linux-2.6.33/slob_alloc() の履歴(No.2)

• 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-2.6.33/slob_alloc() へ行く。
  • 1 (2010-12-16 (木) 14:40:01)
  • 2 (2010-12-18 (土) 11:32:49)

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参照元†

• linux-2.6.33/kmem_cache_create()(slob)

説明†

• パス: linux-2.6.33/mm/slob.c

• FIXME: これは何？
  • 説明

引数†

• size_t size
• gfp_t gfp
  • linux-2.6.33/gfp_t
• int align
• int node

返り値†

• void *

参考†

実装†

/*
 * slob_alloc: entry point into the slob allocator.
 */
static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
{
	struct slob_page *sp;
	struct list_head *prev;
	struct list_head *slob_list;
	slob_t *b = NULL;
	unsigned long flags;

• • linux-2.6.33/slob_page

• linux-2.6.33/list_head

• • linux-2.6.33/slob_t

	if (size < SLOB_BREAK1)
		slob_list = &free_slob_small;
	else if (size < SLOB_BREAK2)
		slob_list = &free_slob_medium;
	else
		slob_list = &free_slob_large;

• 256バイト、1024バイトを境界として、 使用する SLOB のリストを選択する

          size < 256  : small リスト
  256  <= size < 1024 : medium リスト
  1024 <= size        : large リスト

  • linux-2.6.33/SLOB_BREAK1
  • linux-2.6.33/SLOB_BREAK2
  • linux-2.6.33/free_slob_small(global)
  • linux-2.6.33/free_slob_medium(global)
  • linux-2.6.33/free_slob_large(global)

	spin_lock_irqsave(&slob_lock, flags);

• • linux-2.6.33/spin_lock_irqsave()

• linux-2.6.33/slob_lock(global)

	/* Iterate through each partially free page, try to find room */
	list_for_each_entry(sp, slob_list, list) {

• • linux-2.6.33/list_for_each_entry()

#ifdef CONFIG_NUMA

• • linux-2.6.33/CONFIG_NUMA

		/*
		 * If there's a node specification, search for a partial
		 * page with a matching node id in the freelist.
		 */
		if (node != -1 && page_to_nid(&sp->page) != node)
			continue;

• • linux-2.6.33/page_to_nid()

#endif
		/* Enough room on this page? */
		if (sp->units < SLOB_UNITS(size))
			continue;

• • linux-2.6.33/SLOB_UNITS()

		/* Attempt to alloc */
		prev = sp->list.prev;
		b = slob_page_alloc(sp, size, align);
		if (!b)
			continue;

• • linux-2.6.33/slob_page_alloc()

		/* Improve fragment distribution and reduce our average
		 * search time by starting our next search here. (see
		 * Knuth vol 1, sec 2.5, pg 449) */
		if (prev != slob_list->prev &&
				slob_list->next != prev->next)
			list_move_tail(slob_list, prev->next);

• • linux-2.6.33/list_move_tail()

		break;
	}
	spin_unlock_irqrestore(&slob_lock, flags);

• • linux-2.6.33/spin_unlock_irqrestore()

	/* Not enough space: must allocate a new page */
	if (!b) {
		b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node);
		if (!b)
			return NULL;

• • linux-2.6.33/slob_new_pages()

• linux-2.6.33/__GFP_ZERO

		sp = slob_page(b);
		set_slob_page(sp);

• • linux-2.6.33/slob_page()

• linux-2.6.33/set_slob_page()

		spin_lock_irqsave(&slob_lock, flags);
		sp->units = SLOB_UNITS(PAGE_SIZE);
		sp->free = b;
		INIT_LIST_HEAD(&sp->list);

• • linux-2.6.33/INIT_LIST_HEAD()

		set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
		set_slob_page_free(sp, slob_list);
		b = slob_page_alloc(sp, size, align);
		BUG_ON(!b);

• • linux-2.6.33/set_slob()

• linux-2.6.33/set_slob_page_free()

• • linux-2.6.33/slob_page_alloc()

		spin_unlock_irqrestore(&slob_lock, flags);
	}
	if (unlikely((gfp & __GFP_ZERO) && b))
		memset(b, 0, size);

• • linux-2.6.33/unlikely()

• linux-2.6.33/memset()

	return b;
}

コメント†