here we go, figured it out. sorry about that. This patch adds PROTO_CMSG_DATA_ONLY to inet_dgram_ops and inet6_dgram_ops so that UDP_SEGMENT (GSO) and UDP_GRO can be used through io_uring. GSO and GRO are vital to bring QUIC servers on par with TCP throughputs, and together offer a higher throughput gain than io_uring alone (rate of data transit considering), thus io_uring is presently the lesser performance choice. RE http://vger.kernel.org/lpc_net2018_talks/willemdebruijn-lpc2018-udpgso-paper-DRAFT-1.pdf, GSO is about +~63% and GRO +~82%. this patch closes that loophole. net/ipv4/af_inet.c | 1 + net/ipv6/af_inet6.c | 1 + net/socket.c | 8 +++++--- 3 files changed, 7 insertions(+), 3 deletions(-)