[dpdk-stable] patch 'net/bonding: fix Rx slave fairness' has been queued to stable release 18.08.1

[Kevin Traynor]

Hi,

FYI, your patch has been queued to stable release 18.08.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 11/26/18. 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. If the code is different (ie: not only metadata diffs), due for example to
a change in context or macro names, please double check it.

Thanks.

Kevin Traynor

---
>From ad543312c488172e15a70799d390288d18c79029 Mon Sep 17 00:00:00 2001
From: Chas Williams <chas3 at att.com>
Date: Thu, 20 Sep 2018 08:52:26 -0400
Subject: [PATCH] net/bonding: fix Rx slave fairness

[ upstream commit e1110e97764873de0af28e6fa11dcd9c170d4e53 ]

Some PMDs, especially ones with vector receives, require a minimum number
of receive buffers in order to receive any packets.  If the first slave
read leaves less than this number available, a read from the next slave
may return 0 implying that the slave doesn't have any packets which
results in skipping over that slave as the next active slave.

To fix this, implement round robin for the slaves during receive that
is only advanced to the next slave at the end of each receive burst.
This is also done to provide some additional fairness in processing in
other bonding RX burst routines as well.

Fixes: 2efb58cbab6e ("bond: new link bonding library")

Signed-off-by: Chas Williams <chas3 at att.com>
Acked-by: Luca Boccassi <bluca at debian.org>
Acked-by: Matan Azrad <matan at mellanox.com>
---
 drivers/net/bonding/rte_eth_bond_pmd.c | 53 +++++++++++++++++---------
 1 file changed, 34 insertions(+), 19 deletions(-)

diff --git a/drivers/net/bonding/rte_eth_bond_pmd.c b/drivers/net/bonding/rte_eth_bond_pmd.c
index 7814258f2..86e78bde8 100644
--- a/drivers/net/bonding/rte_eth_bond_pmd.c
+++ b/drivers/net/bonding/rte_eth_bond_pmd.c
@@ -59,26 +59,32 @@ bond_ethdev_rx_burst(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 	struct bond_dev_private *internals;
 
-	uint16_t num_rx_slave = 0;
 	uint16_t num_rx_total = 0;
-
+	uint16_t slave_count;
+	uint16_t active_slave;
 	int i;
 
 	/* Cast to structure, containing bonded device's port id and queue id */
 	struct bond_rx_queue *bd_rx_q = (struct bond_rx_queue *)queue;
-
 	internals = bd_rx_q->dev_private;
+	slave_count = internals->active_slave_count;
+	active_slave = internals->active_slave;
 
+	for (i = 0; i < slave_count && nb_pkts; i++) {
+		uint16_t num_rx_slave;
 
-	for (i = 0; i < internals->active_slave_count && nb_pkts; i++) {
 		/* Offset of pointer to *bufs increases as packets are received
 		 * from other slaves */
-		num_rx_slave = rte_eth_rx_burst(internals->active_slaves[i],
-				bd_rx_q->queue_id, bufs + num_rx_total, nb_pkts);
-		if (num_rx_slave) {
-			num_rx_total += num_rx_slave;
-			nb_pkts -= num_rx_slave;
-		}
+		num_rx_slave =
+			rte_eth_rx_burst(internals->active_slaves[active_slave],
+					 bd_rx_q->queue_id,
+					 bufs + num_rx_total, nb_pkts);
+		num_rx_total += num_rx_slave;
+		nb_pkts -= num_rx_slave;
+		if (++active_slave == slave_count)
+			active_slave = 0;
 	}
 
+	if (++internals->active_slave == slave_count)
+		internals->active_slave = 0;
 	return num_rx_total;
 }
@@ -259,23 +265,30 @@ bond_ethdev_rx_burst_8023ad_fast_queue(void *queue, struct rte_mbuf **bufs,
 	uint16_t slaves[RTE_MAX_ETHPORTS];
 	uint16_t slave_count;
-
-	uint16_t i, idx;
+	uint16_t active_slave;
+	uint16_t i;
 
 	/* Copy slave list to protect against slave up/down changes during tx
 	 * bursting */
 	slave_count = internals->active_slave_count;
+	active_slave = internals->active_slave;
 	memcpy(slaves, internals->active_slaves,
 			sizeof(internals->active_slaves[0]) * slave_count);
 
-	for (i = 0, idx = internals->active_slave;
-			i < slave_count && num_rx_total < nb_pkts; i++, idx++) {
-		idx = idx % slave_count;
+	for (i = 0; i < slave_count && nb_pkts; i++) {
+		uint16_t num_rx_slave;
 
 		/* Read packets from this slave */
-		num_rx_total += rte_eth_rx_burst(slaves[idx], bd_rx_q->queue_id,
-				&bufs[num_rx_total], nb_pkts - num_rx_total);
+		num_rx_slave = rte_eth_rx_burst(slaves[active_slave],
+						bd_rx_q->queue_id,
+						bufs + num_rx_total, nb_pkts);
+		num_rx_total += num_rx_slave;
+		nb_pkts -= num_rx_slave;
+
+		if (++active_slave == slave_count)
+			active_slave = 0;
 	}
 
-	internals->active_slave = idx;
+	if (++internals->active_slave == slave_count)
+		internals->active_slave = 0;
 
 	return num_rx_total;
@@ -460,5 +473,7 @@ bond_ethdev_rx_burst_8023ad(void *queue, struct rte_mbuf **bufs,
 	}
 
-	internals->active_slave = idx;
+	if (++internals->active_slave == slave_count)
+		internals->active_slave = 0;
+
 	return num_rx_total;
 }
-- 
2.19.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2018-11-21 15:59:14.293272268 +0000
+++ 0026-net-bonding-fix-Rx-slave-fairness.patch	2018-11-21 15:59:13.000000000 +0000
@@ -1,8 +1,10 @@
-From e1110e97764873de0af28e6fa11dcd9c170d4e53 Mon Sep 17 00:00:00 2001
+From ad543312c488172e15a70799d390288d18c79029 Mon Sep 17 00:00:00 2001
 From: Chas Williams <chas3 at att.com>
 Date: Thu, 20 Sep 2018 08:52:26 -0400
 Subject: [PATCH] net/bonding: fix Rx slave fairness
 
+[ upstream commit e1110e97764873de0af28e6fa11dcd9c170d4e53 ]
+
 Some PMDs, especially ones with vector receives, require a minimum number
 of receive buffers in order to receive any packets.  If the first slave
 read leaves less than this number available, a read from the next slave
@@ -15,7 +17,6 @@
 other bonding RX burst routines as well.
 
 Fixes: 2efb58cbab6e ("bond: new link bonding library")
-Cc: stable at dpdk.org
 
 Signed-off-by: Chas Williams <chas3 at att.com>
 Acked-by: Luca Boccassi <bluca at debian.org>