Hi Srikar,
On Thu, Apr 15, 2021 at 05:39:32PM +0530, Srikar Dronamraju wrote:
[..snip..]
> @@ -1485,12 +1486,36 @@ static void add_cpu_to_masks(int cpu)
> add_cpu_to_smallcore_masks(cpu);
>
> /* In CPU-hotplug path, hence use GFP_ATOMIC */
> - alloc_cpumask_var_node(&mask, GFP_ATOMIC, cpu_to_node(cpu));
> + ret = alloc_cpumask_var_node(&mask, GFP_ATOMIC, cpu_to_node(cpu));
> update_mask_by_l2(cpu, &mask);
>
> if (has_coregroup_support())
> update_coregroup_mask(cpu, &mask);
>
> + if (chip_id == -1 || !ret) {
> + cpumask_copy(per_cpu(cpu_core_map, cpu), cpu_cpu_mask(cpu));
> + goto out;
> + }
> +
> + if (shared_caches)
> + submask_fn = cpu_l2_cache_mask;
> +
> + /* Update core_mask with all the CPUs that are part of submask */
> + or_cpumasks_related(cpu, cpu, submask_fn, cpu_core_mask);
>
If coregroups exist, we can add the cpus of the coregroup to the
cpu_core_mask thereby reducing the scope of the for_each_cpu() search
below. This will still cut down the time on Baremetal systems
supporting coregroups.
> + /* Skip all CPUs already part of current CPU core mask */
> + cpumask_andnot(mask, cpu_online_mask, cpu_core_mask(cpu));
> +
> + for_each_cpu(i, mask) {
> + if (chip_id == cpu_to_chip_id(i)) {
> + or_cpumasks_related(cpu, i, submask_fn, cpu_core_mask);
> + cpumask_andnot(mask, mask, submask_fn(i));
> + } else {
> + cpumask_andnot(mask, mask, cpu_core_mask(i));
> + }
> + }
> +
> +out:
> free_cpumask_var(mask);
> }
>
> --
> 2.25.1
>
