linux-4.4.1/expand() の履歴(No.1)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• linux-4.4.1/expand() へ行く。
  • 1 (2017-09-26 (火) 19:28:43)
  • 2 (2017-09-27 (水) 10:44:57)

参照元†

• linux-4.4.1/__rmqueue_fallback()
• linux-4.4.1/__rmqueue_smallest()
• linux-4.4.1/page_order()

説明†

• パス: linux-4.4.1/mm/page_alloc.c

• FIXME: これは何？
  • 説明

引数†

• struct zone *zone
  • linux-4.4.1/zone
• struct page *page
  • linux-4.4.1/page
• int low
• int high
• struct free_area *area
  • linux-4.4.1/free_area
• int migratetype

返り値†

• void

参考†

実装†

/*
 * The order of subdivision here is critical for the IO subsystem.
 * Please do not alter this order without good reasons and regression
 * testing. Specifically, as large blocks of memory are subdivided,
 * the order in which smaller blocks are delivered depends on the order
 * they're subdivided in this function. This is the primary factor
 * influencing the order in which pages are delivered to the IO
 * subsystem according to empirical testing, and this is also justified
 * by considering the behavior of a buddy system containing a single
 * large block of memory acted on by a series of small allocations.
 * This behavior is a critical factor in sglist merging's success.
 *
 * -- nyc
 */
static inline void expand(struct zone *zone, struct page *page,
	int low, int high, struct free_area *area,
	int migratetype)
{
	unsigned long size = 1 << high;

	while (high > low) {
		area--;
		high--;
		size >>= 1;
		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);

• • linux-4.4.1/VM_BUG_ON_PAGE()
  • linux-4.4.1/bad_range()

		if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) &&
			debug_guardpage_enabled() &&
			high < debug_guardpage_minorder()) {

• • linux-4.4.1/IS_ENABLED()
  • linux-4.4.1/CONFIG_DEBUG_PAGEALLOC
  • linux-4.4.1/debug_guardpage_enabled()
  • linux-4.4.1/debug_guardpage_minorder()

			/*
			 * Mark as guard pages (or page), that will allow to
			 * merge back to allocator when buddy will be freed.
			 * Corresponding page table entries will not be touched,
			 * pages will stay not present in virtual address space
			 */
			set_page_guard(zone, &page[size], high, migratetype);
			continue;

• • linux-4.4.1/set_page_guard()

		}
		list_add(&page[size].lru, &area->free_list[migratetype]);
		area->nr_free++;
		set_page_order(&page[size], high);

• • linux-4.4.1/list_add()
  • linux-4.4.1/set_page_order()

	}
}

コメント†