From 6d714a237d8a306837a5f87711f9af9063376fed Mon Sep 17 00:00:00 2001 From: Olivier Matz Date: Fri, 8 Dec 2017 16:46:51 +0100 Subject: [PATCH] mbuf: fix performance of freeing with non atomic refcnt When RTE_MBUF_REFCNT_ATOMIC=n, the decrement of the mbuf reference counter uses an atomic operation. This is not necessary and impacts the performance (seen with TRex traffic generator). We cannot replace rte_atomic16_add_return() by rte_mbuf_refcnt_update() because it would add an additional check. Solves this by introducing __rte_mbuf_refcnt_update(), which updates the reference counter without doing anything else. Fixes: 8f094a9ac5d7 ("mbuf: set mbuf fields while in pool") Cc: stable@dpdk.org Suggested-by: Hanoch Haim Signed-off-by: Olivier Matz --- lib/librte_mbuf/rte_mbuf.h | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h index a827e6e2ff..a594e4772e 100644 --- a/lib/librte_mbuf/rte_mbuf.h +++ b/lib/librte_mbuf/rte_mbuf.h @@ -772,6 +772,13 @@ rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value) rte_atomic16_set(&m->refcnt_atomic, new_value); } +/* internal */ +static inline uint16_t +__rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) +{ + return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value)); +} + /** * Adds given value to an mbuf's refcnt and returns its new value. * @param m @@ -796,19 +803,26 @@ rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) return 1 + value; } - return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value)); + return __rte_mbuf_refcnt_update(m, value); } #else /* ! RTE_MBUF_REFCNT_ATOMIC */ +/* internal */ +static inline uint16_t +__rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) +{ + m->refcnt = (uint16_t)(m->refcnt + value); + return m->refcnt; +} + /** * Adds given value to an mbuf's refcnt and returns its new value. */ static inline uint16_t rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value) { - m->refcnt = (uint16_t)(m->refcnt + value); - return m->refcnt; + return __rte_mbuf_refcnt_update(m, value); } /** @@ -1372,8 +1386,7 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) return m; - } else if (rte_atomic16_add_return(&m->refcnt_atomic, -1) == 0) { - + } else if (__rte_mbuf_refcnt_update(m, -1) == 0) { if (RTE_MBUF_INDIRECT(m)) rte_pktmbuf_detach(m); -- 2.20.1