# Re: \[PATCH 2/3\] powerpc/numa: Populate distance map correctly

- From: Valentin Schneider \<hidden\>
- Date: 2021-05-24 14:16:37 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2021/05/1389455
- Thread: https://ratatoskr.run/linuxppc-dev/2021/05/1386294/t.md

```text
On 20/05/21 21:14, Srikar Dronamraju wrote:
> +int arch_populate_distance_map(unsigned long *distance_map)
> +{
> +	int i;
> +	int distance = LOCAL_DISTANCE;
> +
> +	bitmap_set(distance_map, distance, 1);
> +
> +	if (!form1_affinity) {
> +		bitmap_set(distance_map, REMOTE_DISTANCE, 1);
> +		return 0;
> +	}
> +
> +	for (i = 0; i < distance_ref_points_depth; i++) {
> +		distance *= 2;
> +		bitmap_set(distance_map, distance, 1);

Do you have guarantees your distance values will always be in the form of

  LOCAL_DISTANCE * 2^i

because that certainly isn't true for x86/arm64.

> +	}
> +	return 0;
> +}
> +
>  /*
>   * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
>   * info is found.
> --
> 2.27.0
```