diff options
Diffstat (limited to 'include/linux/topology.h')
| -rw-r--r-- | include/linux/topology.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/topology.h b/include/linux/topology.h index 52f5850730b3..a1815f4395ab 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -262,6 +262,36 @@ sched_numa_hop_mask(unsigned int node, unsigned int hops) #endif /* CONFIG_NUMA */ /** + * for_each_node_numadist() - iterate over nodes in increasing distance + * order, starting from a given node + * @node: the iteration variable and the starting node. + * @unvisited: a nodemask to keep track of the unvisited nodes. + * + * This macro iterates over NUMA node IDs in increasing distance from the + * starting @node and yields MAX_NUMNODES when all the nodes have been + * visited. + * + * Note that by the time the loop completes, the @unvisited nodemask will + * be fully cleared, unless the loop exits early. + * + * The difference between for_each_node() and for_each_node_numadist() is + * that the former allows to iterate over nodes in numerical order, whereas + * the latter iterates over nodes in increasing order of distance. + * + * This complexity of this iterator is O(N^2), where N represents the + * number of nodes, as each iteration involves scanning all nodes to + * find the one with the shortest distance. + * + * Requires rcu_lock to be held. + */ +#define for_each_node_numadist(node, unvisited) \ + for (int __start = (node), \ + (node) = nearest_node_nodemask((__start), &(unvisited)); \ + (node) < MAX_NUMNODES; \ + node_clear((node), (unvisited)), \ + (node) = nearest_node_nodemask((__start), &(unvisited))) + +/** * for_each_numa_hop_mask - iterate over cpumasks of increasing NUMA distance * from a given node. * @mask: the iteration variable. |