vxlan: vxlan dev should inherit lowerdev's gso_max_size

[ Upstream commit d6acfeb17d030bb3907e77c048b0e7783ad8e5a9 ]

vxlan dev currently ignores lowerdev's gso_max_size, which adversely
affects TSO performance of liquidio if it's the lowerdev.  Egress TCP
packets' skb->len often exceed liquidio's advertised gso_max_size.  This
may happen on other NIC drivers.

Fix it by assigning lowerdev's gso_max_size to that of vxlan dev.  Might as
well do likewise for gso_max_segs.

Single flow TSO throughput of liquidio as lowerdev (using iperf3):

    Before the patch:    139 Mbps
    After the patch :   8.68 Gbps
    Percent increase:  6,144 %

Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: Satanand Burla <satananda.burla@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 983e941..50570d7 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2912,6 +2912,11 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
                return -EINVAL;
        }
 
+       if (lowerdev) {
+               dev->gso_max_size = lowerdev->gso_max_size;
+               dev->gso_max_segs = lowerdev->gso_max_segs;
+       }
+
        if (conf->mtu) {
                err = __vxlan_change_mtu(dev, lowerdev, dst, conf->mtu, false);
                if (err)