X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fsvm%2Ffifo_segment.c;h=2ff272e2f8812ca9172d2cfed659d13c3efffc29;hb=afbb33aaf254ebfe6ebf2477b1a4859cec40e34b;hp=758b2648ece6281e8337a2c679d6f764a5adf401;hpb=cefd5d8806b9db7210192f53fdc2b8a60d4dc271;p=vpp.git

diff --git a/src/svm/fifo_segment.c b/src/svm/fifo_segment.c
index 758b2648ece..2ff272e2f88 100644
--- a/src/svm/fifo_segment.c
+++ b/src/svm/fifo_segment.c
@@ -14,81 +14,330 @@
  */
 
 #include <svm/fifo_segment.h>
+#include <vppinfra/mem.h>
 
-/**
- * Initialize fifo segment shared header
- */
-int
-fifo_segment_init (fifo_segment_t * fs)
+static inline void *
+fsh_alloc_aligned (fifo_segment_header_t *fsh, uword size, uword align)
 {
-  fifo_segment_header_t *fsh;
-  ssvm_shared_header_t *sh;
-  void *oldheap;
+  uword cur_pos, cur_pos_align, new_pos;
 
-  sh = fs->ssvm.sh;
-  oldheap = ssvm_push_heap (sh);
+  cur_pos = clib_atomic_load_relax_n (&fsh->byte_index);
+  cur_pos_align = round_pow2_u64 (cur_pos, align);
+  size = round_pow2_u64 (size, align);
+  new_pos = cur_pos_align + size;
 
-  fsh = clib_mem_alloc (sizeof (*fsh));
-  clib_memset (fsh, 0, sizeof (*fsh));
-  fs->h = sh->opaque[0] = fsh;
+  if (new_pos >= fsh->max_byte_index)
+    return 0;
 
-  ssvm_pop_heap (oldheap);
+  while (!clib_atomic_cmp_and_swap_acq_relax (&fsh->byte_index, &cur_pos,
+					      &new_pos, 1 /* weak */))
+    {
+      cur_pos_align = round_pow2_u64 (cur_pos, align);
+      new_pos = cur_pos_align + size;
+      if (new_pos >= fsh->max_byte_index)
+	return 0;
+    }
+  return uword_to_pointer ((u8 *) fsh + cur_pos_align, void *);
+}
 
-  sh->ready = 1;
-  return (0);
+static inline void *
+fsh_alloc (fifo_segment_header_t *fsh, uword size)
+{
+  return fsh_alloc_aligned (fsh, size, 8);
+}
+
+static inline fifo_segment_slice_t *
+fsh_slice_get (fifo_segment_header_t * fsh, u32 slice_index)
+{
+  return &fsh->slices[slice_index];
+}
+
+static inline fifo_slice_private_t *
+fs_slice_private_get (fifo_segment_t *fs, u32 slice_index)
+{
+  ASSERT (slice_index < fs->n_slices);
+  return &fs->slices[slice_index];
+}
+
+static char *fifo_segment_mem_status_strings[] = {
+#define _(sym,str) str,
+  foreach_segment_mem_status
+#undef _
+};
+
+static inline uword
+fsh_n_free_bytes (fifo_segment_header_t * fsh)
+{
+  uword cur_pos = clib_atomic_load_relax_n (&fsh->byte_index);
+  ASSERT (fsh->max_byte_index > cur_pos);
+  return fsh->max_byte_index - cur_pos;
+}
+
+static inline void
+fsh_cached_bytes_add (fifo_segment_header_t * fsh, uword size)
+{
+  clib_atomic_fetch_add_rel (&fsh->n_cached_bytes, size);
+}
+
+static inline void
+fsh_cached_bytes_sub (fifo_segment_header_t * fsh, uword size)
+{
+  clib_atomic_fetch_sub_rel (&fsh->n_cached_bytes, size);
+}
+
+static inline uword
+fsh_n_cached_bytes (fifo_segment_header_t * fsh)
+{
+  uword n_cached = clib_atomic_load_relax_n (&fsh->n_cached_bytes);
+  return n_cached;
+}
+
+static inline void
+fsh_active_fifos_update (fifo_segment_header_t * fsh, int inc)
+{
+  clib_atomic_fetch_add_rel (&fsh->n_active_fifos, inc);
+}
+
+static inline u32
+fsh_n_active_fifos (fifo_segment_header_t * fsh)
+{
+  return clib_atomic_load_relax_n (&fsh->n_active_fifos);
+}
+
+static inline uword
+fs_virtual_mem (fifo_segment_t *fs)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_segment_slice_t *fss;
+  uword total_vm = 0;
+  int i;
+
+  for (i = 0; i < fs->n_slices; i++)
+    {
+      fss = fsh_slice_get (fsh, i);
+      total_vm += clib_atomic_load_relax_n (&fss->virtual_mem);
+    }
+  return total_vm;
+}
+
+void
+fsh_virtual_mem_update (fifo_segment_header_t * fsh, u32 slice_index,
+			int n_bytes)
+{
+  fifo_segment_slice_t *fss = fsh_slice_get (fsh, slice_index);
+  fss->virtual_mem += n_bytes;
+}
+
+static inline int
+fss_chunk_fl_index_is_valid (fifo_segment_slice_t *fss, u32 fl_index)
+{
+  return (fl_index < FS_CHUNK_VEC_LEN);
+}
+
+#define FS_CL_HEAD_MASK	 0xFFFFFFFFFFFF
+#define FS_CL_HEAD_TMASK 0xFFFF000000000000
+#define FS_CL_HEAD_TINC	 (1ULL << 48)
+
+static svm_fifo_chunk_t *
+fss_chunk_free_list_head (fifo_segment_header_t *fsh,
+			  fifo_segment_slice_t *fss, u32 fl_index)
+{
+  fs_sptr_t headsp = clib_atomic_load_relax_n (&fss->free_chunks[fl_index]);
+  return fs_chunk_ptr (fsh, headsp & FS_CL_HEAD_MASK);
+}
+
+static void
+fss_chunk_free_list_push (fifo_segment_header_t *fsh,
+			  fifo_segment_slice_t *fss, u32 fl_index,
+			  svm_fifo_chunk_t *c)
+{
+  fs_sptr_t old_head, new_head, csp;
+
+  csp = fs_chunk_sptr (fsh, c);
+  ASSERT (csp <= FS_CL_HEAD_MASK);
+  old_head = clib_atomic_load_acq_n (&fss->free_chunks[fl_index]);
+
+  do
+    {
+      c->next = old_head & FS_CL_HEAD_MASK;
+      new_head = csp + ((old_head + FS_CL_HEAD_TINC) & FS_CL_HEAD_TMASK);
+    }
+  while (!__atomic_compare_exchange (&fss->free_chunks[fl_index], &old_head,
+				     &new_head, 0 /* weak */, __ATOMIC_RELEASE,
+				     __ATOMIC_ACQUIRE));
+}
+
+static void
+fss_chunk_free_list_push_list (fifo_segment_header_t *fsh,
+			       fifo_segment_slice_t *fss, u32 fl_index,
+			       svm_fifo_chunk_t *head, svm_fifo_chunk_t *tail)
+{
+  fs_sptr_t old_head, new_head, headsp;
+
+  headsp = fs_chunk_sptr (fsh, head);
+  ASSERT (headsp <= FS_CL_HEAD_MASK);
+  old_head = clib_atomic_load_acq_n (&fss->free_chunks[fl_index]);
+
+  do
+    {
+      tail->next = old_head & FS_CL_HEAD_MASK;
+      new_head = headsp + ((old_head + FS_CL_HEAD_TINC) & FS_CL_HEAD_TMASK);
+    }
+  while (!__atomic_compare_exchange (&fss->free_chunks[fl_index], &old_head,
+				     &new_head, 0 /* weak */, __ATOMIC_RELEASE,
+				     __ATOMIC_ACQUIRE));
+}
+
+static svm_fifo_chunk_t *
+fss_chunk_free_list_pop (fifo_segment_header_t *fsh, fifo_segment_slice_t *fss,
+			 u32 fl_index)
+{
+  fs_sptr_t old_head, new_head;
+  svm_fifo_chunk_t *c;
+
+  ASSERT (fss_chunk_fl_index_is_valid (fss, fl_index));
+
+  old_head = clib_atomic_load_acq_n (&fss->free_chunks[fl_index]);
+
+  /* Lock-free stacks are affected by ABA if a side allocates a chunk and
+   * shortly thereafter frees it. To circumvent that, reuse the upper bits
+   * of the head of the list shared pointer, i.e., offset to where the chunk
+   * is, as a tag. The tag is incremented with each push/pop operation and
+   * therefore collisions can only happen if an element is popped and pushed
+   * exactly after a complete wrap of the tag (16 bits). It's unlikely either
+   * of the sides will be descheduled for that long */
+  do
+    {
+      if (!(old_head & FS_CL_HEAD_MASK))
+	return 0;
+      c = fs_chunk_ptr (fsh, old_head & FS_CL_HEAD_MASK);
+      new_head = c->next + ((old_head + FS_CL_HEAD_TINC) & FS_CL_HEAD_TMASK);
+    }
+  while (!__atomic_compare_exchange (&fss->free_chunks[fl_index], &old_head,
+				     &new_head, 0 /* weak */, __ATOMIC_RELEASE,
+				     __ATOMIC_ACQUIRE));
+
+  return c;
+}
+
+static void
+fss_fifo_free_list_push (fifo_segment_header_t *fsh, fifo_segment_slice_t *fss,
+			 svm_fifo_shared_t *sf)
+{
+  sf->next = fss->free_fifos;
+  fss->free_fifos = fs_sptr (fsh, sf);
+}
+
+static void
+fss_fifo_free_list_push_list (fifo_segment_header_t *fsh,
+			      fifo_segment_slice_t *fss,
+			      svm_fifo_shared_t *head, svm_fifo_shared_t *tail)
+{
+  tail->next = fss->free_fifos;
+  fss->free_fifos = fs_sptr (fsh, head);
+}
+
+svm_fifo_shared_t *
+fss_fifo_free_list_pop (fifo_segment_header_t *fsh, fifo_segment_slice_t *fss)
+{
+  svm_fifo_shared_t *sf;
+  sf = fs_ptr (fsh, fss->free_fifos);
+  fss->free_fifos = sf->next;
+  return sf;
+}
+
+static inline void
+pfss_fifo_add_active_list (fifo_slice_private_t *pfss, svm_fifo_t *f)
+{
+  if (pfss->active_fifos)
+    {
+      pfss->active_fifos->prev = f;
+      f->next = pfss->active_fifos;
+    }
+  pfss->active_fifos = f;
+}
+
+static inline void
+pfss_fifo_del_active_list (fifo_slice_private_t *pfss, svm_fifo_t *f)
+{
+  if (f->flags & SVM_FIFO_F_LL_TRACKED)
+    {
+      if (f->prev)
+	f->prev->next = f->next;
+      else
+	pfss->active_fifos = f->next;
+      if (f->next)
+	f->next->prev = f->prev;
+    }
+}
+
+static inline uword
+fss_fl_chunk_bytes (fifo_segment_slice_t * fss)
+{
+  return clib_atomic_load_relax_n (&fss->n_fl_chunk_bytes);
+}
+
+static inline void
+fss_fl_chunk_bytes_add (fifo_segment_slice_t * fss, uword size)
+{
+  clib_atomic_fetch_add_relax (&fss->n_fl_chunk_bytes, size);
+}
+
+static inline void
+fss_fl_chunk_bytes_sub (fifo_segment_slice_t * fss, uword size)
+{
+  clib_atomic_fetch_sub_relax (&fss->n_fl_chunk_bytes, size);
 }
 
 /**
- * Create a fifo segment in process-private memory
+ * Initialize fifo segment shared header
  */
-static int
-fifo_segment_create_process_private (fifo_segment_main_t * sm,
-				     fifo_segment_create_args_t * a)
+int
+fifo_segment_init (fifo_segment_t * fs)
 {
-  u32 pagesize = clib_mem_get_page_size ();
+  u32 align = 8, offset = 2 * 4096, slices_sz, i;
+  uword max_fifo, seg_start, seg_sz;
+  fifo_segment_header_t *fsh;
   ssvm_shared_header_t *sh;
-  fifo_segment_t *s;
-  u32 rnd_size = 0;
-  u8 *heap;
+  void *seg_data;
 
-  pool_get (sm->segments, s);
-  clib_memset (s, 0, sizeof (*s));
+  /* TODO remove ssvm heap entirely */
+  sh = fs->ssvm.sh;
 
-  rnd_size = (a->segment_size + (pagesize - 1)) & ~pagesize;
+  seg_data = (u8 *) sh + offset;
+  seg_sz = sh->ssvm_size - offset;
 
-#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
+  fs->n_slices = clib_max (fs->n_slices, 1);
+  slices_sz = sizeof (fifo_segment_slice_t) * fs->n_slices;
 
-  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;
+  seg_start = round_pow2_u64 (pointer_to_uword (seg_data), align);
+  fsh = uword_to_pointer (seg_start, void *);
+  CLIB_MEM_UNPOISON (fsh, seg_sz);
+  memset (fsh, 0, sizeof (*fsh) + slices_sz);
 
-  /* Allocate a [sic] shared memory header, in process memory... */
-  sh = clib_mem_alloc_aligned (sizeof (*sh), CLIB_CACHE_LINE_BYTES);
-  s->ssvm.sh = sh;
+  fsh->byte_index = sizeof (*fsh) + slices_sz;
+  fsh->max_byte_index = seg_sz;
+  fsh->n_slices = fs->n_slices;
+  max_fifo = clib_min ((seg_sz - slices_sz) / 2, FIFO_SEGMENT_MAX_FIFO_SIZE);
+  fsh->max_log2_fifo_size = min_log2 (max_fifo);
+  fsh->n_cached_bytes = 0;
+  fsh->n_reserved_bytes = fsh->byte_index;
+  fsh->start_byte_index = fsh->byte_index;
+  ASSERT (fsh->max_byte_index <= sh->ssvm_size - offset);
 
-  clib_memset (sh, 0, sizeof (*sh));
-  sh->heap = heap;
+  fs->max_byte_index = fsh->max_byte_index;
+  fs->h = fsh;
+  sh->opaque[0] = (void *) ((u8 *) fsh - (u8 *) fs->ssvm.sh);
 
-  fifo_segment_init (s);
-  vec_add1 (a->new_segment_indices, s - sm->segments);
+  /* Allow random offsets */
+  fs->ssvm.sh->ssvm_va = 0;
 
+  vec_validate (fs->slices, fs->n_slices - 1);
+  for (i = 0; i < fs->n_slices; i++)
+    fs->slices[i].fifos =
+      clib_mem_bulk_init (sizeof (svm_fifo_t), CLIB_CACHE_LINE_BYTES, 32);
+
+  sh->ready = 1;
   return (0);
 }
 
@@ -98,33 +347,31 @@ fifo_segment_create_process_private (fifo_segment_main_t * sm,
 int
 fifo_segment_create (fifo_segment_main_t * sm, fifo_segment_create_args_t * a)
 {
-  fifo_segment_t *s;
+  fifo_segment_t *fs;
+  uword baseva;
   int rv;
 
-  if (a->segment_type == SSVM_SEGMENT_PRIVATE)
-    return fifo_segment_create_process_private (sm, a);
-
   /* Allocate a fresh segment */
-  pool_get (sm->segments, s);
-  clib_memset (s, 0, sizeof (*s));
+  pool_get_zero (sm->segments, fs);
 
-  s->ssvm.ssvm_size = a->segment_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 = sm->next_baseva;
+  baseva = a->segment_type == SSVM_SEGMENT_PRIVATE ? ~0ULL : sm->next_baseva;
+  fs->ssvm.ssvm_size = a->segment_size;
+  fs->ssvm.is_server = 1;
+  fs->ssvm.my_pid = getpid ();
+  fs->ssvm.name = format (0, "%s%c", a->segment_name, 0);
+  fs->ssvm.requested_va = baseva;
 
-  if ((rv = ssvm_master_init (&s->ssvm, a->segment_type)))
+  if ((rv = ssvm_server_init (&fs->ssvm, a->segment_type)))
     {
-      pool_put (sm->segments, s);
+      pool_put (sm->segments, fs);
       return (rv);
     }
 
   /* Note: requested_va updated due to seg base addr randomization */
-  sm->next_baseva = s->ssvm.sh->ssvm_va + a->segment_size;
+  sm->next_baseva = fs->ssvm.sh->ssvm_va + fs->ssvm.ssvm_size;
 
-  fifo_segment_init (s);
-  vec_add1 (a->new_segment_indices, s - sm->segments);
+  fifo_segment_init (fs);
+  vec_add1 (a->new_segment_indices, fs - sm->segments);
   return (0);
 }
 
@@ -134,36 +381,46 @@ fifo_segment_create (fifo_segment_main_t * sm, fifo_segment_create_args_t * a)
 int
 fifo_segment_attach (fifo_segment_main_t * sm, fifo_segment_create_args_t * a)
 {
-  fifo_segment_t *s;
+  fifo_segment_header_t *fsh;
+  fifo_segment_t *fs;
   int rv;
 
-  pool_get_zero (sm->segments, s);
+  pool_get_zero (sm->segments, fs);
 
-  s->ssvm.ssvm_size = a->segment_size;
-  s->ssvm.my_pid = getpid ();
-  s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
-  s->ssvm.requested_va = sm->next_baseva;
+  fs->ssvm.ssvm_size = a->segment_size;
+  fs->ssvm.my_pid = getpid ();
+  fs->ssvm.name = format (0, "%s%c", a->segment_name, 0);
+  fs->ssvm.requested_va = 0;
   if (a->segment_type == SSVM_SEGMENT_MEMFD)
-    s->ssvm.fd = a->memfd_fd;
+    fs->ssvm.fd = a->memfd_fd;
   else
-    s->ssvm.attach_timeout = sm->timeout_in_seconds;
+    fs->ssvm.attach_timeout = sm->timeout_in_seconds;
 
-  if ((rv = ssvm_slave_init (&s->ssvm, a->segment_type)))
+  if ((rv = ssvm_client_init (&fs->ssvm, a->segment_type)))
     {
-      _vec_len (s) = vec_len (s) - 1;
+      pool_put (sm->segments, fs);
       return (rv);
     }
 
-  /* Fish the segment header */
-  s->h = s->ssvm.sh->opaque[0];
+  /* Probably a segment without fifos */
+  if (!fs->ssvm.sh->opaque[0])
+    goto done;
+
+  fsh = fs->h = (void *) fs->ssvm.sh + (uword) fs->ssvm.sh->opaque[0];
+  fs->max_byte_index = fsh->max_byte_index;
+  vec_validate (fs->slices, 0);
+  fs->slices[0].fifos =
+    clib_mem_bulk_init (sizeof (svm_fifo_t), CLIB_CACHE_LINE_BYTES, 32);
 
-  vec_add1 (a->new_segment_indices, s - sm->segments);
+done:
+  vec_add1 (a->new_segment_indices, fs - sm->segments);
   return (0);
 }
 
 void
 fifo_segment_delete (fifo_segment_main_t * sm, fifo_segment_t * s)
 {
+  fifo_segment_cleanup (s);
   ssvm_delete (&s->ssvm);
   clib_memset (s, 0xfe, sizeof (*s));
   pool_put (sm->segments, s);
@@ -175,281 +432,774 @@ fifo_segment_index (fifo_segment_main_t * sm, fifo_segment_t * s)
   return s - sm->segments;
 }
 
-void *
-svm_fifo_segment_heap (fifo_segment_t * seg)
+fifo_segment_t *
+fifo_segment_get_segment (fifo_segment_main_t * sm, u32 segment_index)
 {
-  return seg->ssvm.sh->heap;
+  return pool_elt_at_index (sm->segments, segment_index);
 }
 
 fifo_segment_t *
-fifo_segment_get_segment (fifo_segment_main_t * sm, u32 segment_index)
+fifo_segment_get_segment_if_valid (fifo_segment_main_t *sm, u32 segment_index)
 {
+  if (pool_is_free_index (sm->segments, segment_index))
+    return 0;
   return pool_elt_at_index (sm->segments, segment_index);
 }
 
 void
 fifo_segment_info (fifo_segment_t * seg, char **address, size_t * size)
 {
-  if (ssvm_type (&seg->ssvm) == SSVM_SEGMENT_PRIVATE)
+  *address = (char *) seg->ssvm.sh->ssvm_va;
+  *size = seg->ssvm.ssvm_size;
+}
+
+void
+fifo_segment_main_init (fifo_segment_main_t * sm, u64 baseva,
+			u32 timeout_in_seconds)
+{
+  sm->next_baseva = baseva;
+  sm->timeout_in_seconds = timeout_in_seconds;
+}
+
+static inline u32
+fs_freelist_for_size (u32 size)
+{
+  if (PREDICT_FALSE (size < FIFO_SEGMENT_MIN_FIFO_SIZE))
+    return 0;
+  return clib_min (max_log2 (size) - FIFO_SEGMENT_MIN_LOG2_FIFO_SIZE,
+		   FS_CHUNK_VEC_LEN - 1);
+}
+
+static inline u32
+fs_freelist_index_to_size (u32 fl_index)
+{
+  return 1 << (fl_index + FIFO_SEGMENT_MIN_LOG2_FIFO_SIZE);
+}
+
+static inline int
+fs_chunk_size_is_valid (fifo_segment_header_t * fsh, u32 size)
+{
+  /*
+   * 4K minimum. It's not likely that anything good will happen
+   * with a smaller FIFO.
+   */
+  return size >= FIFO_SEGMENT_MIN_FIFO_SIZE &&
+	 size <= (1ULL << fsh->max_log2_fifo_size);
+}
+
+svm_fifo_chunk_t *
+fs_try_alloc_multi_chunk (fifo_segment_header_t * fsh,
+			  fifo_segment_slice_t * fss, u32 data_bytes)
+{
+  u32 fl_index, fl_size, n_alloc = 0, req_bytes = data_bytes;
+  svm_fifo_chunk_t *c, *first = 0, *next;
+
+  fl_index = fs_freelist_for_size (req_bytes);
+  if (fl_index > 0)
+    fl_index -= 1;
+
+  fl_size = fs_freelist_index_to_size (fl_index);
+
+  while (req_bytes)
     {
-#if USE_DLMALLOC == 0
-      mheap_t *heap_header;
+      c = fss_chunk_free_list_pop (fsh, fss, fl_index);
+      if (c)
+	{
+	  c->next = fs_chunk_sptr (fsh, first);
+	  first = c;
+	  n_alloc += fl_size;
+	  req_bytes -= clib_min (fl_size, req_bytes);
+	}
+      else
+	{
+	  /* Failed to allocate with smaller chunks */
+	  if (fl_index == 0)
+	    {
+	      /* Free all chunks if any allocated */
+	      c = first;
+	      while (c)
+		{
+		  fl_index = fs_freelist_for_size (c->length);
+		  next = fs_chunk_ptr (fsh, c->next);
+		  fss_chunk_free_list_push (fsh, fss, fl_index, c);
+		  c = next;
+		}
+	      n_alloc = 0;
+	      first = 0;
+	      /* As last attempt, try allocating a chunk larger than
+	       * the requested size, if possible */
+	      fl_index = fs_freelist_for_size (data_bytes) + 1;
+	      if (!fss_chunk_fl_index_is_valid (fss, fl_index))
+		return 0;
+	      first = fss_chunk_free_list_pop (fsh, fss, fl_index);
+	      if (first)
+		{
+		  first->next = 0;
+		  n_alloc = fs_freelist_index_to_size (fl_index);
+		  goto done;
+		}
+	      return 0;
+	    }
+	  fl_index -= 1;
+	  fl_size = fl_size >> 1;
+	}
+    }
 
-      *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, address, size);
-#endif
+done:
+  fss_fl_chunk_bytes_sub (fss, n_alloc);
+  fsh_cached_bytes_sub (fsh, n_alloc);
+  return first;
+}
+
+static int
+fsh_try_alloc_fifo_hdr_batch (fifo_segment_header_t * fsh,
+			      fifo_segment_slice_t * fss, u32 batch_size)
+{
+  svm_fifo_shared_t *f, *head = 0, *tail;
+  uword size;
+  u8 *fmem;
+  int i;
+
+  ASSERT (batch_size != 0);
+
+  size = (uword) sizeof (*f) * batch_size;
+
+  fmem = fsh_alloc_aligned (fsh, size, CLIB_CACHE_LINE_BYTES);
+  if (fmem == 0)
+    return -1;
+
+  /* Carve fifo hdr space */
+  tail = f = (svm_fifo_shared_t *) fmem;
+  for (i = 0; i < batch_size; i++)
+    {
+      clib_memset (f, 0, sizeof (*f));
+      f->next = fs_sptr (fsh, head);
+      head = f;
+      fmem += sizeof (*f);
+      f = (svm_fifo_shared_t *) fmem;
+    }
+
+  fss_fifo_free_list_push_list (fsh, fss, head, tail);
+
+  return 0;
+}
+
+static int
+fsh_try_alloc_chunk_batch (fifo_segment_header_t * fsh,
+			   fifo_segment_slice_t * fss,
+			   u32 fl_index, u32 batch_size)
+{
+  svm_fifo_chunk_t *c, *head = 0, *tail;
+  uword size, total_chunk_bytes;
+  u32 rounded_data_size;
+  u8 *cmem;
+  int i;
+
+  ASSERT (batch_size != 0);
+
+  rounded_data_size = fs_freelist_index_to_size (fl_index);
+  total_chunk_bytes = (uword) batch_size *rounded_data_size;
+  size = (uword) (sizeof (*c) + rounded_data_size) * batch_size;
+
+  cmem = fsh_alloc_aligned (fsh, size, 8 /* chunk hdr is 24B */);
+  if (cmem == 0)
+    return -1;
+
+  /* Carve fifo + chunk space */
+  tail = c = (svm_fifo_chunk_t *) cmem;
+  for (i = 0; i < batch_size; i++)
+    {
+      c->start_byte = 0;
+      c->length = rounded_data_size;
+      c->next = fs_chunk_sptr (fsh, head);
+      head = c;
+      cmem += sizeof (*c) + rounded_data_size;
+      c = (svm_fifo_chunk_t *) cmem;
+    }
+
+  fss_chunk_free_list_push_list (fsh, fss, fl_index, head, tail);
+  fss->num_chunks[fl_index] += batch_size;
+  fss_fl_chunk_bytes_add (fss, total_chunk_bytes);
+  fsh_cached_bytes_add (fsh, total_chunk_bytes);
+
+  return 0;
+}
+
+static int
+fs_try_alloc_fifo_batch (fifo_segment_header_t * fsh,
+			 fifo_segment_slice_t * fss,
+			 u32 fl_index, u32 batch_size)
+{
+  if (fsh_try_alloc_fifo_hdr_batch (fsh, fss, batch_size))
+    return 0;
+  return fsh_try_alloc_chunk_batch (fsh, fss, fl_index, batch_size);
+}
+
+static svm_fifo_shared_t *
+fsh_try_alloc_fifo_hdr (fifo_segment_header_t *fsh, fifo_segment_slice_t *fss)
+{
+  svm_fifo_shared_t *sf;
+
+  if (!fss->free_fifos)
+    {
+      if (fsh_try_alloc_fifo_hdr_batch (fsh, fss,
+					FIFO_SEGMENT_ALLOC_BATCH_SIZE))
+	return 0;
+    }
+
+  sf = fss_fifo_free_list_pop (fsh, fss);
+  clib_memset (sf, 0, sizeof (*sf));
+
+  return sf;
+}
+
+static svm_fifo_chunk_t *
+fsh_try_alloc_chunk (fifo_segment_header_t * fsh,
+		     fifo_segment_slice_t * fss, u32 data_bytes)
+{
+  svm_fifo_chunk_t *c;
+  u32 fl_index;
+
+  fl_index = fs_freelist_for_size (data_bytes);
+
+free_list:
+  c = fss_chunk_free_list_pop (fsh, fss, fl_index);
+  if (c)
+    {
+      c->next = 0;
+      fss_fl_chunk_bytes_sub (fss, fs_freelist_index_to_size (fl_index));
+      fsh_cached_bytes_sub (fsh, fs_freelist_index_to_size (fl_index));
     }
   else
     {
-      *address = (char *) seg->ssvm.sh->ssvm_va;
-      *size = seg->ssvm.ssvm_size;
+      u32 chunk_size, batch = FIFO_SEGMENT_ALLOC_BATCH_SIZE;
+      uword n_free;
+
+      chunk_size = fs_freelist_index_to_size (fl_index);
+      n_free = fsh_n_free_bytes (fsh);
+
+      if (chunk_size <= n_free)
+	{
+	  batch = chunk_size * batch <= n_free ? batch : 1;
+	  if (!fsh_try_alloc_chunk_batch (fsh, fss, fl_index, batch))
+	    goto free_list;
+	}
+      /* Failed to allocate larger chunk, try to allocate multi-chunk
+       * that is close to what was actually requested */
+      if (data_bytes <= fss_fl_chunk_bytes (fss))
+	{
+	  c = fs_try_alloc_multi_chunk (fsh, fss, data_bytes);
+	  if (c)
+	    goto done;
+	  batch = n_free / FIFO_SEGMENT_MIN_FIFO_SIZE;
+	  if (!batch || fsh_try_alloc_chunk_batch (fsh, fss, 0, batch))
+	    goto done;
+	}
+      if (data_bytes <= fss_fl_chunk_bytes (fss) + n_free)
+	{
+	  u32 min_size = FIFO_SEGMENT_MIN_FIFO_SIZE;
+	  if (n_free < min_size)
+	    goto done;
+	  batch = (data_bytes - fss_fl_chunk_bytes (fss)) / min_size;
+	  batch = clib_min (batch + 1, n_free / min_size);
+	  if (fsh_try_alloc_chunk_batch (fsh, fss, 0, batch))
+	    goto done;
+	  c = fs_try_alloc_multi_chunk (fsh, fss, data_bytes);
+	}
     }
+
+done:
+
+  return c;
 }
 
-void
-fifo_segment_main_init (fifo_segment_main_t * sm, u64 baseva,
-			u32 timeout_in_seconds)
+/**
+ * Try to allocate new fifo
+ *
+ * Tries the following steps in order:
+ * - grab fifo and chunk from freelists
+ * - batch fifo and chunk allocation
+ * - single fifo allocation
+ * - grab multiple fifo chunks from freelists
+ */
+static svm_fifo_shared_t *
+fs_try_alloc_fifo (fifo_segment_header_t *fsh, u32 slice_index, u32 data_bytes)
 {
-  sm->next_baseva = baseva;
-  sm->timeout_in_seconds = timeout_in_seconds;
+  fifo_segment_slice_t *fss;
+  u32 fl_index, min_size;
+  svm_fifo_chunk_t *c;
+  svm_fifo_shared_t *sf = 0;
+
+  fss = fsh_slice_get (fsh, slice_index);
+  min_size = clib_max ((fsh->pct_first_alloc * data_bytes) / 100, 4096);
+  fl_index = fs_freelist_for_size (min_size);
+
+  if (!fss_chunk_fl_index_is_valid (fss, fl_index))
+    return 0;
+
+  sf = fsh_try_alloc_fifo_hdr (fsh, fss);
+  if (!sf)
+    return 0;
+
+  c = fsh_try_alloc_chunk (fsh, fss, min_size);
+  if (!c)
+    {
+      fss_fifo_free_list_push (fsh, fss, sf);
+      return 0;
+    }
+
+  sf->start_chunk = fs_chunk_sptr (fsh, c);
+  while (c->next)
+    c = fs_chunk_ptr (fsh, c->next);
+  sf->end_chunk = fs_chunk_sptr (fsh, c);
+  sf->size = data_bytes;
+  sf->slice_index = slice_index;
+
+  return sf;
 }
 
-static void
-fifo_init_for_segment (svm_fifo_t * f, svm_fifo_chunk_t * c)
+svm_fifo_chunk_t *
+fsh_alloc_chunk (fifo_segment_header_t * fsh, u32 slice_index, u32 chunk_size)
 {
-  f->start_chunk = f->end_chunk = c->next = c;
-  f->head_chunk = f->tail_chunk = f->ooo_enq = f->ooo_deq = f->start_chunk;
+  fifo_segment_slice_t *fss;
+  svm_fifo_chunk_t *c;
+
+  fss = fsh_slice_get (fsh, slice_index);
+  c = fsh_try_alloc_chunk (fsh, fss, chunk_size);
+
+  return c;
 }
 
 static void
-fifo_init_chunk_for_segment (svm_fifo_chunk_t * c, u32 size)
+fsh_slice_collect_chunks (fifo_segment_header_t * fsh,
+			  fifo_segment_slice_t * fss, svm_fifo_chunk_t * c)
+{
+  u32 n_collect = 0, fl_index;
+  svm_fifo_chunk_t *next;
+
+  while (c)
+    {
+      CLIB_MEM_UNPOISON (c, sizeof (*c));
+      next = fs_chunk_ptr (fsh, c->next);
+      fl_index = fs_freelist_for_size (c->length);
+      fss_chunk_free_list_push (fsh, fss, fl_index, c);
+      n_collect += fs_freelist_index_to_size (fl_index);
+      c = next;
+    }
+
+  fss_fl_chunk_bytes_add (fss, n_collect);
+  fsh_cached_bytes_add (fsh, n_collect);
+}
+
+void
+fsh_collect_chunks (fifo_segment_header_t * fsh, u32 slice_index,
+		    svm_fifo_chunk_t * c)
 {
-  c->start_byte = 0;
-  c->length = size;
-  c->next = 0;
+  fifo_segment_slice_t *fss;
+  fss = fsh_slice_get (fsh, slice_index);
+  fsh_slice_collect_chunks (fsh, fss, c);
 }
 
-static inline int
-fs_free_list_for_size (u32 size)
+svm_fifo_t *
+fs_fifo_alloc (fifo_segment_t *fs, u32 slice_index)
 {
-  return max_log2 (size) - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
+  fifo_slice_private_t *pfss = &fs->slices[slice_index];
+  svm_fifo_t *f;
+
+  f = clib_mem_bulk_alloc (pfss->fifos);
+  clib_memset (f, 0, sizeof (*f));
+  return f;
 }
 
-static inline int
-fs_chunk_size_is_valid (u32 size)
+void
+fs_fifo_free (fifo_segment_t *fs, svm_fifo_t *f, u32 slice_index)
 {
+  fifo_slice_private_t *pfss;
+
+  if (CLIB_DEBUG)
+    clib_memset (f, 0xfc, sizeof (*f));
+
+  pfss = &fs->slices[slice_index];
+  clib_mem_bulk_free (pfss->fifos, f);
+}
+
+void
+fifo_segment_cleanup (fifo_segment_t *fs)
+{
+  int slice_index;
+  svm_msg_q_t *mq = 0;
+
+  for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
+    clib_mem_bulk_destroy (fs->slices[slice_index].fifos);
+
+  vec_free (fs->slices);
+
+  vec_foreach (fs->mqs, mq)
+    svm_msg_q_cleanup (mq);
+
+  vec_free (fs->mqs);
+}
+
+/**
+ * Allocate fifo in fifo segment
+ */
+svm_fifo_t *
+fifo_segment_alloc_fifo_w_slice (fifo_segment_t * fs, u32 slice_index,
+				 u32 data_bytes, fifo_segment_ftype_t ftype)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_slice_private_t *pfss;
+  fifo_segment_slice_t *fss;
+  svm_fifo_shared_t *sf;
+  svm_fifo_t *f = 0;
+
+  ASSERT (slice_index < fs->n_slices);
+
+  if (PREDICT_FALSE (data_bytes > 1 << fsh->max_log2_fifo_size))
+    return 0;
+
+  sf = fs_try_alloc_fifo (fsh, slice_index, data_bytes);
+  if (!sf)
+    goto done;
+
+  f = fs_fifo_alloc (fs, slice_index);
+  f->fs_hdr = fsh;
+  f->shr = sf;
+
+  svm_fifo_init (f, data_bytes);
+
+  fss = fsh_slice_get (fsh, slice_index);
+  pfss = fs_slice_private_get (fs, slice_index);
+
+  /* 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
+   * both rx and tx fifos keep pointers to the session, it's enough to track
+   * only one. */
+  if (ftype == FIFO_SEGMENT_RX_FIFO)
+    {
+      pfss_fifo_add_active_list (pfss, f);
+      f->flags |= SVM_FIFO_F_LL_TRACKED;
+    }
+
+  fsh_active_fifos_update (fsh, 1);
+  fss->virtual_mem += svm_fifo_size (f);
+
+done:
+  return (f);
+}
+
+svm_fifo_t *
+fifo_segment_alloc_fifo_w_offset (fifo_segment_t *fs, uword offset)
+{
+  svm_fifo_t *f = fs_fifo_alloc (fs, 0);
+  svm_fifo_shared_t *sf;
+
+  sf = (svm_fifo_shared_t *) ((u8 *) fs->h + offset);
+  f->fs_hdr = fs->h;
+  f->shr = sf;
+
+  f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
+  f->segment_index = SVM_FIFO_INVALID_INDEX;
+  f->refcnt = 1;
+  return f;
+}
+
+svm_fifo_t *
+fifo_segment_duplicate_fifo (fifo_segment_t *fs, svm_fifo_t *f)
+{
+  svm_fifo_t *nf = fs_fifo_alloc (fs, 0);
+  clib_memcpy (nf, f, sizeof (*f));
+  return nf;
+}
+
+/**
+ * Free fifo allocated in fifo segment
+ */
+void
+fifo_segment_free_fifo (fifo_segment_t * fs, svm_fifo_t * f)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_slice_private_t *pfss;
+  fifo_segment_slice_t *fss;
+  svm_fifo_shared_t *sf;
+
+  ASSERT (f->refcnt > 0);
+
+  if (--f->refcnt > 0)
+    return;
+
   /*
-   * 4K minimum. It's not likely that anything good will happen
-   * with a smaller FIFO.
+   * Cleanup shared state
    */
-  return size >= FIFO_SEGMENT_MIN_FIFO_SIZE
-    && size <= FIFO_SEGMENT_MAX_FIFO_SIZE;
+
+  sf = f->shr;
+  fss = fsh_slice_get (fsh, sf->slice_index);
+  pfss = fs_slice_private_get (fs, sf->slice_index);
+
+  /* Free fifo chunks */
+  fsh_slice_collect_chunks (fsh, fss, fs_chunk_ptr (fsh, f->shr->start_chunk));
+
+  sf->start_chunk = sf->end_chunk = 0;
+  sf->head_chunk = sf->tail_chunk = 0;
+
+  /* Add to free list */
+  fss_fifo_free_list_push (fsh, fss, sf);
+
+  fss->virtual_mem -= svm_fifo_size (f);
+
+  /*
+   *  Cleanup private state
+   */
+
+  /* Remove from active list. Only rx fifos are tracked */
+  if (f->flags & SVM_FIFO_F_LL_TRACKED)
+    {
+      pfss_fifo_del_active_list (pfss, f);
+      f->flags &= ~SVM_FIFO_F_LL_TRACKED;
+    }
+
+  svm_fifo_free_chunk_lookup (f);
+  svm_fifo_free_ooo_data (f);
+
+  if (CLIB_DEBUG)
+    {
+      sf->master_session_index = ~0;
+      f->master_thread_index = ~0;
+    }
+
+  f->ooo_enq = f->ooo_deq = 0;
+  f->prev = 0;
+
+  fs_fifo_free (fs, f, f->shr->slice_index);
+
+  fsh_active_fifos_update (fsh, -1);
+}
+
+void
+fifo_segment_free_client_fifo (fifo_segment_t *fs, svm_fifo_t *f)
+{
+  fs_fifo_free (fs, f, 0 /* clients attach fifos in slice 0 */);
+}
+
+void
+fifo_segment_detach_fifo (fifo_segment_t *fs, svm_fifo_t **f)
+{
+  fifo_slice_private_t *pfss;
+  fifo_segment_slice_t *fss;
+  svm_fifo_t *of = *f;
+  u32 slice_index;
+
+  slice_index = of->master_thread_index;
+  fss = fsh_slice_get (fs->h, slice_index);
+  pfss = fs_slice_private_get (fs, slice_index);
+  fss->virtual_mem -= svm_fifo_size (of);
+  if (of->flags & SVM_FIFO_F_LL_TRACKED)
+    pfss_fifo_del_active_list (pfss, of);
+
+  /* Collect chunks that were provided in return for those detached */
+  fsh_slice_collect_chunks (fs->h, fss, of->chunks_at_attach);
+  of->chunks_at_attach = 0;
+
+  /* Collect hdr that was provided in return for the detached */
+  fss_fifo_free_list_push (fs->h, fss, of->hdr_at_attach);
+  of->hdr_at_attach = 0;
+
+  clib_mem_bulk_free (pfss->fifos, *f);
+  *f = 0;
+}
+
+void
+fifo_segment_attach_fifo (fifo_segment_t *fs, svm_fifo_t **f, u32 slice_index)
+{
+  svm_fifo_chunk_t *c, *nc, *pc = 0;
+  fifo_slice_private_t *pfss;
+  fifo_segment_slice_t *fss;
+  svm_fifo_t *nf, *of;
+
+  nf = fs_fifo_alloc (fs, slice_index);
+  clib_memcpy_fast (nf, *f, sizeof (*nf));
+
+  fss = fsh_slice_get (fs->h, slice_index);
+  pfss = fs_slice_private_get (fs, slice_index);
+  fss->virtual_mem += svm_fifo_size (nf);
+  nf->next = nf->prev = 0;
+  if (nf->flags & SVM_FIFO_F_LL_TRACKED)
+    pfss_fifo_add_active_list (pfss, nf);
+
+  /* Allocate shared hdr and chunks to be collected at detach in return
+   * for those that are being attached now */
+  of = *f;
+  of->hdr_at_attach = fsh_try_alloc_fifo_hdr (fs->h, fss);
+
+  c = fs_chunk_ptr (fs->h, nf->shr->start_chunk);
+  of->chunks_at_attach = pc = fsh_try_alloc_chunk (fs->h, fss, c->length);
+
+  while ((c = fs_chunk_ptr (fs->h, c->next)))
+    {
+      nc = fsh_try_alloc_chunk (fs->h, fss, c->length);
+      pc->next = fs_chunk_sptr (fs->h, nc);
+      pc = nc;
+    }
+
+  nf->shr->slice_index = slice_index;
+  *f = nf;
 }
 
-static svm_fifo_t *
-fs_try_alloc_fifo_from_freelist (fifo_segment_header_t * fsh, u32 data_bytes)
+uword
+fifo_segment_fifo_offset (svm_fifo_t *f)
 {
-  svm_fifo_chunk_t *c;
-  svm_fifo_t *f;
-  u32 fl_index;
-
-  f = fsh->free_fifos;
-  fl_index = fs_free_list_for_size (data_bytes);
-  vec_validate_init_empty (fsh->free_chunks, fl_index, 0);
-  c = fsh->free_chunks[fl_index];
+  return (u8 *) f->shr - (u8 *) f->fs_hdr;
+}
 
-  if (!f || !c)
-    return 0;
+svm_fifo_chunk_t *
+fifo_segment_alloc_chunk_w_slice (fifo_segment_t *fs, u32 slice_index,
+				  u32 chunk_size)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_segment_slice_t *fss;
 
-  fsh->free_fifos = f->next;
-  fsh->free_chunks[fl_index] = c->next;
-  c->next = c;
-  c->start_byte = 0;
-  c->length = data_bytes;
-  memset (f, 0, sizeof (*f));
-  f->start_chunk = c;
-  f->end_chunk = c;
-  return f;
+  fss = fsh_slice_get (fsh, slice_index);
+  return fsh_try_alloc_chunk (fsh, fss, chunk_size);
 }
 
-static svm_fifo_t *
-fs_try_allocate_fifo_batch (ssvm_shared_header_t * sh,
-			    fifo_segment_header_t * fsh, u32 data_bytes)
+void
+fifo_segment_collect_chunk (fifo_segment_t *fs, u32 slice_index,
+			    svm_fifo_chunk_t *c)
 {
-  u32 size, rounded_data_size;
-  svm_fifo_chunk_t *c;
-  u32 fl_index, hdrs;
-  svm_fifo_t *f;
-  void *oldheap;
-  u8 *fmem;
-  int i;
-
-  rounded_data_size = (1 << (max_log2 (data_bytes)));
-  fl_index = fs_free_list_for_size (data_bytes);
-  vec_validate_init_empty (fsh->free_chunks, fl_index, 0);
+  fsh_collect_chunks (fs->h, slice_index, c);
+}
 
-  oldheap = ssvm_push_heap (sh);
-  hdrs = sizeof (*f) + sizeof (*c);
-  size = (hdrs + rounded_data_size) * FIFO_SEGMENT_ALLOC_BATCH_SIZE;
-  fmem = clib_mem_alloc_aligned_at_offset (size, CLIB_CACHE_LINE_BYTES,
-					   0 /* align_offset */ ,
-					   0 /* os_out_of_memory */ );
-  ssvm_pop_heap (oldheap);
+uword
+fifo_segment_chunk_offset (fifo_segment_t *fs, svm_fifo_chunk_t *c)
+{
+  return (u8 *) c - (u8 *) fs->h;
+}
 
-  /* Out of space.. */
-  if (fmem == 0)
-    return 0;
+svm_msg_q_t *
+fifo_segment_msg_q_alloc (fifo_segment_t *fs, u32 mq_index,
+			  svm_msg_q_cfg_t *cfg)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  svm_msg_q_shared_t *smq;
+  svm_msg_q_t *mq;
+  void *base;
+  u32 size;
 
-  /* Carve fifo + chunk space */
-  for (i = 0; i < FIFO_SEGMENT_ALLOC_BATCH_SIZE; i++)
+  if (!fs->mqs)
     {
-      f = (svm_fifo_t *) fmem;
-      memset (f, 0, sizeof (*f));
-      f->next = fsh->free_fifos;
-      fsh->free_fifos = f;
-      c = (svm_fifo_chunk_t *) (fmem + sizeof (*f));
-      c->start_byte = 0;
-      c->length = rounded_data_size;
-      c->next = fsh->free_chunks[fl_index];
-      fsh->free_chunks[fl_index] = c;
-      fmem += hdrs + rounded_data_size;
+      u32 n_mqs = clib_max (fs->h->n_mqs, 1);
+      vec_validate (fs->mqs, n_mqs - 1);
     }
 
-  return fs_try_alloc_fifo_from_freelist (fsh, data_bytes);
+  size = svm_msg_q_size_to_alloc (cfg);
+  base = fsh_alloc_aligned (fsh, size, 8);
+  fsh->n_reserved_bytes += size;
+
+  smq = svm_msg_q_init (base, cfg);
+  mq = vec_elt_at_index (fs->mqs, mq_index);
+  svm_msg_q_attach (mq, smq);
+
+  return mq;
 }
 
-/**
- * Allocate fifo in fifo segment
- */
-svm_fifo_t *
-fifo_segment_alloc_fifo (fifo_segment_t * fs, u32 data_bytes,
-			 fifo_segment_ftype_t ftype)
+svm_msg_q_t *
+fifo_segment_msg_q_attach (fifo_segment_t *fs, uword offset, u32 mq_index)
 {
-  fifo_segment_header_t *fsh;
-  ssvm_shared_header_t *sh;
-  svm_fifo_t *f = 0;
+  svm_msg_q_t *mq;
 
-  if (!fs_chunk_size_is_valid (data_bytes))
+  if (!fs->mqs)
     {
-      clib_warning ("fifo size out of range %d", data_bytes);
-      return 0;
+      u32 n_mqs = clib_max (fs->h->n_mqs, 1);
+      vec_validate (fs->mqs, n_mqs - 1);
     }
 
-  sh = fs->ssvm.sh;
-  ssvm_lock_non_recursive (sh, 1);
-  fsh = fs->h;
+  mq = vec_elt_at_index (fs->mqs, mq_index);
 
-  /* Try the following steps in order:
-   * - grab fifo and chunk from freelists
-   * - batch fifo and chunk allocation
-   * - single fifo allocation
-   */
-  f = fs_try_alloc_fifo_from_freelist (fsh, data_bytes);
-  if (!f)
-    f = fs_try_allocate_fifo_batch (sh, fsh, data_bytes);
-  if (!f)
+  if (!mq->q.shr)
     {
-      void *oldheap = ssvm_push_heap (sh);
-      f = svm_fifo_create (data_bytes);
-      ssvm_pop_heap (oldheap);
-      if (!f)
-	goto done;
+      svm_msg_q_shared_t *smq;
+      smq = (svm_msg_q_shared_t *) ((u8 *) fs->h + offset);
+      svm_msg_q_attach (mq, smq);
     }
 
-  /* (re)initialize the fifo, as in svm_fifo_create */
-  svm_fifo_init (f, data_bytes);
-
-  /* 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
-   * both rx and tx fifos keep pointers to the session, it's enough to track
-   * only one. */
-  if (ftype == FIFO_SEGMENT_RX_FIFO)
-    {
-      if (fsh->fifos)
-	{
-	  fsh->fifos->prev = f;
-	  f->next = fsh->fifos;
-	}
-      fsh->fifos = f;
-      f->flags |= SVM_FIFO_F_LL_TRACKED;
-    }
-  fsh->n_active_fifos++;
+  ASSERT (fifo_segment_msg_q_offset (fs, mq_index) == offset);
 
-done:
-  ssvm_unlock_non_recursive (sh);
-  return (f);
+  return mq;
 }
 
-/**
- * Free fifo allocated in fifo segment
- */
 void
-fifo_segment_free_fifo (fifo_segment_t * fs, svm_fifo_t * f)
+fifo_segment_msg_qs_discover (fifo_segment_t *fs, int *fds, u32 n_fds)
 {
-  svm_fifo_chunk_t *cur, *next;
-  fifo_segment_header_t *fsh;
-  ssvm_shared_header_t *sh;
-  void *oldheap;
-  int fl_index;
-
-  ASSERT (f->refcnt > 0);
-
-  if (--f->refcnt > 0)
-    return;
-
-  sh = fs->ssvm.sh;
-  fsh = fs->h;
+  svm_msg_q_shared_t *smq;
+  u32 n_mqs, size, i;
+  uword offset = 0, n_alloced;
+  svm_msg_q_t *mq;
 
-  ssvm_lock_non_recursive (sh, 2);
-
-  /* Remove from active list. Only rx fifos are tracked */
-  if (f->flags & SVM_FIFO_F_LL_TRACKED)
+  n_mqs = fs->h->n_mqs;
+  if (n_fds && n_mqs != n_fds)
     {
-      if (f->prev)
-	f->prev->next = f->next;
-      else
-	fsh->fifos = f->next;
-      if (f->next)
-	f->next->prev = f->prev;
-      f->flags &= ~SVM_FIFO_F_LL_TRACKED;
+      clib_warning ("expected %u fds got %u", n_mqs, n_fds);
+      return;
     }
 
-  /* Add to free list */
-  f->next = fsh->free_fifos;
-  f->prev = 0;
-  fsh->free_fifos = f;
+  vec_validate (fs->mqs, n_mqs - 1);
+  n_alloced = fs->h->n_reserved_bytes - fs->h->start_byte_index;
+  ASSERT (n_alloced % n_mqs == 0);
+  size = n_alloced / n_mqs;
 
-  /* Free fifo chunks */
-  cur = f->start_chunk;
-  do
+  offset = fs->h->start_byte_index;
+  for (i = 0; i < n_mqs; i++)
     {
-      next = cur->next;
-      fl_index = fs_free_list_for_size (cur->length);
-      ASSERT (fl_index < vec_len (fsh->free_chunks));
-      cur->next = fsh->free_chunks[fl_index];
-      fsh->free_chunks[fl_index] = cur;
-      cur = next;
+      mq = vec_elt_at_index (fs->mqs, i);
+      smq = (svm_msg_q_shared_t *) ((u8 *) fs->h + offset);
+      svm_msg_q_attach (mq, smq);
+      if (n_fds)
+	svm_msg_q_set_eventfd (mq, fds[i]);
+      offset += size;
     }
-  while (cur != f->start_chunk);
+}
 
-  oldheap = ssvm_push_heap (sh);
-  svm_fifo_free_chunk_lookup (f);
-  ssvm_pop_heap (oldheap);
+uword
+fifo_segment_msg_q_offset (fifo_segment_t *fs, u32 mq_index)
+{
+  svm_msg_q_t *mq = vec_elt_at_index (fs->mqs, mq_index);
 
-  /* not allocated on segment heap */
-  svm_fifo_free_ooo_data (f);
+  if (mq->q.shr == 0)
+    return ~0ULL;
 
-  if (CLIB_DEBUG)
+  return (uword) ((u8 *) mq->q.shr - (u8 *) fs->h) -
+	 sizeof (svm_msg_q_shared_t);
+}
+
+int
+fifo_segment_prealloc_fifo_hdrs (fifo_segment_t * fs, u32 slice_index,
+				 u32 batch_size)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_segment_slice_t *fss;
+
+  fss = fsh_slice_get (fsh, slice_index);
+  return fsh_try_alloc_fifo_hdr_batch (fsh, fss, batch_size);
+}
+
+int
+fifo_segment_prealloc_fifo_chunks (fifo_segment_t * fs, u32 slice_index,
+				   u32 chunk_size, u32 batch_size)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_segment_slice_t *fss;
+  u32 fl_index;
+
+  if (!fs_chunk_size_is_valid (fsh, chunk_size))
     {
-      f->master_session_index = ~0;
-      f->master_thread_index = ~0;
+      clib_warning ("chunk size out of range %d", chunk_size);
+      return -1;
     }
 
-  fsh->n_active_fifos--;
-  ssvm_unlock_non_recursive (sh);
+  fl_index = fs_freelist_for_size (chunk_size);
+  fss = fsh_slice_get (fsh, slice_index);
+
+  return fsh_try_alloc_chunk_batch (fsh, fss, fl_index, batch_size);
 }
 
 /**
@@ -460,172 +1210,62 @@ fifo_segment_preallocate_fifo_pairs (fifo_segment_t * fs,
 				     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;
-  ssvm_shared_header_t *sh = fs->ssvm.sh;
+  u32 rx_rounded_data_size, tx_rounded_data_size, pair_size, pairs_to_alloc;
+  u32 hdrs, pairs_per_slice, alloc_now;
   fifo_segment_header_t *fsh = fs->h;
-  int i, rx_fl_index, tx_fl_index;
-  u8 *rx_fifo_mem, *tx_fifo_mem;
+  int rx_fl_index, tx_fl_index, i;
+  fifo_segment_slice_t *fss;
   uword space_available;
-  svm_fifo_chunk_t *c;
-  void *oldheap;
-  svm_fifo_t *f;
-  u32 hdrs;
 
   /* Parameter check */
   if (rx_fifo_size == 0 || tx_fifo_size == 0 || *n_fifo_pairs == 0)
     return;
 
-  if (!fs_chunk_size_is_valid (rx_fifo_size))
+  if (!fs_chunk_size_is_valid (fsh, rx_fifo_size))
     {
       clib_warning ("rx fifo_size out of range %d", rx_fifo_size);
       return;
     }
 
-  if (!fs_chunk_size_is_valid (tx_fifo_size))
+  if (!fs_chunk_size_is_valid (fsh, tx_fifo_size))
     {
       clib_warning ("tx fifo_size out of range %d", tx_fifo_size);
       return;
     }
 
   rx_rounded_data_size = (1 << (max_log2 (rx_fifo_size)));
-  rx_fl_index = fs_free_list_for_size (rx_fifo_size);
+  rx_fl_index = fs_freelist_for_size (rx_fifo_size);
   tx_rounded_data_size = (1 << (max_log2 (tx_fifo_size)));
-  tx_fl_index = fs_free_list_for_size (tx_fifo_size);
+  tx_fl_index = fs_freelist_for_size (tx_fifo_size);
 
-  hdrs = sizeof (*f) + sizeof (*c);
+  hdrs = sizeof (svm_fifo_t) + sizeof (svm_fifo_chunk_t);
 
   /* Calculate space requirements */
   pair_size = 2 * hdrs + rx_rounded_data_size + tx_rounded_data_size;
-#if USE_DLMALLOC == 0
-  space_available = fs->ssvm.ssvm_size - mheap_bytes (sh->heap);
-#else
-  space_available = fs->ssvm.ssvm_size - mspace_usable_size (sh->heap);
-#endif
-
-  pairs_to_allocate = clib_min (space_available / pair_size, *n_fifo_pairs);
-  rx_fifos_size = (hdrs + rx_rounded_data_size) * pairs_to_allocate;
-  tx_fifos_size = (hdrs + tx_rounded_data_size) * pairs_to_allocate;
-
-  vec_validate_init_empty (fsh->free_chunks,
-			   clib_max (rx_fl_index, tx_fl_index), 0);
-
-  oldheap = ssvm_push_heap (sh);
-
-  /* Allocate rx and tx fifo memory. May fail. */
-  rx_fifo_mem = clib_mem_alloc_aligned_at_offset (rx_fifos_size,
-						  CLIB_CACHE_LINE_BYTES,
-						  0 /* align_offset */ ,
-						  0 /* os_out_of_memory */ );
-  tx_fifo_mem = 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_mem == 0 || tx_fifo_mem == 0)
-    {
-      rx_fifo_mem ? clib_mem_free (rx_fifo_mem) : clib_mem_free (tx_fifo_mem);
-      clib_warning ("fifo preallocation failure: rx size %d tx size %u "
-		    "npairs %d", rx_fifo_size, tx_fifo_size, *n_fifo_pairs);
-      ssvm_pop_heap (oldheap);
-      return;
-    }
-
-  /* Carve rx and tx fifo memory */
-  for (i = 0; i < pairs_to_allocate; i++)
-    {
-      f = (svm_fifo_t *) rx_fifo_mem;
-      c = (svm_fifo_chunk_t *) (rx_fifo_mem + sizeof (*f));
-      fifo_init_chunk_for_segment (c, rx_rounded_data_size);
-      fifo_init_for_segment (f, c);
-      rx_fifo_mem += hdrs + rx_rounded_data_size;
-
-      f = (svm_fifo_t *) tx_fifo_mem;
-      c = (svm_fifo_chunk_t *) (tx_fifo_mem + sizeof (*f));
-      fifo_init_chunk_for_segment (c, tx_rounded_data_size);
-      fifo_init_for_segment (f, c);
-      tx_fifo_mem += hdrs + tx_rounded_data_size;
-    }
-
-  /* Account for the pairs allocated */
-  *n_fifo_pairs -= pairs_to_allocate;
-  ssvm_pop_heap (oldheap);
-}
-
-int
-fifo_segment_grow_fifo (fifo_segment_t * fs, svm_fifo_t * f, u32 chunk_size)
-{
-  ssvm_shared_header_t *sh;
-  svm_fifo_chunk_t *c;
-  void *oldheap;
-  int fl_index;
-
-  if (!fs_chunk_size_is_valid (chunk_size))
-    {
-      clib_warning ("chunk size out of range %d", chunk_size);
-      return 0;
-    }
-
-  fl_index = fs_free_list_for_size (chunk_size);
-
-  sh = fs->ssvm.sh;
-  ssvm_lock_non_recursive (sh, 1);
-
-  vec_validate_init_empty (fs->h->free_chunks, fl_index, 0);
-  c = fs->h->free_chunks[fl_index];
-
-  oldheap = ssvm_push_heap (sh);
-
-  if (!c)
-    {
-      c = svm_fifo_chunk_alloc (chunk_size);
-      if (!c)
-	{
-	  ssvm_pop_heap (oldheap);
-	  return -1;
-	}
-    }
-  else
-    {
-      fs->h->free_chunks[fl_index] = c->next;
-      c->next = 0;
-    }
-
-  svm_fifo_add_chunk (f, c);
-
-  ssvm_pop_heap (oldheap);
-  ssvm_unlock_non_recursive (sh);
-  return 0;
-}
-
-int
-fifo_segment_collect_fifo_chunks (fifo_segment_t * fs, svm_fifo_t * f)
-{
-  svm_fifo_chunk_t *cur, *next;
-  ssvm_shared_header_t *sh;
-  void *oldheap;
-  int fl_index;
-
-  sh = fs->ssvm.sh;
-  ssvm_lock_non_recursive (sh, 1);
+  space_available = fsh_n_free_bytes (fsh);
+  pairs_to_alloc = space_available / pair_size;
+  pairs_to_alloc = clib_min (pairs_to_alloc, *n_fifo_pairs);
+  pairs_per_slice = pairs_to_alloc / fs->n_slices;
+  pairs_per_slice += pairs_to_alloc % fs->n_slices ? 1 : 0;
 
-  oldheap = ssvm_push_heap (sh);
-  cur = svm_fifo_collect_chunks (f);
+  if (!pairs_per_slice)
+    return;
 
-  while (cur)
+  for (i = 0; i < fs->n_slices; i++)
     {
-      next = cur->next;
-      fl_index = fs_free_list_for_size (cur->length);
-      cur->next = fs->h->free_chunks[fl_index];
-      fs->h->free_chunks[fl_index] = cur;
-      cur = next;
+      alloc_now = clib_min (pairs_per_slice, *n_fifo_pairs);
+      if (0 == alloc_now)
+	break;
+
+      fss = fsh_slice_get (fsh, i);
+      if (fs_try_alloc_fifo_batch (fsh, fss, rx_fl_index, alloc_now))
+	clib_warning ("rx prealloc failed: pairs %u", alloc_now);
+      if (fs_try_alloc_fifo_batch (fsh, fss, tx_fl_index, alloc_now))
+	clib_warning ("tx prealloc failed: pairs %u", alloc_now);
+
+      /* Account for the pairs allocated */
+      *n_fifo_pairs -= alloc_now;
     }
-
-  ssvm_pop_heap (oldheap);
-  ssvm_unlock_non_recursive (sh);
-
-  return 0;
 }
 
 /**
@@ -634,54 +1274,63 @@ fifo_segment_collect_fifo_chunks (fifo_segment_t * fs, svm_fifo_t * f)
 u32
 fifo_segment_num_fifos (fifo_segment_t * fs)
 {
-  return fs->h->n_active_fifos;
+  return fsh_n_active_fifos (fs->h);
 }
 
-u32
-fifo_segment_num_free_fifos (fifo_segment_t * fs, u32 fifo_size_in_bytes)
+static u32
+fs_slice_num_free_fifos (fifo_segment_header_t *fsh, fifo_segment_slice_t *fss)
 {
-  fifo_segment_header_t *fsh;
-  ssvm_shared_header_t *sh;
-  svm_fifo_t *f;
+  svm_fifo_shared_t *f;
   u32 count = 0;
 
-  sh = fs->ssvm.sh;
-  fsh = (fifo_segment_header_t *) sh->opaque[0];
-
-  f = fsh->free_fifos;
+  f = fs_ptr (fsh, fss->free_fifos);
   if (f == 0)
     return 0;
 
   while (f)
     {
-      f = f->next;
+      f = fs_ptr (fsh, f->next);
       count++;
     }
   return count;
 }
 
 u32
-fifo_segment_num_free_chunks (fifo_segment_t * fs, u32 size)
+fifo_segment_num_free_fifos (fifo_segment_t * fs)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_segment_slice_t *fss;
+  int slice_index;
+  u32 count = 0;
+
+  for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
+    {
+      fss = fsh_slice_get (fsh, slice_index);
+      count += fs_slice_num_free_fifos (fsh, fss);
+    }
+  return count;
+}
+
+static u32
+fs_slice_num_free_chunks (fifo_segment_header_t *fsh,
+			  fifo_segment_slice_t *fss, u32 size)
 {
   u32 count = 0, rounded_size, fl_index;
-  fifo_segment_header_t *fsh;
   svm_fifo_chunk_t *c;
   int i;
 
-  fsh = fs->h;
-
   /* Count all free chunks? */
   if (size == ~0)
     {
-      for (i = 0; i < vec_len (fsh->free_chunks); i++)
+      for (i = 0; i < FS_CHUNK_VEC_LEN; i++)
 	{
-	  c = fsh->free_chunks[i];
+	  c = fss_chunk_free_list_head (fsh, fss, i);
 	  if (c == 0)
 	    continue;
 
 	  while (c)
 	    {
-	      c = c->next;
+	      c = fs_chunk_ptr (fsh, c->next);
 	      count++;
 	    }
 	}
@@ -689,33 +1338,160 @@ fifo_segment_num_free_chunks (fifo_segment_t * fs, u32 size)
     }
 
   rounded_size = (1 << (max_log2 (size)));
-  fl_index = fs_free_list_for_size (rounded_size);
+  fl_index = fs_freelist_for_size (rounded_size);
 
-  if (fl_index >= vec_len (fsh->free_chunks))
+  if (fl_index >= FS_CHUNK_VEC_LEN)
     return 0;
 
-  c = fsh->free_chunks[fl_index];
+  c = fss_chunk_free_list_head (fsh, fss, fl_index);
   if (c == 0)
     return 0;
 
   while (c)
     {
-      c = c->next;
+      c = fs_chunk_ptr (fsh, c->next);
       count++;
     }
   return count;
 }
 
+u32
+fifo_segment_num_free_chunks (fifo_segment_t * fs, u32 size)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_segment_slice_t *fss;
+  int slice_index;
+  u32 count = 0;
+
+  for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
+    {
+      fss = fsh_slice_get (fsh, slice_index);
+      count += fs_slice_num_free_chunks (fsh, fss, size);
+    }
+  return count;
+}
+
+uword
+fifo_segment_size (fifo_segment_t * fs)
+{
+  return fs->h->max_byte_index - fs->h->n_reserved_bytes;
+}
+
+static u8
+fs_has_reached_mem_limit (fifo_segment_t *fs)
+{
+  return (fs->flags & FIFO_SEGMENT_F_MEM_LIMIT) ? 1 : 0;
+}
+
+static void
+fs_reset_mem_limit (fifo_segment_t *fs)
+{
+  fs->flags &= ~FIFO_SEGMENT_F_MEM_LIMIT;
+}
+
+void *
+fifo_segment_alloc (fifo_segment_t *fs, uword size)
+{
+  void *rv = fsh_alloc (fs->h, size);
+  /* Mark externally allocated bytes as reserved. This helps
+   * @ref fifo_segment_size report bytes used only for fifos */
+  fs->h->n_reserved_bytes += size;
+  return rv;
+}
+
+uword
+fifo_segment_free_bytes (fifo_segment_t * fs)
+{
+  return fsh_n_free_bytes (fs->h);
+}
+
+uword
+fifo_segment_cached_bytes (fifo_segment_t * fs)
+{
+  return fsh_n_cached_bytes (fs->h);
+}
+
+uword
+fifo_segment_available_bytes (fifo_segment_t * fs)
+{
+  return fsh_n_free_bytes (fs->h) + fsh_n_cached_bytes (fs->h);
+}
+
+uword
+fifo_segment_fl_chunk_bytes (fifo_segment_t * fs)
+{
+  fifo_segment_header_t *fsh = fs->h;
+  fifo_segment_slice_t *fss;
+  uword n_bytes = 0;
+  int slice_index;
+
+  for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
+    {
+      fss = fsh_slice_get (fsh, slice_index);
+      n_bytes += fss_fl_chunk_bytes (fss);
+    }
+
+  return n_bytes;
+}
+
 u8
 fifo_segment_has_fifos (fifo_segment_t * fs)
 {
-  return fs->h->fifos != 0;
+  return (fsh_n_active_fifos (fs->h) != 0);
 }
 
 svm_fifo_t *
-fifo_segment_get_fifo_list (fifo_segment_t * fs)
+fifo_segment_get_slice_fifo_list (fifo_segment_t * fs, u32 slice_index)
+{
+  fifo_slice_private_t *pfss;
+
+  pfss = fs_slice_private_get (fs, slice_index);
+  return pfss->active_fifos;
+}
+
+u8
+fifo_segment_get_mem_usage (fifo_segment_t * fs)
+{
+  uword size, in_use;
+
+  size = fifo_segment_size (fs);
+  in_use =
+    size - fifo_segment_free_bytes (fs) - fifo_segment_cached_bytes (fs);
+  return (in_use * 100) / size;
+}
+
+fifo_segment_mem_status_t
+fifo_segment_determine_status (fifo_segment_t *fs, u8 usage)
+{
+  if (!fs->high_watermark || !fs->low_watermark)
+    return MEMORY_PRESSURE_NO_PRESSURE;
+
+  /* once the no-memory is detected, the status continues
+   * until memory usage gets below the high watermark
+   */
+  if (fs_has_reached_mem_limit (fs))
+    {
+      if (usage >= fs->high_watermark)
+	return MEMORY_PRESSURE_NO_MEMORY;
+      else
+	fs_reset_mem_limit (fs);
+    }
+
+  if (usage >= fs->high_watermark)
+    return MEMORY_PRESSURE_HIGH_PRESSURE;
+
+  else if (usage >= fs->low_watermark)
+    return MEMORY_PRESSURE_LOW_PRESSURE;
+
+  return MEMORY_PRESSURE_NO_PRESSURE;
+}
+
+fifo_segment_mem_status_t
+fifo_segment_get_mem_status (fifo_segment_t * fs)
 {
-  return fs->h->fifos;
+  u8 usage = fifo_segment_get_mem_usage (fs);
+
+  return fifo_segment_determine_status (fs, usage);
 }
 
 u8 *
@@ -726,7 +1502,7 @@ format_fifo_segment_type (u8 * s, va_list * args)
   ssvm_segment_type_t st = ssvm_type (&sp->ssvm);
 
   if (st == SSVM_SEGMENT_PRIVATE)
-    s = format (s, "%s", "private-heap");
+    s = format (s, "%s", "private");
   else if (st == SSVM_SEGMENT_MEMFD)
     s = format (s, "%s", "memfd");
   else if (st == SSVM_SEGMENT_SHM)
@@ -742,38 +1518,108 @@ format_fifo_segment_type (u8 * s, va_list * args)
 u8 *
 format_fifo_segment (u8 * s, va_list * args)
 {
-  fifo_segment_t *sp = va_arg (*args, fifo_segment_t *);
+  u32 count, indent, active_fifos, free_fifos;
+  fifo_segment_t *fs = va_arg (*args, fifo_segment_t *);
   int verbose __attribute__ ((unused)) = va_arg (*args, int);
-  fifo_segment_header_t *fsh = sp->h;
-  u32 count, indent;
+  uword est_chunk_bytes, est_free_seg_bytes, free_chunks;
+  uword chunk_bytes = 0, free_seg_bytes, chunk_size;
+  uword tracked_cached_bytes;
+  uword fifo_hdr = 0, reserved;
+  fifo_segment_header_t *fsh;
+  fifo_segment_slice_t *fss;
   svm_fifo_chunk_t *c;
+  u32 slice_index;
+  char *address;
+  size_t size;
   int i;
+  uword allocated, in_use, virt;
+  f64 usage;
+  fifo_segment_mem_status_t mem_st;
 
   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, fifo_segment_num_fifos (sp));
-#endif
-
-  for (i = 0; i < vec_len (fsh->free_chunks); i++)
-    {
-      c = fsh->free_chunks[i];
-      if (c == 0)
-	continue;
-      count = 0;
-      while (c)
+
+  if (fs == 0)
+    {
+      s = format (s, "%-20s%10s%15s%15s%15s%15s", "Name", "Type",
+		  "HeapSize (M)", "ActiveFifos", "FreeFifos", "Address");
+      return s;
+    }
+
+  fifo_segment_info (fs, &address, &size);
+  active_fifos = fifo_segment_num_fifos (fs);
+  free_fifos = fifo_segment_num_free_fifos (fs);
+
+  s = format (s, "%-20v%10U%15llu%15u%15u%15llx", ssvm_name (&fs->ssvm),
+	      format_fifo_segment_type, fs, size >> 20ULL, active_fifos,
+	      free_fifos, address);
+
+  if (!verbose)
+    return s;
+
+  fsh = fs->h;
+
+  free_chunks = fifo_segment_num_free_chunks (fs, ~0);
+  if (free_chunks)
+    s =
+      format (s, "\n\n%UFree/Allocated chunks by size:\n", format_white_space,
+	      indent + 2);
+  else
+    s = format (s, "\n");
+
+  for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
+    {
+      fss = fsh_slice_get (fsh, slice_index);
+      for (i = 0; i < FS_CHUNK_VEC_LEN; i++)
 	{
-	  c = c->next;
-	  count++;
-	}
+	  c = fss_chunk_free_list_head (fsh, fss, i);
+	  if (c == 0 && fss->num_chunks[i] == 0)
+	    continue;
+	  count = 0;
+	  while (c)
+	    {
+	      c = fs_chunk_ptr (fsh, c->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);
+	  chunk_size = fs_freelist_index_to_size (i);
+	  s = format (s, "%U%-5u kB: %u/%u\n", format_white_space, indent + 2,
+		      chunk_size >> 10, count, fss->num_chunks[i]);
+
+	  chunk_bytes += count * chunk_size;
+	}
     }
+
+  fifo_hdr = free_fifos * sizeof (svm_fifo_t);
+  est_chunk_bytes = fifo_segment_fl_chunk_bytes (fs);
+  est_free_seg_bytes = fifo_segment_free_bytes (fs);
+  free_seg_bytes = fifo_segment_free_bytes (fs);
+  tracked_cached_bytes = fifo_segment_cached_bytes (fs);
+  allocated = fifo_segment_size (fs);
+  in_use = fifo_segment_size (fs) - est_free_seg_bytes - tracked_cached_bytes;
+  usage = (100.0 * in_use) / allocated;
+  mem_st = fifo_segment_get_mem_status (fs);
+  virt = fs_virtual_mem (fs);
+  reserved = fsh->n_reserved_bytes;
+
+  s = format (s, "\n%Useg free bytes: %U (%lu) estimated: %U (%lu) reserved:"
+	      " %U (%lu)\n", format_white_space, indent + 2,
+	      format_memory_size, free_seg_bytes, free_seg_bytes,
+	      format_memory_size, est_free_seg_bytes, est_free_seg_bytes,
+	      format_memory_size, reserved, reserved);
+  s = format (s, "%Uchunk free bytes: %U (%lu) estimated: %U (%lu) tracked:"
+	      " %U (%lu)\n", format_white_space, indent + 2,
+	      format_memory_size, chunk_bytes, chunk_bytes,
+	      format_memory_size, est_chunk_bytes, est_chunk_bytes,
+	      format_memory_size, tracked_cached_bytes, tracked_cached_bytes);
+  s = format (s, "%Ufifo active: %u hdr free: %u bytes: %U (%u) \n",
+	      format_white_space, indent + 2, fsh->n_active_fifos, free_fifos,
+	      format_memory_size, fifo_hdr, fifo_hdr);
+  s = format (s, "%Usegment usage: %.2f%% (%U / %U) virt: %U status: %s\n",
+	      format_white_space, indent + 2, usage, format_memory_size,
+	      in_use, format_memory_size, allocated, format_memory_size, virt,
+	      fifo_segment_mem_status_strings[mem_st]);
+  s = format (s, "\n");
+
   return s;
 }