From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
To: dev@dpdk.org, honnappa.nagarahalli@arm.com, phil.yang@arm.com,
jgrajcia@cisco.com, ferruh.yigit@intel.com
Cc: nd@arm.com
Subject: [dpdk-dev] [PATCH v2 8/8] net/memif: move the barrier outside the loop
Date: Mon, 28 Sep 2020 14:03:34 -0500 [thread overview]
Message-ID: <20200928190334.40624-8-honnappa.nagarahalli@arm.com> (raw)
In-Reply-To: <20200928190334.40624-1-honnappa.nagarahalli@arm.com>
load-acquire memory order has a barrier. Loading it inside
the loop will result in a barrier in every iteration. Hence,
load the variable once outside the loop.
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
drivers/net/memif/rte_eth_memif.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c
index 704350022..c73cde8fd 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -249,16 +249,17 @@ memif_get_buffer(struct pmd_process_private *proc_private, memif_desc_t *d)
static void
memif_free_stored_mbufs(struct pmd_process_private *proc_private, struct memif_queue *mq)
{
+ uint16_t cur_tail;
uint16_t mask = (1 << mq->log2_ring_size) - 1;
memif_ring_t *ring = memif_get_ring_from_queue(proc_private, mq);
/* FIXME: improve performance */
/* The ring->tail acts as a guard variable between Tx and Rx
* threads, so using load-acquire pairs with store-release
- * to synchronize it between threads.
+ * in function eth_memif_rx for S2M queues.
*/
- while (mq->last_tail != __atomic_load_n(&ring->tail,
- __ATOMIC_ACQUIRE)) {
+ cur_tail = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
+ while (mq->last_tail != cur_tail) {
RTE_MBUF_PREFETCH_TO_FREE(mq->buffers[(mq->last_tail + 1) & mask]);
/* Decrement refcnt and free mbuf. (current segment) */
rte_mbuf_refcnt_update(mq->buffers[mq->last_tail & mask], -1);
--
2.17.1
next prev parent reply other threads:[~2020-09-28 19:06 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 19:22 [dpdk-dev] [PATCH 1/4] net/memif: do not update local copy of tail in tx function Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-dev] [PATCH 2/4] net/memif: relax the load of ring tail pointer for M2S ring Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-dev] [PATCH 3/4] net/memif: relax the load of ring head pointer for S2M ring Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-dev] [PATCH 4/4] net/memif: relax the load of ring head pointer for M2S ring Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 1/8] net/memif: do not update local copy of tail in tx function Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 2/8] net/memif: relax the load of ring tail pointer for M2S ring Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 3/8] net/memif: relax the load of ring head " Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 4/8] net/memif: relax the load of ring head pointer for S2M ring Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 5/8] net/memif: relax the load of ring head pointer for M2S zc ring Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 6/8] net/memif: remove extra check Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 7/8] net/memif: relax the load of ring head pointer for S2M zc ring Honnappa Nagarahalli
2020-09-28 19:03 ` Honnappa Nagarahalli [this message]
2020-09-28 20:53 ` [dpdk-dev] [PATCH v2 1/8] net/memif: do not update local copy of tail in tx function Stephen Hemminger
2020-09-29 5:24 ` Honnappa Nagarahalli
2020-10-07 17:08 ` Honnappa Nagarahalli
2020-10-09 11:23 ` Jakub Grajciar -X (jgrajcia - PANTHEON TECH SRO at Cisco)
2020-10-09 15:59 ` Ferruh Yigit
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