netdev - Re: [PATCH net-next] net: sock_rps_record

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Date:   Tue, 06 Dec 2016 22:47:27 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>,
        Tom Herbert <tom@...bertland.com>
Subject: Re: [PATCH net-next] net: sock_rps_record_flow() is for connected
 sockets

On Tue, 2016-12-06 at 19:32 -0800, Eric Dumazet wrote:
> A follow up patch will provide a static_key (Jump Label) since most
> hosts do not even use RFS.

Speaking of static_key, it appears we now have GRO on UDP, and this
consumes a considerable amount of cpu cycles.

Turning off GRO allows me to get +20 % more packets on my single UDP
socket. (1.2 Mpps instead of 1.0 Mpps)

Surely udp_gro_receive() should be bypassed if no UDP socket has
registered a udp_sk(sk)->gro_receive handler 

And/or delay the inet_add_offload(&udpv{4|6}_offload, IPPROTO_UDP); to
the first UDP sockets setting udp_sk(sk)->gro_receive handler,
ie udp_encap_enable() and udpv6_encap_enable()


:(