opensm: connect switches in tree - implemented in up/down

This patch implements connect_switches option in up/down routing. Also, connect_roots is now handled as a special case of connect_switches.

The idea is the following: when clearing hops, preserve the entries for switches that are above the highest leaf in the tree.
So if the highest leaf in the tree has rank N, preserve hops to all the switches with ranks 0 to (N-1). When connecting roots (--connect_roots option), just set N to 1.

[v2 - no changes, just rebased and resolved conflicts]

Signed-off-by Yevgeny Kliteynik <[email protected]>

---
 opensm/opensm/osm_ucast_updn.c |   87 +++++++++++++++++++++++++++++++---------
 1 files changed, 68 insertions(+), 19 deletions(-)

opensm/opensm/osm_ucast_updn.c +68 -19

index 01e40eb..cb99730 100644
@@ -279,24 +279,80 @@ static int updn_subn_rank(IN updn_t * p_updn)
 	return 0;
 }
 
-/* hack: preserve min hops entries to any other root switches */
-static void updn_clear_non_root_hops(updn_t * p_updn, osm_switch_t * p_sw)
+/**********************************************************************
+ **********************************************************************/
+/* Preserve min hops entries to any switch
+ * above certain level in the tree */
+static void updn_switch_clear_hops_below_rank(updn_t * p_updn,
+	osm_switch_t * p_sw, unsigned min_leaf_rank)
 {
 	osm_port_t *p_port;
 	unsigned i;
 
 	for (i = 0; i < p_sw->num_hops; i++)
 		if (p_sw->hops[i]) {
-			p_port =
-			    cl_ptr_vector_get(&p_updn->p_osm->subn.port_lid_tbl,
-					      i);
-			if (!p_port || !p_port->p_node->sw
-			    || ((struct updn_node *)p_port->p_node->sw->priv)->
-			    rank != 0)
+			p_port = cl_ptr_vector_get(
+				&p_updn->p_osm->subn.port_lid_tbl, i);
+			if (!p_port || !p_port->p_node->sw ||
+			    ((struct updn_node *)
+			    p_port->p_node->sw->priv)->rank >= min_leaf_rank)
 				memset(p_sw->hops[i], 0xff, p_sw->num_ports);
 		}
 }
 
+/**********************************************************************
+ **********************************************************************/
+static void updn_clear_hops(IN updn_t * p_updn)
+{
+	osm_subn_t *p_subn = &p_updn->p_osm->subn;
+	osm_switch_t *p_sw;
+	struct updn_node * p_updn_sw;
+	osm_physp_t * p_physp;
+	osm_port_t * p_port;
+	cl_map_item_t *item;
+	unsigned min_leaf_rank = 0xff;
+
+	if (p_subn->opt.connect_switches) {
+		/*
+		 * Preserve roots to switches above the highest leaf
+		 * switch (leaf switch with the lowest rank).
+		 *
+		 * Need to find the minimal rank of leaf switch.
+		 * The fastest way would be to go through all the
+		 * CA ports in the fabric and check the switch that
+		 * is connected to them.
+		 */
+		for (item = cl_qmap_head(&p_updn->p_osm->subn.port_guid_tbl);
+		     item != cl_qmap_end(&p_updn->p_osm->subn.port_guid_tbl);
+		     item = cl_qmap_next(item)) {
+			p_port = (osm_port_t *)item;
+			if (p_port->p_node->sw)
+				continue;
+			p_physp = p_port->p_physp->p_remote_physp;
+			if (!p_physp || !p_physp->p_node->sw)
+				continue;
+
+			p_updn_sw = (struct updn_node*)p_physp->p_node->sw->priv;
+			if (p_updn_sw->rank < min_leaf_rank)
+				min_leaf_rank = p_updn_sw->rank;
+		}
+	} else if (p_subn->opt.connect_roots)
+		min_leaf_rank = 1;
+
+	for (item = cl_qmap_head(&p_updn->p_osm->subn.sw_guid_tbl);
+	     item != cl_qmap_end(&p_updn->p_osm->subn.sw_guid_tbl);
+	     item = cl_qmap_next(item)) {
+		p_sw = (osm_switch_t *)item;
+		if (p_subn->opt.connect_switches || p_subn->opt.connect_roots)
+			updn_switch_clear_hops_below_rank(
+				p_updn, p_sw, min_leaf_rank);
+		else
+			osm_switch_clear_hops(p_sw);
+	}
+}
+
+/**********************************************************************
+ **********************************************************************/
 static int updn_set_min_hop_table(IN updn_t * p_updn)
 {
 	osm_subn_t *p_subn = &p_updn->p_osm->subn;

@@ -311,16 +367,8 @@ static int updn_set_min_hop_table(IN updn_t * p_updn)
 	OSM_LOG(p_log, OSM_LOG_VERBOSE,
 		"Init Min Hop Table of all switches [\n");
 
-	for (item = cl_qmap_head(&p_updn->p_osm->subn.sw_guid_tbl);
-	     item != cl_qmap_end(&p_updn->p_osm->subn.sw_guid_tbl);
-	     item = cl_qmap_next(item)) {
-		p_sw = (osm_switch_t *)item;
-		/* Clear Min Hop Table */
-		if (p_subn->opt.connect_roots)
-			updn_clear_non_root_hops(p_updn, p_sw);
-		else
-			osm_switch_clear_hops(p_sw);
-	}
+	/* Clear Min Hop Table */
+	updn_clear_hops(p_updn);
 
 	OSM_LOG(p_log, OSM_LOG_VERBOSE,
 		"Init Min Hop Table of all switches ]\n");

@@ -598,7 +646,8 @@ static int updn_lid_matrices(void *ctx)
 			OSM_LOG(&p_updn->p_osm->log, OSM_LOG_ERROR, "ERR : "
 				"cannot parse root guids file \'%s\'\n",
 				p_updn->p_osm->subn.opt.root_guid_file);
-		if (p_updn->p_osm->subn.opt.connect_roots &&
+		if ((p_updn->p_osm->subn.opt.connect_roots ||
+		     p_updn->p_osm->subn.opt.connect_switches) &&
 		    p_updn->num_roots > 1)
 			osm_ucast_mgr_build_lid_matrices(&p_updn->p_osm->sm.ucast_mgr);
 	} else {

Signature · 6 lines

1.5.1.4

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Quoted 11 lines · Yevgeny Kliteynik

This patch implements connect_switches option in up/down routing. Also, connect_roots is now handled as a special case of connect_switches.

The idea is the following: when clearing hops, preserve the entries for switches that are above the highest leaf in the tree.
So if the highest leaf in the tree has rank N, preserve hops to all the switches with ranks 0 to (N-1). When connecting roots (--connect_roots option), just set N to 1.

Would this affect multicast routing in sense of a credit loop generation?

Hi Sasha,

Quoted 13 lines · Sasha Khapyorsky

Quoted 11 lines · Yevgeny Kliteynik

This patch implements connect_switches option in up/down routing. Also, connect_roots is now handled as a special case of connect_switches.

The idea is the following: when clearing hops, preserve the entries for switches that are above the highest leaf in the tree.
So if the highest leaf in the tree has rank N, preserve hops to all the switches with ranks 0 to (N-1). When connecting roots (--connect_roots option), just set N to 1.

Quoted 2 lines

Would this affect multicast routing in sense of a credit loop generation?

Since I sent these patches, I had it running in various simulations and setups, and there are couple of fundamental issue with this approach. Basically, what I did here (in up/dn) is wrong. Not only for multicast, but for unicast too. It interferes with the usual up/down paths routing.

I will issue V3 of the patches, and it will be only connect_roots implementation for fat-tree with the two small remarks that you found.