Re: [PATCH RFC] cpumask: Randomly distribute the tasks within affinity mask

[Josh Don]

Hey Peter,

> +static struct cpumask *root_domain_allowed(struct cpumask *newmask,
> +                                          struct cpumask *scratch,
> +                                          struct cpumask *valid)
> +{
> +       struct root_domain *rd;
> +       struct cpumask *mask;
> +       struct rq *rq;
> +
> +       int first = cpumask_first_and(newmask, valid);
> +       if (first >= nr_cpu_ids)
> +               return NULL;

This picks the first arbitrarily, but isn't it possible for the mask
to span both isolated and non-isolated cpus? In which case, the rest
of this just boils down to chance (ie. whatever the span happens to be
for the first cpu here)?