This patch adds unlikely and likely hints to the function mempool_free. It
lays out the code in such a way that the common path is executed
straighforward and saves a cache line.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
mm/mempool.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-3.13.5/mm/mempool.c
===================================================================
--- linux-3.13.5.orig/mm/mempool.c 2014-02-23 22:50:11.481071417 +0100
+++ linux-3.13.5/mm/mempool.c 2014-03-06 23:02:24.264538587 +0100
@@ -306,9 +306,9 @@ void mempool_free(void *element, mempool
* ensures that there will be frees which return elements to the
* pool waking up the waiters.
*/
- if (pool->curr_nr < pool->min_nr) {
+ if (unlikely(pool->curr_nr < pool->min_nr)) {
spin_lock_irqsave(&pool->lock, flags);
- if (pool->curr_nr < pool->min_nr) {
+ if (likely(pool->curr_nr < pool->min_nr)) {
add_element(pool, element);
spin_unlock_irqrestore(&pool->lock, flags);
wake_up(&pool->wait);
--
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