On Wed, 2011-08-24 at 08:57 +0800, Li, Shaohua wrote:

On Tue, 2011-08-23 at 23:25 +0800, Christoph Lameter wrote:

quoted

On Tue, 23 Aug 2011, Shaohua Li wrote:

quoted

Adding slab to partial list head/tail is sensentive to performance.
So adding a type to document it to avoid we get it wrong.

I think that if you want to make it more descriptive then using the stats
values (DEACTIVATE_TO_TAIL/HEAD) would avoid having to introduce an
additional enum and it would also avoid the if statement in the stat call.

ok, that's better.

Subject: slub: explicitly document position of inserting slab to partial list

Adding slab to partial list head/tail is sensitive to performance.
So explicitly uses DEACTIVATE_TO_TAIL/DEACTIVATE_TO_HEAD to document
it to avoid we get it wrong.

Frankly speaking, using DEACTIVATE_TO_TAIL/DEACTIVATE_TO_HEAD in
slab_alloc, slab_free make code hard to understand. Just adding some
comments will be more clear and understandable. like the following: 
Do you think so? 

--- a/mm/slub.c
+++ b/mm/slub.c

@@ -2377,6 +2377,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page,
                 */
                if (unlikely(!prior)) {
                        remove_full(s, page);
+                       /* only one object left in the page, so add to partial tail */
                        add_partial(n, page, 1);
                        stat(s, FREE_ADD_PARTIAL);
                }


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