[POWERPC] rheap - eliminates internal fragments caused by alignment

The patch adds fragments caused by rh_alloc_align() back to free list, instead
of allocating the whole chunk of memory.  This will greatly improve memory
utilization managed by rheap.

It solves MURAM not enough problem with 3 UCCs enabled on MPC8323.

Signed-off-by: Li Yang <leoli@freescale.com>
Acked-by: Joakim Tjernlund <joakim.tjernlund@transmode.se> 
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 29 insertions, 19 deletions

diff --git a/arch/powerpc/lib/rheap.c b/arch/powerpc/lib/rheap.c
index 180ee2933ab9..2f24ea0d723a 100644
--- a/arch/powerpc/lib/rheap.c
+++ b/arch/powerpc/lib/rheap.c
@@ -437,27 +437,26 @@ unsigned long rh_alloc_align(rh_info_t * info, int size, int alignment, const ch
         struct list_head *l;
         rh_block_t *blk;
         rh_block_t *newblk;
-        unsigned long start;
+        unsigned long start, sp_size;
 
         /* Validate size, and alignment must be power of two */
         if (size <= 0 || (alignment & (alignment - 1)) != 0)
                 return (unsigned long) -EINVAL;
 
-        /* given alignment larger that default rheap alignment */
-        if (alignment > info->alignment)
-                size += alignment - 1;
-
         /* Align to configured alignment */
         size = (size + (info->alignment - 1)) & ~(info->alignment - 1);
 
-        if (assure_empty(info, 1) < 0)
+        if (assure_empty(info, 2) < 0)
                 return (unsigned long) -ENOMEM;
 
         blk = NULL;
         list_for_each(l, &info->free_list) {
                 blk = list_entry(l, rh_block_t, list);
-                if (size <= blk->size)
-                        break;
+                if (size <= blk->size) {
+                        start = (blk->start + alignment - 1) & ~(alignment - 1);
+                        if (start + size <= blk->start + blk->size)
+                                break;
+                }
                 blk = NULL;
         }
 
@@ -470,25 +469,36 @@ unsigned long rh_alloc_align(rh_info_t * info, int size, int alignment, const ch
                 list_del(&blk->list);
                 newblk = blk;
         } else {
+                /* Fragment caused, split if needed */
+                /* Create block for fragment in the beginning */
+                sp_size = start - blk->start;
+                if (sp_size) {
+                        rh_block_t *spblk;
+
+                        spblk = get_slot(info);
+                        spblk->start = blk->start;
+                        spblk->size = sp_size;
+                        /* add before the blk */
+                        list_add(&spblk->list, blk->list.prev);
+                }
                 newblk = get_slot(info);
-                newblk->start = blk->start;
+                newblk->start = start;
                 newblk->size = size;
 
-                /* blk still in free list, with updated start, size */
-                blk->start += size;
-                blk->size -= size;
+                /* blk still in free list, with updated start and size
+                 * for fragment in the end */
+                blk->start = start + size;
+                blk->size -= sp_size + size;
+                /* No fragment in the end, remove blk */
+                if (blk->size == 0) {
+                        list_del(&blk->list);
+                        release_slot(info, blk);
+                }
         }
 
         newblk->owner = owner;
-        start = newblk->start;
         attach_taken_block(info, newblk);
 
-        /* for larger alignment return fixed up pointer  */
-        /* this is no problem with the deallocator since */
-        /* we scan for pointers that lie in the blocks   */
-        if (alignment > info->alignment)
-                start = (start + alignment - 1) & ~(alignment - 1);
-
         return start;
 }