Re: [PATCH mptcp-next v2 0/7] mptcp: rx path refactor

[Matthieu Baerts <matttbe@kernel.org>]

Hi Paolo, Mat,

On 06/12/2024 13:09, Paolo Abeni wrote:
> This is a batch of changes I had sitting in my local tree for a while.
> Why another refactor you may ask? Two main resons:
> 
> - currently the mptcp RX path introduces quite a bit of 'exceptional'
>  accounting/locking processing WRT to plain TCP, adding up to the
>  implementation complexity in a misurable way
> - the performance gap WRT plain TCP for single subflow connections is
>  quite measurable.
> 
> The present refactor addresses both the above items: most of the
> additional complexity is dropped, and single stream performances
> increase measurably - from 55Gbps to 71Gbps in my loopback test. As a
> reference, plain TCP is around 84Gps on the same host.
> 
> The above comes to a price: the patch are invasive, even in subtle ways:
> the chance of destabilizing the implementation is real (ence the
> additional, intentional '-next' into the subj).
> 
> In any case keeping the patch hidden for longer was not going to do any
> good, so here we are.

Thank you for the patches and the reviews!

Patches 2 and 3 are now in the "fixes for net", while the others are in
"feat. for next". I think patch 1 can go to "Fixes for net", any objections?

New patches for t/upstream-net and t/upstream:
- d443f83de23d: mptcp: fix recvbuffer adjust on sleeping rcvmsg
- 11d4943d66ee: mptcp: don't always assume copied data in
mptcp_cleanup_rbuf()
- Results: 3a0f411ba1c5..2116e71814b7 (export-net)
- Results: df3193ae83eb..953b0d388720 (export)

Tests are now in progress:

- export-net:
https://github.com/multipath-tcp/mptcp_net-next/commit/047c2f99575350d9971b6257f96ce5f734f0186a/checks

New patches for t/upstream:
- 972d8a5b7f20: mptcp: prevent excessive coalescing on receive
- 0b0a25a24d21: mptcp: consolidate subflow cleanup
- 533bb69f1b0d: mptcp: move the whole rx path under msk socket lock
protection
- c5d13b230497: mptcp: cleanup mem accounting
- a564b9923a94: net: dismiss sk_forward_alloc_get()
- Results: 953b0d388720..9213903d77ba (export)

Tests are now in progress:

- export:
https://github.com/multipath-tcp/mptcp_net-next/commit/6aae9c8bd8361dd90a7def87459ca0173915c56c/checks

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.