GSO with udp_tunnel_xmit_skb

From: Jason A. Donenfeld
Date: Thu Nov 05 2015 - 05:52:41 EST

Hi folks,

When sending arbitrary SKBs with udp_tunnel_xmit_skb, the networking
stack does not appear to be utilizing UFO on the outgoing UDP packets,
which significantly caps the transmission speed. I see about 50% CPU
usage in this send path, triggered for every single outgoing packet.
Is there a particular skb option I need to set to enable this? I read
Tom's patch [1] from last year, but this seems to be about setting the
inner packet type. In my case, the inner type is opaque encrypted
data, so there's not a relevant setting.


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