[dpdk-dev] [PATCH] mbuf: optimize refcnt handling during free

[Zoltan Kiss]

The current way is not the most efficient: if m->refcnt is 1, the second
condition never evaluates, and we set it to 0. If refcnt > 1, the 2nd
condition fails again, although the code suggest otherwise to branch
prediction. Instead we should keep the second condition only, and remove the
duplicate set to zero.

Signed-off-by: Zoltan Kiss <zoltan.kiss at linaro.org>
---
 lib/librte_mbuf/rte_mbuf.h | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 17ba791..3ec4024 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -764,10 +764,7 @@ __rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
 {
 	__rte_mbuf_sanity_check(m, 0);
 
-	if (likely (rte_mbuf_refcnt_read(m) == 1) ||
-			likely (rte_mbuf_refcnt_update(m, -1) == 0)) {
-
-		rte_mbuf_refcnt_set(m, 0);
+	if (likely (rte_mbuf_refcnt_update(m, -1) == 0)) {
 
 		/* if this is an indirect mbuf, then
 		 *  - detach mbuf
-- 
1.9.1