Thread safe internal buffer manager, take two

First attempt to make internal buffer manager thread safe was not
succesfull, so trying again. This time with more testing.

Change-Id: I01b8385a9c26d233934a3339255ea4bd31c865ac
Signed-off-by: Damjan Marion <damarion@cisco.com>

3 files changed, 32 insertions, 4 deletions

diff --git a/src/vlib/buffer.c b/src/vlib/buffer.c
index a5c955c7..908368c0 100644
--- a/src/vlib/buffer.c
+++ b/src/vlib/buffer.c
@@ -396,6 +396,8 @@ vlib_buffer_create_free_list_helper (vlib_main_t * vm,
 	hash_set (bm->free_list_by_size, f->n_data_bytes, f->index);
     }
 
+  clib_spinlock_init (&f->global_buffers_lock);
+
   for (i = 1; i < vec_len (vlib_mains); i++)
     {
       vlib_buffer_main_t *wbm = vlib_mains[i]->buffer_main;
@@ -509,6 +511,7 @@ fill_free_list (vlib_main_t * vm,
 		vlib_buffer_free_list_t * fl, uword min_free_buffers)
 {
   vlib_buffer_t *buffers, *b;
+  vlib_buffer_free_list_t *mfl;
   int n, n_bytes, i;
   u32 *bi;
   u32 n_remaining, n_alloc, n_this_chunk;
@@ -518,6 +521,22 @@ fill_free_list (vlib_main_t * vm,
   if (n <= 0)
     return min_free_buffers;
 
+  mfl = vlib_buffer_get_free_list (vlib_mains[0], fl->index);
+  if (vec_len (mfl->global_buffers) > 0)
+    {
+      int n_copy, n_left;
+      clib_spinlock_lock (&mfl->global_buffers_lock);
+      n_copy = clib_min (vec_len (mfl->global_buffers), n);
+      n_left = vec_len (mfl->global_buffers) - n_copy;
+      vec_add_aligned (fl->buffers, mfl->global_buffers + n_left, n_copy,
+		       CLIB_CACHE_LINE_BYTES);
+      _vec_len (mfl->global_buffers) = n_left;
+      clib_spinlock_unlock (&mfl->global_buffers_lock);
+      n = min_free_buffers - vec_len (fl->buffers);
+      if (n <= 0)
+	return min_free_buffers;
+    }
+
   /* Always allocate round number of buffers. */
   n = round_pow2 (n, CLIB_CACHE_LINE_BYTES / sizeof (u32));
 
diff --git a/src/vlib/buffer.h b/src/vlib/buffer.h
index 9047ca9a..5504bf7c 100644
--- a/src/vlib/buffer.h
+++ b/src/vlib/buffer.h
@@ -350,6 +350,12 @@ typedef struct vlib_buffer_free_list_t
   /* Vector of free buffers.  Each element is a byte offset into I/O heap. */
   u32 *buffers;
 
+  /* global vector of free buffers, used only on main thread.
+     Bufers are returned to global buffers only in case when number of
+     buffers on free buffers list grows about threshold */
+  u32 *global_buffers;
+  clib_spinlock_t global_buffers_lock;
+
   /* Memory chunks allocated for this free list
      recorded here so they can be freed when free list
      is deleted. */
diff --git a/src/vlib/buffer_funcs.h b/src/vlib/buffer_funcs.h
index 6a662416..78bf9317 100644
--- a/src/vlib/buffer_funcs.h
+++ b/src/vlib/buffer_funcs.h
@@ -848,18 +848,21 @@ vlib_buffer_add_to_free_list (vlib_main_t * vm,
 			      u32 buffer_index, u8 do_init)
 {
   vlib_buffer_t *b;
-  u32 i;
   b = vlib_get_buffer (vm, buffer_index);
   if (PREDICT_TRUE (do_init))
     vlib_buffer_init_for_free_list (b, f);
   vec_add1_aligned (f->buffers, buffer_index, CLIB_CACHE_LINE_BYTES);
 
-  if (vec_len (f->buffers) > 3 * VLIB_FRAME_SIZE)
+  if (vec_len (f->buffers) > 4 * VLIB_FRAME_SIZE)
     {
+      vlib_buffer_free_list_t *mf;
+      mf = vlib_buffer_get_free_list (vlib_mains[0], f->index);
+      clib_spinlock_lock (&mf->global_buffers_lock);
       /* keep last stored buffers, as they are more likely hot in the cache */
-      for (i = 0; i < VLIB_FRAME_SIZE; i++)
-	vm->os_physmem_free (vlib_get_buffer (vm, i));
+      vec_add_aligned (mf->global_buffers, f->buffers, VLIB_FRAME_SIZE,
+		       CLIB_CACHE_LINE_BYTES);
       vec_delete (f->buffers, VLIB_FRAME_SIZE, 0);
+      clib_spinlock_unlock (&mf->global_buffers_lock);
     }
 }