From: Antoine Tenart <antoine.tenart@bootlin.com>
Date: Thu, 12 Jul 2018 13:54:21 +0200
Subject: net: mvpp2: improve the distribution of packets on CPUs when using
 RSS
Patch-mainline: v4.19-rc1
Git-commit: 662ae3fe65000a6b7ceeed1ecf510346d8fec447
References: bsc#1119113 FATE#326472

This patch adds an extra indirection when setting the indirection table
into the RSS hardware table to improve the packets distribution across
CPUs. For example, if 2 queues are used on a multi-core system this new
indirection will choose two queues on two different CPUs instead of the
two first queues which are on the same first CPU.

Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_cls.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_cls.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_cls.c
@@ -107,6 +107,19 @@ void mvpp2_cls_oversize_rxq_set(struct m
 	mvpp2_write(port->priv, MVPP2_CLS_SWFWD_PCTRL_REG, val);
 }
 
+static inline u32 mvpp22_rxfh_indir(struct mvpp2_port *port, u32 rxq)
+{
+	int nrxqs, cpus = num_possible_cpus();
+
+	/* Number of RXQs per CPU */
+	nrxqs = port->nrxqs / cpus;
+
+	/* Indirection to better distribute the paquets on the CPUs when
+	 * configuring the RSS queues.
+	 */
+	return port->first_rxq + ((rxq * nrxqs + rxq / cpus) % port->nrxqs);
+}
+
 void mvpp22_rss_fill_table(struct mvpp2_port *port, u32 table)
 {
 	struct mvpp2 *priv = port->priv;
@@ -117,7 +130,8 @@ void mvpp22_rss_fill_table(struct mvpp2_
 			  MVPP22_RSS_INDEX_TABLE_ENTRY(i);
 		mvpp2_write(priv, MVPP22_RSS_INDEX, sel);
 
-		mvpp2_write(priv, MVPP22_RSS_TABLE_ENTRY, port->indir[i]);
+		mvpp2_write(priv, MVPP22_RSS_TABLE_ENTRY,
+			    mvpp22_rxfh_indir(port, port->indir[i]));
 	}
 }