linux-kernel - [PATCH net-next 0/7] mptcp: rx path refactor

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Message-Id: <20250218-net-next-mptcp-rx-path-refactor-v1-0-4a47d90d7998@kernel.org>
Date: Tue, 18 Feb 2025 19:36:11 +0100
From: "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
To: mptcp@...ts.linux.dev, Mat Martineau <martineau@...nel.org>, 
 Geliang Tang <geliang@...nel.org>, "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: Kuniyuki Iwashima <kuniyu@...zon.com>, 
 Willem de Bruijn <willemb@...gle.com>, David Ahern <dsahern@...nel.org>, 
 Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>, 
 Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
Subject: [PATCH net-next 0/7] mptcp: rx path refactor

Paolo worked on this RX path refactor for these two main reasons:

- 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 miserable 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 Paolo's loopback test. As
a reference, plain TCP was around 84Gbps on the same host.

The above comes to a price: the patch are invasive, even in subtle ways.

Note: patch 5/7 removes the sk_forward_alloc_get() helper, which caused
some trivial modifications in different places in the net tree: sockets,
IPv4, sched. That's why a few more people have been Cc here. Feel free
to only look at this patch 5/7.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>
---
Paolo Abeni (7):
      mptcp: consolidate subflow cleanup
      mptcp: drop __mptcp_fastopen_gen_msk_ackseq()
      mptcp: move the whole rx path under msk socket lock protection
      mptcp: cleanup mem accounting
      net: dismiss sk_forward_alloc_get()
      mptcp: dismiss __mptcp_rmem()
      mptcp: micro-optimize __mptcp_move_skb()

 include/net/sock.h   |  13 ---
 net/core/sock.c      |   2 +-
 net/ipv4/af_inet.c   |   2 +-
 net/ipv4/inet_diag.c |   2 +-
 net/mptcp/fastopen.c |  27 +----
 net/mptcp/protocol.c | 317 ++++++++++++++++-----------------------------------
 net/mptcp/protocol.h |  22 ++--
 net/mptcp/subflow.c  |  36 +++---
 net/sched/em_meta.c  |   2 +-
 9 files changed, 134 insertions(+), 289 deletions(-)
---
base-commit: b4cb730862cf4f59ac3dcb83b9ac4eeb29dbfb0e
change-id: 20250106-net-next-mptcp-rx-path-refactor-f44579efb57c

Best regards,
-- 
Matthieu Baerts (NGI0) <matttbe@...nel.org>