diff options
| -rw-r--r-- | kernel/sched/core.c | 53 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 6 |
2 files changed, 59 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4007595f87e4..cde848149dd6 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6128,6 +6128,7 @@ static void claim_allocations(int cpu, struct sched_domain *sd) #ifdef CONFIG_NUMA static int sched_domains_numa_levels; +enum numa_topology_type sched_numa_topology_type; static int *sched_domains_numa_distance; int sched_max_numa_distance; static struct cpumask ***sched_domains_numa_masks; @@ -6316,6 +6317,56 @@ bool find_numa_distance(int distance) return false; } +/* + * A system can have three types of NUMA topology: + * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system + * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes + * NUMA_BACKPLANE: nodes can reach other nodes through a backplane + * + * The difference between a glueless mesh topology and a backplane + * topology lies in whether communication between not directly + * connected nodes goes through intermediary nodes (where programs + * could run), or through backplane controllers. This affects + * placement of programs. + * + * The type of topology can be discerned with the following tests: + * - If the maximum distance between any nodes is 1 hop, the system + * is directly connected. + * - If for two nodes A and B, located N > 1 hops away from each other, + * there is an intermediary node C, which is < N hops away from both + * nodes A and B, the system is a glueless mesh. + */ +static void init_numa_topology_type(void) +{ + int a, b, c, n; + + n = sched_max_numa_distance; + + 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_distance(a, b) < n) + continue; + + /* Is there an intermediary node between a and b? */ + for_each_online_node(c) { + if (node_distance(a, c) < n && + node_distance(b, c) < n) { + sched_numa_topology_type = + NUMA_GLUELESS_MESH; + return; + } + } + + sched_numa_topology_type = NUMA_BACKPLANE; + return; + } + } +} + static void sched_init_numa(void) { int next_distance, curr_distance = node_distance(0, 0); @@ -6449,6 +6500,8 @@ static void sched_init_numa(void) sched_domains_numa_levels = level; sched_max_numa_distance = sched_domains_numa_distance[level - 1]; + + init_numa_topology_type(); } static void sched_domains_numa_masks_set(int cpu) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 443d6e152a03..57aacea1cbdf 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -679,6 +679,12 @@ static inline u64 rq_clock_task(struct rq *rq) } #ifdef CONFIG_NUMA +enum numa_topology_type { + NUMA_DIRECT, + NUMA_GLUELESS_MESH, + NUMA_BACKPLANE, +}; +extern enum numa_topology_type sched_numa_topology_type; extern int sched_max_numa_distance; extern bool find_numa_distance(int distance); #endif |
