It was observed that sending data via batadv over vxlan (on top of
wireguard) reduced the performance massively compared to raw ethernet or
batadv on raw ethernet. A check of perf data showed that the
vxlan_build_skb was calling all the time pskb_expand_head to allocate
enough headroom for:
min_headroom = LL_RESERVED_SPACE(dst->dev) + dst->header_len
+ VXLAN_HLEN + iphdr_len;
But the vxlan_config_apply only requested needed headroom for:
lowerdev->hard_header_len + VXLAN6_HEADROOM or VXLAN_HEADROOM
So it completely ignored the needed_headroom of the lower device. The first
caller of net_dev_xmit could therefore never make sure that enough headroom
was allocated for the rest of the transmit path.
Cc: Annika Wickert <annika.wick...@exaring.de>
Signed-off-by: Sven Eckelmann <s...@narfation.org>
---
drivers/net/vxlan.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 236fcc55a5fd..25b5b5a2dfea 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -3799,6 +3799,7 @@ static void vxlan_config_apply(struct net_device *dev,
dev->gso_max_segs = lowerdev->gso_max_segs;
needed_headroom = lowerdev->hard_header_len;
+ needed_headroom += lowerdev->needed_headroom;
max_mtu = lowerdev->mtu - (use_ipv6 ? VXLAN6_HEADROOM :
VXLAN_HEADROOM);
--
2.29.2
