[RFC PATCH 2/2] Revert "sched/topology: Warn when NUMA diameter > 2"

Valentin Schneider
2021-02-03T15:59:56Z

The scheduler topology code can now figure out what to do with such
topologies.

This reverts commit b5b217346de85ed1b03fdecd5c5076b34fbb2f0b.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
---
kernel/sched/topology.c | 33 ---------------------------------
1 file changed, 33 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index a8f69f234258..0fa41aab74e0 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -688,7 +688,6 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct sched_domain *tmp;
- int numa_distance = 0;

/* Remove the sched domains which do not contribute to scheduling. */
for (tmp = sd; tmp; ) {
@@ -720,38 +719,6 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
sd->child = NULL;
}

- for (tmp = sd; tmp; tmp = tmp->parent)
- numa_distance += !!(tmp->flags & SD_NUMA);
-
- /*
- * FIXME: Diameter >=3 is misrepresented.
- *
- * Smallest diameter=3 topology is:
- *
- * node 0 1 2 3
- * 0: 10 20 30 40
- * 1: 20 10 20 30
- * 2: 30 20 10 20
- * 3: 40 30 20 10
- *
- * 0 --- 1 --- 2 --- 3
- *
- * NUMA-3 0-3 N/A N/A 0-3
- * groups: {0-2},{1-3} {1-3},{0-2}
- *
- * NUMA-2 0-2 0-3 0-3 1-3
- * groups: {0-1},{1-3} {0-2},{2-3} {1-3},{0-1} {2-3},{0-2}
- *
- * NUMA-1 0-1 0-2 1-3 2-3
- * groups: {0},{1} {1},{2},{0} {2},{3},{1} {3},{2}
- *
- * NUMA-0 0 1 2 3
- *
- * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
- * group span isn't a subset of the domain span.
- */
- WARN_ONCE(numa_distance > 2, "Shortest NUMA path spans too many nodes\n");
-
sched_domain_debug(sd, cpu);

rq_attach_root(rq, rd);
--
2.27.0