Subject: [PATCH] net: disable GRO by default
From: Rafał Miłecki <[email-masked]>
Date: Mon, 20 Jun 2022 10:01:18 +0200

In many cases GRO improves network performance however it comes at a
cost of chacksums calculations. In case of slow CPU and missing hardware
csum calculation support GRO can actually decrease network speed.

On BCM4708 *disabling* GRO results in following NAT masquarade speed
changes:
1. 364 Mb/s → 396 Mb/s (packet steering disabled)
2. 341 Mb/s → 566 Mb/s (packet steering enabled)

Signed-off-by: Rafał Miłecki <[email-masked]>
---
 include/linux/netdev_features.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -231,10 +231,10 @@ static inline int find_next_netdev_featu
 #define NETIF_F_UPPER_DISABLES	NETIF_F_LRO
 
 /* changeable features with no special hardware requirements */
-#define NETIF_F_SOFT_FEATURES	(NETIF_F_GSO | NETIF_F_GRO)
+#define NETIF_F_SOFT_FEATURES	(NETIF_F_GSO)
 
 /* Changeable features with no special hardware requirements that defaults to off. */
-#define NETIF_F_SOFT_FEATURES_OFF	NETIF_F_GRO_FRAGLIST
+#define NETIF_F_SOFT_FEATURES_OFF	(NETIF_F_GRO_FRAGLIST | NETIF_F_GRO)
 
 #define NETIF_F_VLAN_FEATURES	(NETIF_F_HW_VLAN_CTAG_FILTER | \
 				 NETIF_F_HW_VLAN_CTAG_RX | \