linux/Documentation/networking/mptcp-sysctl.rst
Paolo Abeni d866ae9aaa mptcp: add a new sysctl for make after break timeout
The MPTCP protocol allows sockets with no alive subflows to stay
in ESTABLISHED status for and user-defined timeout, to allow for
later subflows creation.

Currently such timeout is constant - TCP_TIMEWAIT_LEN. Let the
user-space configure them via a newly added sysctl, to better cope
with busy servers and simplify (make them faster) the relevant
pktdrill tests.

Note that the new know does not apply to orphaned MPTCP socket
waiting for the data_fin handshake completion: they always wait
TCP_TIMEWAIT_LEN.

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-2-v1-1-9dc60939d371@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-10-25 12:23:33 -07:00

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ReStructuredText

.. SPDX-License-Identifier: GPL-2.0
=====================
MPTCP Sysfs variables
=====================
/proc/sys/net/mptcp/* Variables
===============================
enabled - BOOLEAN
Control whether MPTCP sockets can be created.
MPTCP sockets can be created if the value is 1. This is a
per-namespace sysctl.
Default: 1 (enabled)
add_addr_timeout - INTEGER (seconds)
Set the timeout after which an ADD_ADDR control message will be
resent to an MPTCP peer that has not acknowledged a previous
ADD_ADDR message.
The default value matches TCP_RTO_MAX. This is a per-namespace
sysctl.
Default: 120
close_timeout - INTEGER (seconds)
Set the make-after-break timeout: in absence of any close or
shutdown syscall, MPTCP sockets will maintain the status
unchanged for such time, after the last subflow removal, before
moving to TCP_CLOSE.
The default value matches TCP_TIMEWAIT_LEN. This is a per-namespace
sysctl.
Default: 60
checksum_enabled - BOOLEAN
Control whether DSS checksum can be enabled.
DSS checksum can be enabled if the value is nonzero. This is a
per-namespace sysctl.
Default: 0
allow_join_initial_addr_port - BOOLEAN
Allow peers to send join requests to the IP address and port number used
by the initial subflow if the value is 1. This controls a flag that is
sent to the peer at connection time, and whether such join requests are
accepted or denied.
Joins to addresses advertised with ADD_ADDR are not affected by this
value.
This is a per-namespace sysctl.
Default: 1
pm_type - INTEGER
Set the default path manager type to use for each new MPTCP
socket. In-kernel path management will control subflow
connections and address advertisements according to
per-namespace values configured over the MPTCP netlink
API. Userspace path management puts per-MPTCP-connection subflow
connection decisions and address advertisements under control of
a privileged userspace program, at the cost of more netlink
traffic to propagate all of the related events and commands.
This is a per-namespace sysctl.
* 0 - In-kernel path manager
* 1 - Userspace path manager
Default: 0
stale_loss_cnt - INTEGER
The number of MPTCP-level retransmission intervals with no traffic and
pending outstanding data on a given subflow required to declare it stale.
The packet scheduler ignores stale subflows.
A low stale_loss_cnt value allows for fast active-backup switch-over,
an high value maximize links utilization on edge scenarios e.g. lossy
link with high BER or peer pausing the data processing.
This is a per-namespace sysctl.
Default: 4
scheduler - STRING
Select the scheduler of your choice.
Support for selection of different schedulers. This is a per-namespace
sysctl.
Default: "default"