Hello, On Thursday, we had our 80th meeting with Mat, Peter and Ossama (Intel OTC), Paolo (RedHat) and myself (Tessares). Thanks again for this new good meeting! Here are the minutes of the meeting: Accepted patches: - The list of accepted patches can be seen on PatchWork: https://patchwork.ozlabs.org/project/mptcp/list/?state=3 - By Paolo Abeni, Matthieu Baerts 1214271 Squash-to: "tcp: coalesce/collapse must respect MPTCP extension 1214225 Squash-to: "mptcp: Add MPTCP to skb extensions" 1213556 [v3] Squash-to: "tcp: Prevent coalesce/collapse when skb has MP 1212550 Squash-to: "mptcp: Add MPTCP socket stubs" 1212331 [2/2] Squash-to: "mptcp: Implement MPTCP receive path" 1212314 [1/2] Squash-to: "mptcp: Add MPTCP socket stubs" 1212209 Squash-to: "mptcp: recvmsg() can drain data from multiple subfl 1211460 Squash-to: "mptcp: Add key generation and token tree" 1211244 Squash-to: "sock: Make sk_protocol a 16-bit value" 1210776 Squash-to: "mptcp: Implement MPTCP receive path" 1210775 Squash-to: "mptcp: Handle MP_CAPABLE options for outgoing conne 1210697 [v2] Squash-to: "mptcp: cope with later TCP fallback" 1210382 Squash-to: tcp: Check for filled TCP option space before SACK 1210375 Squash-to: "sock: Make sk_protocol a 16-bit value" 1209395 Re: [PATCH] mptcp: cope with later TCP fallback. Pending patches: - The list of pending patches can be seen on PatchWork: https://patchwork.ozlabs.org/project/mptcp/list/?state=* - By Paolo Abeni, Matthieu Baerts, Peter Krystad 1194592: Changes Requested: [RFC,1/1] mptcp: Optimize struct mptcp_recei 1196109: RFC: [10/10,RFC] selftests:mptcp: decrease timeout to 100 sec 1214280: Changes Requested: [RFC,1/4] Squash-to: "mptcp: Handle MP_CAPAB 1214277: Changes Requested: [RFC,2/4] Squash-to "mptcp: Create SUBFLOW s 1214278: Changes Requested: [RFC,3/4] Squash-to: "mptcp: Implement MPTCP 1214279: Changes Requested: [RFC,4/4] Squash-to: "mptcp: cope with later FYI: Current Roadmap: - Part 1 (mainly TCP changes, will be sent with Part 2): - Sent to Netdev, in review - Part 2 (minimum set for MPTCP, up to KSelftests, one subflow): - Sent to Netdev, in review, waiting for Part 1 to be ready - Part 3 (MPTCPv1): - Ready to be sent to Netdev, waiting for Part 2 to be ready - Part 4 (to be sent before the end of the merge window or more probably at the next one) - Full DATA_FIN support [WIP] - Shared recv window (drop data received on other subflows) [TODO] - Active backup support [WIP] - Opti in TCP option structures (unions) [to be rebased) - Part 5 (to fully support MPTCP): - Shared recv window (full support) - IPv6 - IPv4 mapped support - not dropping MPTCP options (ADD_ADDR, etc.) - FAST_CLOSE - full MPTCP v1 support (reliable add_addr, etc.) - after a few attempts of failed MPTCP, we fallback to TCP (like TFO is doing) - Part 6 (extra needed for prod): - opti/perfs - TFO Initial submission to net-next: - Part 1: - We got some reviews from Eric Dumazet and recommendations from Davem - v1 has been sent on Friday: - comments from Eric about patch 2 (struct sock) and patch 9 (SACK) - v2 has been sent on Monday: - v1 -> v2: sk_pacing_shift left as a regular struct member (patch 2), and modified SACK space check based on recent -net fix (patch 9). - comment from Eric about patch 2 again (struct sock) - v3 has been sent on Tuesday: - v2 -> v3: Ensure sk_type alignment in struct sock (patch 2) - discussions on: tcp: Prevent coalesce/collapse when skb has MPTCP extensions: - Eric: This seems a very pessimistic change to me. Are you planing later to refine this limitation ? Surely if a sender sends TSO packet, we allow all the segments being aggregated at receive side either by GRO or TCP coalescing. - Davem: This turns off absolutely crucial functional elements of our TCP stack, and will avoid all of the machinery that avoids wastage in TCP packets sitting in the various queues. skb->truesize management, etc. I will not apply these patches with such a non-trivial regression in place for MPTCP streams, sorry. - Paolo has just added support of coalescing for MPTCP: - to coalesce the ones with the same options - some room to improvement (DSN/ACK in sequence) but additional hooks needed and it will increase the complexity - here we address Eric concerns - for the moment we are checking the bit-field on each packet. We can optimise this later. Compiler can optimise stuff but maybe not to that point. - *Paolo* will check what the binary looks like just after the meeting → The compiler did well his job! - v4 & v5 have been sent on Thursday after the meeting: - We got a full review from Eric (except the last patch) - v6 is ready but will be sent in January - Part 2: - v1 was sent on Friday - v2 was sent on Wednesday (rebase) but rejected until part 1 is applied. → https://lore.kernel.org/netdev/20191218.124244.864160487872326152.davem@d... - Part 3: - v1 was not sent on Wednesday, David Miller prefers to wait. - We are not going to send Part 3 until part 1 & 2 are merged, not even as an RFC Other WIP items: - Mostly on hold, focusing on part 1 → 3 mptcpd: - mptcpd 0.3: Beta release - https://github.com/intel/mptcpd/releases/tag/v0.3 - mainly plugin API, fixes, stabilisation, it's now a beta! - could be nice to stress it (and the kernel part) to see if we can use it for servers with a lot of connections (we can lose netlink messages) Perfs figures: - saw issues with the unblocked connect → mptcp_finish_connect() can set msk fields async. In a specific sequences from the userspace, we can have issues. - we can address that later - tests were done with MPTCP, one subflow, loopback, same machine - we are close to TCP so that's good! Plan for the next weeks: - Rest - Enjoy the end of the year! Merry Xmas and Happy New Year everybody! - Check patches from Part 1, ideally around the 2nd/3rd of January - Tag "netdev-v6-part1" using: $ git fetch origin $ git tag -sfm "Multipath TCP part 1: Prerequisites, version 6" \ netdev-v6-part1 $(git log -1 --format=%H --grep \ '^skb: add helpers to allocate ext independently from s' \ origin/net-next..origin/export) $ git tag -sfm "Multipath TCP: full working branch, version 7" \ netdev-v7-full origin/export - Send part 1 v6 to netdev, ideally around the 2nd/3rd of January Misc: - Let's do it! https://www.tessares.net/a-key-step-for-mptcp-integration-in-linux-5-x/ Next meeting: - We decided to *skip the two next meetings* (26th / 2nd) - We propose to have the next meeting on Thursday, the 9th of January. - Usual time: 17:00 UTC (9am PST, 6pm CET) - Still open to everyone! - https://annuel2.framapad.org/p/mptcp_upstreaming_20200109 Feel free to comment on these points and propose new ones for the next meeting! Merry Xmas and Happy New Year everybody! Talk to you next year, Matt -- Matthieu Baerts | R&D Engineer matthieu.baerts(a)tessares.net Tessares SA | Hybrid Access Solutions www.tessares.net 1 Avenue Jean Monnet, 1348 Louvain-la-Neuve, Belgium