X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fsvm%2Fsvm_fifo_segment.c;h=a42225c8345876a174b561f04e70d9e44bf7eabc;hb=b7b929931a07fbb27b43d5cd105f366c3e29807e;hp=eef2168c47759e9c86f5a5850688678623f44cd2;hpb=10d8cc6bf92851fcaec4a6b4c6d3554dc1eb2386;p=vpp.git

diff --git a/src/svm/svm_fifo_segment.c b/src/svm/svm_fifo_segment.c
index eef2168c477..a42225c8345 100644
--- a/src/svm/svm_fifo_segment.c
+++ b/src/svm/svm_fifo_segment.c
@@ -18,31 +18,118 @@
 svm_fifo_segment_main_t svm_fifo_segment_main;
 
 static void
-preallocate_fifo_pairs (svm_fifo_segment_header_t * fsh,
-			svm_fifo_segment_create_args_t * a)
+allocate_new_fifo_chunk (svm_fifo_segment_header_t * fsh,
+			 u32 data_size_in_bytes, int chunk_size)
 {
-  u32 rx_fifo_size, tx_fifo_size;
+  int freelist_index;
+  u32 size;
+  u8 *fifo_space;
+  u32 rounded_data_size;
   svm_fifo_t *f;
+  int i;
+
+  rounded_data_size = (1 << (max_log2 (data_size_in_bytes)));
+  freelist_index = max_log2 (rounded_data_size)
+    - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
+
+  /* Calculate space requirement $$$ round-up data_size_in_bytes */
+  size = (sizeof (*f) + rounded_data_size) * chunk_size;
+
+  /* Allocate fifo space. May fail. */
+  fifo_space = clib_mem_alloc_aligned_at_offset
+    (size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
+     0 /* os_out_of_memory */ );
+
+  /* Out of space.. */
+  if (fifo_space == 0)
+    return;
+
+  /* Carve fifo space */
+  f = (svm_fifo_t *) fifo_space;
+  for (i = 0; i < chunk_size; i++)
+    {
+      f->freelist_index = freelist_index;
+      f->next = fsh->free_fifos[freelist_index];
+      fsh->free_fifos[freelist_index] = f;
+      fifo_space += sizeof (*f) + rounded_data_size;
+      f = (svm_fifo_t *) fifo_space;
+    }
+}
+
+/**
+ * Pre-allocates fifo pairs in fifo segment
+ *
+ * The number of fifos pre-allocated is the minimum of the requested number
+ * of pairs and the maximum number that fit within the segment. If the maximum
+ * is hit, the number of fifo pairs requested is updated by subtracting the
+ * number of fifos that have been successfully allocated.
+ */
+void
+svm_fifo_segment_preallocate_fifo_pairs (svm_fifo_segment_private_t * s,
+					 u32 rx_fifo_size, u32 tx_fifo_size,
+					 u32 * n_fifo_pairs)
+{
+  u32 rx_rounded_data_size, tx_rounded_data_size, pair_size;
+  u32 rx_fifos_size, tx_fifos_size, pairs_to_allocate;
+  int rx_freelist_index, tx_freelist_index;
+  ssvm_shared_header_t *sh = s->ssvm.sh;
+  svm_fifo_segment_header_t *fsh = s->h;
   u8 *rx_fifo_space, *tx_fifo_space;
+  uword space_available;
+  void *oldheap;
+  svm_fifo_t *f;
   int i;
 
   /* Parameter check */
-  if (a->rx_fifo_size == 0 || a->tx_fifo_size == 0
-      || a->preallocated_fifo_pairs == 0)
+  if (rx_fifo_size == 0 || tx_fifo_size == 0 || *n_fifo_pairs == 0)
     return;
 
+  if (rx_fifo_size < FIFO_SEGMENT_MIN_FIFO_SIZE ||
+      rx_fifo_size > FIFO_SEGMENT_MAX_FIFO_SIZE)
+    {
+      clib_warning ("rx fifo_size out of range %d", rx_fifo_size);
+      return;
+    }
+
+  if (tx_fifo_size < FIFO_SEGMENT_MIN_FIFO_SIZE ||
+      tx_fifo_size > FIFO_SEGMENT_MAX_FIFO_SIZE)
+    {
+      clib_warning ("tx fifo_size out of range %d", rx_fifo_size);
+      return;
+    }
+
+  rx_rounded_data_size = (1 << (max_log2 (rx_fifo_size)));
+  rx_freelist_index = max_log2 (rx_fifo_size)
+    - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
+  tx_rounded_data_size = (1 << (max_log2 (tx_fifo_size)));
+  tx_freelist_index = max_log2 (tx_fifo_size)
+    - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
+
   /* Calculate space requirements */
-  rx_fifo_size = (sizeof (*f) + a->rx_fifo_size) * a->preallocated_fifo_pairs;
-  tx_fifo_size = (sizeof (*f) + a->tx_fifo_size) * a->preallocated_fifo_pairs;
+  pair_size = 2 * sizeof (*f) + rx_rounded_data_size + tx_rounded_data_size;
+#if USE_DLMALLOC == 0
+  space_available = s->ssvm.ssvm_size - mheap_bytes (sh->heap);
+#else
+  space_available = s->ssvm.ssvm_size - mspace_usable_size (sh->heap);
+#endif
+
+  pairs_to_allocate = clib_min (space_available / pair_size, *n_fifo_pairs);
+  rx_fifos_size = (sizeof (*f) + rx_rounded_data_size) * pairs_to_allocate;
+  tx_fifos_size = (sizeof (*f) + tx_rounded_data_size) * pairs_to_allocate;
 
+  vec_validate_init_empty (fsh->free_fifos,
+			   clib_max (rx_freelist_index, tx_freelist_index),
+			   0);
+
+  oldheap = ssvm_push_heap (sh);
   /* Allocate rx fifo space. May fail. */
   rx_fifo_space = clib_mem_alloc_aligned_at_offset
-    (rx_fifo_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
+    (rx_fifos_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
      0 /* os_out_of_memory */ );
 
   /* Same for TX */
   tx_fifo_space = clib_mem_alloc_aligned_at_offset
-    (tx_fifo_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
+    (tx_fifos_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
      0 /* os_out_of_memory */ );
 
   /* Make sure it worked. Clean up if it didn't... */
@@ -52,160 +139,187 @@ preallocate_fifo_pairs (svm_fifo_segment_header_t * fsh,
 	clib_mem_free (rx_fifo_space);
       else
 	clib_warning ("rx fifo preallocation failure: size %d npairs %d",
-		      a->rx_fifo_size, a->preallocated_fifo_pairs);
+		      rx_fifo_size, *n_fifo_pairs);
 
       if (tx_fifo_space)
 	clib_mem_free (tx_fifo_space);
       else
 	clib_warning ("tx fifo preallocation failure: size %d nfifos %d",
-		      a->tx_fifo_size, a->preallocated_fifo_pairs);
+		      tx_fifo_size, *n_fifo_pairs);
+      ssvm_pop_heap (oldheap);
       return;
     }
 
   /* Carve rx fifo space */
   f = (svm_fifo_t *) rx_fifo_space;
-  for (i = 0; i < a->preallocated_fifo_pairs; i++)
+  for (i = 0; i < pairs_to_allocate; i++)
     {
-      f->next = fsh->free_fifos[FIFO_SEGMENT_RX_FREELIST];
-      fsh->free_fifos[FIFO_SEGMENT_RX_FREELIST] = f;
-      rx_fifo_space += sizeof (*f) + a->rx_fifo_size;
+      f->freelist_index = rx_freelist_index;
+      f->next = fsh->free_fifos[rx_freelist_index];
+      fsh->free_fifos[rx_freelist_index] = f;
+      rx_fifo_space += sizeof (*f) + rx_rounded_data_size;
       f = (svm_fifo_t *) rx_fifo_space;
     }
   /* Carve tx fifo space */
   f = (svm_fifo_t *) tx_fifo_space;
-  for (i = 0; i < a->preallocated_fifo_pairs; i++)
+  for (i = 0; i < pairs_to_allocate; i++)
     {
-      f->next = fsh->free_fifos[FIFO_SEGMENT_TX_FREELIST];
-      fsh->free_fifos[FIFO_SEGMENT_TX_FREELIST] = f;
-      tx_fifo_space += sizeof (*f) + a->tx_fifo_size;
+      f->freelist_index = tx_freelist_index;
+      f->next = fsh->free_fifos[tx_freelist_index];
+      fsh->free_fifos[tx_freelist_index] = f;
+      tx_fifo_space += sizeof (*f) + tx_rounded_data_size;
       f = (svm_fifo_t *) tx_fifo_space;
     }
+
+  /* Account for the pairs allocated */
+  *n_fifo_pairs -= pairs_to_allocate;
+  ssvm_pop_heap (oldheap);
 }
 
-/** (master) create an svm fifo segment */
+/**
+ * Initialize svm fifo segment shared header
+ */
 int
-svm_fifo_segment_create (svm_fifo_segment_create_args_t * a)
+svm_fifo_segment_init (svm_fifo_segment_private_t * s)
 {
-  int rv;
-  svm_fifo_segment_private_t *s;
-  svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
-  ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
+  ssvm_shared_header_t *sh;
   void *oldheap;
 
+  sh = s->ssvm.sh;
+  oldheap = ssvm_push_heap (sh);
+
+  fsh = clib_mem_alloc (sizeof (*fsh));
+  clib_memset (fsh, 0, sizeof (*fsh));
+  s->h = sh->opaque[0] = fsh;
+
+  ssvm_pop_heap (oldheap);
+
+  sh->ready = 1;
+  return (0);
+}
+
+/**
+ * Create an svm fifo segment and initialize as master
+ */
+int
+svm_fifo_segment_create (svm_fifo_segment_create_args_t * a)
+{
+  svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
+  svm_fifo_segment_private_t *s;
+  int rv;
+
   /* Allocate a fresh segment */
   pool_get (sm->segments, s);
-  memset (s, 0, sizeof (*s));
+  clib_memset (s, 0, sizeof (*s));
 
   s->ssvm.ssvm_size = a->segment_size;
   s->ssvm.i_am_master = 1;
   s->ssvm.my_pid = getpid ();
-  s->ssvm.name = (u8 *) a->segment_name;
+  s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
   s->ssvm.requested_va = sm->next_baseva;
 
-  rv = ssvm_master_init (&s->ssvm, s - sm->segments);
-
-  if (rv)
+  if ((rv = ssvm_master_init (&s->ssvm, a->segment_type)))
     {
-      _vec_len (s) = vec_len (s) - 1;
+      pool_put (sm->segments, s);
       return (rv);
     }
 
-  /* Note; requested_va updated due to seg base addr randomization */
-  sm->next_baseva = s->ssvm.requested_va + a->segment_size;
-
-  sh = s->ssvm.sh;
-  oldheap = ssvm_push_heap (sh);
-
-  /* Set up svm_fifo_segment shared header */
-  fsh = clib_mem_alloc (sizeof (*fsh));
-  memset (fsh, 0, sizeof (*fsh));
-  sh->opaque[0] = fsh;
-  s->h = fsh;
-  fsh->segment_name = format (0, "%s%c", a->segment_name, 0);
-
-  preallocate_fifo_pairs (fsh, a);
-
-  ssvm_pop_heap (oldheap);
+  /* Note: requested_va updated due to seg base addr randomization */
+  sm->next_baseva = s->ssvm.sh->ssvm_va + a->segment_size;
 
-  sh->ready = 1;
-  a->new_segment_index = s - sm->segments;
+  svm_fifo_segment_init (s);
+  vec_add1 (a->new_segment_indices, s - sm->segments);
   return (0);
 }
 
-/** Create an svm fifo segment in process-private memory */
+/**
+ * Create an svm fifo segment in process-private memory
+ */
 int
 svm_fifo_segment_create_process_private (svm_fifo_segment_create_args_t * a)
 {
-  svm_fifo_segment_private_t *s;
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
+  svm_fifo_segment_private_t *s;
   ssvm_shared_header_t *sh;
-  svm_fifo_segment_header_t *fsh;
+  u32 rnd_size = 0;
+  u8 *heap;
+  u32 pagesize = clib_mem_get_page_size ();
 
-  /* Allocate a fresh segment */
   pool_get (sm->segments, s);
-  memset (s, 0, sizeof (*s));
+  clib_memset (s, 0, sizeof (*s));
 
-  s->ssvm.ssvm_size = ~0;
+  rnd_size = (a->segment_size + (pagesize - 1)) & ~pagesize;
+
+#if USE_DLMALLOC == 0
+  heap = mheap_alloc (0, rnd_size);
+  if (heap == 0)
+    {
+      clib_unix_warning ("mheap alloc");
+      pool_put (sm->segments, s);
+      return -1;
+    }
+  {
+    mheap_t *heap_header;
+    heap_header = mheap_header (heap);
+    heap_header->flags |= MHEAP_FLAG_THREAD_SAFE;
+  }
+#else
+  heap = create_mspace (rnd_size, 1 /* locked */ );
+#endif
+
+  s->ssvm.ssvm_size = rnd_size;
   s->ssvm.i_am_master = 1;
   s->ssvm.my_pid = getpid ();
-  s->ssvm.name = (u8 *) a->segment_name;
+  s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
   s->ssvm.requested_va = ~0;
 
   /* Allocate a [sic] shared memory header, in process memory... */
   sh = clib_mem_alloc_aligned (sizeof (*sh), CLIB_CACHE_LINE_BYTES);
   s->ssvm.sh = sh;
 
-  memset (sh, 0, sizeof (*sh));
-  sh->heap = clib_mem_get_heap ();
-
-  /* Set up svm_fifo_segment shared header */
-  fsh = clib_mem_alloc (sizeof (*fsh));
-  memset (fsh, 0, sizeof (*fsh));
-  sh->opaque[0] = fsh;
-  s->h = fsh;
-  fsh->segment_name = format (0, "%s%c", a->segment_name, 0);
+  clib_memset (sh, 0, sizeof (*sh));
+  sh->heap = heap;
 
-  preallocate_fifo_pairs (fsh, a);
+  svm_fifo_segment_init (s);
+  vec_add1 (a->new_segment_indices, s - sm->segments);
 
-  sh->ready = 1;
-  a->new_segment_index = s - sm->segments;
   return (0);
 }
 
-/** (slave) attach to an svm fifo segment */
+/**
+ * Attach as slave to an svm fifo segment
+ */
 int
 svm_fifo_segment_attach (svm_fifo_segment_create_args_t * a)
 {
-  int rv;
-  svm_fifo_segment_private_t *s;
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
-  ssvm_shared_header_t *sh;
-  svm_fifo_segment_header_t *fsh;
+  svm_fifo_segment_private_t *s;
+  int rv;
 
   /* Allocate a fresh segment */
   pool_get (sm->segments, s);
-  memset (s, 0, sizeof (*s));
+  clib_memset (s, 0, sizeof (*s));
 
   s->ssvm.ssvm_size = a->segment_size;
   s->ssvm.my_pid = getpid ();
-  s->ssvm.name = (u8 *) a->segment_name;
+  s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
   s->ssvm.requested_va = sm->next_baseva;
+  if (a->segment_type == SSVM_SEGMENT_MEMFD)
+    s->ssvm.fd = a->memfd_fd;
+  else
+    s->ssvm.attach_timeout = sm->timeout_in_seconds;
 
-  rv = ssvm_slave_init (&s->ssvm, sm->timeout_in_seconds);
-
-  if (rv)
+  if ((rv = ssvm_slave_init (&s->ssvm, a->segment_type)))
     {
       _vec_len (s) = vec_len (s) - 1;
       return (rv);
     }
 
   /* Fish the segment header */
-  sh = s->ssvm.sh;
-  fsh = (svm_fifo_segment_header_t *) sh->opaque[0];
-  s->h = fsh;
+  s->h = s->ssvm.sh->opaque[0];
 
-  a->new_segment_index = s - sm->segments;
+  vec_add1 (a->new_segment_indices, s - sm->segments);
   return (0);
 }
 
@@ -213,10 +327,15 @@ void
 svm_fifo_segment_delete (svm_fifo_segment_private_t * s)
 {
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
+
   ssvm_delete (&s->ssvm);
+  clib_memset (s, 0xfe, sizeof (*s));
   pool_put (sm->segments, s);
 }
 
+/**
+ * Allocate fifo in svm segment
+ */
 svm_fifo_t *
 svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * s,
 			     u32 data_size_in_bytes,
@@ -224,30 +343,59 @@ svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * s,
 {
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
-  svm_fifo_t *f;
+  svm_fifo_t *f = 0;
   void *oldheap;
+  int freelist_index;
+
+  /*
+   * 4K minimum. It's not likely that anything good will happen
+   * with a smaller FIFO.
+   */
+  if (data_size_in_bytes < FIFO_SEGMENT_MIN_FIFO_SIZE ||
+      data_size_in_bytes > FIFO_SEGMENT_MAX_FIFO_SIZE)
+    {
+      clib_warning ("fifo size out of range %d", data_size_in_bytes);
+      return 0;
+    }
+
+  freelist_index = max_log2 (data_size_in_bytes)
+    - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
 
   sh = s->ssvm.sh;
+  ssvm_lock_non_recursive (sh, 1);
   fsh = (svm_fifo_segment_header_t *) sh->opaque[0];
 
-  ssvm_lock (sh, 1, 0);
-  oldheap = ssvm_push_heap (sh);
-
   switch (list_index)
     {
     case FIFO_SEGMENT_RX_FREELIST:
     case FIFO_SEGMENT_TX_FREELIST:
-      f = fsh->free_fifos[list_index];
-      if (f)
+      vec_validate_init_empty (fsh->free_fifos, freelist_index, 0);
+      f = fsh->free_fifos[freelist_index];
+      if (PREDICT_FALSE (!f))
 	{
-	  fsh->free_fifos[list_index] = f->next;
+	  /* Preallocated and no fifo left. Don't even try */
+	  if (fsh->flags & FIFO_SEGMENT_F_IS_PREALLOCATED)
+	    goto done;
+
+	  oldheap = ssvm_push_heap (sh);
+	  allocate_new_fifo_chunk (fsh, data_size_in_bytes,
+				   FIFO_SEGMENT_ALLOC_CHUNK_SIZE);
+	  ssvm_pop_heap (oldheap);
+	  f = fsh->free_fifos[freelist_index];
+	}
+      if (PREDICT_TRUE (f != 0))
+	{
+	  fsh->free_fifos[freelist_index] = f->next;
 	  /* (re)initialize the fifo, as in svm_fifo_create */
-	  memset (f, 0, sizeof (*f));
+	  clib_memset (f, 0, sizeof (*f));
 	  f->nitems = data_size_in_bytes;
 	  f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
+	  f->ct_session_index = SVM_FIFO_INVALID_SESSION_INDEX;
+	  f->refcnt = 1;
+	  f->freelist_index = freelist_index;
 	  goto found;
 	}
-      /* FALLTHROUGH */
+      break;
     case FIFO_SEGMENT_FREELIST_NONE:
       break;
 
@@ -256,14 +404,14 @@ svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * s,
       break;
     }
 
-  /* Note: this can fail, in which case: create another segment */
+  /* Catch all that allocates just one fifo. Note: this can fail,
+   * in which case: create another segment */
+  oldheap = ssvm_push_heap (sh);
   f = svm_fifo_create (data_size_in_bytes);
+  ssvm_pop_heap (oldheap);
   if (PREDICT_FALSE (f == 0))
-    {
-      ssvm_pop_heap (oldheap);
-      ssvm_unlock (sh);
-      return (0);
-    }
+    goto done;
+  f->freelist_index = freelist_index;
 
 found:
   /* If rx_freelist add to active fifos list. When cleaning up segment,
@@ -279,9 +427,10 @@ found:
 	}
       fsh->fifos = f;
     }
+  fsh->n_active_fifos++;
 
-  ssvm_pop_heap (oldheap);
-  ssvm_unlock (sh);
+done:
+  ssvm_unlock_non_recursive (sh);
   return (f);
 }
 
@@ -292,11 +441,21 @@ svm_fifo_segment_free_fifo (svm_fifo_segment_private_t * s, svm_fifo_t * f,
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
   void *oldheap;
+  int freelist_index;
+
+  ASSERT (f->refcnt > 0);
+
+  if (--f->refcnt > 0)
+    return;
 
   sh = s->ssvm.sh;
   fsh = (svm_fifo_segment_header_t *) sh->opaque[0];
 
-  ssvm_lock (sh, 1, 0);
+  freelist_index = f->freelist_index;
+
+  ASSERT (freelist_index < vec_len (fsh->free_fifos));
+
+  ssvm_lock_non_recursive (sh, 2);
   oldheap = ssvm_push_heap (sh);
 
   switch (list_index)
@@ -305,14 +464,17 @@ svm_fifo_segment_free_fifo (svm_fifo_segment_private_t * s, svm_fifo_t * f,
       /* Remove from active list */
       if (f->prev)
 	f->prev->next = f->next;
+      else
+	fsh->fifos = f->next;
       if (f->next)
 	f->next->prev = f->prev;
-      /* FALLTHROUGH */
+      /* Fall through: we add only rx fifos to active pool */
     case FIFO_SEGMENT_TX_FREELIST:
       /* Add to free list */
-      f->next = fsh->free_fifos[list_index];
-      fsh->free_fifos[list_index] = f;
-      /* FALLTHROUGH */
+      f->next = fsh->free_fifos[freelist_index];
+      f->prev = 0;
+      fsh->free_fifos[freelist_index] = f;
+      break;
     case FIFO_SEGMENT_FREELIST_NONE:
       break;
 
@@ -321,12 +483,19 @@ svm_fifo_segment_free_fifo (svm_fifo_segment_private_t * s, svm_fifo_t * f,
       break;
     }
 
+  if (CLIB_DEBUG)
+    {
+      f->master_session_index = ~0;
+      f->master_thread_index = ~0;
+    }
+
+  fsh->n_active_fifos--;
   ssvm_pop_heap (oldheap);
-  ssvm_unlock (sh);
+  ssvm_unlock_non_recursive (sh);
 }
 
 void
-svm_fifo_segment_init (u64 baseva, u32 timeout_in_seconds)
+svm_fifo_segment_main_init (u64 baseva, u32 timeout_in_seconds)
 {
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
 
@@ -340,6 +509,166 @@ svm_fifo_segment_index (svm_fifo_segment_private_t * s)
   return s - svm_fifo_segment_main.segments;
 }
 
+/**
+ * Retrieve svm segments pool. Used only for debug purposes.
+ */
+svm_fifo_segment_private_t *
+svm_fifo_segment_segments_pool (void)
+{
+  svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
+  return sm->segments;
+}
+
+/**
+ * Get number of active fifos
+ */
+u32
+svm_fifo_segment_num_fifos (svm_fifo_segment_private_t * fifo_segment)
+{
+  return fifo_segment->h->n_active_fifos;
+}
+
+u32
+svm_fifo_segment_num_free_fifos (svm_fifo_segment_private_t * fifo_segment,
+				 u32 fifo_size_in_bytes)
+{
+  ssvm_shared_header_t *sh;
+  svm_fifo_segment_header_t *fsh;
+  svm_fifo_t *f;
+  int i;
+  u32 count = 0, rounded_data_size, freelist_index;
+
+  sh = fifo_segment->ssvm.sh;
+  fsh = (svm_fifo_segment_header_t *) sh->opaque[0];
+
+  /* Count all free fifos? */
+  if (fifo_size_in_bytes == ~0)
+    {
+      for (i = 0; i < vec_len (fsh->free_fifos); i++)
+	{
+	  f = fsh->free_fifos[i];
+	  if (f == 0)
+	    continue;
+
+	  while (f)
+	    {
+	      f = f->next;
+	      count++;
+	    }
+	}
+      return count;
+    }
+
+  rounded_data_size = (1 << (max_log2 (fifo_size_in_bytes)));
+  freelist_index = max_log2 (rounded_data_size)
+    - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
+
+  if (freelist_index >= vec_len (fsh->free_fifos))
+    return 0;
+
+  f = fsh->free_fifos[freelist_index];
+  if (f == 0)
+    return 0;
+
+  while (f)
+    {
+      f = f->next;
+      count++;
+    }
+  return count;
+}
+
+void
+svm_fifo_segment_info (svm_fifo_segment_private_t * seg, uword * address,
+		       u64 * size)
+{
+  if (ssvm_type (&seg->ssvm) == SSVM_SEGMENT_PRIVATE)
+    {
+#if USE_DLMALLOC == 0
+      mheap_t *heap_header;
+
+      *address = pointer_to_uword (seg->ssvm.sh->heap);
+      heap_header = mheap_header (seg->ssvm.sh->heap);
+      *size = heap_header->max_size;
+#else
+      mspace_get_address_and_size (seg->ssvm.sh->heap,
+				   (unsigned long long *) address,
+				   (unsigned long long *) size);
+#endif
+    }
+  else
+    {
+      *address = seg->ssvm.sh->ssvm_va;
+      *size = seg->ssvm.ssvm_size;
+    }
+}
+
+void *
+svm_fifo_segment_heap (svm_fifo_segment_private_t * seg)
+{
+  return seg->ssvm.sh->heap;
+}
+
+u8 *
+format_svm_fifo_segment_type (u8 * s, va_list * args)
+{
+  svm_fifo_segment_private_t *sp;
+  sp = va_arg (*args, svm_fifo_segment_private_t *);
+  ssvm_segment_type_t st = ssvm_type (&sp->ssvm);
+
+  if (st == SSVM_SEGMENT_PRIVATE)
+    s = format (s, "%s", "private-heap");
+  else if (st == SSVM_SEGMENT_MEMFD)
+    s = format (s, "%s", "memfd");
+  else if (st == SSVM_SEGMENT_SHM)
+    s = format (s, "%s", "shm");
+  else
+    s = format (s, "%s", "unknown");
+  return s;
+}
+
+/**
+ * Segment format function
+ */
+u8 *
+format_svm_fifo_segment (u8 * s, va_list * args)
+{
+  svm_fifo_segment_private_t *sp
+    = va_arg (*args, svm_fifo_segment_private_t *);
+  int verbose __attribute__ ((unused)) = va_arg (*args, int);
+  svm_fifo_segment_header_t *fsh = sp->h;
+  u32 count, indent;
+  svm_fifo_t *f;
+  int i;
+
+  indent = format_get_indent (s) + 2;
+#if USE_DLMALLOC == 0
+  s = format (s, "%U segment heap: %U\n", format_white_space, indent,
+	      format_mheap, svm_fifo_segment_heap (sp), verbose);
+  s = format (s, "%U segment has %u active fifos\n",
+	      format_white_space, indent, svm_fifo_segment_num_fifos (sp));
+#endif
+
+  for (i = 0; i < vec_len (fsh->free_fifos); i++)
+    {
+      f = fsh->free_fifos[i];
+      if (f == 0)
+	continue;
+      count = 0;
+      while (f)
+	{
+	  f = f->next;
+	  count++;
+	}
+
+      s = format (s, "%U%-5u Kb: %u free",
+		  format_white_space, indent + 2,
+		  1 << (i + max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE) - 10),
+		  count);
+    }
+  return s;
+}
+
 /*
  * fd.io coding-style-patch-verification: ON
  *