sendmmsg & Generic Segmentation Offloading?

[CreativePSofficial]

Hello,

I wanted to ask you @lsalzman, whether ENet could see an optimization with GSO and sendmmsg (instead of the plain 'sendmsg') in order to optimize throughput? ( see: https://blog.cloudflare.com/accelerating-udp-packet-transmission-for-quic/ ) I have heard QUIC already leverages these, so I am asking how much sense it would make to implement them in ENet at least on the unix/linux side of things...

Thank you!

[CreativePSofficial]

@lsalzman Hello,

are there any updates on this?

[dimage1]

Hi, sendmmsg optimizes CPU by reducing system calls. It should be relatively easy to implement by accumulating mmsghdr inside enet_socket_send and flushing it on buffers' limit reach or by direct calls of enet_socket_send_flush. ENetSocket can be extended to a structure to store intermediate buffers. BTW, a similar technique can be used for receiving, with recvmmsg.

[CreativePSofficial]

Hello sir, thanks for your reply.

Yes... We have sendmmsg in already, but now I am asking about GSO, how could this be possibly done?

I am looking forward to hearing from you. Thank you.

[dimage1]

Sorry, I don't know a good way to benefit from GSO on enet. Enet already tries to split data close to the MTU size. All enet packets are below MTU, but have various sizes. So pushing them to the kernel as one big buffer (e.g. 64K) with predefined segment size might break enet.  A complete OS kernel bypassing can be another way to go. Technologies like DPDK will help there.