Implementation of the connect_roots option in fat tree.
Actually, it will not only connect all the roots, but
also all the other switches that are above leaf switch
level.

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

---
 opensm/opensm/osm_ucast_ftree.c |   82 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 82 insertions(+), 0 deletions(-)

diff --git a/opensm/opensm/osm_ucast_ftree.c b/opensm/opensm/osm_ucast_ftree.c
index 5b403f7..366a225 100644
--- a/opensm/opensm/osm_ucast_ftree.c
+++ b/opensm/opensm/osm_ucast_ftree.c
@@ -2949,6 +2949,82 @@ static void fabric_route_to_switches(IN ftree_fabric_t * 
p_ftree)
 /***************************************************
  ***************************************************/

+static void fabric_route_roots(IN ftree_fabric_t * p_ftree)
+{
+       uint16_t lid;
+       uint8_t port_num;
+       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;
+
+                       /*
+                        * 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 +4054,12 @@ 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) {
+               OSM_LOG(&p_ftree->p_osm->log, OSM_LOG_VERBOSE,
+                       "Connecting nodes that are unreachable within Up/Down 
rules\n");
+               fabric_route_roots(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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