This series collects a few follow-up for the backlog refactor, with some
of them posing as fixes just to confuse the enemy.

Targeting net-next as the issues addressed are very old, the change
is quite invasive and, as mentioned, based on the BL refactor.

Overall this:
- introduces a tracepoint similar to tcp useful to track down the issues
  addressed here
- avoid rx drop in corner case scenarios, improving tput stability and
  peak tput over fast link
- refactor the rcv space and rtt estimator, overall making DRS more
  correct and avoiding rcv buffer drifting to tcp_rmem[2], which in
  turn makes the tput more stable and less bursty
---
v4 -> v5:
  - dropped patch 4/6; it proved to be useless together with new version
    of patch 4/5
  - refactor rtt estimator: use sliding window instead of dropping "too
    high" values

v3 -> v4:
  - dropped already merged patch 1
  - update comment in patch 6/6

v2 -> v3:
  - use __entry->family in patch 1/7
  - more verbose commit message for patch 6/7

v1 -> v2:
  - new patch 1/7
  - old patch 2/4 has been split in 3: 3/7, 4/7 and 5/7
  - refactor both the rcv space init and rtt estimator

Paolo Abeni (5):
  trace: mptcp: add mptcp_rcvbuf_grow tracepoint
  mptcp: fix receive space timestamp initialization.
  mptcp: consolidate rcv space init
  mptcp: better mptcp-level RTT estimator
  mptcp: add receive queue awareness in tcp_rcv_space_adjust()

 include/trace/events/mptcp.h |  80 +++++++++++++++++++++++++
 net/mptcp/protocol.c         | 112 +++++++++++++++++++----------------
 net/mptcp/protocol.h         |  44 +++++++++++++-
 net/mptcp/subflow.c          |   2 -
 4 files changed, 184 insertions(+), 54 deletions(-)

-- 
2.51.1

On 11/19/25 1:12 PM, Paolo Abeni wrote:
> This series collects a few follow-up for the backlog refactor, with some
> of them posing as fixes just to confuse the enemy.
> 
> Targeting net-next as the issues addressed are very old, the change
> is quite invasive and, as mentioned, based on the BL refactor.
> 
> Overall this:
> - introduces a tracepoint similar to tcp useful to track down the issues
>   addressed here
> - avoid rx drop in corner case scenarios, improving tput stability and
>   peak tput over fast link
> - refactor the rcv space and rtt estimator, overall making DRS more
>   correct and avoiding rcv buffer drifting to tcp_rmem[2], which in
>   turn makes the tput more stable and less bursty

I forgot to mention that after this upstream series will be merged:

https://patchwork.kernel.org/user/todo/netdevbpf/?series=1025209

we want to introduce similar changes in mptcp, too.

/P

Hi Paolo,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join): Critical: 1 Call Trace(s) - Critical: Global Timeout ❌
- KVM Validation: normal (only selftest_mptcp_join): Critical: 1 Call Trace(s) - Critical: Global Timeout ❌
- KVM Validation: debug (except selftest_mptcp_join): Critical: 1 Call Trace(s) - Critical: Global Timeout ❌
- KVM Validation: debug (only selftest_mptcp_join): Critical: 1 Call Trace(s) - Critical: Global Timeout ❌
- KVM Validation: btf-normal (only bpftest_all): Success! ✅
- KVM Validation: btf-debug (only bpftest_all): Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/19501595339

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/f3d6bb310960
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1025302


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-normal

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)