X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fsvm%2Ffifo_segment.c;h=2ff272e2f8812ca9172d2cfed659d13c3efffc29;hb=afbb33aaf254ebfe6ebf2477b1a4859cec40e34b;hp=815c5a29e8dbc59f86fef3ae013ed998d954b0ba;hpb=79b3f8ce33849fd789c8fc31b219373749ad9678;p=vpp.git

diff --git a/src/svm/fifo_segment.c b/src/svm/fifo_segment.c
index 815c5a29e8d..2ff272e2f88 100644
--- a/src/svm/fifo_segment.c
+++ b/src/svm/fifo_segment.c
@@ -14,6 +14,37 @@
  */
 
 #include <svm/fifo_segment.h>
+#include <vppinfra/mem.h>
+
+static inline void *
+fsh_alloc_aligned (fifo_segment_header_t *fsh, uword size, uword align)
+{
+  uword cur_pos, cur_pos_align, new_pos;
+
+  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;
+
+  if (new_pos >= fsh->max_byte_index)
+    return 0;
+
+  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 *);
+}
+
+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)
@@ -21,45 +52,25 @@ 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 _
 };
 
-/**
- * Fifo segment free space
- *
- * Queries the underlying memory manager, dlmalloc, for free space. Since this
- * ends up walking the internal data structures, it should not be called
- * indiscriminately.
- *
- * @param fs		fifo segment
- * @return		number of free bytes
- */
-static uword
-fsh_free_space (fifo_segment_header_t * fsh)
-{
-  return clib_mem_get_heap_free_space (fsh->ssvm_sh->heap);
-}
-
-static inline void
-fsh_free_bytes_sub (fifo_segment_header_t * fsh, int size)
-{
-  clib_atomic_fetch_sub_rel (&fsh->n_free_bytes, size);
-}
-
 static inline uword
 fsh_n_free_bytes (fifo_segment_header_t * fsh)
 {
-  uword n_free = clib_atomic_load_relax_n (&fsh->n_free_bytes);
-  return n_free > fsh->n_reserved_bytes ? n_free - fsh->n_reserved_bytes : 0;
-}
-
-static inline void
-fsh_update_free_bytes (fifo_segment_header_t * fsh)
-{
-  clib_atomic_store_rel_n (&fsh->n_free_bytes, fsh_free_space (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
@@ -94,13 +105,14 @@ fsh_n_active_fifos (fifo_segment_header_t * fsh)
 }
 
 static inline uword
-fsh_virtual_mem (fifo_segment_header_t * fsh)
+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 < fsh->n_slices; 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);
@@ -116,93 +128,144 @@ fsh_virtual_mem_update (fifo_segment_header_t * fsh, u32 slice_index,
   fss->virtual_mem += n_bytes;
 }
 
-static void
-fsh_check_mem (fifo_segment_header_t * fsh)
+static inline int
+fss_chunk_fl_index_is_valid (fifo_segment_slice_t *fss, u32 fl_index)
 {
-  uword thresh;
-
-  if (fsh->flags & FIFO_SEGMENT_F_MEM_LIMIT)
-    return;
-
-  thresh = clib_max (0.01 * fsh->ssvm_sh->ssvm_size,
-		     2 * fsh->n_reserved_bytes);
-  if (fsh->n_free_bytes > thresh)
-    return;
-
-  fsh->flags |= FIFO_SEGMENT_F_MEM_LIMIT;
-  fsh_update_free_bytes (fsh);
+  return (fl_index < FS_CHUNK_VEC_LEN);
 }
 
-static inline int
-fss_chunk_fl_index_is_valid (fifo_segment_slice_t * fss, u32 fl_index)
+#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)
 {
-  return (fl_index < vec_len (fss->free_chunks));
+  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_slice_t * fss, u32 fl_index,
-			  svm_fifo_chunk_t * c)
+fss_chunk_free_list_push (fifo_segment_header_t *fsh,
+			  fifo_segment_slice_t *fss, u32 fl_index,
+			  svm_fifo_chunk_t *c)
 {
-  clib_spinlock_lock (&fss->chunk_lock);
-  c->next = fss->free_chunks[fl_index];
-  fss->free_chunks[fl_index] = c;
-  clib_spinlock_unlock (&fss->chunk_lock);
+  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_slice_t * fss, u32 fl_index,
-			       svm_fifo_chunk_t * head,
-			       svm_fifo_chunk_t * tail)
+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)
 {
-  clib_spinlock_lock (&fss->chunk_lock);
-  tail->next = fss->free_chunks[fl_index];
-  fss->free_chunks[fl_index] = head;
-  clib_spinlock_unlock (&fss->chunk_lock);
+  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_slice_t * fss, u32 fl_index)
+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));
 
-  clib_spinlock_lock (&fss->chunk_lock);
+  old_head = clib_atomic_load_acq_n (&fss->free_chunks[fl_index]);
 
-  if (!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
     {
-      clib_spinlock_unlock (&fss->chunk_lock);
-      return 0;
+      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));
 
-  c = fss->free_chunks[fl_index];
-  fss->free_chunks[fl_index] = c->next;
+  return c;
+}
 
-  clib_spinlock_unlock (&fss->chunk_lock);
+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);
+}
 
-  return c;
+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
-fss_fifo_add_active_list (fifo_segment_slice_t * fss, svm_fifo_t * f)
+pfss_fifo_add_active_list (fifo_slice_private_t *pfss, svm_fifo_t *f)
 {
-  if (fss->fifos)
+  if (pfss->active_fifos)
     {
-      fss->fifos->prev = f;
-      f->next = fss->fifos;
+      pfss->active_fifos->prev = f;
+      f->next = pfss->active_fifos;
     }
-  fss->fifos = f;
+  pfss->active_fifos = f;
 }
 
 static inline void
-fss_fifo_del_active_list (fifo_segment_slice_t * fss, svm_fifo_t * f)
+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
-	fss->fifos = f->next;
+	pfss->active_fifos = f->next;
       if (f->next)
 	f->next->prev = f->prev;
     }
@@ -232,54 +295,48 @@ fss_fl_chunk_bytes_sub (fifo_segment_slice_t * fss, uword size)
 int
 fifo_segment_init (fifo_segment_t * fs)
 {
+  u32 align = 8, offset = 2 * 4096, slices_sz, i;
+  uword max_fifo, seg_start, seg_sz;
   fifo_segment_header_t *fsh;
-  fifo_segment_slice_t *fss;
   ssvm_shared_header_t *sh;
-  u32 max_chunk_sz;
-  uword max_fifo;
-  void *oldheap;
-  int i;
+  void *seg_data;
 
+  /* TODO remove ssvm heap entirely */
   sh = fs->ssvm.sh;
-  oldheap = ssvm_push_heap (sh);
 
-  /*
-   * Manually align the fifo segment header to sizeof(uword) = 8 bytes.
-   * Long story made short: the "process-private" fifo segment
-   * is allocated from the main heap, not mmapped. dlmalloc
-   * only guarantees 4-byte alignment, and on aarch64
-   * the fsh can end up 4-byte but not 8-byte aligned.
-   * That eventually causes the atomic op in fifo_segment_update_free_bytes
-   * to backfire.
-   */
-  fsh = clib_mem_alloc_aligned (sizeof (*fsh), sizeof (uword));
-  clib_memset (fsh, 0, sizeof (*fsh));
-  fs->h = sh->opaque[0] = fsh;
+  seg_data = (u8 *) sh + offset;
+  seg_sz = sh->ssvm_size - offset;
+
   fs->n_slices = clib_max (fs->n_slices, 1);
+  slices_sz = sizeof (fifo_segment_slice_t) * fs->n_slices;
 
-  fsh->ssvm_sh = fs->ssvm.sh;
+  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);
+
+  fsh->byte_index = sizeof (*fsh) + slices_sz;
+  fsh->max_byte_index = seg_sz;
   fsh->n_slices = fs->n_slices;
-  max_fifo = clib_min ((fsh_free_space (fsh) - 4096) / 2,
-		       FIFO_SEGMENT_MAX_FIFO_SIZE);
-  fsh->max_log2_chunk_size = max_log2 (max_fifo);
+  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);
 
-  fsh->slices = clib_mem_alloc (sizeof (*fss) * fs->n_slices);
-  clib_memset (fsh->slices, 0, sizeof (*fss) * fs->n_slices);
-  max_chunk_sz = fsh->max_log2_chunk_size - FIFO_SEGMENT_MIN_LOG2_FIFO_SIZE;
+  fs->max_byte_index = fsh->max_byte_index;
+  fs->h = fsh;
+  sh->opaque[0] = (void *) ((u8 *) fsh - (u8 *) fs->ssvm.sh);
 
-  for (i = 0; i < fs->n_slices; i++)
-    {
-      fss = fsh_slice_get (fsh, i);
-      vec_validate_init_empty (fss->free_chunks, max_chunk_sz, 0);
-      vec_validate_init_empty (fss->num_chunks, max_chunk_sz, 0);
-      clib_spinlock_init (&fss->chunk_lock);
-    }
+  /* Allow random offsets */
+  fs->ssvm.sh->ssvm_va = 0;
 
-  ssvm_pop_heap (oldheap);
+  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);
 
-  fsh->n_free_bytes = fsh_free_space (fsh);
-  fsh->n_cached_bytes = 0;
-  fsh->n_reserved_bytes = clib_min (0.01 * fsh->n_free_bytes, 256 << 10);
   sh->ready = 1;
   return (0);
 }
@@ -324,6 +381,7 @@ 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_header_t *fsh;
   fifo_segment_t *fs;
   int rv;
 
@@ -332,7 +390,7 @@ fifo_segment_attach (fifo_segment_main_t * sm, fifo_segment_create_args_t * a)
   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 = sm->next_baseva;
+  fs->ssvm.requested_va = 0;
   if (a->segment_type == SSVM_SEGMENT_MEMFD)
     fs->ssvm.fd = a->memfd_fd;
   else
@@ -340,13 +398,21 @@ fifo_segment_attach (fifo_segment_main_t * sm, fifo_segment_create_args_t * a)
 
   if ((rv = ssvm_client_init (&fs->ssvm, a->segment_type)))
     {
-      _vec_len (fs) = vec_len (fs) - 1;
+      pool_put (sm->segments, fs);
       return (rv);
     }
 
-  /* Fish the segment header */
-  fs->h = fs->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);
 
+done:
   vec_add1 (a->new_segment_indices, fs - sm->segments);
   return (0);
 }
@@ -354,6 +420,7 @@ fifo_segment_attach (fifo_segment_main_t * sm, fifo_segment_create_args_t * a)
 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);
@@ -371,6 +438,14 @@ fifo_segment_get_segment (fifo_segment_main_t * sm, u32 segment_index)
   return pool_elt_at_index (sm->segments, segment_index);
 }
 
+fifo_segment_t *
+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)
 {
@@ -391,7 +466,8 @@ fs_freelist_for_size (u32 size)
 {
   if (PREDICT_FALSE (size < FIFO_SEGMENT_MIN_FIFO_SIZE))
     return 0;
-  return max_log2 (size) - FIFO_SEGMENT_MIN_LOG2_FIFO_SIZE;
+  return clib_min (max_log2 (size) - FIFO_SEGMENT_MIN_LOG2_FIFO_SIZE,
+		   FS_CHUNK_VEC_LEN - 1);
 }
 
 static inline u32
@@ -407,8 +483,8 @@ 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_chunk_size);
+  return size >= FIFO_SEGMENT_MIN_FIFO_SIZE &&
+	 size <= (1ULL << fsh->max_log2_fifo_size);
 }
 
 svm_fifo_chunk_t *
@@ -426,10 +502,10 @@ fs_try_alloc_multi_chunk (fifo_segment_header_t * fsh,
 
   while (req_bytes)
     {
-      c = fss_chunk_free_list_pop (fss, fl_index);
+      c = fss_chunk_free_list_pop (fsh, fss, fl_index);
       if (c)
 	{
-	  c->next = first;
+	  c->next = fs_chunk_sptr (fsh, first);
 	  first = c;
 	  n_alloc += fl_size;
 	  req_bytes -= clib_min (fl_size, req_bytes);
@@ -444,8 +520,8 @@ fs_try_alloc_multi_chunk (fifo_segment_header_t * fsh,
 	      while (c)
 		{
 		  fl_index = fs_freelist_for_size (c->length);
-		  next = c->next;
-		  fss_chunk_free_list_push (fss, fl_index, c);
+		  next = fs_chunk_ptr (fsh, c->next);
+		  fss_chunk_free_list_push (fsh, fss, fl_index, c);
 		  c = next;
 		}
 	      n_alloc = 0;
@@ -455,7 +531,7 @@ fs_try_alloc_multi_chunk (fifo_segment_header_t * fsh,
 	      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 (fss, fl_index);
+	      first = fss_chunk_free_list_pop (fsh, fss, fl_index);
 	      if (first)
 		{
 		  first->next = 0;
@@ -479,34 +555,32 @@ static int
 fsh_try_alloc_fifo_hdr_batch (fifo_segment_header_t * fsh,
 			      fifo_segment_slice_t * fss, u32 batch_size)
 {
-  svm_fifo_t *f;
-  void *oldheap;
+  svm_fifo_shared_t *f, *head = 0, *tail;
   uword size;
   u8 *fmem;
   int i;
 
-  size = (uword) sizeof (*f) * batch_size;
+  ASSERT (batch_size != 0);
 
-  oldheap = ssvm_push_heap (fsh->ssvm_sh);
-  fmem = clib_mem_alloc_aligned_at_offset (size, CLIB_CACHE_LINE_BYTES,
-					   0 /* align_offset */ ,
-					   0 /* os_out_of_memory */ );
-  ssvm_pop_heap (oldheap);
+  size = (uword) sizeof (*f) * batch_size;
 
-  /* Out of space.. */
+  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++)
     {
-      f = (svm_fifo_t *) fmem;
-      memset (f, 0, sizeof (*f));
-      f->next = fss->free_fifos;
-      fss->free_fifos = f;
+      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;
 }
 
@@ -518,21 +592,16 @@ fsh_try_alloc_chunk_batch (fifo_segment_header_t * fsh,
   svm_fifo_chunk_t *c, *head = 0, *tail;
   uword size, total_chunk_bytes;
   u32 rounded_data_size;
-  void *oldheap;
   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;
 
-  oldheap = ssvm_push_heap (fsh->ssvm_sh);
-  cmem = clib_mem_alloc_aligned_at_offset (size, CLIB_CACHE_LINE_BYTES,
-					   0 /* align_offset */ ,
-					   0 /* os_out_of_memory */ );
-  ssvm_pop_heap (oldheap);
-
-  /* Out of space.. */
+  cmem = fsh_alloc_aligned (fsh, size, 8 /* chunk hdr is 24B */);
   if (cmem == 0)
     return -1;
 
@@ -542,17 +611,16 @@ fsh_try_alloc_chunk_batch (fifo_segment_header_t * fsh,
     {
       c->start_byte = 0;
       c->length = rounded_data_size;
-      c->next = head;
+      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 (fss, fl_index, head, tail);
+  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);
-  fsh_free_bytes_sub (fsh, size);
 
   return 0;
 }
@@ -567,11 +635,10 @@ fs_try_alloc_fifo_batch (fifo_segment_header_t * fsh,
   return fsh_try_alloc_chunk_batch (fsh, fss, fl_index, batch_size);
 }
 
-static svm_fifo_t *
-fsh_try_alloc_fifo_hdr (fifo_segment_header_t * fsh,
-			fifo_segment_slice_t * fss)
+static svm_fifo_shared_t *
+fsh_try_alloc_fifo_hdr (fifo_segment_header_t *fsh, fifo_segment_slice_t *fss)
 {
-  svm_fifo_t *f;
+  svm_fifo_shared_t *sf;
 
   if (!fss->free_fifos)
     {
@@ -580,10 +647,10 @@ fsh_try_alloc_fifo_hdr (fifo_segment_header_t * fsh,
 	return 0;
     }
 
-  f = fss->free_fifos;
-  fss->free_fifos = f->next;
-  memset (f, 0, sizeof (*f));
-  return f;
+  sf = fss_fifo_free_list_pop (fsh, fss);
+  clib_memset (sf, 0, sizeof (*sf));
+
+  return sf;
 }
 
 static svm_fifo_chunk_t *
@@ -596,7 +663,7 @@ fsh_try_alloc_chunk (fifo_segment_header_t * fsh,
   fl_index = fs_freelist_for_size (data_bytes);
 
 free_list:
-  c = fss_chunk_free_list_pop (fss, fl_index);
+  c = fss_chunk_free_list_pop (fsh, fss, fl_index);
   if (c)
     {
       c->next = 0;
@@ -626,22 +693,17 @@ free_list:
 	    goto done;
 	  batch = n_free / FIFO_SEGMENT_MIN_FIFO_SIZE;
 	  if (!batch || fsh_try_alloc_chunk_batch (fsh, fss, 0, batch))
-	    {
-	      fsh_check_mem (fsh);
-	      goto done;
-	    }
+	    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))
-	    {
-	      fsh_check_mem (fsh);
-	      goto done;
-	    }
+	    goto done;
 	  c = fs_try_alloc_multi_chunk (fsh, fss, data_bytes);
 	}
     }
@@ -660,40 +722,40 @@ done:
  * - single fifo allocation
  * - grab multiple fifo chunks from freelists
  */
-static svm_fifo_t *
-fs_try_alloc_fifo (fifo_segment_header_t * fsh, fifo_segment_slice_t * fss,
-		   u32 data_bytes)
+static svm_fifo_shared_t *
+fs_try_alloc_fifo (fifo_segment_header_t *fsh, u32 slice_index, u32 data_bytes)
 {
+  fifo_segment_slice_t *fss;
   u32 fl_index, min_size;
   svm_fifo_chunk_t *c;
-  svm_fifo_t *f = 0;
+  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;
 
-  f = fsh_try_alloc_fifo_hdr (fsh, fss);
-  if (!f)
+  sf = fsh_try_alloc_fifo_hdr (fsh, fss);
+  if (!sf)
     return 0;
 
   c = fsh_try_alloc_chunk (fsh, fss, min_size);
   if (!c)
     {
-      f->next = fss->free_fifos;
-      fss->free_fifos = f;
+      fss_fifo_free_list_push (fsh, fss, sf);
       return 0;
     }
 
-  f->start_chunk = c;
+  sf->start_chunk = fs_chunk_sptr (fsh, c);
   while (c->next)
-    c = c->next;
-  f->end_chunk = c;
-  f->size = data_bytes;
-  f->fs_hdr = fsh;
+    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 f;
+  return sf;
 }
 
 svm_fifo_chunk_t *
@@ -718,9 +780,9 @@ fsh_slice_collect_chunks (fifo_segment_header_t * fsh,
   while (c)
     {
       CLIB_MEM_UNPOISON (c, sizeof (*c));
-      next = c->next;
+      next = fs_chunk_ptr (fsh, c->next);
       fl_index = fs_freelist_for_size (c->length);
-      fss_chunk_free_list_push (fss, fl_index, c);
+      fss_chunk_free_list_push (fsh, fss, fl_index, c);
       n_collect += fs_freelist_index_to_size (fl_index);
       c = next;
     }
@@ -738,6 +800,46 @@ fsh_collect_chunks (fifo_segment_header_t * fsh, u32 slice_index,
   fsh_slice_collect_chunks (fsh, fss, c);
 }
 
+svm_fifo_t *
+fs_fifo_alloc (fifo_segment_t *fs, u32 slice_index)
+{
+  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;
+}
+
+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
  */
@@ -746,30 +848,36 @@ 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_chunk_size))
+  if (PREDICT_FALSE (data_bytes > 1 << fsh->max_log2_fifo_size))
     return 0;
 
-  fss = fsh_slice_get (fsh, slice_index);
-  f = fs_try_alloc_fifo (fsh, fss, data_bytes);
-  if (!f)
+  sf = fs_try_alloc_fifo (fsh, slice_index, data_bytes);
+  if (!sf)
     goto done;
 
-  f->slice_index = slice_index;
+  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)
     {
-      fss_fifo_add_active_list (fss, f);
+      pfss_fifo_add_active_list (pfss, f);
       f->flags |= SVM_FIFO_F_LL_TRACKED;
     }
 
@@ -780,6 +888,30 @@ 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
  */
@@ -787,132 +919,267 @@ 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;
 
-  fss = fsh_slice_get (fsh, f->slice_index);
+  /*
+   * Cleanup shared state
+   */
+
+  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)
     {
-      fss_fifo_del_active_list (fss, f);
+      pfss_fifo_del_active_list (pfss, f);
       f->flags &= ~SVM_FIFO_F_LL_TRACKED;
     }
 
-  /* Free fifo chunks */
-  fsh_slice_collect_chunks (fsh, fss, f->start_chunk);
-
-  f->start_chunk = f->end_chunk = 0;
-  f->head_chunk = f->tail_chunk = f->ooo_enq = f->ooo_deq = 0;
-
-  /* not allocated on segment heap */
   svm_fifo_free_chunk_lookup (f);
   svm_fifo_free_ooo_data (f);
 
   if (CLIB_DEBUG)
     {
-      f->master_session_index = ~0;
+      sf->master_session_index = ~0;
       f->master_thread_index = ~0;
     }
 
-  fss->virtual_mem -= svm_fifo_size (f);
-
-  /* Add to free list */
-  f->next = fss->free_fifos;
+  f->ooo_enq = f->ooo_deq = 0;
   f->prev = 0;
-  fss->free_fifos = f;
+
+  fs_fifo_free (fs, f, f->shr->slice_index);
 
   fsh_active_fifos_update (fsh, -1);
 }
 
 void
-fifo_segment_detach_fifo (fifo_segment_t * fs, svm_fifo_t * f)
+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_chunk_t *c;
-  u32 fl_index;
+  svm_fifo_t *of = *f;
+  u32 slice_index;
 
-  ASSERT (f->refcnt == 1);
+  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);
 
-  fss = fsh_slice_get (fs->h, f->slice_index);
-  fss->virtual_mem -= svm_fifo_size (f);
-  if (f->flags & SVM_FIFO_F_LL_TRACKED)
-    fss_fifo_del_active_list (fss, f);
+  /* 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;
 
-  c = f->start_chunk;
-  while (c)
-    {
-      fl_index = fs_freelist_for_size (c->length);
-      clib_atomic_fetch_sub_rel (&fss->num_chunks[fl_index], 1);
-      c = c->next;
-    }
+  /* 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)
+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_chunk_t *c;
-  u32 fl_index;
+  svm_fifo_t *nf, *of;
 
-  f->slice_index = slice_index;
-  fss = fsh_slice_get (fs->h, f->slice_index);
-  fss->virtual_mem += svm_fifo_size (f);
-  if (f->flags & SVM_FIFO_F_LL_TRACKED)
-    fss_fifo_add_active_list (fss, f);
+  nf = fs_fifo_alloc (fs, slice_index);
+  clib_memcpy_fast (nf, *f, sizeof (*nf));
 
-  c = f->start_chunk;
-  while (c)
+  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)))
     {
-      fl_index = fs_freelist_for_size (c->length);
-      clib_atomic_fetch_add_rel (&fss->num_chunks[fl_index], 1);
-      c = 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;
 }
 
-int
-fifo_segment_prealloc_fifo_hdrs (fifo_segment_t * fs, u32 slice_index,
-				 u32 batch_size)
+uword
+fifo_segment_fifo_offset (svm_fifo_t *f)
+{
+  return (u8 *) f->shr - (u8 *) f->fs_hdr;
+}
+
+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;
-  svm_fifo_t *f;
-  void *oldheap;
-  uword size;
-  u8 *fmem;
-  int i;
 
   fss = fsh_slice_get (fsh, slice_index);
-  size = (uword) (sizeof (*f)) * batch_size;
+  return fsh_try_alloc_chunk (fsh, fss, chunk_size);
+}
 
-  oldheap = ssvm_push_heap (fsh->ssvm_sh);
-  fmem = clib_mem_alloc_aligned_at_offset (size, CLIB_CACHE_LINE_BYTES,
-					   0 /* align_offset */ ,
-					   0 /* os_out_of_memory */ );
-  ssvm_pop_heap (oldheap);
+void
+fifo_segment_collect_chunk (fifo_segment_t *fs, u32 slice_index,
+			    svm_fifo_chunk_t *c)
+{
+  fsh_collect_chunks (fs->h, slice_index, c);
+}
 
-  /* Out of space.. */
-  if (fmem == 0)
-    return -1;
+uword
+fifo_segment_chunk_offset (fifo_segment_t *fs, svm_fifo_chunk_t *c)
+{
+  return (u8 *) c - (u8 *) fs->h;
+}
 
-  /* Carve fifo + chunk space */
-  for (i = 0; i < batch_size; i++)
+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;
+
+  if (!fs->mqs)
     {
-      f = (svm_fifo_t *) fmem;
-      memset (f, 0, sizeof (*f));
-      f->next = fss->free_fifos;
-      fss->free_fifos = f;
-      fmem += sizeof (*f);
+      u32 n_mqs = clib_max (fs->h->n_mqs, 1);
+      vec_validate (fs->mqs, n_mqs - 1);
     }
 
-  fsh_free_bytes_sub (fsh, size);
+  size = svm_msg_q_size_to_alloc (cfg);
+  base = fsh_alloc_aligned (fsh, size, 8);
+  fsh->n_reserved_bytes += size;
 
-  return 0;
+  smq = svm_msg_q_init (base, cfg);
+  mq = vec_elt_at_index (fs->mqs, mq_index);
+  svm_msg_q_attach (mq, smq);
+
+  return mq;
+}
+
+svm_msg_q_t *
+fifo_segment_msg_q_attach (fifo_segment_t *fs, uword offset, u32 mq_index)
+{
+  svm_msg_q_t *mq;
+
+  if (!fs->mqs)
+    {
+      u32 n_mqs = clib_max (fs->h->n_mqs, 1);
+      vec_validate (fs->mqs, n_mqs - 1);
+    }
+
+  mq = vec_elt_at_index (fs->mqs, mq_index);
+
+  if (!mq->q.shr)
+    {
+      svm_msg_q_shared_t *smq;
+      smq = (svm_msg_q_shared_t *) ((u8 *) fs->h + offset);
+      svm_msg_q_attach (mq, smq);
+    }
+
+  ASSERT (fifo_segment_msg_q_offset (fs, mq_index) == offset);
+
+  return mq;
+}
+
+void
+fifo_segment_msg_qs_discover (fifo_segment_t *fs, int *fds, u32 n_fds)
+{
+  svm_msg_q_shared_t *smq;
+  u32 n_mqs, size, i;
+  uword offset = 0, n_alloced;
+  svm_msg_q_t *mq;
+
+  n_mqs = fs->h->n_mqs;
+  if (n_fds && n_mqs != n_fds)
+    {
+      clib_warning ("expected %u fds got %u", n_mqs, n_fds);
+      return;
+    }
+
+  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;
+
+  offset = fs->h->start_byte_index;
+  for (i = 0; i < n_mqs; i++)
+    {
+      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;
+    }
+}
+
+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);
+
+  if (mq->q.shr == 0)
+    return ~0ULL;
+
+  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
@@ -975,7 +1242,7 @@ fifo_segment_preallocate_fifo_pairs (fifo_segment_t * fs,
 
   /* Calculate space requirements */
   pair_size = 2 * hdrs + rx_rounded_data_size + tx_rounded_data_size;
-  space_available = fsh_free_space (fsh);
+  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;
@@ -986,8 +1253,11 @@ fifo_segment_preallocate_fifo_pairs (fifo_segment_t * fs,
 
   for (i = 0; i < fs->n_slices; i++)
     {
-      fss = fsh_slice_get (fsh, i);
       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))
@@ -1008,18 +1278,18 @@ fifo_segment_num_fifos (fifo_segment_t * fs)
 }
 
 static u32
-fs_slice_num_free_fifos (fifo_segment_slice_t * fss)
+fs_slice_num_free_fifos (fifo_segment_header_t *fsh, fifo_segment_slice_t *fss)
 {
-  svm_fifo_t *f;
+  svm_fifo_shared_t *f;
   u32 count = 0;
 
-  f = fss->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;
@@ -1036,13 +1306,14 @@ fifo_segment_num_free_fifos (fifo_segment_t * fs)
   for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
     {
       fss = fsh_slice_get (fsh, slice_index);
-      count += fs_slice_num_free_fifos (fss);
+      count += fs_slice_num_free_fifos (fsh, fss);
     }
   return count;
 }
 
 static u32
-fs_slice_num_free_chunks (fifo_segment_slice_t * fss, u32 size)
+fs_slice_num_free_chunks (fifo_segment_header_t *fsh,
+			  fifo_segment_slice_t *fss, u32 size)
 {
   u32 count = 0, rounded_size, fl_index;
   svm_fifo_chunk_t *c;
@@ -1051,15 +1322,15 @@ fs_slice_num_free_chunks (fifo_segment_slice_t * fss, u32 size)
   /* Count all free chunks? */
   if (size == ~0)
     {
-      for (i = 0; i < vec_len (fss->free_chunks); i++)
+      for (i = 0; i < FS_CHUNK_VEC_LEN; i++)
 	{
-	  c = fss->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++;
 	    }
 	}
@@ -1069,16 +1340,16 @@ fs_slice_num_free_chunks (fifo_segment_slice_t * fss, u32 size)
   rounded_size = (1 << (max_log2 (size)));
   fl_index = fs_freelist_for_size (rounded_size);
 
-  if (fl_index >= vec_len (fss->free_chunks))
+  if (fl_index >= FS_CHUNK_VEC_LEN)
     return 0;
 
-  c = fss->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;
@@ -1095,33 +1366,37 @@ fifo_segment_num_free_chunks (fifo_segment_t * fs, u32 size)
   for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
     {
       fss = fsh_slice_get (fsh, slice_index);
-      count += fs_slice_num_free_chunks (fss, size);
+      count += fs_slice_num_free_chunks (fsh, fss, size);
     }
   return count;
 }
 
-void
-fifo_segment_update_free_bytes (fifo_segment_t * fs)
+uword
+fifo_segment_size (fifo_segment_t * fs)
 {
-  fsh_update_free_bytes (fs->h);
+  return fs->h->max_byte_index - fs->h->n_reserved_bytes;
 }
 
-uword
-fifo_segment_size (fifo_segment_t * fs)
+static u8
+fs_has_reached_mem_limit (fifo_segment_t *fs)
 {
-  return fs->ssvm.ssvm_size;
+  return (fs->flags & FIFO_SEGMENT_F_MEM_LIMIT) ? 1 : 0;
 }
 
-u8
-fsh_has_reached_mem_limit (fifo_segment_header_t * fsh)
+static void
+fs_reset_mem_limit (fifo_segment_t *fs)
 {
-  return (fsh->flags & FIFO_SEGMENT_F_MEM_LIMIT) ? 1 : 0;
+  fs->flags &= ~FIFO_SEGMENT_F_MEM_LIMIT;
 }
 
-void
-fsh_reset_mem_limit (fifo_segment_header_t * fsh)
+void *
+fifo_segment_alloc (fifo_segment_t *fs, uword size)
 {
-  fsh->flags &= ~FIFO_SEGMENT_F_MEM_LIMIT;
+  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
@@ -1168,11 +1443,10 @@ fifo_segment_has_fifos (fifo_segment_t * fs)
 svm_fifo_t *
 fifo_segment_get_slice_fifo_list (fifo_segment_t * fs, u32 slice_index)
 {
-  fifo_segment_header_t *fsh = fs->h;
-  fifo_segment_slice_t *fss;
+  fifo_slice_private_t *pfss;
 
-  fss = fsh_slice_get (fsh, slice_index);
-  return fss->fifos;
+  pfss = fs_slice_private_get (fs, slice_index);
+  return pfss->active_fifos;
 }
 
 u8
@@ -1187,26 +1461,26 @@ fifo_segment_get_mem_usage (fifo_segment_t * fs)
 }
 
 fifo_segment_mem_status_t
-fifo_segment_determine_status (fifo_segment_header_t * fsh, u8 usage)
+fifo_segment_determine_status (fifo_segment_t *fs, u8 usage)
 {
-  if (!fsh->high_watermark || !fsh->low_watermark)
+  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 (fsh_has_reached_mem_limit (fsh))
+  if (fs_has_reached_mem_limit (fs))
     {
-      if (usage >= fsh->high_watermark)
+      if (usage >= fs->high_watermark)
 	return MEMORY_PRESSURE_NO_MEMORY;
       else
-	fsh_reset_mem_limit (fsh);
+	fs_reset_mem_limit (fs);
     }
 
-  if (usage >= fsh->high_watermark)
+  if (usage >= fs->high_watermark)
     return MEMORY_PRESSURE_HIGH_PRESSURE;
 
-  else if (usage >= fsh->low_watermark)
+  else if (usage >= fs->low_watermark)
     return MEMORY_PRESSURE_LOW_PRESSURE;
 
   return MEMORY_PRESSURE_NO_PRESSURE;
@@ -1215,10 +1489,9 @@ fifo_segment_determine_status (fifo_segment_header_t * fsh, u8 usage)
 fifo_segment_mem_status_t
 fifo_segment_get_mem_status (fifo_segment_t * fs)
 {
-  fifo_segment_header_t *fsh = fs->h;
   u8 usage = fifo_segment_get_mem_usage (fs);
 
-  return fifo_segment_determine_status (fsh, usage);
+  return fifo_segment_determine_status (fs, usage);
 }
 
 u8 *
@@ -1296,15 +1569,15 @@ format_fifo_segment (u8 * s, va_list * args)
   for (slice_index = 0; slice_index < fs->n_slices; slice_index++)
     {
       fss = fsh_slice_get (fsh, slice_index);
-      for (i = 0; i < vec_len (fss->free_chunks); i++)
+      for (i = 0; i < FS_CHUNK_VEC_LEN; i++)
 	{
-	  c = fss->free_chunks[i];
+	  c = fss_chunk_free_list_head (fsh, fss, i);
 	  if (c == 0 && fss->num_chunks[i] == 0)
 	    continue;
 	  count = 0;
 	  while (c)
 	    {
-	      c = c->next;
+	      c = fs_chunk_ptr (fsh, c->next);
 	      count++;
 	    }
 
@@ -1319,14 +1592,13 @@ format_fifo_segment (u8 * s, va_list * args)
   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);
-  fifo_segment_update_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 = fsh_virtual_mem (fsh);
+  virt = fs_virtual_mem (fs);
   reserved = fsh->n_reserved_bytes;
 
   s = format (s, "\n%Useg free bytes: %U (%lu) estimated: %U (%lu) reserved:"
@@ -1339,8 +1611,8 @@ format_fifo_segment (u8 * s, va_list * args)
 	      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 bytes: %U (%u) \n",
-	      format_white_space, indent + 2, fsh->n_active_fifos,
+  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,