First-fit virtual space allocator

Change-Id: I75e6c7d1a6ff1fcebc81ec10bd86b79f2bf3dc22
Signed-off-by: Dave Barach <dave@barachs.net>

1 files changed, 362 insertions, 0 deletions

diff --git a/src/vppinfra/valloc.c b/src/vppinfra/valloc.c
new file mode 100644
index 00000000000..cd1d89bb9a1
--- /dev/null
+++ b/src/vppinfra/valloc.c
@@ -0,0 +1,362 @@
+/*
+ * Copyright (c) 2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vppinfra/valloc.h>
+
+/** @file
+    @brief Simple first-fit virtual space allocator
+*/
+
+/** Add a chunk of memory to a virtual allocation arena
+    @param vam - clib_valloc_main_t * pointer to the allocation arena
+    @param template - clib_valloc_chunk_t * pointer to a template chunk which
+    describes the virtual address range to add
+
+    @note only the baseva and size member of the template chunk are significant
+    It's perfectly OK for the new chunk to be discontinuous with previous
+    chunks, the chunk fusion algorithm won't merge them.
+ */
+
+void
+clib_valloc_add_chunk (clib_valloc_main_t * vam,
+		       clib_valloc_chunk_t * template)
+{
+  clib_valloc_chunk_t *ch, *new_ch;
+  u32 index;
+
+  ASSERT (vam->flags & CLIB_VALLOC_INITIALIZED);
+
+  clib_spinlock_lock_if_init (&vam->lock);
+
+  /* Add at the beginning, or at the end... */
+  index = vam->first_index;
+
+  /*
+   * Make sure we're not trying to add an overlapping chunk..
+   * It's worth checking, because someone will eventually do that.
+   */
+  if (CLIB_DEBUG > 0 && index != ~0)
+    {
+      while (index != ~0)
+	{
+	  ch = pool_elt_at_index (vam->chunks, index);
+	  ASSERT (template->baseva < ch->baseva || template->baseva >=
+		  (ch->baseva + ch->size));
+	  ASSERT (template->baseva + template->size < ch->baseva ||
+		  template->baseva + template->size >=
+		  (ch->baseva + ch->size));
+	  index = ch->next;
+	}
+      index = vam->first_index;
+    }
+
+  if (index != ~0)
+    ch = pool_elt_at_index (vam->chunks, index);
+
+  if (index == ~0 || template->baseva < ch->baseva)
+    {
+      pool_get (vam->chunks, new_ch);
+      memset (new_ch, 0, sizeof (*new_ch));
+
+      if (index != ~0)
+	{
+	  ch = pool_elt_at_index (vam->chunks, index);
+
+	  new_ch->next = index;
+	  new_ch->prev = ~0;
+	  ch->prev = new_ch - vam->chunks;
+	}
+      else
+	{
+	  new_ch->next = new_ch->prev = ~0;
+	}
+
+      new_ch->baseva = template->baseva;
+      new_ch->size = template->size;
+
+      vam->first_index = new_ch - vam->chunks;
+
+      hash_set (vam->chunk_index_by_baseva, new_ch->baseva, vam->first_index);
+    }
+  else
+    {
+      /* Walk to the end of the chunk chain */
+      while (index != ~0)
+	{
+	  ch = pool_elt_at_index (vam->chunks, index);
+	  index = ch->next;
+	}
+      /* we want the last chunk index */
+      index = ch - vam->chunks;
+
+      pool_get (vam->chunks, new_ch);
+      memset (new_ch, 0, sizeof (*new_ch));
+
+      ch = pool_elt_at_index (vam->chunks, index);
+
+      new_ch->next = ~0;
+      new_ch->prev = index;
+      ch->next = new_ch - vam->chunks;
+
+      new_ch->baseva = template->baseva;
+      new_ch->size = template->size;
+
+      hash_set (vam->chunk_index_by_baseva, new_ch->baseva,
+		new_ch - vam->chunks);
+    }
+
+  clib_spinlock_unlock_if_init (&vam->lock);
+}
+
+/** Initialize a virtual memory allocation arena
+    @param vam - clib_valloc_main_t * pointer to the arena to initialize
+    @param template - clib_valloc_chunk_t * pointer to a template chunk which
+    describes the initial virtual address range
+*/
+void
+clib_valloc_init (clib_valloc_main_t * vam, clib_valloc_chunk_t * template,
+		  int need_lock)
+{
+  ASSERT (template && template->baseva && template->size);
+  memset (vam, 0, sizeof (*vam));
+  if (need_lock)
+    clib_spinlock_init (&vam->lock);
+
+  vam->chunk_index_by_baseva = hash_create (0, sizeof (uword));
+  vam->first_index = ~0;
+  vam->flags |= CLIB_VALLOC_INITIALIZED;
+
+  clib_valloc_add_chunk (vam, template);
+}
+
+/** Allocate virtual space
+    @param vam - clib_valloc_main_t * pointer to the allocation arena
+    @param size - u64 number of bytes to allocate
+    @os_out_of_memory_on_failure - 1=> panic on allocation failure
+    @return uword allocated space, 0=> failure
+*/
+uword
+clib_valloc_alloc (clib_valloc_main_t * vam, uword size,
+		   int os_out_of_memory_on_failure)
+{
+  clib_valloc_chunk_t *ch, *new_ch, *next_ch;
+  u32 index;
+
+  clib_spinlock_lock_if_init (&vam->lock);
+
+  index = vam->first_index;
+
+  while (index != ~0)
+    {
+      ch = pool_elt_at_index (vam->chunks, index);
+      /* If the chunk is free... */
+      if ((ch->flags & CLIB_VALLOC_BUSY) == 0)
+	{
+	  /* Too small? */
+	  if (ch->size < size)
+	    goto next_chunk;
+	  /* Exact match? */
+	  if (ch->size == size)
+	    {
+	      ch->flags |= CLIB_VALLOC_BUSY;
+	      clib_spinlock_unlock_if_init (&vam->lock);
+	      return ch->baseva;
+	    }
+	  /*
+	   * The current free chunk is larger than necessary, split the block.
+	   */
+	  pool_get (vam->chunks, new_ch);
+	  /* ch might have just moved */
+	  ch = pool_elt_at_index (vam->chunks, index);
+	  memset (new_ch, 0, sizeof (*new_ch));
+	  new_ch->next = new_ch->prev = ~0;
+	  new_ch->baseva = ch->baseva + size;
+	  new_ch->size = ch->size - size;
+	  ch->size = size;
+
+	  /* Insert into doubly-linked list */
+	  new_ch->next = ch->next;
+	  new_ch->prev = ch - vam->chunks;
+
+	  if (ch->next != ~0)
+	    {
+	      next_ch = pool_elt_at_index (vam->chunks, ch->next);
+	      next_ch->prev = new_ch - vam->chunks;
+	    }
+	  ch->next = new_ch - vam->chunks;
+
+	  hash_set (vam->chunk_index_by_baseva, new_ch->baseva,
+		    new_ch - vam->chunks);
+
+	  ch->flags |= CLIB_VALLOC_BUSY;
+	  clib_spinlock_unlock_if_init (&vam->lock);
+	  return ch->baseva;
+	}
+
+    next_chunk:
+      index = ch->next;
+    }
+  clib_spinlock_unlock_if_init (&vam->lock);
+
+  if (os_out_of_memory_on_failure)
+    os_out_of_memory ();
+
+  return 0;
+}
+
+
+/** Free virtual space
+    @param vam - clib_valloc_main_t * pointer to the allocation arena
+    @param baseva - uword base virtual address of the returned space
+    @return uword - size of the freed virtual chunk
+    @note the size is returned since we know it / in case the caller
+    doesn't memorize chunk sizes
+*/
+uword
+clib_valloc_free (clib_valloc_main_t * vam, uword baseva)
+{
+  clib_valloc_chunk_t *ch, *prev_ch, *next_ch, *n2_ch;
+  u32 index;
+  uword return_size = 0;
+  uword *p;
+
+  clib_spinlock_lock_if_init (&vam->lock);
+
+  p = hash_get (vam->chunk_index_by_baseva, baseva);
+
+  /* Check even in production images */
+  if (p == 0)
+    os_panic ();
+
+  index = p[0];
+
+  ch = pool_elt_at_index (vam->chunks, index);
+
+  return_size = ch->size;
+
+  ASSERT (ch->baseva == baseva);
+  ASSERT ((ch->flags & CLIB_VALLOC_BUSY) != 0);
+
+  ch->flags &= ~CLIB_VALLOC_BUSY;
+
+  /* combine with previous entry? */
+  if (ch->prev != ~0)
+    {
+      prev_ch = pool_elt_at_index (vam->chunks, ch->prev);
+      /*
+       * Previous item must be free as well, and
+       * tangent to this block.
+       */
+      if ((prev_ch->flags & CLIB_VALLOC_BUSY) == 0
+	  && ((prev_ch->baseva + prev_ch->size) == ch->baseva))
+	{
+	  hash_unset (vam->chunk_index_by_baseva, baseva);
+	  prev_ch->size += ch->size;
+	  prev_ch->next = ch->next;
+	  if (ch->next != ~0)
+	    {
+	      next_ch = pool_elt_at_index (vam->chunks, ch->next);
+	      next_ch->prev = ch->prev;
+	    }
+	  ASSERT (ch - vam->chunks != vam->first_index);
+	  memset (ch, 0xfe, sizeof (*ch));
+	  pool_put (vam->chunks, ch);
+	  /* See about combining with next elt */
+	  ch = prev_ch;
+	}
+    }
+
+  /* Combine with next entry? */
+  if (ch->next != ~0)
+    {
+      next_ch = pool_elt_at_index (vam->chunks, ch->next);
+
+      if ((next_ch->flags & CLIB_VALLOC_BUSY) == 0
+	  && ((ch->baseva + ch->size) == next_ch->baseva))
+	{
+	  hash_unset (vam->chunk_index_by_baseva, next_ch->baseva);
+	  ch->size += next_ch->size;
+	  ch->next = next_ch->next;
+	  if (ch->next != ~0)
+	    {
+	      n2_ch = pool_elt_at_index (vam->chunks, next_ch->next);
+	      n2_ch->prev = ch - vam->chunks;
+	    }
+	  ASSERT (next_ch - vam->chunks != vam->first_index);
+	  memset (next_ch, 0xfe, sizeof (*ch));
+	  pool_put (vam->chunks, next_ch);
+	}
+    }
+
+  clib_spinlock_unlock_if_init (&vam->lock);
+  return return_size;
+}
+
+/** format a virtual allocation arena (varargs)
+    @param vam - clib_valloc_main_t pointer to the arena to format
+    @param verbose - int - verbosity level
+    @return u8 vector
+*/
+u8 *
+format_valloc (u8 * s, va_list * va)
+{
+  clib_valloc_main_t *vam = va_arg (*va, clib_valloc_main_t *);
+  int verbose = va_arg (*va, int);
+  clib_valloc_chunk_t *ch;
+  u32 index;
+  uword *p;
+
+  clib_spinlock_lock_if_init (&vam->lock);
+
+  s = format (s, "%d chunks, first index %d\n",
+	      pool_elts (vam->chunks), vam->first_index);
+
+  if (verbose)
+    {
+      index = vam->first_index;
+      while (index != ~0)
+	{
+	  ch = pool_elt_at_index (vam->chunks, index);
+
+	  s = format (s, "[%d] base %llx size %llx (%lld) prev %d %s\n",
+		      index, ch->baseva, ch->size, ch->size, ch->prev,
+		      (ch->flags & CLIB_VALLOC_BUSY) ? "busy" : "free");
+
+	  p = hash_get (vam->chunk_index_by_baseva, ch->baseva);
+	  if (p == 0)
+	    {
+	      s = format (s, "   BUG: baseva not in hash table!\n");
+	    }
+	  else if (p[0] != index)
+	    {
+	      s = format (s, "   BUG: baseva in hash table %d not %d!\n",
+			  p[0], index);
+	    }
+	  index = ch->next;
+	}
+    }
+
+  clib_spinlock_unlock_if_init (&vam->lock);
+
+  return s;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */