Re: [Xen-devel] [PATCH RESEND 01/12] xen: numa-sched: leave node-affinity alone if not in "auto" mode

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 11/05/2013 02:34 PM, Dario Faggioli wrote:
> If the domain's NUMA node-affinity is being specified by the
> user/toolstack (instead of being automatically computed by Xen),
> we really should stick to that. This means domain_update_node_affinity()
> is wrong when it filters out some stuff from there even in "!auto"
> mode.
>
> This commit fixes that. Of course, this does not mean node-affinity
> is always honoured (e.g., a vcpu won't run on a pcpu of a different
> cpupool) but the necessary logic for taking into account all the
> possible situations lives in the scheduler code, where it belongs.
>
> What could happen without this change is that, under certain
> circumstances, the node-affinity of a domain may change when the
> user modifies the vcpu-affinity of the domain's vcpus. This, even
> if probably not a real bug, is at least something the user does
> not expect, so let's avoid it.
>
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> ---
> This has been submitted already as a single patch on its own.
> Since this series needs the change done here, just include it
> in here, instead of pinging the original submission and deferring
> posting this series.
Just reiterating what I said on the last send... this one is independent 
and can be checked in whenever you're ready.
 -George

> ---
>   xen/common/domain.c |   28 +++++++++-------------------
>   1 file changed, 9 insertions(+), 19 deletions(-)
>
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 5999779..af31ab4 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -352,7 +352,6 @@ void domain_update_node_affinity(struct domain *d)
>       cpumask_var_t cpumask;
>       cpumask_var_t online_affinity;
>       const cpumask_t *online;
> -    nodemask_t nodemask = NODE_MASK_NONE;
>       struct vcpu *v;
>       unsigned int node;
>
> @@ -374,28 +373,19 @@ void domain_update_node_affinity(struct domain *d)
>           cpumask_or(cpumask, cpumask, online_affinity);
>       }
>
> +    /*
> +     * If d->auto_node_affinity is true, the domain's node-affinity mask
> +     * (d->node_affinity) is automaically computed from all the domain's
> +     * vcpus' vcpu-affinity masks (the union of which we have just built
> +     * above in cpumask). OTOH, if d->auto_node_affinity is false, we
> +     * must leave the node-affinity of the domain alone.
> +     */
>       if ( d->auto_node_affinity )
>       {
> -        /* Node-affinity is automaically computed from all vcpu-affinities */
> +        nodes_clear(d->node_affinity);
>           for_each_online_node ( node )
>               if ( cpumask_intersects(&node_to_cpumask(node), cpumask) )
> -                node_set(node, nodemask);
> -
> -        d->node_affinity = nodemask;
> -    }
> -    else
> -    {
> -        /* Node-affinity is provided by someone else, just filter out cpus
> -         * that are either offline or not in the affinity of any vcpus. */
> -        nodemask = d->node_affinity;
> -        for_each_node_mask ( node, d->node_affinity )
> -            if ( !cpumask_intersects(&node_to_cpumask(node), cpumask) )
> -                node_clear(node, nodemask);//d->node_affinity);
> -
> -        /* Avoid loosing track of node-affinity because of a bad
> -         * vcpu-affinity has been specified. */
> -        if ( !nodes_empty(nodemask) )
> -            d->node_affinity = nodemask;
> +                node_set(node, d->node_affinity);
>       }
>
>       sched_set_node_affinity(d, &d->node_affinity);

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