ethernet: put vlib_get_buffers together

The patch brings 0.8 clocks saved per pkt in IPv4 l3fwd case on Skylake.

Type: improvement

Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
Change-Id: Ia8d3a27773bf959433380d7c219602b1e4a8e5bd

1 files changed, 6 insertions, 11 deletions

diff --git a/src/vnet/ethernet/node.c b/src/vnet/ethernet/node.c
index 29c0a5b9dee..cc27b6f5da9 100755
--- a/src/vnet/ethernet/node.c
+++ b/src/vnet/ethernet/node.c
@@ -842,18 +842,15 @@ eth_input_process_frame (vlib_main_t * vm, vlib_node_runtime_t * node,
   u16 et_vlan = clib_host_to_net_u16 (ETHERNET_TYPE_VLAN);
   u16 et_dot1ad = clib_host_to_net_u16 (ETHERNET_TYPE_DOT1AD);
   i32 n_left = n_packets;
-  vlib_buffer_t *b[20];
-  u32 *from;
+  vlib_buffer_t *bufs[VLIB_FRAME_SIZE];
+  vlib_buffer_t **b = bufs;
   ethernet_interface_t *ei = ethernet_get_interface (em, hi->hw_if_index);
 
-  from = buffer_indices;
+  vlib_get_buffers (vm, buffer_indices, b, n_left);
 
   while (n_left >= 20)
     {
       vlib_buffer_t **ph = b + 16, **pd = b + 8;
-      vlib_get_buffers (vm, from, b, 4);
-      vlib_get_buffers (vm, from + 8, pd, 4);
-      vlib_get_buffers (vm, from + 16, ph, 4);
 
       vlib_prefetch_buffer_header (ph[0], LOAD);
       vlib_prefetch_buffer_data (pd[0], LOAD);
@@ -874,15 +871,14 @@ eth_input_process_frame (vlib_main_t * vm, vlib_node_runtime_t * node,
       eth_input_adv_and_flags_x4 (b, main_is_l3);
 
       /* next */
+      b += 4;
       n_left -= 4;
       etype += 4;
       tag += 4;
       dmac += 4;
-      from += 4;
     }
   while (n_left >= 4)
     {
-      vlib_get_buffers (vm, from, b, 4);
       eth_input_get_etype_and_tags (b, etype, tag, dmac, 0, dmac_check);
       eth_input_get_etype_and_tags (b, etype, tag, dmac, 1, dmac_check);
       eth_input_get_etype_and_tags (b, etype, tag, dmac, 2, dmac_check);
@@ -890,24 +886,23 @@ eth_input_process_frame (vlib_main_t * vm, vlib_node_runtime_t * node,
       eth_input_adv_and_flags_x4 (b, main_is_l3);
 
       /* next */
+      b += 4;
       n_left -= 4;
       etype += 4;
       tag += 4;
       dmac += 4;
-      from += 4;
     }
   while (n_left)
     {
-      vlib_get_buffers (vm, from, b, 1);
       eth_input_get_etype_and_tags (b, etype, tag, dmac, 0, dmac_check);
       eth_input_adv_and_flags_x1 (b, main_is_l3);
 
       /* next */
+      b += 1;
       n_left -= 1;
       etype += 1;
       tag += 1;
       dmac += 4;
-      from += 1;
     }
 
   if (dmac_check)