Hi Paolo, Mat,
On 16/02/2024 12:28, Paolo Abeni wrote:
> Patch 6/7 does the magic, all the others are minor cleanup and fix of
> buglet exposed by such feature. I'll push a paired pktdrill test.
>
> Note that this relies on the existing accounting for snd_nxt. As I
> stated such accounting is not 110% accurate as it tracks the most recent
> sequence number queued to any subflow, and not the actual sequence
> number sent on the wire.
>
> I experimented a lot trying to implement the latter and in the end it
> proved to be both "too complex" and "not necessary".
>
> The complexity raises from the need for additional lock and a lot of
> refactory to introduce such protection without adding significant
> overhead. Additionally, snd_nxt is currenly used and exposed with the
> current semantic both eBPF and the internal packet scheduling.
> Introducing a different tracking will still require us to keep the old
> one.
>
> More interesting, a more accurate tracking could be not strictly
> necessary: as the MPTCP protocol enqueues data to the subflows only up
> the available send window, any enqueue data is sent on the wire
> instantly, without any blocking operation short of a drop in the tx path
> at the nft or TC layer.
>
> The individual patches changelog carry the gory details.
>
> Still sending a single series to outline the functional requirements,
> even if the first 3 patches could land on mptcp-net directly.
Thank you for the patches, and the reviews!
Now in our tree (fixes for -net, and feat. for net-next):
New patches for t/upstream-net and t/upstream:
- d9b01cb9adc7: mptcp: push at DSS boundaries
- 1ea124e2ca57: mptcp: fix snd_wnd initialization for passive socket
- c64351cfe29e: mptcp: fix potential wake-up event loss
- Results: 086d253b7038..9dcf86462a59 (export-net)
- efe1cf277159: conflict in top-bases/t/DO-NOT-MERGE-git-markup-net-next
- Results: 8de48203098c..4f7ce06a0f9e (export)
New patches for t/upstream (only):
- 232c91fcaf38: mptcp: cleanup writer wake-up
- 1e762225d9b2: mptcp: avoid some duplicate code in socket option handling
- 51913f3f330f: mptcp: implement TCP_NOTSENT_LOWAT support
- eb5db737fdac: mptcp: cleanup SOL_TCP handling
- Results: 4f7ce06a0f9e..f2fb9bec2195 (export)
Cheers,
Matt
--
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