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30549eebc4
Currently the ADD_ADDR option is retransmitted with a fixed timeout. This patch makes the retransmission timeout adaptive by using the maximum RTO among all the subflows, while still capping it at the configured maximum value (add_addr_timeout_max). This improves responsiveness when establishing new subflows. Specifically: 1. Adds mptcp_adjust_add_addr_timeout() helper to compute the adaptive timeout. 2. Uses maximum subflow RTO (icsk_rto) when available. 3. Applies exponential backoff based on retransmission count. 4. Maintains fallback to configured max timeout when no RTO data exists. This slightly changes the behaviour of the MPTCP "add_addr_timeout" sysctl knob to be used as a maximum instead of a fixed value. But this is seen as an improvement: the ADD_ADDR might be sent quicker than before to improve the overall MPTCP connection. Also, the default value is set to 2 min, which was already way too long, and caused the ADD_ADDR not to be retransmitted for connections shorter than 2 minutes. Suggested-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/576 Reviewed-by: Christoph Paasch <cpaasch@openai.com> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20250907-net-next-mptcp-add_addr-retrans-adapt-v1-1-824cc805772b@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
154 lines
4.9 KiB
ReStructuredText
154 lines
4.9 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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=====================
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MPTCP Sysfs variables
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=====================
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/proc/sys/net/mptcp/* Variables
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===============================
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add_addr_timeout - INTEGER (seconds)
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Set the maximum value of timeout after which an ADD_ADDR control message
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will be resent to an MPTCP peer that has not acknowledged a previous
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ADD_ADDR message. A dynamically estimated retransmission timeout based
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on the estimated connection round-trip-time is used if this value is
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lower than the maximum one.
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Do not retransmit if set to 0.
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The default value matches TCP_RTO_MAX. This is a per-namespace
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sysctl.
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Default: 120
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allow_join_initial_addr_port - BOOLEAN
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Allow peers to send join requests to the IP address and port number used
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by the initial subflow if the value is 1. This controls a flag that is
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sent to the peer at connection time, and whether such join requests are
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accepted or denied.
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Joins to addresses advertised with ADD_ADDR are not affected by this
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value.
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This is a per-namespace sysctl.
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Default: 1
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available_path_managers - STRING
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Shows the available path managers choices that are registered. More
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path managers may be available, but not loaded.
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available_schedulers - STRING
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Shows the available schedulers choices that are registered. More packet
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schedulers may be available, but not loaded.
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blackhole_timeout - INTEGER (seconds)
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Initial time period in second to disable MPTCP on active MPTCP sockets
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when a MPTCP firewall blackhole issue happens. This time period will
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grow exponentially when more blackhole issues get detected right after
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MPTCP is re-enabled and will reset to the initial value when the
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blackhole issue goes away.
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0 to disable the blackhole detection. This is a per-namespace sysctl.
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Default: 3600
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checksum_enabled - BOOLEAN
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Control whether DSS checksum can be enabled.
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DSS checksum can be enabled if the value is nonzero. This is a
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per-namespace sysctl.
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Default: 0
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close_timeout - INTEGER (seconds)
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Set the make-after-break timeout: in absence of any close or
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shutdown syscall, MPTCP sockets will maintain the status
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unchanged for such time, after the last subflow removal, before
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moving to TCP_CLOSE.
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The default value matches TCP_TIMEWAIT_LEN. This is a per-namespace
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sysctl.
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Default: 60
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enabled - BOOLEAN
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Control whether MPTCP sockets can be created.
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MPTCP sockets can be created if the value is 1. This is a
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per-namespace sysctl.
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Default: 1 (enabled)
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path_manager - STRING
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Set the default path manager name to use for each new MPTCP
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socket. In-kernel path management will control subflow
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connections and address advertisements according to
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per-namespace values configured over the MPTCP netlink
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API. Userspace path management puts per-MPTCP-connection subflow
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connection decisions and address advertisements under control of
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a privileged userspace program, at the cost of more netlink
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traffic to propagate all of the related events and commands.
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This is a per-namespace sysctl.
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* "kernel" - In-kernel path manager
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* "userspace" - Userspace path manager
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Default: "kernel"
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pm_type - INTEGER
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Set the default path manager type to use for each new MPTCP
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socket. In-kernel path management will control subflow
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connections and address advertisements according to
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per-namespace values configured over the MPTCP netlink
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API. Userspace path management puts per-MPTCP-connection subflow
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connection decisions and address advertisements under control of
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a privileged userspace program, at the cost of more netlink
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traffic to propagate all of the related events and commands.
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This is a per-namespace sysctl.
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Deprecated since v6.15, use path_manager instead.
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* 0 - In-kernel path manager
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* 1 - Userspace path manager
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Default: 0
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scheduler - STRING
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Select the scheduler of your choice.
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Support for selection of different schedulers. This is a per-namespace
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sysctl.
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Default: "default"
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stale_loss_cnt - INTEGER
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The number of MPTCP-level retransmission intervals with no traffic and
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pending outstanding data on a given subflow required to declare it stale.
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The packet scheduler ignores stale subflows.
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A low stale_loss_cnt value allows for fast active-backup switch-over,
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an high value maximize links utilization on edge scenarios e.g. lossy
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link with high BER or peer pausing the data processing.
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This is a per-namespace sysctl.
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Default: 4
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syn_retrans_before_tcp_fallback - INTEGER
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The number of SYN + MP_CAPABLE retransmissions before falling back to
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TCP, i.e. dropping the MPTCP options. In other words, if all the packets
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are dropped on the way, there will be:
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* The initial SYN with MPTCP support
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* This number of SYN retransmitted with MPTCP support
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* The next SYN retransmissions will be without MPTCP support
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0 means the first retransmission will be done without MPTCP options.
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>= 128 means that all SYN retransmissions will keep the MPTCP options. A
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lower number might increase false-positive MPTCP blackholes detections.
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This is a per-namespace sysctl.
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Default: 2
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