netdev - [PATCH net-next] net: cadence: macb: Enable software IRQ coalescing by default

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Message-Id: <20240903184912.4151926-1-sean.anderson@linux.dev>
Date: Tue,  3 Sep 2024 14:49:12 -0400
From: Sean Anderson <sean.anderson@...ux.dev>
To: Nicolas Ferre <nicolas.ferre@...rochip.com>,
	Claudiu Beznea <claudiu.beznea@...on.dev>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org
Cc: Michal Simek <michal.simek@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Sean Anderson <sean.anderson@...ux.dev>
Subject: [PATCH net-next] net: cadence: macb: Enable software IRQ coalescing by default

This NIC doesn't have hardware IRQ coalescing. Under high load,
interrupts can adversely affect performance. To mitigate this, enable
software IRQ coalescing by default. On my system this increases receive
throughput with iperf3 from 853 MBit/sec to 934 MBit/s, decreases
interrupts from 69489/sec to 2016/sec, and decreases CPU utilization
from 27% (4x Cortex-A53) to 14%. Latency is not affected (as far as I
can tell).

Signed-off-by: Sean Anderson <sean.anderson@...ux.dev>
---

 drivers/net/ethernet/cadence/macb_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 127bb3208034..8e1e4b2b2386 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -4184,6 +4184,8 @@ static int macb_init(struct platform_device *pdev)
 		dev->ethtool_ops = &macb_ethtool_ops;
 	}
 
+	netdev_sw_irq_coalesce_default_on(dev);
+
 	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
 
 	/* Set features */
-- 
2.35.1.1320.gc452695387.dirty