[Bf-blender-cvs] [19b7bb5] master: Optimize mempool: round chunk size to powers of 2, account for slop-space

[Campbell Barton]

Commit: 19b7bb5975afdc2340538cb48d85e445828e9d7f
Author: Campbell Barton
Date:   Sat Apr 5 12:09:36 2014 +1100
https://developer.blender.org/rB19b7bb5975afdc2340538cb48d85e445828e9d7f

Optimize mempool: round chunk size to powers of 2, account for slop-space

This helps to reduce memory fragmentation.

===================================================================

M       source/blender/blenlib/intern/BLI_mempool.c

===================================================================

diff --git a/source/blender/blenlib/intern/BLI_mempool.c 
b/source/blender/blenlib/intern/BLI_mempool.c
index e4cff4c..673dfde 100644
--- a/source/blender/blenlib/intern/BLI_mempool.c
+++ b/source/blender/blenlib/intern/BLI_mempool.c
@@ -63,6 +63,10 @@
 /* when undefined, merge the allocs for BLI_mempool_chunk and its data */
 // #define USE_DATA_PTR
 
+/* optimize pool size */
+#define USE_CHUNK_POW2
+
+
 #ifndef NDEBUG
 static bool mempool_debug_memset = false;
 #endif
@@ -116,6 +120,26 @@ struct BLI_mempool {
 #  define CHUNK_DATA(chunk) (CHECK_TYPE_INLINE(chunk, BLI_mempool_chunk *), 
(void *)((chunk) + 1))
 #endif
 
+/* extra bytes implicitly used for every chunk alloc */
+#ifdef USE_CHUNK_POW2
+#  define CHUNK_OVERHEAD (unsigned int)(MEM_SIZE_OVERHEAD + 
sizeof(BLI_mempool_chunk))
+#else
+#  define CHUNK_OVERHEAD (unsigned int)(MEM_SIZE_OVERHEAD)
+#endif
+
+#ifdef USE_CHUNK_POW2
+static unsigned int power_of_2_max_u(unsigned int x)
+{
+       x -= 1;
+       x = x | (x >> 1);
+       x = x | (x >> 2);
+       x = x | (x >> 4);
+       x = x | (x >> 8);
+       x = x | (x >>16);
+       return x + 1;
+}
+#endif
+
 BLI_INLINE BLI_mempool_chunk *mempool_chunk_find(BLI_mempool_chunk *head, 
unsigned int index)
 {
        while (index-- && head) {
@@ -230,7 +254,7 @@ static void mempool_chunk_free_all(BLI_mempool_chunk 
*mpchunk)
 BLI_mempool *BLI_mempool_create(unsigned int esize, unsigned int totelem,
                                 unsigned int pchunk, unsigned int flag)
 {
-       BLI_mempool *pool = NULL;
+       BLI_mempool *pool;
        BLI_freenode *lasttail = NULL;
        unsigned int i, maxchunks;
 
@@ -243,18 +267,28 @@ BLI_mempool *BLI_mempool_create(unsigned int esize, 
unsigned int totelem,
        }
 
        if (flag & BLI_MEMPOOL_ALLOW_ITER) {
-               pool->esize = MAX2(esize, (unsigned int)sizeof(BLI_freenode));
-       }
-       else {
-               pool->esize = esize;
+               esize = MAX2(esize, (unsigned int)sizeof(BLI_freenode));
        }
 
        maxchunks = mempool_maxchunks(totelem, pchunk);
 
-       pool->flag = flag;
-       pool->pchunk = pchunk;
-       pool->csize = esize * pchunk;
        pool->chunks = NULL;
+       pool->esize = esize;
+       pool->csize = esize * pchunk;
+
+
+       /* Optimize chunk size to powers of 2, accounting for slop-space */
+#ifdef USE_CHUNK_POW2
+       {
+               BLI_assert(pool->csize > CHUNK_OVERHEAD);
+               pool->csize = power_of_2_max_u(pool->csize) - CHUNK_OVERHEAD;
+               pchunk = pool->csize / esize;
+       }
+#endif
+
+
+       pool->pchunk = pchunk;
+       pool->flag = flag;
        pool->free = NULL;  /* mempool_chunk_add assigns */
        pool->maxchunks = maxchunks;
 #ifdef USE_TOTALLOC

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