On Fri, Mar 14, 2025 at 08:21:49AM -1000, Tejun Heo wrote:
> Hello,
>
> On Fri, Mar 14, 2025 at 10:45:35AM +0100, Andrea Righi wrote:
> ...
> > - if (p->nr_cpus_allowed >= num_possible_cpus()) {
> > - if (static_branch_maybe(CONFIG_NUMA, &scx_selcpu_topo_numa))
> > - numa_cpus = numa_span(prev_cpu);
> > -
> > - if (static_branch_maybe(CONFIG_SCHED_MC, &scx_selcpu_topo_llc))
> > - llc_cpus = llc_span(prev_cpu);
> > + if (static_branch_maybe(CONFIG_NUMA, &scx_selcpu_topo_numa)) {
> > + struct cpumask *cpus = numa_span(prev_cpu);
> > +
> > + if (cpus && !cpumask_equal(cpus, p->cpus_ptr)) {
> > + if (cpumask_subset(cpus, p->cpus_ptr)) {
> > + numa_cpus = cpus;
> > + } else {
> > + numa_cpus = this_cpu_cpumask_var_ptr(local_numa_idle_cpumask);
> > + if (!cpumask_and(numa_cpus, cpus, p->cpus_ptr))
> > + numa_cpus = NULL;
> > + }
> > + }
> > + }
> > + if (static_branch_maybe(CONFIG_SCHED_MC, &scx_selcpu_topo_llc)) {
> > + struct cpumask *cpus = llc_span(prev_cpu);
> > +
> > + if (cpus && !cpumask_equal(cpus, p->cpus_ptr)) {
> > + if (cpumask_subset(cpus, p->cpus_ptr)) {
> > + llc_cpus = cpus;
> > + } else {
> > + llc_cpus = this_cpu_cpumask_var_ptr(local_llc_idle_cpumask);
> > + if (!cpumask_and(llc_cpus, cpus, p->cpus_ptr))
> > + llc_cpus = NULL;
> > + }
> > + }
> >
>
> Wouldn't it still make sense to special case p->nr_cpus_allowed >=
> num_possible_cpus()? That'd be vast majority of cases and we can skip all
> the cpumask comparisons for them.
Yeah, that's probably a good idea, I'll re-add that in the next version.
Thanks,
-Andrea
