Remove useless prefetch in ip4-rewrite node

Prefetching first 2 packets' header is useless cause of the prefetching
action is not done before using the packets.

There's no performance drop in Xeon platform and slightly performance
gain in Atom platform after rmoving the prefetch.

Change-Id: Ib4b074af20d7cd5053aecc7147b162141aec31f5
Signed-off-by: Simon Zhang <yuwei1.zhang@intel.com>

diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index 9963f6b..1911f08 100644 (file)
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -2197,7 +2197,7 @@ ip4_rewrite_inline (vlib_main_t * vm,
   if (n_left_from >= 6)
     {
       int i;
-      for (i = 0; i < 6; i++)
+      for (i = 2; i < 6; i++)
        vlib_prefetch_buffer_header (bufs[i], LOAD);
     }