[dpdk-stable] patch 'net/i40e: relax barrier in Tx for NEON' has been queued to LTS release 18.11.9

[Kevin Traynor]

Hi,

FYI, your patch has been queued to LTS release 18.11.9

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 06/03/20. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable-queue

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable-queue/commit/25c139043a4cc1e3beb4735242b3764fe65f292e

Thanks.

Kevin.

---
>From 25c139043a4cc1e3beb4735242b3764fe65f292e Mon Sep 17 00:00:00 2001
From: Gavin Hu <gavin.hu at arm.com>
Date: Tue, 14 Apr 2020 00:40:24 +0800
Subject: [PATCH] net/i40e: relax barrier in Tx for NEON

[ upstream commit 6b50c489a3bb1d82e2549ae2f1e2c46961572c27 ]

To keep ordering of mixed accesses, 'DMB OSH' is sufficient.
'DSB' inside the I40E_PCI_REG_WRITE is overkill.[1]

This patch fixes by replacing with just sufficient barriers in the
normal PMD and vPMD.

It showed 7% performance uplift on ThunderX2 and 4% on Arm N1SDP.
The test case is the RFC2544 zero-loss test running testpmd.

[1] http://inbox.dpdk.org/dev/CALBAE1M-ezVWCjqCZDBw+MMDEC4O9
qf0Kpn89EMdGDajepKoZQ at mail.gmail.com

Fixes: ae0eb310f253 ("net/i40e: implement vector PMD for ARM")

Signed-off-by: Gavin Hu <gavin.hu at arm.com>
Acked-by: Jerin Jacob <jerinj at marvell.com>
---
 drivers/net/i40e/i40e_rxtx_vec_neon.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/i40e/i40e_rxtx_vec_neon.c b/drivers/net/i40e/i40e_rxtx_vec_neon.c
index deb185fe2f..4376d8911c 100644
--- a/drivers/net/i40e/i40e_rxtx_vec_neon.c
+++ b/drivers/net/i40e/i40e_rxtx_vec_neon.c
@@ -73,6 +73,7 @@ i40e_rxq_rearm(struct i40e_rx_queue *rxq)
 			     (rxq->nb_rx_desc - 1) : (rxq->rxrearm_start - 1));
 
+	rte_cio_wmb();
 	/* Update the tail pointer on the NIC */
-	I40E_PCI_REG_WRITE(rxq->qrx_tail, rx_id);
+	I40E_PCI_REG_WRITE_RELAXED(rxq->qrx_tail, rx_id);
 }
 
@@ -565,5 +566,6 @@ i40e_xmit_fixed_burst_vec(void *tx_queue, struct rte_mbuf **tx_pkts,
 	txq->tx_tail = tx_id;
 
-	I40E_PCI_REG_WRITE(txq->qtx_tail, txq->tx_tail);
+	rte_cio_wmb();
+	I40E_PCI_REG_WRITE_RELAXED(txq->qtx_tail, tx_id);
 
 	return nb_pkts;
-- 
2.21.3

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2020-05-28 17:13:03.146539953 +0100
+++ 0078-net-i40e-relax-barrier-in-Tx-for-NEON.patch	2020-05-28 17:12:59.161555043 +0100
@@ -1 +1 @@
-From 6b50c489a3bb1d82e2549ae2f1e2c46961572c27 Mon Sep 17 00:00:00 2001
+From 25c139043a4cc1e3beb4735242b3764fe65f292e Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 6b50c489a3bb1d82e2549ae2f1e2c46961572c27 ]
+
@@ -19 +20,0 @@
-Cc: stable at dpdk.org
@@ -28 +29 @@
-index d7d6decafd..8b99354a5f 100644
+index deb185fe2f..4376d8911c 100644