Reduce amount of updated memory

Author: dstogov

Zend/zend_alloc.c

@@ -2274,8 +2274,6 @@ void zend_mm_shutdown(zend_mm_heap *heap, int full, int silent)
 		/* free the first chunk */
 		zend_mm_chunk_free(heap, heap->main_chunk, ZEND_MM_CHUNK_SIZE);
 	} else {
-		zend_mm_heap old_heap;
-
 		/* free some cached chunks to keep average count */
 		heap->avg_chunks_count = (heap->avg_chunks_count + (double)heap->peak_chunks_count) / 2.0;
 		while ((double)heap->cached_chunks_count + 0.9 > heap->avg_chunks_count &&
@@ -2295,30 +2293,32 @@ void zend_mm_shutdown(zend_mm_heap *heap, int full, int silent)
 		}
 
 		/* reinitialize the first chunk and heap */
-		old_heap = *heap;
 		p = heap->main_chunk;
-		memset(p, 0, ZEND_MM_FIRST_PAGE * ZEND_MM_PAGE_SIZE);
-		*heap = old_heap;
-		memset(heap->free_slot, 0, sizeof(heap->free_slot));
-		heap->main_chunk = p;
 		p->heap = &p->heap_slot;
 		p->next = p;
 		p->prev = p;
 		p->free_pages = ZEND_MM_PAGES - ZEND_MM_FIRST_PAGE;
 		p->free_tail = ZEND_MM_FIRST_PAGE;
-		p->free_map[0] = (1L << ZEND_MM_FIRST_PAGE) - 1;
-		p->map[0] = ZEND_MM_LRUN(ZEND_MM_FIRST_PAGE);
-		heap->chunks_count = 1;
-		heap->peak_chunks_count = 1;
-		heap->last_chunks_delete_boundary = 0;
-		heap->last_chunks_delete_count = 0;
+		p->num = 0;
+
+#if ZEND_MM_STAT
+		heap->size = heap->peak = 0;
+#endif
+		memset(heap->free_slot, 0, sizeof(heap->free_slot));
 #if ZEND_MM_STAT || ZEND_MM_LIMIT
 		heap->real_size = ZEND_MM_CHUNK_SIZE;
 #endif
 #if ZEND_MM_STAT
 		heap->real_peak = ZEND_MM_CHUNK_SIZE;
-		heap->size = heap->peak = 0;
 #endif
+		heap->chunks_count = 1;
+		heap->peak_chunks_count = 1;
+		heap->last_chunks_delete_boundary = 0;
+		heap->last_chunks_delete_count = 0;
+
+		memset(p->free_map, 0, sizeof(p->free_map) + sizeof(p->map));
+		p->free_map[0] = (1L << ZEND_MM_FIRST_PAGE) - 1;
+		p->map[0] = ZEND_MM_LRUN(ZEND_MM_FIRST_PAGE);
 	}
 }