linux-kernel - [net-next PATCH v4 5/7] net: ravb: Enable SW IRQ Coalescing for GbEth

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Message-Id: <20240528150339.6791-6-paul.barker.ct@bp.renesas.com>
Date: Tue, 28 May 2024 16:03:37 +0100
From: Paul Barker <paul.barker.ct@...renesas.com>
To: Sergey Shtylyov <s.shtylyov@....ru>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
Cc: Paul Barker <paul.barker.ct@...renesas.com>,
	Biju Das <biju.das.jz@...renesas.com>,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	netdev@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [net-next PATCH v4 5/7] net: ravb: Enable SW IRQ Coalescing for GbEth

Software IRQ Coalescing is required to improve network stack performance
in the RZ/G2L SoC family and the RZ/G3S SoC, i.e. the SoCs which use the
GbEth IP.

This patch gives the following improvements during testing with iperf3:

  * RZ/G2L:
    * TCP RX: same bandwidth with -6% CPU load (76% -> 71%)
    * UDP RX: same bandwidth with -10% CPU load (99% -> 89%)

  * RZ/G2UL:
    * UDP RX: +4200% bandwidth (1.23Mbps -> 53Mbps)

  * RZ/G3S:
    * UDP RX: +425% bandwidth (1.23Mbps -> 6.46Mbps)

The improvement of UDP RX bandwidth for the single core SoCs (RZ/G2UL &
RZ/G3S) is particularly critical.

Signed-off-by: Paul Barker <paul.barker.ct@...renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>
---
Changes v3-v4:
  * Renamed needs_irq_coalesce -> coalesce_irqs.
  * Added Sergey's Reviewed-by tag.

 drivers/net/ethernet/renesas/ravb.h      | 1 +
 drivers/net/ethernet/renesas/ravb_main.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 71de2a7aa27c..6a7aa7dd17e6 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h
@@ -1054,6 +1054,7 @@ struct ravb_hw_info {
 	u32 rx_max_desc_use;
 	u32 rx_desc_size;
 	unsigned aligned_tx: 1;
+	unsigned coalesce_irqs:1;	/* Needs software IRQ coalescing */
 
 	/* hardware features */
 	unsigned internal_delay:1;	/* AVB-DMAC has internal delays */
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index c9c5cc641589..e95e0b6e1fe6 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2667,6 +2667,7 @@ static const struct ravb_hw_info gbeth_hw_info = {
 	.rx_max_desc_use = 4080,
 	.rx_desc_size = sizeof(struct ravb_rx_desc),
 	.aligned_tx = 1,
+	.coalesce_irqs = 1,
 	.tx_counters = 1,
 	.carrier_counters = 1,
 	.half_duplex = 1,
@@ -2943,6 +2944,9 @@ static int ravb_probe(struct platform_device *pdev)
 	if (info->nc_queues)
 		netif_napi_add(ndev, &priv->napi[RAVB_NC], ravb_poll);
 
+	if (info->coalesce_irqs)
+		netdev_sw_irq_coalesce_default_on(ndev);
+
 	/* Network device register */
 	error = register_netdev(ndev);
 	if (error)
-- 
2.39.2