L2-learn; cache prefetch fix

the header is written (STORE) the data is only read (LOAD)

Change-Id: Ia3ac0c81224a0db736c329ed3e2e55b7417f08a0
Signed-off-by: Neale Ranns <nranns@cisco.com>

3 files changed, 23 insertions, 16 deletions

diff --git a/src/vnet/CMakeLists.txt b/src/vnet/CMakeLists.txt
index 29f5fef8626..549b3ac3c4a 100644
--- a/src/vnet/CMakeLists.txt
+++ b/src/vnet/CMakeLists.txt
@@ -120,7 +120,7 @@ list(APPEND VNET_SOURCES
   ethernet/p2p_ethernet_api.c
 )
 
-list(APPEND VNET_MULTIARCH_SOURCES ethernet/node.c l2/l2_output.c)
+list(APPEND VNET_MULTIARCH_SOURCES ethernet/node.c)
 
 list(APPEND VNET_HEADERS
   ethernet/error.def
@@ -158,6 +158,8 @@ list(APPEND VNET_SOURCES
   l2/l2_xcrw.c
 )
 
+list(APPEND VNET_MULTIARCH_SOURCES l2/l2_output.c l2/l2_learn.c)
+
 list(APPEND VNET_HEADERS
   l2/feat_bitmap.h
   l2/l2_input.h
diff --git a/src/vnet/l2/l2_fib.h b/src/vnet/l2/l2_fib.h
index 77b5e7b9454..a5050c44bb9 100644
--- a/src/vnet/l2/l2_fib.h
+++ b/src/vnet/l2/l2_fib.h
@@ -363,10 +363,10 @@ static_always_inline void
 l2fib_lookup_4 (BVT (clib_bihash) * mac_table,
 		l2fib_entry_key_t * cached_key,
 		l2fib_entry_result_t * cached_result,
-		u8 * mac0,
-		u8 * mac1,
-		u8 * mac2,
-		u8 * mac3,
+		const u8 * mac0,
+		const u8 * mac1,
+		const u8 * mac2,
+		const u8 * mac3,
 		u16 bd_index0,
 		u16 bd_index1,
 		u16 bd_index2,
diff --git a/src/vnet/l2/l2_learn.c b/src/vnet/l2/l2_learn.c
index eff5822cb5f..732a1fc5d85 100644
--- a/src/vnet/l2/l2_learn.c
+++ b/src/vnet/l2/l2_learn.c
@@ -29,7 +29,9 @@
 #include <vppinfra/error.h>
 #include <vppinfra/hash.h>
 
+#ifndef CLIB_MARCH_VARIANT
 l2learn_main_t l2learn_main;
+#endif
 
 /**
  * @file
@@ -271,7 +273,7 @@ l2learn_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  vlib_buffer_t *b0, *b1, *b2, *b3;
 	  u32 next0, next1, next2, next3;
 	  u32 sw_if_index0, sw_if_index1, sw_if_index2, sw_if_index3;
-	  ethernet_header_t *h0, *h1, *h2, *h3;
+	  const ethernet_header_t *h0, *h1, *h2, *h3;
 	  l2fib_entry_key_t key0, key1, key2, key3;
 	  l2fib_entry_result_t result0, result1, result2, result3;
 	  u32 bucket0, bucket1, bucket2, bucket3;
@@ -285,15 +287,17 @@ l2learn_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    p6 = vlib_get_buffer (vm, from[6]);
 	    p7 = vlib_get_buffer (vm, from[7]);
 
+	    /* buffer header is read and written, so use LOAD
+	     * prefetch */
 	    vlib_prefetch_buffer_header (p4, LOAD);
 	    vlib_prefetch_buffer_header (p5, LOAD);
 	    vlib_prefetch_buffer_header (p6, LOAD);
 	    vlib_prefetch_buffer_header (p7, LOAD);
 
-	    CLIB_PREFETCH (p4->data, CLIB_CACHE_LINE_BYTES, STORE);
-	    CLIB_PREFETCH (p5->data, CLIB_CACHE_LINE_BYTES, STORE);
-	    CLIB_PREFETCH (p6->data, CLIB_CACHE_LINE_BYTES, STORE);
-	    CLIB_PREFETCH (p7->data, CLIB_CACHE_LINE_BYTES, STORE);
+	    CLIB_PREFETCH (p4->data, CLIB_CACHE_LINE_BYTES, LOAD);
+	    CLIB_PREFETCH (p5->data, CLIB_CACHE_LINE_BYTES, LOAD);
+	    CLIB_PREFETCH (p6->data, CLIB_CACHE_LINE_BYTES, LOAD);
+	    CLIB_PREFETCH (p7->data, CLIB_CACHE_LINE_BYTES, LOAD);
 	  }
 
 	  /* speculatively enqueue b0 and b1 to the current next frame */
@@ -465,9 +469,8 @@ l2learn_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
   return frame->n_vectors;
 }
 
-static uword
-l2learn_node_fn (vlib_main_t * vm,
-		 vlib_node_runtime_t * node, vlib_frame_t * frame)
+VLIB_NODE_FN (l2learn_node) (vlib_main_t * vm,
+			     vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
     return l2learn_node_inline (vm, node, frame, 1 /* do_trace */ );
@@ -476,7 +479,6 @@ l2learn_node_fn (vlib_main_t * vm,
 
 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (l2learn_node,static) = {
-  .function = l2learn_node_fn,
   .name = "l2-learn",
   .vector_size = sizeof (u32),
   .format_trace = format_l2learn_trace,
@@ -495,8 +497,9 @@ VLIB_REGISTER_NODE (l2learn_node,static) = {
 };
 /* *INDENT-ON* */
 
-VLIB_NODE_FUNCTION_MULTIARCH (l2learn_node, l2learn_node_fn)
-     clib_error_t *l2learn_init (vlib_main_t * vm)
+#ifndef CLIB_MARCH_VARIANT
+clib_error_t *
+l2learn_init (vlib_main_t * vm)
 {
   l2learn_main_t *mp = &l2learn_main;
 
@@ -599,6 +602,8 @@ l2learn_config (vlib_main_t * vm, unformat_input_t * input)
 
 VLIB_CONFIG_FUNCTION (l2learn_config, "l2learn");
 
+#endif
+
 
 /*
  * fd.io coding-style-patch-verification: ON