From: Simon Zhang <yuwei1.zhang@intel.com>
Date: Mon, 26 Nov 2018 09:15:24 +0000 (+0800)
Subject: Remove useless prefetch in ip4-rewrite node
X-Git-Tag: v19.04-rc0~300
X-Git-Url: https://gerrit.fd.io/r/gitweb?p=vpp.git;a=commitdiff_plain;h=5a5a86987b1b5bd792e9615c3f26471abd4babb4

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 9963f6b1e26..1911f088008 100644
--- 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);
     }