restrict: reorder children when modified

If we first bit of the cpuset of some children increases during restrict(),
these children might become out-of-order.

Example:
  Core P#0
    PU P#0
    PU P#2
  Core P#1
    PU P#1
    PU P#3
If restrict() removes PU P#0, Cores must be swapped because of
their updated cpusets.

In v2.x, reordering might also be needed for memory children
but it's so unlikely and harmless that we don't do it yet.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

hwloc/topology.c

@@ -3683,8 +3683,13 @@ restrict_object_by_cpuset(hwloc_topology_t topology, unsigned long flags, hwloc_
   if (modified) {
     for_each_child_safe(child, obj, pchild)
       restrict_object_by_cpuset(topology, flags, pchild, droppedcpuset, droppednodeset);
+    /* if some hwloc_bitmap_first(child->complete_cpuset) changed, children might need to be reordered */
+    hwloc__reorder_children(obj);
+
     for_each_memory_child_safe(child, obj, pchild)
       restrict_object_by_cpuset(topology, flags, pchild, droppedcpuset, droppednodeset);
+    /* local NUMA nodes have the same cpusets, no need to reorder them */
+
     /* Nothing to restrict under I/O or Misc */
   }
 
@@ -3744,8 +3749,15 @@ restrict_object_by_nodeset(hwloc_topology_t topology, unsigned long flags, hwloc
   if (modified) {
     for_each_child_safe(child, obj, pchild)
       restrict_object_by_nodeset(topology, flags, pchild, droppedcpuset, droppednodeset);
+    if (flags & HWLOC_RESTRICT_FLAG_REMOVE_MEMLESS)
+      /* cpuset may have changed above where some NUMA nodes were removed.
+       * if some hwloc_bitmap_first(child->complete_cpuset) changed, children might need to be reordered */
+      hwloc__reorder_children(obj);
+
     for_each_memory_child_safe(child, obj, pchild)
       restrict_object_by_nodeset(topology, flags, pchild, droppedcpuset, droppednodeset);
+    /* FIXME: we may have to reorder CPU-less groups of NUMA nodes if some of their nodes were removed */
+
     /* Nothing to restrict under I/O or Misc */
   }