FIB: elide cover walk for insert of host route

Change-Id: I2d39e56ff605e3a24927d6330d65d0406f588381
Signed-off-by: Neale Ranns <nranns@cisco.com>

3 files changed, 25 insertions, 3 deletions

diff --git a/src/vnet/fib/fib_entry.c b/src/vnet/fib/fib_entry.c
index cd1300dee39..a12edcb1867 100644
--- a/src/vnet/fib/fib_entry.c
+++ b/src/vnet/fib/fib_entry.c
@@ -1428,6 +1428,19 @@ fib_entry_get_best_source (fib_node_index_t entry_index)
 }
 
 /**
+ * Return !0 is the entry represents a host prefix
+ */
+int
+fib_entry_is_host (fib_node_index_t fib_entry_index)
+{
+    fib_prefix_t pfx;
+
+    fib_entry_get_prefix(fib_entry_index, &pfx);
+
+    return (fib_prefix_is_host(&pfx));
+}
+
+/**
  * Return !0 is the entry is reoslved, i.e. will return a valid forwarding
  * chain
  */
diff --git a/src/vnet/fib/fib_entry.h b/src/vnet/fib/fib_entry.h
index ddaf914389e..dcc310e8fbc 100644
--- a/src/vnet/fib/fib_entry.h
+++ b/src/vnet/fib/fib_entry.h
@@ -613,6 +613,7 @@ extern int fib_entry_is_sourced(fib_node_index_t fib_entry_index,
 
 extern fib_node_index_t fib_entry_get_path_list(fib_node_index_t fib_entry_index);
 extern int fib_entry_is_resolved(fib_node_index_t fib_entry_index);
+extern int fib_entry_is_host(fib_node_index_t fib_entry_index);
 extern void fib_entry_set_flow_hash_config(fib_node_index_t fib_entry_index,
                                            flow_hash_config_t hash_config);
 
diff --git a/src/vnet/fib/fib_table.c b/src/vnet/fib/fib_table.c
index d0bc33639b9..c37ac1dbd49 100644
--- a/src/vnet/fib/fib_table.c
+++ b/src/vnet/fib/fib_table.c
@@ -197,10 +197,18 @@ fib_table_post_insert_actions (fib_table_t *fib_table,
 
         /*
          * inform the covering entry that a new more specific
-         * has been inserted beneath it
+         * has been inserted beneath it.
+         * If the prefix that has been inserted is a host route
+         * then it is not possible that it will be the cover for any
+         * other entry, so we can elide the walk. This is particularly
+         * beneficial since there are often many host entries sharing the
+         * same cover (i.e. ADJ or RR sourced entries).
          */
-	fib_entry_cover_change_notify(fib_entry_cover_index,
-				      fib_entry_index);
+        if (!fib_entry_is_host(fib_entry_index))
+        {
+            fib_entry_cover_change_notify(fib_entry_cover_index,
+                                          fib_entry_index);
+        }
     }
 }