2012/7/28 Christoph Lameter [off-list ref]:

On Sat, 28 Jul 2012, Joonsoo Kim wrote:

quoted

Subject and commit log are changed from v1.

That looks a bit better. But the changelog could use more cleanup and
clearer expression.

quoted

@@ -2490,25 +2492,17 @@ static void __slab_free(struct kmem_cache *s, struct page *page,
                 return;
         }

+     if (unlikely(!new.inuse && n->nr_partial > s->min_partial))
+             goto slab_empty;
+

So we can never encounter a empty slab that was frozen before? Really?

In my suggestion,  'was_frozen = 1' is "always" handled without taking a lock.
Then, never hit following code.
+     if (unlikely(!new.inuse && n->nr_partial > s->min_partial))
+             goto slab_empty;
+

Instead, hit following code.
        if (likely(!n)) {

                /*
                 * If we just froze the page then put it onto the
                 * per cpu partial list.
                 */
                if (new.frozen && !was_frozen) {
                        put_cpu_partial(s, page, 1);
                        stat(s, CPU_PARTIAL_FREE);
                }
                /*
                 * The list lock was not taken therefore no list
                 * activity can be necessary.
                 */
                if (was_frozen)
                        stat(s, FREE_FROZEN);
                return;
        }

So, even if we encounter a empty slab that was frozen before, we just
do "stat(s, FREE_FROZEN)".
Please let me know my answer is sufficient.
Thanks!!

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