[PATCH net-next] openvswitch: raise internal port TSO limit

[Wang Zhan <wang.zhan@smartx.com>]

Set the internal port TSO limit to GSO_MAX_SIZE (512 KB), as for
loopback and veth. This allows the admin/user to set a GSO limit up to
this value, to use BIG TCP for traffic routed through the internal port.

Only the capability limit changes: the IPv4 and IPv6 GSO and GRO limits
remain at 64 KiB until changed by the administrator.

Validation used a same-host test with a temporary OVS bridge, a veth pair,
and a network namespace:

  TCP client -> OVS internal -> OVS bridge -> veth -> TCP server

The veth endpoints were BIG TCP capable throughout the test, and only the
OVS internal port limits changed between 64 KiB and 524280 bytes. A single
iperf3 3.19 TCP flow, run separately over IPv4 and IPv6 with six
alternating runs per state (`-t 15 -O 5`, fixed CPU affinity and port
tuple), increased throughput by 18.1% for IPv4 and 34.7% for IPv6:

  protocol  BIG TCP off  BIG TCP on   CV off / on
  TCP/IPv4  65.567 Gbps  77.420 Gbps  1.12% / 0.37%
  TCP/IPv6  55.355 Gbps  74.568 Gbps  1.20% / 0.68%

Assisted-by: LLM
Signed-off-by: Wang Zhan <wang.zhan@smartx.com>
---
 net/openvswitch/vport-internal_dev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
index 125d310871e93..73f5184afba42 100644
--- a/net/openvswitch/vport-internal_dev.c
+++ b/net/openvswitch/vport-internal_dev.c
@@ -116,6 +116,7 @@ static void do_setup(struct net_device *netdev)
 	netdev->hw_enc_features = netdev->features;
 	netdev->features |= NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX;
 	netdev->hw_features = netdev->features;
+	netif_set_tso_max_size(netdev, GSO_MAX_SIZE);
 
 	eth_hw_addr_random(netdev);
 }

base-commit: 211f2a875f6f447745d80d5762d6d614503ac84a
-- 
2.47.3