Merge branch 'r8169-irq-coalesce'

Heiner Kallweit says:

====================
net: add and use netdev_sw_irq_coalesce_default_on()

There are reports about r8169 not reaching full line speed on certain
systems (e.g. SBC's) with a 2.5Gbps link.
There was a time when hardware interrupt coalescing was enabled per
default, but this was changed due to ASPM-related issues on few systems.

Meanwhile we have sysfs attributes for controlling kind of
"software interrupt coalescing" on the GRO level. However most distros
and users don't know about it. So lets set a conservative default for
both involved parameters. Users can still override the defaults via
sysfs. Don't enable these settings on the fast ethernet chip versions,
they are slow enough.

Even with these conservative setting interrupt load on my 1Gbps test
system reduced significantly.

Follow Jakub's suggestion and put this functionality into net core
so that other MAC drivers can reuse it.
====================

Signed-off-by: David S. Miller <[email protected]>

Author: davem330

drivers/net/ethernet/realtek/r8169_main.c

@@ -5283,6 +5283,8 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	dev->hw_features |= NETIF_F_RXALL;
 	dev->hw_features |= NETIF_F_RXFCS;
 
+	netdev_sw_irq_coalesce_default_on(dev);
+
 	/* configure chip for default features */
 	rtl8169_set_features(dev, dev->features);
 

include/linux/netdevice.h

@@ -78,6 +78,7 @@ struct xdp_buff;
 void synchronize_net(void);
 void netdev_set_default_ethtool_ops(struct net_device *dev,
 				    const struct ethtool_ops *ops);
+void netdev_sw_irq_coalesce_default_on(struct net_device *dev);
 
 /* Backlog congestion levels */
 #define NET_RX_SUCCESS		0	/* keep 'em coming, baby */

net/core/dev.c

@@ -10517,6 +10517,22 @@ void netdev_set_default_ethtool_ops(struct net_device *dev,
 }
 EXPORT_SYMBOL_GPL(netdev_set_default_ethtool_ops);
 
+/**
+ * netdev_sw_irq_coalesce_default_on() - enable SW IRQ coalescing by default
+ * @dev: netdev to enable the IRQ coalescing on
+ *
+ * Sets a conservative default for SW IRQ coalescing. Users can use
+ * sysfs attributes to override the default values.
+ */
+void netdev_sw_irq_coalesce_default_on(struct net_device *dev)
+{
+	WARN_ON(dev->reg_state == NETREG_REGISTERED);
+
+	dev->gro_flush_timeout = 20000;
+	dev->napi_defer_hard_irqs = 1;
+}
+EXPORT_SYMBOL_GPL(netdev_sw_irq_coalesce_default_on);
+
 void netdev_freemem(struct net_device *dev)
 {
 	char *addr = (char *)dev - dev->padded;