session: cleanup session tx function

- rework the function to declutter and avoid building more than one tx
  frame
- add dual loop although benefits in my tests seem to be minimal
- improve tcp/udp echo external apps. They have slightly better
  throughput than internal echo apps.
- udp bugfixes

Change-Id: Iea4a245b1b1bb407a7f403dedcce2664a49f774b
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/svm/svm_fifo.c b/src/svm/svm_fifo.c
index 3552192a768..dbdb813a7df 100644
--- a/src/svm/svm_fifo.c
+++ b/src/svm/svm_fifo.c
@@ -622,14 +622,14 @@ void
 svm_fifo_overwrite_head (svm_fifo_t * f, u8 * data, u32 len)
 {
   u32 first_chunk;
+  first_chunk = f->nitems - f->head;
   ASSERT (len <= f->nitems);
-  if (len < f->nitems - f->head)
+  if (len <= first_chunk)
     clib_memcpy (&f->data[f->head], data, len);
   else
     {
-      first_chunk = len - (f->nitems - f->head);
       clib_memcpy (&f->data[f->head], data, first_chunk);
-      clib_memcpy (f->data, data + first_chunk, len - first_chunk);
+      clib_memcpy (&f->data[0], data + first_chunk, len - first_chunk);
     }
 }