ipv4: 16 slots in initial fib_info hash table

A small host typically needs ~10 fib_info structures, so create initial
hash table with 16 slots instead of only one. This removes potential
false sharing and reallocs/rehashes (1->2->4->8->16)
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/fib_semantics.c

@@ -803,7 +803,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
 		unsigned int bytes;
 
 		if (!new_size)
-			new_size = 1;
+			new_size = 16;
 		bytes = new_size * sizeof(struct hlist_head *);
 		new_info_hash = fib_info_hash_alloc(bytes);
 		new_laddrhash = fib_info_hash_alloc(bytes);