* Valentin Schneider [off-list ref] [2021-05-24 15:16:22]:

On 20/05/21 21:14, Srikar Dronamraju wrote:

quoted

+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.

This is true till now. It don't think that's going to change anytime soon, but
we never know what lies ahead.

For all practical purposes, (unless a newer, shinier property is proposed,)
distance_ref_points_depth is going to give us the unique distances.

quoted

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

-- 
Thanks and Regards
Srikar Dronamraju