astitcher commented on a change in pull request #525: DISPATCH-1372 alloc_pool
intrusive linked list can be replaced by a linked stack
URL: https://github.com/apache/qpid-dispatch/pull/525#discussion_r297288448
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File path: src/alloc_pool.c
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@@ -44,20 +46,97 @@ DEQ_DECLARE(qd_alloc_type_t, qd_alloc_type_list_t);
#define PATTERN_BACK 0xbabecafe
struct qd_alloc_item_t {
- DEQ_LINKS(qd_alloc_item_t);
uint32_t sequence;
#ifdef QD_MEMORY_DEBUG
qd_alloc_type_desc_t *desc;
uint32_t header;
#endif
};
-DEQ_DECLARE(qd_alloc_item_t, qd_alloc_item_list_t);
+#define CHUNK_SIZE 128/sizeof(void*)
+struct qd_alloc_chunk_t {
+ qd_alloc_chunk_t *prev;
+ qd_alloc_item_t *items[CHUNK_SIZE];
+ qd_alloc_chunk_t *next;
+};
+
+struct qd_alloc_linked_stack_t {
+ //the base
+ qd_alloc_chunk_t *top_chunk;
+ uint32_t top; //qd_alloc_item* top_item =
top_chunk->items[top+1] <-> top > 0
Review comment:
Hmm, difficult to say - in any event it's going to be close to some entries
in the list and far from others. Perhaps eliminating it completely might be
possible.
Another thing to think about is not to use pointers at all, but rather use a
base (64 bit address) and smaller offset (32 bit entry count) - that should
allow more entries into the same number of cache lines - you would have to
allocate larger and contiguous blocks though.
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