 @@
         SCHED_OP(VCPU2OP(v), destroy_vcpu, v);
 
         cpus_setall(v->cpu_affinity);
-        domain_update_node_affinity(d);
         v->processor = new_p;
         v->sched_priv = vcpu_priv[v->vcpu_id];
         evtchn_move_pirqs(v);
 
         new_p = cycle_cpu(new_p, c->cpu_valid);
     }
+    domain_update_node_affinity(d);
 
     d->cpupool = c;
     SCHED_OP(DOM2OP(d), free_domdata, d->sched_priv);
@@ -478,7 +478,6 @@
                 printk("Breaking vcpu affinity for domain %d vcpu %d\n",
                         v->domain->domain_id, v->vcpu_id);
                 cpus_setall(v->cpu_affinity);
-                domain_update_node_affinity(d);
             }
 
             if ( v->processor == cpu )
@@ -501,6 +500,7 @@
             if ( v->processor == cpu )
                 ret = -EAGAIN;
         }
+        domain_update_node_affinity(d);
     }
     return ret;
 }

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