[dpdk-dev] [PATCH v3 0/2] malloc: fix malloc and free linear complexity

[Robert Sanford]

Comments on previous versions of this patch:
http://dpdk.org/ml/archives/dev/2014-May/002297.html
http://dpdk.org/ml/archives/dev/2014-June/003518.html

Additional changes from original to v3:
* Reduce the minimum-sized block that we put on a free list when
  splitting a larger block, from 192 to 64. Although memory is
  plentiful, why waste 64 and 128-byte (plus overhead) blocks?

-#define MIN_DATA_SIZE (CACHE_LINE_SIZE * 2)
+#define MIN_DATA_SIZE (CACHE_LINE_SIZE)

-       if (old_elem_size <= MALLOC_ELEM_OVERHEAD + MIN_DATA_SIZE){
+       if (old_elem_size < MALLOC_ELEM_OVERHEAD + MIN_DATA_SIZE){

-       if (elem->size - new_size > MIN_DATA_SIZE + MALLOC_ELEM_OVERHEAD){
+       if (elem->size - new_size >= MIN_DATA_SIZE + MALLOC_ELEM_OVERHEAD){

Changes from v2 to v3:
* Change the size ranges of the five free lists per heap. The first
  list will effectively contain blocks of size [64,256].

-  *   heap->free_head[0] - (0   , 2^7]
-  *   heap->free_head[1] - (2^7 , 2^9]
-  *   heap->free_head[2] - (2^9 , 2^11]
-  *   heap->free_head[3] - (2^11, 2^13]
-  *   heap->free_head[4] - (2^13, MAX_SIZE]
+  *   heap->free_head[0] - (0   , 2^8]
+  *   heap->free_head[1] - (2^8 , 2^10]
+  *   heap->free_head[2] - (2^10 ,2^12]
+  *   heap->free_head[3] - (2^12, 2^14]
+  *   heap->free_head[4] - (2^14, MAX_SIZE]

- #define MALLOC_MINSIZE_LOG2   7
+ #define MALLOC_MINSIZE_LOG2   8

* Fix typos and false assumptions in malloc unit tests. Even without
  linked-list enhancements to lib rte_malloc, malloc autotest fails
  every second (2nd) run.