1 files changed, 208 insertions, 54 deletions

diff --git a/src/svm/svm_fifo.c b/src/svm/svm_fifo.c
index d5638777290..e017b619d15 100644
--- a/src/svm/svm_fifo.c
+++ b/src/svm/svm_fifo.c
@@ -135,7 +135,7 @@ svm_fifo_free_ooo_data (svm_fifo_t * f)
 }
 
 static inline ooo_segment_t *
-ooo_segment_get_prev (svm_fifo_t * f, ooo_segment_t * s)
+ooo_segment_prev (svm_fifo_t * f, ooo_segment_t * s)
 {
   if (s->prev == OOO_SEGMENT_INVALID_INDEX)
     return 0;
@@ -222,7 +222,7 @@ ooo_segment_add (svm_fifo_t * f, u32 offset, u32 head, u32 tail, u32 length)
     s = pool_elt_at_index (f->ooo_segments, s->next);
 
   /* If we have a previous and we overlap it, use it as starting point */
-  prev = ooo_segment_get_prev (f, s);
+  prev = ooo_segment_prev (f, s);
   if (prev
       && position_leq (f, offset_pos, ooo_segment_end_pos (f, prev), tail))
     {
@@ -374,6 +374,20 @@ ooo_segment_try_collect (svm_fifo_t * f, u32 n_bytes_enqueued, u32 * tail)
   return bytes;
 }
 
+static ooo_segment_t *
+ooo_segment_last (svm_fifo_t * f)
+{
+  ooo_segment_t *s;
+
+  if (f->ooos_list_head == OOO_SEGMENT_INVALID_INDEX)
+    return 0;
+
+  s = svm_fifo_first_ooo_segment (f);
+  while (s->next != OOO_SEGMENT_INVALID_INDEX)
+    s = pool_elt_at_index (f->ooo_segments, s->next);
+  return s;
+}
+
 void
 svm_fifo_init (svm_fifo_t * f, u32 size)
 {
@@ -434,8 +448,63 @@ svm_fifo_chunk_alloc (u32 size)
   return c;
 }
 
+static inline u8
+svm_fifo_chunk_includes_pos (svm_fifo_chunk_t * c, u32 pos)
+{
+  return (pos >= c->start_byte && pos < c->start_byte + c->length);
+}
+
+/**
+ * Find chunk for given byte position
+ *
+ * @param f	fifo
+ * @param pos	normalized position in fifo
+ *
+ * @return chunk that includes given position or 0
+ */
+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)
+    {
+      prev = cur;
+      if (pos < cur->key)
+	cur = rb_node_left (rt, cur);
+      else
+	cur = rb_node_right (rt, cur);
+
+      if (rb_node_is_tnil (rt, cur))
+	{
+	  /* Hit tnil as a left child. Find predecessor */
+	  if (pos < prev->key)
+	    {
+	      cur = rb_tree_predecessor (rt, prev);
+	      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;
+
+	  return 0;
+	}
+    }
+
+  if (!rb_node_is_tnil (rt, cur))
+    return uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
+  return 0;
+}
+
 static inline void
-svm_fifo_size_update (svm_fifo_t * f, svm_fifo_chunk_t * c)
+svm_fifo_grow (svm_fifo_t * f, svm_fifo_chunk_t * c)
 {
   svm_fifo_chunk_t *prev;
   u32 add_bytes = 0;
@@ -458,13 +527,13 @@ svm_fifo_size_update (svm_fifo_t * f, svm_fifo_chunk_t * c)
 }
 
 static void
-svm_fifo_try_size_update (svm_fifo_t * f, u32 new_head)
+svm_fifo_try_grow (svm_fifo_t * f, u32 new_head)
 {
   if (new_head > f->tail)
     return;
 
-  svm_fifo_size_update (f, f->new_chunks);
-  f->flags &= ~SVM_FIFO_F_SIZE_UPDATE;
+  svm_fifo_grow (f, f->new_chunks);
+  f->flags &= ~SVM_FIFO_F_GROW;
 }
 
 void
@@ -472,7 +541,8 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
 {
   svm_fifo_chunk_t *cur, *prev;
 
-  /* Initialize rbtree if needed and add default chunk to it */
+  /* Initialize rbtree if needed and add default chunk to it. Expectation is
+   * that this is called with the heap where the rbtree's pool is pushed. */
   if (!(f->flags & SVM_FIFO_F_MULTI_CHUNK))
     {
       rb_tree_init (&f->chunk_lookup);
@@ -480,8 +550,7 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
       f->flags |= SVM_FIFO_F_MULTI_CHUNK;
     }
 
-  /* Initialize chunks and add to lookup rbtree. Expectation is that this is
-   * called with the heap where the rbtree's pool is pushed. */
+  /* Initialize chunks and add to lookup rbtree */
   cur = c;
   if (f->new_chunks)
     {
@@ -506,7 +575,7 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
   if (!svm_fifo_is_wrapped (f))
     {
       ASSERT (!f->new_chunks);
-      svm_fifo_size_update (f, c);
+      svm_fifo_grow (f, c);
       return;
     }
 
@@ -514,63 +583,129 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
   if (!f->new_chunks)
     {
       f->new_chunks = c;
-      f->flags |= SVM_FIFO_F_SIZE_UPDATE;
+      f->flags |= SVM_FIFO_F_GROW;
     }
 }
 
-static inline u8
-svm_fifo_chunk_includes_pos (svm_fifo_chunk_t * c, u32 pos)
+/**
+ * Removes chunks that are after fifo end byte
+ */
+svm_fifo_chunk_t *
+svm_fifo_collect_chunks (svm_fifo_t * f)
 {
-  return (pos >= c->start_byte && pos < c->start_byte + c->length);
+  svm_fifo_chunk_t *list, *cur;
+
+  f->flags &= ~SVM_FIFO_F_COLLECT_CHUNKS;
+
+  list = f->new_chunks;
+  f->new_chunks = 0;
+  cur = list;
+  while (cur)
+    {
+      rb_tree_del (&f->chunk_lookup, cur->start_byte);
+      cur = cur->next;
+    }
+
+  return list;
+}
+
+void
+svm_fifo_try_shrink (svm_fifo_t * f, u32 head, u32 tail)
+{
+  u32 len_to_shrink = 0, tail_pos, len;
+  svm_fifo_chunk_t *cur, *prev, *next, *start;
+
+  tail_pos = tail;
+  if (f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX)
+    {
+      ooo_segment_t *last = ooo_segment_last (f);
+      tail_pos = ooo_segment_end_pos (f, last);
+    }
+
+  if (f->size_decrement)
+    {
+      /* Figure out available free space considering that there may be
+       * ooo segments */
+      len = clib_min (f->size_decrement, f_free_count (f, head, tail_pos));
+      f->nitems -= len;
+      f->size_decrement -= len;
+    }
+
+  /* Remove tail chunks if the following hold:
+   * - not wrapped
+   * - last used byte less than start of last chunk
+   */
+  if (tail_pos >= head && tail_pos <= f->end_chunk->start_byte)
+    {
+      /* Lookup the last position not to be removed. Since size still needs
+       * to be nitems + 1, nitems must fall within the usable space */
+      tail_pos = tail_pos > 0 ? tail_pos - 1 : tail_pos;
+      prev = svm_fifo_find_chunk (f, clib_max (f->nitems, tail_pos));
+      next = prev->next;
+      while (next != f->start_chunk)
+	{
+	  cur = next;
+	  next = cur->next;
+	  len_to_shrink += cur->length;
+	}
+      if (len_to_shrink)
+	{
+	  f->size -= len_to_shrink;
+	  start = prev->next;
+	  prev->next = f->start_chunk;
+	  f->end_chunk = prev;
+	  cur->next = f->new_chunks;
+	  f->new_chunks = start;
+	}
+    }
+
+  if (!f->size_decrement && f->size == f->nitems + 1)
+    {
+      f->flags &= ~SVM_FIFO_F_SHRINK;
+      f->flags |= SVM_FIFO_F_COLLECT_CHUNKS;
+      if (f->start_chunk == f->start_chunk->next)
+	f->flags &= ~SVM_FIFO_F_MULTI_CHUNK;
+    }
 }
 
 /**
- * Find chunk for given byte position
- *
- * @param f	fifo
- * @param pos	normalized position in fifo
- *
- * @return chunk that includes given position or 0
+ * Request to reduce fifo size by amount of bytes
  */
-static svm_fifo_chunk_t *
-svm_fifo_find_chunk (svm_fifo_t * f, u32 pos)
+int
+svm_fifo_reduce_size (svm_fifo_t * f, u32 len, u8 try_shrink)
 {
-  rb_tree_t *rt = &f->chunk_lookup;
-  rb_node_t *cur, *prev;
-  svm_fifo_chunk_t *c;
+  svm_fifo_chunk_t *cur;
+  u32 actual_len = 0;
 
-  cur = rb_node (rt, rt->root);
-  while (pos != cur->key)
+  if (len > f->nitems)
+    return 0;
+
+  /* last chunk that will not be removed */
+  cur = svm_fifo_find_chunk (f, f->nitems - len);
+
+  /* sum length of chunks that will be removed */
+  cur = cur->next;
+  while (cur != f->start_chunk)
     {
-      prev = cur;
-      if (pos < cur->key)
-	cur = rb_node_left (rt, cur);
-      else
-	cur = rb_node_right (rt, cur);
+      actual_len += cur->length;
+      cur = cur->next;
+    }
 
-      if (rb_node_is_tnil (rt, cur))
-	{
-	  /* Hit tnil as a left child. Find predecessor */
-	  if (pos < prev->key)
-	    {
-	      cur = rb_tree_predecessor (rt, prev);
-	      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;
+  ASSERT (actual_len <= len);
+  if (!actual_len)
+    return 0;
 
-	  return 0;
-	}
+  f->size_decrement = actual_len;
+  f->flags |= SVM_FIFO_F_SHRINK;
+
+  if (try_shrink)
+    {
+      u32 head, tail;
+      f_load_head_tail_prod (f, &head, &tail);
+      svm_fifo_try_shrink (f, head, tail);
     }
 
-  if (!rb_node_is_tnil (rt, cur))
-    return uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
-  return 0;
+  return actual_len;
 }
 
 void
@@ -660,6 +795,9 @@ svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len, u8 * src)
 
   f_load_head_tail_prod (f, &head, &tail);
 
+  if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SHRINK))
+    svm_fifo_try_shrink (f, head, tail);
+
   /* free space in fifo can only increase during enqueue: SPSC */
   free_count = f_free_count (f, head, tail);
 
@@ -680,6 +818,22 @@ svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len, u8 * src)
   return 0;
 }
 
+/**
+ * Advance tail
+ */
+void
+svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len)
+{
+  u32 tail;
+
+  ASSERT (len <= svm_fifo_max_enqueue_prod (f));
+  /* load-relaxed: producer owned index */
+  tail = f->tail;
+  tail = (tail + len) % f->size;
+  /* store-rel: producer owned index (paired with load-acq in consumer) */
+  clib_atomic_store_rel_n (&f->tail, tail);
+}
+
 int
 svm_fifo_dequeue (svm_fifo_t * f, u32 len, u8 * dst)
 {
@@ -697,8 +851,8 @@ svm_fifo_dequeue (svm_fifo_t * f, u32 len, u8 * dst)
   svm_fifo_copy_from_chunk (f, f->head_chunk, head, dst, len, &f->head_chunk);
   head = (head + len) % f->size;
 
-  if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SIZE_UPDATE))
-    svm_fifo_try_size_update (f, head);
+  if (PREDICT_FALSE (f->flags & SVM_FIFO_F_GROW))
+    svm_fifo_try_grow (f, head);
 
   /* store-rel: consumer owned index (paired with load-acq in producer) */
   clib_atomic_store_rel_n (&f->head, head);