session: segment handle in accept/connect notifications
[vpp.git] / src / svm / svm_fifo_segment.c
index acabb3b..6cb402f 100644 (file)
 
 svm_fifo_segment_main_t svm_fifo_segment_main;
 
-/** (master) create an svm fifo segment */
+static void
+allocate_new_fifo_chunk (svm_fifo_segment_header_t * fsh,
+                        u32 data_size_in_bytes, int chunk_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 (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 */
+  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_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_fifos_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
+     0 /* os_out_of_memory */ );
+
+  /* Make sure it worked. Clean up if it didn't... */
+  if (rx_fifo_space == 0 || tx_fifo_space == 0)
+    {
+      if (rx_fifo_space)
+       clib_mem_free (rx_fifo_space);
+      else
+       clib_warning ("rx fifo preallocation failure: size %d npairs %d",
+                     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",
+                     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 < pairs_to_allocate; i++)
+    {
+      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 < pairs_to_allocate; i++)
+    {
+      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);
+}
+
+/**
+ * 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;
+  /* Note: requested_va updated due to seg base addr randomization */
+  sm->next_baseva = s->ssvm.sh->ssvm_va + a->segment_size;
 
-  sh = s->ssvm.sh;
-  oldheap = ssvm_push_heap (sh);
+  svm_fifo_segment_init (s);
+  vec_add1 (a->new_segment_indices, s - sm->segments);
+  return (0);
+}
 
-  /* 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);
+/**
+ * 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_main_t *sm = &svm_fifo_segment_main;
+  svm_fifo_segment_private_t *s;
+  ssvm_shared_header_t *sh;
+  u32 rnd_size = 0;
+  u8 *heap;
+  u32 pagesize = clib_mem_get_page_size ();
 
-  /* Avoid vec_add1(...) failure when adding a fifo, etc. */
-  vec_validate (fsh->fifos, 64);
-  _vec_len (fsh->fifos) = 0;
+  pool_get (sm->segments, s);
+  clib_memset (s, 0, sizeof (*s));
 
-  ssvm_pop_heap (oldheap);
+  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 = 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;
+
+  clib_memset (sh, 0, sizeof (*sh));
+  sh->heap = heap;
+
+  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);
 }
 
@@ -111,66 +327,175 @@ 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)
+svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * fs,
+                            u32 data_size_in_bytes,
+                            svm_fifo_segment_freelist_t list_index)
 {
   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;
+    }
 
-  sh = s->ssvm.sh;
+  freelist_index = max_log2 (data_size_in_bytes)
+    - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
+
+  sh = fs->ssvm.sh;
+  ssvm_lock_non_recursive (sh, 1);
   fsh = (svm_fifo_segment_header_t *) sh->opaque[0];
-  oldheap = ssvm_push_heap (sh);
 
-  /* Note: this can fail, in which case: create another segment */
-  f = svm_fifo_create (data_size_in_bytes);
-  if (f == 0)
+  switch (list_index)
     {
-      ssvm_pop_heap (oldheap);
-      return (0);
-    }
+    case FIFO_SEGMENT_RX_FREELIST:
+    case FIFO_SEGMENT_TX_FREELIST:
+      vec_validate_init_empty (fsh->free_fifos, freelist_index, 0);
+      f = fsh->free_fifos[freelist_index];
+      if (PREDICT_FALSE (!f))
+       {
+         /* 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 */
+         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;
+       }
+      break;
+    case FIFO_SEGMENT_FREELIST_NONE:
+      break;
 
-  vec_add1 (fsh->fifos, f);
+    default:
+      clib_warning ("ignore bogus freelist %d", list_index);
+      break;
+    }
 
+  /* 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))
+    goto done;
+  f->freelist_index = freelist_index;
+
+found:
+  /* If rx_freelist add to active fifos list. When cleaning up segment,
+   * we need a list of active sessions that should be disconnected. Since
+   * both rx and tx fifos keep pointers to the session, it's enough to track
+   * only one. */
+  if (list_index == FIFO_SEGMENT_RX_FREELIST)
+    {
+      if (fsh->fifos)
+       {
+         fsh->fifos->prev = f;
+         f->next = fsh->fifos;
+       }
+      fsh->fifos = f;
+    }
+  fsh->n_active_fifos++;
+
+done:
+  ssvm_unlock_non_recursive (sh);
   return (f);
 }
 
 void
-svm_fifo_segment_free_fifo (svm_fifo_segment_private_t * s, svm_fifo_t * f)
+svm_fifo_segment_free_fifo (svm_fifo_segment_private_t * s, svm_fifo_t * f,
+                           svm_fifo_segment_freelist_t list_index)
 {
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
   void *oldheap;
-  int i;
+  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];
+
+  freelist_index = f->freelist_index;
+
+  ASSERT (freelist_index < vec_len (fsh->free_fifos));
+
+  ssvm_lock_non_recursive (sh, 2);
   oldheap = ssvm_push_heap (sh);
 
-  for (i = 0; i < vec_len (fsh->fifos); i++)
+  switch (list_index)
     {
-      if (fsh->fifos[i] == f)
-       {
-         vec_delete (fsh->fifos, 1, i);
-         goto found;
-       }
+    case FIFO_SEGMENT_RX_FREELIST:
+      /* 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;
+      /* Fall through: we add only rx fifos to active pool */
+    case FIFO_SEGMENT_TX_FREELIST:
+      /* Add to free list */
+      f->next = fsh->free_fifos[freelist_index];
+      f->prev = 0;
+      fsh->free_fifos[freelist_index] = f;
+      break;
+    case FIFO_SEGMENT_FREELIST_NONE:
+      break;
+
+    default:
+      clib_warning ("ignore bogus freelist %d", list_index);
+      break;
     }
-  clib_warning ("fifo 0x%llx not found in fifo table...", f);
 
-found:
-  clib_mem_free (f);
+  if (CLIB_DEBUG)
+    {
+      f->master_session_index = ~0;
+      f->master_thread_index = ~0;
+    }
+
+  fsh->n_active_fifos--;
   ssvm_pop_heap (oldheap);
+  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;
 
@@ -184,6 +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
  *