[PATCH 2/3 v2] opensm: connect switches in tree - implemented in fat-tree

[Yevgeny Kliteynik <kliteyn-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

This patch implements connect_roots and connect_switches
option in fat-tree. Actually, both options mapped to the
same implementation.

The idea is the following: pick some leaf switch in the
fabric. Now go over all the switches above the leaf level
in the tree. If these switches don't know how to route to
some LID and the selected leaf switch does know, route this
LID to the leaf switch.

[v2 - no changes, just rebased]

Signed-off-by: Yevgeny Kliteynik <kliteyn-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
---
 opensm/opensm/osm_ucast_ftree.c |   92 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 92 insertions(+), 0 deletions(-)

diff --git a/opensm/opensm/osm_ucast_ftree.c b/opensm/opensm/osm_ucast_ftree.c
index 1b1da19..ddb77b7 100644
--- a/opensm/opensm/osm_ucast_ftree.c
+++ b/opensm/opensm/osm_ucast_ftree.c
@@ -2949,6 +2949,90 @@ static void fabric_route_to_switches(IN ftree_fabric_t * p_ftree)
 /***************************************************
  ***************************************************/

+static void fabric_route_down_up_switches(IN ftree_fabric_t * p_ftree)
+{
+	uint16_t lid;
+	uint8_t port_num;
+	osm_port_t *p_port;
+	ftree_sw_t *p_sw;
+	ftree_sw_t *p_leaf_sw;
+
+	OSM_LOG_ENTER(&p_ftree->p_osm->log);
+
+	/*
+	 * We need a switch that will accomodate all the down/up turns in
+	 * the fabric. Having these turn in a single place in the fabric
+	 * will not create credit loops.
+	 * So we need to select this switch.
+	 * The idea here is to chose leaf with the highest index. I don't
+	 * have any theory to back me up on this. It's just a general thought
+	 * that this way the switch that might be a bottleneck for many mcast
+	 * groups will be far away from the OpenSM, so it will draw the
+	 * multicast traffic away from the SM.
+	 */
+
+	p_leaf_sw = p_ftree->leaf_switches[p_ftree->leaf_switches_num-1];
+
+	/*
+	 * Now go over all the switches in the fabric that
+	 * have lower rank, and route the missing LIDs to
+	 * the selected leaf switch.
+	 * In short, this leaf switch now poses a target
+	 * for all those missing LIDs.
+	 */
+
+	for (p_sw = (ftree_sw_t *) cl_qmap_head(&p_ftree->sw_tbl);
+	     p_sw != (ftree_sw_t *) cl_qmap_end(&p_ftree->sw_tbl);
+	     p_sw = (ftree_sw_t *) cl_qmap_next(&p_sw->map_item)) {
+
+		if (p_sw->rank >= p_ftree->leaf_switch_rank)
+			continue;
+
+		for (lid = 1; lid <= p_leaf_sw->p_osm_sw->max_lid_ho; lid ++) {
+
+			if (p_sw->p_osm_sw->new_lft[lid] != OSM_NO_PATH ||
+			    p_leaf_sw->hops[lid] == OSM_NO_PATH)
+				continue;
+
+			p_port = cl_ptr_vector_get(
+				&p_ftree->p_osm->subn.port_lid_tbl, lid);
+
+			/* we're interested only in switches */
+			if (!p_port && !p_port->p_node && !p_port->p_node->sw)
+				continue;
+
+			/*
+			 * the missing LID will be routed through the same
+			 * port that routes to the selected leaf switch
+			 */
+			port_num = p_sw->p_osm_sw->new_lft[p_leaf_sw->base_lid];
+
+			OSM_LOG(&p_ftree->p_osm->log, OSM_LOG_DEBUG,
+				"Switch %s: setting path to LID %u "
+				"through port %u\n",
+				tuple_to_str(p_sw->tuple), lid, port_num);
+
+			/* set local lft */
+			p_sw->p_osm_sw->new_lft[lid] = port_num;
+
+			/*
+			 * Set local min hop table.
+			 * The distance to the target LID is a distance
+			 * to the selected leaf switch plus the distance
+			 * from the leaf to the target LID.
+			 */
+			sw_set_hops(p_sw, lid, port_num,
+				p_sw->hops[p_leaf_sw->base_lid] +
+				p_leaf_sw->hops[lid], TRUE);
+		}
+	}
+
+	OSM_LOG_EXIT(&p_ftree->p_osm->log);
+}				/* fabric_route_roots() */
+
+/***************************************************
+ ***************************************************/
+
 static int fabric_populate_nodes(IN ftree_fabric_t * p_ftree)
 {
 	osm_node_t *p_osm_node;
@@ -3978,6 +4062,14 @@ static int do_routing(IN void *context)
 		"Filling switch forwarding tables for switch-to-switch paths\n");
 	fabric_route_to_switches(p_ftree);

+	if (p_ftree->p_osm->subn.opt.connect_roots ||
+	    p_ftree->p_osm->subn.opt.connect_switches) {
+		OSM_LOG(&p_ftree->p_osm->log, OSM_LOG_VERBOSE,
+			"Connecting switches that are unreachable within "
+			"Up/Down rules\n");
+		fabric_route_down_up_switches(p_ftree);
+	}
+
 	/* for each switch, set its fwd table */
 	cl_qmap_apply_func(&p_ftree->sw_tbl, set_sw_fwd_table, (void *)p_ftree);

-- 
1.5.1.4


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