FreeBSD source tree https://cgit-dev.freebsd.org/src/atom?h=releng%2F12.4 2020-09-10T12:54:46Z 2020-09-10T12:54:46Z Michael Tuexen tuexen@FreeBSD.org 2020-09-10T12:54:46Z urn:sha1:20319ec0c70b42591aa0e07609267a1ecec44efc Improve the TCP blackhole detection. The principle is to reduce the MSS in two steps and try each candidate two times. However, if two candidates are the same (which is the case in TCP/IPv6), this candidate was tested four times. This patch ensures that each candidate actually reduced the MSS and is only tested 2 times. This reduces the time window of missclassifying a temporary outage as an MTU issue. 2020-09-10T12:52:50Z Michael Tuexen tuexen@FreeBSD.org 2020-09-10T12:52:50Z urn:sha1:899710f27b1c3523f5aaf74acd27df6ea44a3899 Allow the TCP backhole detection to be disabled at all, enabled only for IPv4, enabled only for IPv6, and enabled for IPv4 and IPv6. The current blackhole detection might classify a temporary outage as an MTU issue and reduces permanently the MSS. Since the consequences of such a reduction due to a misclassification are much more drastically for IPv4 than for IPv6, allow the administrator to enable it for IPv6 only. Manually resolve conflict for BBR, which does not exist in stable/12 2020-01-28T18:08:53Z Bjoern A. Zeeb bz@FreeBSD.org 2020-01-28T18:08:53Z urn:sha1:da858db310c4414a423f8e813ac82f781cb928c8 vnet: virtualise more network stack sysctls. Virtualise tcp_always_keepalive, TCP and UDP log_in_vain. All three are set in the netoptions startup script, which we would love to run for VNETs as well. While virtualising the log_in_vain sysctls seems pointles at first for as long as the kernel message buffer is not virtualised, it at least allows an administrator to debug the base system or an individual jail if needed without turning the logging on for all jails running on a system. Run netoptions startup script in vnet jails. People use rc.conf inside vnet jails to configure networking setups. Presumably because some sysctl were not virtualised up until r356527 the script was not run for vnet jails leaving the rc.conf options without effect for non-obvious reasons. Run the netoptions startup script also for VNET jails now to make the rc.conf options work. PR: 243193 2019-05-04T11:24:19Z Michael Tuexen tuexen@FreeBSD.org 2019-05-04T11:24:19Z urn:sha1:cb72829c75d3a3e5b23d839b0b6db66fee4c38e4 Add sysctl variable net.inet.tcp.rexmit_initial for setting RTO.Initial used by TCP. Reviewed by: rrs@, 0mp@ Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D19355 2019-05-04T10:36:16Z Michael Tuexen tuexen@FreeBSD.org 2019-05-04T10:36:16Z urn:sha1:9635d5746bbd44c7b80e25d7351f4a5f2fedc68d Use exponential backoff for retransmitting SYN segments as specified in the TCP RFCs. Reviewed by: rrs@, Richard Scheffenegger Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D18974 2018-07-04T02:47:16Z Matt Macy mmacy@FreeBSD.org 2018-07-04T02:47:16Z urn:sha1:6573d7580b851d794b6c3cbd5ee3d7bf0b4c0ccb - Add tracker argument to preemptible epochs - Inline epoch read path in kernel and tied modules - Change in_epoch to take an epoch as argument - Simplify tfb_tcp_do_segment to not take a ti_locked argument, there's no longer any benefit to dropping the pcbinfo lock and trying to do so just adds an error prone branchfest to these functions - Remove cases of same function recursion on the epoch as recursing is no longer free. - Remove the the TAILQ_ENTRY and epoch_section from struct thread as the tracker field is now stack or heap allocated as appropriate. Tested by: pho and Limelight Networks Reviewed by: kbowling at llnw dot com Sponsored by: Limelight Networks Differential Revision: https://reviews.freebsd.org/D16066 2018-06-07T18:18:13Z Randall Stewart rrs@FreeBSD.org 2018-06-07T18:18:13Z urn:sha1:89e560f441bb214495715039288c99442b3b5aea Rack includes the following features: - A different SACK processing scheme (the old sack structures are not used). - RACK (Recent acknowledgment) where counting dup-acks is no longer done instead time is used to knwo when to retransmit. (see the I-D) - TLP (Tail Loss Probe) where we will probe for tail-losses to attempt to try not to take a retransmit time-out. (see the I-D) - Burst mitigation using TCPHTPS - PRR (partial rate reduction) see the RFC. Once built into your kernel, you can select this stack by either socket option with the name of the stack is "rack" or by setting the global sysctl so the default is rack. Note that any connection that does not support SACK will be kicked back to the "default" base FreeBSD stack (currently known as "default"). To build this into your kernel you will need to enable in your kernel: makeoptions WITH_EXTRA_TCP_STACKS=1 options TCPHPTS Sponsored by: Netflix Inc. Differential Revision: https://reviews.freebsd.org/D15525 2018-05-08T02:22:34Z Matt Macy mmacy@FreeBSD.org 2018-05-08T02:22:34Z urn:sha1:10d20c84ed8ac35523a3a20d72a91fb505df2192 TCP's smoothed RTT (SRTT) can be much larger than an actual observed RTT. This can be either because of hz restricting the calculable RTT to 10ms in VMs or 1ms using the default 1000hz or simply because SRTT recently incorporated a larger value. If an ACK arrives before the calculated badrxtwin (now + SRTT): tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); We'll erroneously reset snd_una to snd_max. If multiple segments were dropped and this happens repeatedly the transmit rate will be limited to 1MSS per RTO until we've retransmitted all drops. Reported by: rstone Reviewed by: hiren, transport Approved by: sbruno MFC after: 1 month Differential Revision: https://reviews.freebsd.org/D8556 2018-05-02T20:04:31Z Michael Tuexen tuexen@FreeBSD.org 2018-05-02T20:04:31Z urn:sha1:4c6a10903fcbe29ab6472d365177ad43e9688c77 is also done in tcp_drop(). No functional change. Sponsored by: Netflix, Inc. 2018-03-22T09:40:08Z Jonathan T. Looney jtl@FreeBSD.org 2018-03-22T09:40:08Z urn:sha1:2529f56ed32d808dc3911c369c731f1b21664de6 summits at BSDCan and BSDCam in 2017. The TCP Blackbox Recorder allows you to capture events on a TCP connection in a ring buffer. It stores metadata with the event. It optionally stores the TCP header associated with an event (if the event is associated with a packet) and also optionally stores information on the sockets. It supports setting a log ID on a TCP connection and using this to correlate multiple connections that share a common log ID. You can log connections in different modes. If you are doing a coordinated test with a particular connection, you may tell the system to put it in mode 4 (continuous dump). Or, if you just want to monitor for errors, you can put it in mode 1 (ring buffer) and dump all the ring buffers associated with the connection ID when we receive an error signal for that connection ID. You can set a default mode that will be applied to a particular ratio of incoming connections. You can also manually set a mode using a socket option. This commit includes only basic probes. rrs@ has added quite an abundance of probes in his TCP development work. He plans to commit those soon. There are user-space programs which we plan to commit as ports. These read the data from the log device and output pcapng files, and then let you analyze the data (and metadata) in the pcapng files. Reviewed by: gnn (previous version) Obtained from: Netflix, Inc. Relnotes: yes Differential Revision: https://reviews.freebsd.org/D11085