On 10/12/2014 10:30 AM, Peter Zijlstra wrote:
On Wed, Oct 08, 2014 at 03:37:27PM -0400, [email protected] wrote:+static void init_numa_topology_type(void) +{ + int a, b, c, n; + + n = sched_domains_numa_levels; + + if (n <= 1) + sched_numa_topology_type = NUMA_DIRECT; + + for_each_online_node(a) { + for_each_online_node(b) { + /* Find two nodes furthest removed from each other. */ + if (node_hops(a, b) < n) + continue; + + /* Is there an intermediary node between a and b? */ + for_each_online_node(c) { + if (node_hops(a, c) < n && + node_hops(b, c) < n) { + sched_numa_topology_type = + NUMA_GLUELESS_MESH; + return; + } + } + + sched_numa_topology_type = NUMA_BACKPLANE; + return; + } + } +}We can find max_distance nodes in sched_init_numa(), right? Could we not avoid this second iteration?
It's not about finding the max distance, but about finding two nodes that are at the maximum distance from each other, in order to see whether there are intermediate nodes between the two. I suppose we could just directly access the node_hops tables to get two nodes that are the furthest away from each other, but I suspect that searching that table directly will not make a significant difference compared with using the macros above. Especially since this code is only ever run once at system bootup. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
