svm: refactor fifo chunk tracking

Avoid tracking with rbtrees all of the chunks associated to a fifo.
Instead, only track chunks when doing out-of-order operations (peek or
ooo enqueue).

Type: refactor

Change-Id: I9f8bd266211746637d98e6a12ffc4b2d6346950a
Signed-off-by: Florin Coras <fcoras@cisco.com>

5 files changed, 307 insertions, 84 deletions

diff --git a/src/plugins/unittest/svm_fifo_test.c b/src/plugins/unittest/svm_fifo_test.c
index fd2e05f3c3f..8b43ee370f1 100644
--- a/src/plugins/unittest/svm_fifo_test.c
+++ b/src/plugins/unittest/svm_fifo_test.c
@@ -1194,8 +1194,8 @@ sfifo_test_fifo_grow (vlib_main_t * vm, unformat_input_t * input)
   int test_n_bytes, deq_bytes, enq_bytes, n_deqs, n_enqs;
   svm_fifo_chunk_t *c, *next, *prev;
   u8 *test_data = 0, *data_buf = 0;
+  u32 old_tail, offset;
   svm_fifo_t *f;
-  u32 old_tail;
 
   while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
     {
@@ -1278,6 +1278,7 @@ sfifo_test_fifo_grow (vlib_main_t * vm, unformat_input_t * input)
   svm_fifo_add_chunk (f, c);
   SFIFO_TEST (f->size == fifo_size + 200, "size expected %u is %u",
 	      fifo_size + 200, f->size);
+  SFIFO_TEST (svm_fifo_is_sane (f), "fifo should be sane");
 
   prev = 0;
   for (i = 0; i < 5; i++)
@@ -1435,14 +1436,22 @@ sfifo_test_fifo_grow (vlib_main_t * vm, unformat_input_t * input)
 	}
     }
 
+  SFIFO_TEST (svm_fifo_is_sane (f), "fifo should be sane");
   SFIFO_TEST (svm_fifo_max_dequeue (f) == 0, "max deq expected %u is %u",
 	      0, svm_fifo_max_dequeue (f));
 
   svm_fifo_enqueue (f, sizeof (u8), &test_data[0]);
 
   memset (data_buf, 0, vec_len (data_buf));
+  offset = 0;
   for (i = 0; i <= n_deqs; i++)
-    svm_fifo_dequeue (f, deq_bytes, data_buf + i * deq_bytes);
+    {
+      rv = svm_fifo_peek (f, offset, deq_bytes, data_buf + i * deq_bytes);
+      if (rv < 0 || (rv != deq_bytes && i != n_deqs))
+	SFIFO_TEST (0, "unexpected peek %d", rv);
+      offset += rv;
+    }
+  svm_fifo_dequeue_drop (f, offset);
 
   rv = compare_data (data_buf, test_data, 0, vec_len (test_data),
 		     (u32 *) & j);
@@ -1750,6 +1759,7 @@ sfifo_test_fifo_shrink (vlib_main_t * vm, unformat_input_t * input)
   svm_fifo_enqueue (f, 200, test_data);
   svm_fifo_enqueue_with_offset (f, 50, vec_len (test_data) - 250,
 				&test_data[250]);
+  SFIFO_TEST (svm_fifo_is_sane (f), "fifo should be sane");
 
   /* Free space */
   rv = svm_fifo_max_enqueue (f);
diff --git a/src/svm/fifo_segment.c b/src/svm/fifo_segment.c
index 58c11383e43..bc46aba7bf6 100644
--- a/src/svm/fifo_segment.c
+++ b/src/svm/fifo_segment.c
@@ -412,6 +412,7 @@ fs_try_alloc_fifo_batch (fifo_segment_header_t * fsh,
       c = (svm_fifo_chunk_t *) (fmem + sizeof (*f));
       c->start_byte = 0;
       c->length = rounded_data_size;
+      c->rb_index = RBTREE_TNIL_INDEX;
       c->next = fss->free_chunks[fl_index];
       fss->free_chunks[fl_index] = c;
       fmem += hdrs + rounded_data_size;
@@ -506,11 +507,7 @@ fifo_segment_alloc_fifo_w_slice (fifo_segment_t * fs, u32 slice_index,
 
   /* Initialize chunks and rbtree for multi-chunk fifos */
   if (f->start_chunk->next != f->start_chunk)
-    {
-      void *oldheap = ssvm_push_heap (fsh->ssvm_sh);
-      svm_fifo_init_chunks (f);
-      ssvm_pop_heap (oldheap);
-    }
+    svm_fifo_init_chunks (f);
 
   /* If rx fifo type add to active fifos list. When cleaning up segment,
    * we need a list of active sessions that should be disconnected. Since
@@ -541,7 +538,6 @@ fifo_segment_free_fifo (fifo_segment_t * fs, svm_fifo_t * f)
   fifo_segment_header_t *fsh = fs->h;
   svm_fifo_chunk_t *cur, *next;
   fifo_segment_slice_t *fss;
-  void *oldheap;
   int fl_index;
 
   ASSERT (f->refcnt > 0);
@@ -576,6 +572,7 @@ fifo_segment_free_fifo (fifo_segment_t * fs, svm_fifo_t * f)
       fl_index = fs_freelist_for_size (cur->length);
       ASSERT (fl_index < vec_len (fss->free_chunks));
       cur->next = fss->free_chunks[fl_index];
+      cur->rb_index = RBTREE_TNIL_INDEX;
       fss->free_chunks[fl_index] = cur;
       fss->n_fl_chunk_bytes += fs_freelist_index_to_size (fl_index);
       cur = next;
@@ -585,9 +582,7 @@ fifo_segment_free_fifo (fifo_segment_t * fs, svm_fifo_t * f)
   f->start_chunk = f->end_chunk = f->new_chunks = 0;
   f->head_chunk = f->tail_chunk = f->ooo_enq = f->ooo_deq = 0;
 
-  oldheap = ssvm_push_heap (fsh->ssvm_sh);
   svm_fifo_free_chunk_lookup (f);
-  ssvm_pop_heap (oldheap);
 
   /* not allocated on segment heap */
   svm_fifo_free_ooo_data (f);
@@ -768,25 +763,21 @@ fifo_segment_grow_fifo (fifo_segment_t * fs, svm_fifo_t * f, u32 chunk_size)
   fl_index = fs_freelist_for_size (chunk_size);
   fss = fsh_slice_get (fsh, f->slice_index);
 
-  oldheap = ssvm_push_heap (fsh->ssvm_sh);
-
   c = fss->free_chunks[fl_index];
 
   if (!c)
     {
       fsh_check_mem (fsh);
       if (fsh_n_free_bytes (fsh) < chunk_size)
-	{
-	  ssvm_pop_heap (oldheap);
-	  return -1;
-	}
+	return -1;
 
+      oldheap = ssvm_push_heap (fsh->ssvm_sh);
       c = svm_fifo_chunk_alloc (chunk_size);
+      ssvm_pop_heap (oldheap);
+
       if (!c)
-	{
-	  ssvm_pop_heap (oldheap);
-	  return -1;
-	}
+	return -1;
+
       fsh_free_bytes_sub (fsh, chunk_size + sizeof (*c));
     }
   else
@@ -798,7 +789,6 @@ fifo_segment_grow_fifo (fifo_segment_t * fs, svm_fifo_t * f, u32 chunk_size)
 
   svm_fifo_add_chunk (f, c);
 
-  ssvm_pop_heap (oldheap);
   return 0;
 }
 
@@ -808,10 +798,8 @@ fifo_segment_collect_fifo_chunks (fifo_segment_t * fs, svm_fifo_t * f)
   fifo_segment_header_t *fsh = fs->h;
   svm_fifo_chunk_t *cur, *next;
   fifo_segment_slice_t *fss;
-  void *oldheap;
   int fl_index;
 
-  oldheap = ssvm_push_heap (fsh->ssvm_sh);
   cur = svm_fifo_collect_chunks (f);
 
   fss = fsh_slice_get (fsh, f->slice_index);
@@ -825,8 +813,6 @@ fifo_segment_collect_fifo_chunks (fifo_segment_t * fs, svm_fifo_t * f)
       cur = next;
     }
 
-  ssvm_pop_heap (oldheap);
-
   return 0;
 }
 
diff --git a/src/svm/svm_fifo.c b/src/svm/svm_fifo.c
index 975a82026f7..3df67135cfd 100644
--- a/src/svm/svm_fifo.c
+++ b/src/svm/svm_fifo.c
@@ -413,8 +413,8 @@ svm_fifo_init_chunks (svm_fifo_t * f)
     return;
 
   f->flags |= SVM_FIFO_F_MULTI_CHUNK;
-  rb_tree_init (&f->chunk_lookup);
-  rb_tree_add2 (&f->chunk_lookup, 0, pointer_to_uword (f->start_chunk));
+  rb_tree_init (&f->ooo_enq_lookup);
+  rb_tree_init (&f->ooo_deq_lookup);
 
   f->start_chunk->start_byte = 0;
   prev = f->start_chunk;
@@ -423,7 +423,6 @@ svm_fifo_init_chunks (svm_fifo_t * f)
   while (c != f->start_chunk)
     {
       c->start_byte = prev->start_byte + prev->length;
-      rb_tree_add2 (&f->chunk_lookup, c->start_byte, pointer_to_uword (c));
       prev = c;
       c = c->next;
     }
@@ -458,6 +457,7 @@ svm_fifo_create (u32 data_size_in_bytes)
   c->next = c;
   c->start_byte = 0;
   c->length = data_size_in_bytes;
+  c->rb_index = RBTREE_TNIL_INDEX;
   f->start_chunk = f->end_chunk = c;
 
   svm_fifo_init (f, data_size_in_bytes);
@@ -491,6 +491,60 @@ svm_fifo_chunk_includes_pos (svm_fifo_chunk_t * c, u32 pos)
   return (pos >= c->start_byte && pos < c->start_byte + c->length);
 }
 
+static rb_node_t *
+svm_fifo_find_node_rbtree (rb_tree_t * rt, u32 pos)
+{
+  rb_node_t *cur, *prev;
+
+  cur = rb_node (rt, rt->root);
+  if (PREDICT_FALSE (rb_node_is_tnil (rt, cur)))
+    return 0;
+
+  while (pos != cur->key)
+    {
+      prev = cur;
+      if (pos < cur->key)
+	{
+	  cur = rb_node_left (rt, cur);
+	  if (rb_node_is_tnil (rt, cur))
+	    {
+	      cur = rb_tree_predecessor (rt, prev);
+	      break;
+	    }
+	}
+      else
+	{
+	  cur = rb_node_right (rt, cur);
+	  if (rb_node_is_tnil (rt, cur))
+	    {
+	      cur = prev;
+	      break;
+	    }
+	}
+    }
+
+  if (rb_node_is_tnil (rt, cur))
+    return 0;
+
+  return cur;
+}
+
+static svm_fifo_chunk_t *
+svm_fifo_find_chunk_rbtree (rb_tree_t * rt, u32 pos)
+{
+  svm_fifo_chunk_t *c;
+  rb_node_t *n;
+
+  n = svm_fifo_find_node_rbtree (rt, pos);
+  if (!n)
+    return 0;
+  c = uword_to_pointer (n->opaque, svm_fifo_chunk_t *);
+  if (svm_fifo_chunk_includes_pos (c, pos))
+    return c;
+
+  return 0;
+}
+
 /**
  * Find chunk for given byte position
  *
@@ -502,44 +556,170 @@ svm_fifo_chunk_includes_pos (svm_fifo_chunk_t * c, u32 pos)
 static svm_fifo_chunk_t *
 svm_fifo_find_chunk (svm_fifo_t * f, u32 pos)
 {
-  rb_tree_t *rt = &f->chunk_lookup;
-  rb_node_t *cur, *prev;
   svm_fifo_chunk_t *c;
 
-  cur = rb_node (rt, rt->root);
-  while (pos != cur->key)
+  c = f->start_chunk;
+  do
     {
-      prev = cur;
-      if (pos < cur->key)
-	cur = rb_node_left (rt, cur);
-      else
-	cur = rb_node_right (rt, cur);
+      if (svm_fifo_chunk_includes_pos (c, pos))
+	return c;
+      c = c->next;
+    }
+  while (c != f->start_chunk);
+
+  return 0;
+}
+
+static void
+svm_fifo_update_ooo_enq (svm_fifo_t * f, u32 ref_pos, u32 start_pos,
+			 u32 end_pos)
+{
+  rb_tree_t *rt = &f->ooo_enq_lookup;
+  svm_fifo_chunk_t *c;
+  rb_node_t *cur;
+
+  if (svm_fifo_chunk_includes_pos (f->ooo_enq, start_pos)
+      && svm_fifo_chunk_includes_pos (f->ooo_enq, end_pos)
+      && ref_pos < start_pos)
+    return;
 
-      if (rb_node_is_tnil (rt, cur))
+  if (rt->root == RBTREE_TNIL_INDEX)
+    {
+      c = f->tail_chunk;
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+    }
+  else
+    {
+      cur = svm_fifo_find_node_rbtree (rt, start_pos);
+      c = uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
+      if (ref_pos > start_pos && c->start_byte > start_pos)
 	{
-	  /* Hit tnil as a left child. Find predecessor */
-	  if (pos < prev->key)
-	    {
-	      cur = rb_tree_predecessor (rt, prev);
-	      if (rb_node_is_tnil (rt, cur))
-		return 0;
-	      c = uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
-	      if (svm_fifo_chunk_includes_pos (c, pos))
-		return c;
-	      return 0;
-	    }
-	  /* Hit tnil as a right child. Check if this is the one */
-	  c = uword_to_pointer (prev->opaque, svm_fifo_chunk_t *);
-	  if (svm_fifo_chunk_includes_pos (c, pos))
-	    return c;
+	  c = f->end_chunk;
+	  ASSERT (c->rb_index != RBTREE_TNIL_INDEX);
+	}
+    }
 
-	  return 0;
+  if (svm_fifo_chunk_includes_pos (c, start_pos))
+    f->ooo_enq = c;
+
+  if (svm_fifo_chunk_includes_pos (c, end_pos) && ref_pos < end_pos)
+    return;
+
+  do
+    {
+      c = c->next;
+      if (c->rb_index != RBTREE_TNIL_INDEX)
+	break;
+
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+
+      if (svm_fifo_chunk_includes_pos (c, start_pos))
+	f->ooo_enq = c;
+
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+}
+
+static void
+svm_fifo_update_ooo_deq (svm_fifo_t * f, u32 ref_pos, u32 start_pos,
+			 u32 end_pos)
+{
+  rb_tree_t *rt = &f->ooo_deq_lookup;
+  rb_node_t *cur;
+  svm_fifo_chunk_t *c;
+
+  if (svm_fifo_chunk_includes_pos (f->ooo_deq, start_pos)
+      && svm_fifo_chunk_includes_pos (f->ooo_deq, end_pos)
+      && ref_pos < start_pos)
+    return;
+
+  if (rt->root == RBTREE_TNIL_INDEX)
+    {
+      c = f->head_chunk;
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+    }
+  else
+    {
+      cur = svm_fifo_find_node_rbtree (rt, start_pos);
+      c = uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
+      if (ref_pos > start_pos && c->start_byte > start_pos)
+	{
+	  c = f->end_chunk;
+	  ASSERT (c->rb_index != RBTREE_TNIL_INDEX);
 	}
     }
 
-  if (!rb_node_is_tnil (rt, cur))
-    return uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
-  return 0;
+  if (svm_fifo_chunk_includes_pos (c, start_pos))
+    f->ooo_deq = c;
+
+  if (svm_fifo_chunk_includes_pos (c, end_pos) && ref_pos < end_pos)
+    return;
+
+  do
+    {
+      c = c->next;
+      if (c->rb_index != RBTREE_TNIL_INDEX)
+	break;
+
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+
+      if (svm_fifo_chunk_includes_pos (c, start_pos))
+	f->ooo_deq = c;
+
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+}
+
+void
+svm_fifo_ooo_deq_track (svm_fifo_t * f, u32 start_pos, u32 end_pos)
+{
+  rb_tree_t *rt = &f->ooo_deq_lookup;
+  svm_fifo_chunk_t *c;
+
+  if (svm_fifo_chunk_includes_pos (f->ooo_deq, end_pos)
+      && start_pos < end_pos)
+    return;
+
+  c = f->ooo_deq->next;
+  do
+    {
+      ASSERT (c->rb_index == RBTREE_TNIL_INDEX);
+      rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+
+      c = c->next;
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+}
+
+static svm_fifo_chunk_t *
+svm_fifo_lookup_clear_chunks (svm_fifo_t * f, rb_tree_t * rt,
+			      svm_fifo_chunk_t * start, u32 start_pos,
+			      u32 end_pos)
+{
+  svm_fifo_chunk_t *c;
+  rb_node_t *n;
+
+  /* Nothing to do if still in the same chunk and not wrapped */
+  if (svm_fifo_chunk_includes_pos (start, end_pos) && start_pos < end_pos)
+    return start;
+
+  c = start;
+  do
+    {
+      if (c->rb_index == RBTREE_TNIL_INDEX)
+	{
+	  c = c->next;
+	  continue;
+	}
+
+      n = rb_node (rt, c->rb_index);
+      rb_tree_del_node (rt, n);
+      c->rb_index = RBTREE_TNIL_INDEX;
+      c = c->next;
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+
+  return c;
 }
 
 static inline void
@@ -585,8 +765,8 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
   if (!(f->flags & SVM_FIFO_F_MULTI_CHUNK))
     {
       ASSERT (f->start_chunk->next == f->start_chunk);
-      rb_tree_init (&f->chunk_lookup);
-      rb_tree_add2 (&f->chunk_lookup, 0, pointer_to_uword (f->start_chunk));
+      rb_tree_init (&f->ooo_enq_lookup);
+      rb_tree_init (&f->ooo_deq_lookup);
       f->flags |= SVM_FIFO_F_MULTI_CHUNK;
     }
 
@@ -608,8 +788,7 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
       while (cur)
 	{
 	  cur->start_byte = prev->start_byte + prev->length;
-	  rb_tree_add2 (&f->chunk_lookup, cur->start_byte,
-			pointer_to_uword (cur));
+	  cur->rb_index = RBTREE_TNIL_INDEX;
 	  prev = cur;
 	  cur = cur->next;
 	}
@@ -637,7 +816,12 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
 	  while (cur != f->start_chunk)
 	    {
 	      /* remove any existing rb_tree entry */
-	      rb_tree_del (&f->chunk_lookup, cur->start_byte);
+	      if (cur->rb_index != RBTREE_TNIL_INDEX)
+		{
+		  rb_tree_del (&f->ooo_enq_lookup, cur->start_byte);
+		  rb_tree_del (&f->ooo_deq_lookup, cur->start_byte);
+		}
+	      cur->rb_index = RBTREE_TNIL_INDEX;
 	      cur = cur->next;
 	    }
 
@@ -647,8 +831,7 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
 	    {
 	      add_bytes += c->length;
 	      c->start_byte = prev->start_byte + prev->length;
-	      rb_tree_add2 (&f->chunk_lookup, c->start_byte,
-			    pointer_to_uword (c));
+	      cur->rb_index = RBTREE_TNIL_INDEX;
 
 	      prev = c;
 	      c = c->next;
@@ -660,8 +843,6 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
 	  while (cur != f->start_chunk)
 	    {
 	      cur->start_byte = prev->start_byte + prev->length;
-	      rb_tree_add2 (&f->chunk_lookup, cur->start_byte,
-			    pointer_to_uword (cur));
 	      prev = cur;
 	      cur = cur->next;
 	    }
@@ -694,8 +875,7 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
   while (cur)
     {
       cur->start_byte = prev->start_byte + prev->length;
-      rb_tree_add2 (&f->chunk_lookup, cur->start_byte,
-		    pointer_to_uword (cur));
+      cur->rb_index = RBTREE_TNIL_INDEX;
       prev = cur;
       cur = cur->next;
     }
@@ -723,7 +903,11 @@ svm_fifo_collect_chunks (svm_fifo_t * f)
   cur = list;
   while (cur)
     {
-      rb_tree_del (&f->chunk_lookup, cur->start_byte);
+      if (cur->rb_index != RBTREE_TNIL_INDEX)
+	{
+	  rb_tree_del (&f->ooo_enq_lookup, cur->start_byte);
+	  rb_tree_del (&f->ooo_deq_lookup, cur->start_byte);
+	}
       cur = cur->next;
     }
 
@@ -846,7 +1030,8 @@ svm_fifo_reduce_size (svm_fifo_t * f, u32 len, u8 try_shrink)
 void
 svm_fifo_free_chunk_lookup (svm_fifo_t * f)
 {
-  rb_tree_free_nodes (&f->chunk_lookup);
+  rb_tree_free_nodes (&f->ooo_enq_lookup);
+  rb_tree_free_nodes (&f->ooo_deq_lookup);
 }
 
 void
@@ -910,8 +1095,10 @@ svm_fifo_enqueue (svm_fifo_t * f, u32 len, const u8 * src)
   if (PREDICT_FALSE (f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX))
     {
       len += ooo_segment_try_collect (f, len, &tail);
-      if (!svm_fifo_chunk_includes_pos (f->tail_chunk, tail))
-	f->tail_chunk = svm_fifo_find_chunk (f, tail);
+      if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+	f->tail_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_enq_lookup,
+						      f->tail_chunk, f->tail,
+						      tail);
     }
 
   /* store-rel: producer owned index (paired with load-acq in consumer) */
@@ -949,8 +1136,9 @@ svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len, u8 * src)
   ooo_segment_add (f, offset, head, tail, len);
   tail_idx = (tail + offset) % f->size;
 
-  if (!svm_fifo_chunk_includes_pos (f->ooo_enq, tail_idx))
-    f->ooo_enq = svm_fifo_find_chunk (f, tail_idx);
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    svm_fifo_update_ooo_enq (f, f->tail, tail_idx,
+			     (tail_idx + len) % f->size);
 
   svm_fifo_copy_to_chunk (f, f->ooo_enq, tail_idx, src, len, &f->ooo_enq);
 
@@ -970,8 +1158,10 @@ svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len)
   tail = f->tail;
   tail = (tail + len) % f->size;
 
-  if (!svm_fifo_chunk_includes_pos (f->tail_chunk, tail))
-    f->tail_chunk = svm_fifo_find_chunk (f, tail);
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    f->tail_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_enq_lookup,
+						  f->tail_chunk, f->tail,
+						  tail);
 
   /* store-rel: producer owned index (paired with load-acq in consumer) */
   clib_atomic_store_rel_n (&f->tail, tail);
@@ -1018,8 +1208,9 @@ svm_fifo_peek (svm_fifo_t * f, u32 offset, u32 len, u8 * dst)
 
   len = clib_min (cursize - offset, len);
   head_idx = (head + offset) % f->size;
-  if (!svm_fifo_chunk_includes_pos (f->ooo_deq, head_idx))
-    f->ooo_deq = svm_fifo_find_chunk (f, head_idx);
+
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    svm_fifo_update_ooo_deq (f, head, head_idx, (head_idx + len) % f->size);
 
   svm_fifo_copy_from_chunk (f, f->ooo_deq, head_idx, dst, len, &f->ooo_deq);
   return len;
@@ -1045,8 +1236,10 @@ svm_fifo_dequeue_drop (svm_fifo_t * f, u32 len)
   /* move head */
   head = (head + total_drop_bytes) % f->size;
 
-  if (!svm_fifo_chunk_includes_pos (f->head_chunk, head))
-    f->head_chunk = svm_fifo_find_chunk (f, head);
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    f->head_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_deq_lookup,
+						  f->head_chunk, f->head,
+						  head);
 
   if (PREDICT_FALSE (f->flags & SVM_FIFO_F_GROW))
     svm_fifo_try_grow (f, head);
@@ -1063,8 +1256,10 @@ svm_fifo_dequeue_drop_all (svm_fifo_t * f)
   /* consumer foreign index */
   u32 tail = clib_atomic_load_acq_n (&f->tail);
 
-  if (!svm_fifo_chunk_includes_pos (f->head_chunk, tail))
-    f->head_chunk = svm_fifo_find_chunk (f, tail);
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    f->head_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_deq_lookup,
+						  f->head_chunk, tail,
+						  tail - 1);
 
   if (PREDICT_FALSE (f->flags & SVM_FIFO_F_GROW))
     svm_fifo_try_grow (f, tail);
@@ -1220,6 +1415,35 @@ svm_fifo_is_sane (svm_fifo_t * f)
 	    return 0;
 	  if (prev && (prev->start_byte + prev->length != c->start_byte))
 	    return 0;
+
+	  if (c->rb_index != RBTREE_TNIL_INDEX)
+	    {
+	      u8 found = 0;
+
+	      tmp = svm_fifo_find_chunk_rbtree (&f->ooo_enq_lookup,
+						c->start_byte);
+	      if (tmp)
+		{
+		  found = 1;
+		  if (tmp != c)
+		    return 0;
+		}
+
+	      tmp = svm_fifo_find_chunk_rbtree (&f->ooo_deq_lookup,
+						c->start_byte);
+	      if (tmp)
+		{
+		  if (found)
+		    return 0;
+
+		  found = 1;
+		  if (tmp != c)
+		    return 0;
+		}
+	      if (!found)
+		return 0;
+	    }
+
 	  size += c->length;
 	  prev = c;
 	  c = c->next;
diff --git a/src/svm/svm_fifo.h b/src/svm/svm_fifo.h
index 0b7c70790c0..2b6e8542cdf 100644
--- a/src/svm/svm_fifo.h
+++ b/src/svm/svm_fifo.h
@@ -60,6 +60,7 @@ typedef struct svm_fifo_chunk_
   u32 start_byte;		/**< chunk start byte */
   u32 length;			/**< length of chunk in bytes */
   struct svm_fifo_chunk_ *next;	/**< pointer to next chunk in linked-lists */
+  rb_node_index_t rb_index;	/**< node index if chunk in rbtree */
   u8 data[0];			/**< start of chunk data */
 } svm_fifo_chunk_t;
 
@@ -80,8 +81,8 @@ typedef struct _svm_fifo
   u32 nitems;			/**< usable size (size-1) */
   svm_fifo_chunk_t *start_chunk;/**< first chunk in fifo chunk list */
   svm_fifo_chunk_t *end_chunk;	/**< end chunk in fifo chunk list */
-  svm_fifo_chunk_t *new_chunks;	/**< chunks yet to be added to list */
-  rb_tree_t chunk_lookup;	/**< rbtree for chunk lookup */
+  rb_tree_t ooo_enq_lookup;	/**< rbtree for ooo enq chunk lookup */
+  rb_tree_t ooo_deq_lookup;	/**< rbtree for ooo deq chunk lookup */
   u8 flags;			/**< fifo flags */
   u8 slice_index;		/**< segment slice for fifo */
 
@@ -96,6 +97,7 @@ typedef struct _svm_fifo
   u32 segment_index;		/**< segment index in segment manager */
   struct _svm_fifo *next;	/**< next in freelist/active chain */
   struct _svm_fifo *prev;	/**< prev in active chain */
+  svm_fifo_chunk_t *new_chunks;	/**< chunks yet to be added to list */
   u32 size_decrement;		/**< bytes to remove from fifo */
 
     CLIB_CACHE_LINE_ALIGN_MARK (consumer);
diff --git a/src/vppinfra/rbtree.h b/src/vppinfra/rbtree.h
index 65580584b6d..dde2fbfb836 100644
--- a/src/vppinfra/rbtree.h
+++ b/src/vppinfra/rbtree.h
@@ -53,6 +53,7 @@ rb_node_index_t rb_tree_add2 (rb_tree_t * rt, u32 key, uword opaque);
 rb_node_index_t rb_tree_add_custom (rb_tree_t * rt, u32 key, uword opaque,
 				    rb_tree_lt_fn ltfn);
 void rb_tree_del (rb_tree_t * rt, u32 key);
+void rb_tree_del_node (rb_tree_t * rt, rb_node_t * z);
 void rb_tree_del_custom (rb_tree_t * rt, u32 key, rb_tree_lt_fn ltfn);
 void rb_tree_free_nodes (rb_tree_t * rt);
 u32 rb_tree_n_nodes (rb_tree_t * rt);