On Fri, 2017-03-31 at 16:33 +0200, Paolo Abeni wrote: > I did the above to avoid increasing the udp_sock struct size; this will > costs more than a whole cacheline.
Yes, but who cares :) Also note that we discussed about having a secondary receive queue in the future, to decouple the fact that producers/consumer have to grab a contended spinlock for every enqueued and dequeued packet. With a secondary queue, the consumer can transfer one queue into another in one batch. Or simply use ptr_ring / skb_array now these infras are available thanks to Michael. So we will likely increase UDP socket size in a near future... > > I did not hit others false sharing issues because: > - gro_receive/gro_complete are touched only for packets coming from > devices with udp tunnel offload enabled, that hit the tunnel offload > path on the nic; such packets will most probably land in the udp tunnel > and will not use 'forward_deficit' > - encap_destroy is touched only socket shutdown > - encap_rcv is protected by the 'udp_encap_needed' static key > > I think this latter is problematic, so I'm ok with the patch you > suggested. > > The above change could still make sense, the udp code is already > checking for udplite sockets with either pcflag and protocol; > testing always the same data will make the code more cleaner. Where are we testing sk->sk_prototocol in receive path ? Thanks Paolo !
