On Fri, Feb 07, 2025 at 09:40:49PM +0100, Andrea Righi wrote: > +/** > + * for_each_numa_node - iterate over nodes at increasing distances from a > + * given starting node. > + * @node: the iteration variable and the starting node. > + * @unvisited: a nodemask to keep track of the unvisited nodes. > + * @state: state of NUMA nodes to iterate. > + * > + * 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. > + * > + * The difference between for_each_node() and for_each_numa_node() 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_numa_node(node, unvisited, state) \ > + for (int start = (node), \ > + node = numa_nearest_nodemask((start), (state), &(unvisited)); \ > + node < MAX_NUMNODES; \ > + node_clear(node, (unvisited)), \ > + node = numa_nearest_nodemask((start), (state), &(unvisited))) > + > /** > * for_each_numa_hop_mask - iterate over cpumasks of increasing NUMA distance > * from a given node. Bikeshedding: Maybe this has already been argued back and forth but I find the distinction between for_each_node() and for_each_numa_node() way too subtle. I wouldn't suspect that they are doing different things when glancing through their usages in isolation. Can we add *something* to the name that indicates that this is iteration by distance? The next one uses "hop" which is fine, "_by_dist" can be fine too, or even "_from_nearest". I don't really care which but let's make the name clearly signal what it's doing. Thanks. -- tejun
