Mtrie optimisations

1 - make the default route non-special, i.e. like any other less specific route. Consequently, all buckets have a valid valid index of either a leaf or a ply. Checks for special indeices in the data-path can thus be removed.
2 - since all leaves are now 'real' i.e. they represent a real load-balance object, to tell if a ply slot is 'empty' requeirs chekcing that the prefix length of the leaf occupying the slot is slot than the minium value for that ply.
3 - when removing a leaf find the cover first, then recurse down the ply and replace the old leaf with the cover. This saves us a ply walk.

Change-Id: Idd523019e8bb1b6ef527b1f5279a5e24bcf18332
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/vnet/dpo/load_balance.c b/src/vnet/dpo/load_balance.c
index e9fb5d9dd56..d5e98e4e32e 100644
--- a/src/vnet/dpo/load_balance.c
+++ b/src/vnet/dpo/load_balance.c
@@ -829,6 +829,13 @@ load_balance_module_init (void)
 {
     dpo_register(DPO_LOAD_BALANCE, &lb_vft, load_balance_nodes);
 
+    /*
+     * Special LB with index zero. we need to define this since the v4 mtrie
+     * assumes an index of 0 implies the ply is empty. therefore all 'real'
+     * adjs need a non-zero index.
+     */
+    load_balance_create(0, DPO_PROTO_IP4, 0);
+
     load_balance_map_module_init();
 }