ipsec4-output: add pkt header and data prefetching

The graph node running IPsec encap in tunnel mode can be saved
from 65.8 to 57.3 clocks/pkt on Haswell platform.
The graph node can be saved 10 clockes/pkt on DVN as well in the
same case.

Change-Id: I4804879c4d489465ee56a8f8317596b7e79b9331
Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>

diff --git a/src/vnet/ipsec/ipsec_output.c b/src/vnet/ipsec/ipsec_output.c
index 83ab629..47eeb46 100644 (file)
--- a/src/vnet/ipsec/ipsec_output.c
+++ b/src/vnet/ipsec/ipsec_output.c
@@ -194,8 +194,8 @@ ipsec_output_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
   while (n_left_from > 0)
     {
-      u32 bi0, pi0;
-      vlib_buffer_t *b0;
+      u32 bi0, pi0, bi1;
+      vlib_buffer_t *b0, *b1;
       ipsec_policy_t *p0;
       ip4_header_t *ip0;
       ip6_header_t *ip6_0 = 0;
@@ -205,11 +205,18 @@ ipsec_output_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
       u64 bytes0;
 
       bi0 = from[0];
+      bi1 = from[1];
       b0 = vlib_get_buffer (vm, bi0);
+      b1 = vlib_get_buffer (vm, bi1);
       sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_TX];
       iph_offset = vnet_buffer (b0)->ip.save_rewrite_length;
       ip0 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0)
                              + iph_offset);
+      if (n_left_from > 1)
+       {
+         CLIB_PREFETCH (b1, CLIB_CACHE_LINE_BYTES * 2, STORE);
+         vlib_prefetch_buffer_data (b1, LOAD);
+       }
 
       /* lookup for SPD only if sw_if_index is changed */
       if (PREDICT_FALSE (last_sw_if_index != sw_if_index0))