From 78b50591c8e7ae3d010e8f4005e0e95c17800941 Mon Sep 17 00:00:00 2001 From: Gavin Hu Date: Tue, 13 Aug 2019 18:43:30 +0800 Subject: [PATCH] net/i40e: remove memory barrier from NEON Rx For x86, the descriptors needs to be loaded in order, so in between two descriptors loading, there is a compiler barrier in place.[1] For aarch64, a patch [2] is in place to survive with discontinuous DD bits, the barriers can be removed to take full advantage of out-of-order execution. 50% performance gain in the RFC2544 NDR test was measured on ThunderX2. 12.50% performance gain in the RFC2544 NDR test was measured on Ampere eMAG80 platform. [1] http://inbox.dpdk.org/users/039ED4275CED7440929022BC67E7061153D71548@ SHSMSX105.ccr.corp.intel.com/ [2] https://mails.dpdk.org/archives/stable/2017-October/003324.html Fixes: ae0eb310f253 ("net/i40e: implement vector PMD for ARM") Cc: stable@dpdk.org Signed-off-by: Gavin Hu Reviewed-by: Ruifeng Wang Reviewed-by: Steve Capper --- drivers/net/i40e/i40e_rxtx_vec_neon.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/net/i40e/i40e_rxtx_vec_neon.c b/drivers/net/i40e/i40e_rxtx_vec_neon.c index 83572ef843..5555e9b5cf 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_neon.c +++ b/drivers/net/i40e/i40e_rxtx_vec_neon.c @@ -285,7 +285,6 @@ _recv_raw_pkts_vec(struct i40e_rx_queue *rxq, struct rte_mbuf **rx_pkts, /* Read desc statuses backwards to avoid race condition */ /* A.1 load 4 pkts desc */ descs[3] = vld1q_u64((uint64_t *)(rxdp + 3)); - rte_rmb(); /* B.2 copy 2 mbuf point into rx_pkts */ vst1q_u64((uint64_t *)&rx_pkts[pos], mbp1); -- 2.20.1