VPP-106: fix performance hit due to unprefetched data read

Change-Id: I1325b60b6deadcb51631e178011a31ee70c06cc7
Signed-off-by: Dave Barach <dave@barachs.net>

3 files changed, 17 insertions, 6 deletions

diff --git a/vnet/vnet/devices/dpdk/device.c b/vnet/vnet/devices/dpdk/device.c
index 7f759d6104d..bad149f03c6 100644
--- a/vnet/vnet/devices/dpdk/device.c
+++ b/vnet/vnet/devices/dpdk/device.c
@@ -1136,7 +1136,10 @@ dpdk_subif_add_del_function (vnet_main_t * vnm,
   dpdk_device_t * xd = vec_elt_at_index (xm->devices, hw->dev_instance);
   vnet_sw_interface_t * t = (vnet_sw_interface_t *) st;
   int r, vlan_offload;
+  u32 prev_subifs = xd->vlan_subifs;
 
+  if (is_add) xd->vlan_subifs++;
+  else if (xd->vlan_subifs) xd->vlan_subifs--;
 
   if (xd->dev_type != VNET_DPDK_DEV_ETH)
         return 0;
@@ -1149,21 +1152,26 @@ dpdk_subif_add_del_function (vnet_main_t * vnm,
   if (t->sub.eth.flags.no_tags == 1)
         return 0;
 
-  if ((t->sub.eth.flags.one_tag != 1) || (t->sub.eth.flags.exact_match != 1 ))
+  if ((t->sub.eth.flags.one_tag != 1) || (t->sub.eth.flags.exact_match != 1 )) {
+        xd->vlan_subifs = prev_subifs;
         return clib_error_return (0, "unsupported VLAN setup");
-
+  }
 
   vlan_offload = rte_eth_dev_get_vlan_offload(xd->device_index);
   vlan_offload |= ETH_VLAN_FILTER_OFFLOAD;
 
-  if ((r = rte_eth_dev_set_vlan_offload(xd->device_index, vlan_offload)))
+  if ((r = rte_eth_dev_set_vlan_offload(xd->device_index, vlan_offload))) {
+        xd->vlan_subifs = prev_subifs;
         return clib_error_return (0, "rte_eth_dev_set_vlan_offload[%d]: err %d",
                                   xd->device_index, r);
+  }
 
 
-  if ((r = rte_eth_dev_vlan_filter(xd->device_index, t->sub.eth.outer_vlan_id, is_add)))
+  if ((r = rte_eth_dev_vlan_filter(xd->device_index, t->sub.eth.outer_vlan_id, is_add))) {
+        xd->vlan_subifs = prev_subifs;
         return clib_error_return (0, "rte_eth_dev_vlan_filter[%d]: err %d",
                                  xd->device_index, r);
+  }
 
   return 0;
 }
diff --git a/vnet/vnet/devices/dpdk/dpdk.h b/vnet/vnet/devices/dpdk/dpdk.h
index 4123cc9cbef..23c8eb3eaf5 100644
--- a/vnet/vnet/devices/dpdk/dpdk.h
+++ b/vnet/vnet/devices/dpdk/dpdk.h
@@ -210,6 +210,9 @@ typedef struct {
   /* per-worker destination frame queue */
   dpdk_frame_t * frames;
 
+  /* number of sub-interfaces */
+  u16 vlan_subifs;
+
   dpdk_device_type_t dev_type:8;
   dpdk_pmd_t pmd:8;
   i8 cpu_socket;
diff --git a/vnet/vnet/devices/dpdk/node.c b/vnet/vnet/devices/dpdk/node.c
index 2c90d80a31e..d22838f1f06 100644
--- a/vnet/vnet/devices/dpdk/node.c
+++ b/vnet/vnet/devices/dpdk/node.c
@@ -305,9 +305,9 @@ dpdk_rx_next_and_error_from_mb_flags_x1 (dpdk_device_t *xd, struct rte_mbuf *mb,
   else
     {
       *error0 = DPDK_ERROR_NONE;
-      if (xd->per_interface_next_index != ~0)
+      if (PREDICT_FALSE(xd->per_interface_next_index != ~0))
 	n0 = xd->per_interface_next_index;
-      else if (mb_flags & PKT_RX_VLAN_PKT)
+      else if (PREDICT_FALSE(xd->vlan_subifs || (mb_flags & PKT_RX_VLAN_PKT)))
 	n0 = DPDK_RX_NEXT_ETHERNET_INPUT;
       else
 	{