transportprotocols:09february2023

Attendees

  • glebius@
  • olivier@
  • rrs@
  • rscheff@
  • thj@
  • tuexen@
  • Cheng C

Ongoing Short Term Projects

  • It was discussed whether the TCP_LOG socket option should be inherited from the listener. jtl@ said that this should be the case, but interaction with the sysctl-variable net.inet.tcp.bb.log_auto_ratio should be taken into account. The patch is under review: D38436.
  • netstat does not support reading connection information from a core file anymore. tuexen@ will document that in the man-page.
  • glebius@ asks whether it makes sense to improve the TCP timer precision. tuexen@ states that this is very useful for testing purposes. glebius@ will provide a patch to tuexen@ for testing and tuexen@ will provide feedback, if such a patch us useful for FreeBSD in general. This applies to the default stack only, not the the RACK or BBR stack, which uses HPTS for timers.
  • At least for testing purposes (packetdrill) it would be good to have LRO support for tun interfaces. tuexen@ suggested to generalize LRO to not depend on an Ethernet header being present. gallatin@ prefers to not make the LRO code more complex, since it most likely will impact the performance. tjh@ has D37437 under review, which allows the tun interface to add an Ethernet header. tuexen@ will test this to see if it can also be used to enable LRO for the tun interface. This seems netmap specific. tuexen@ will consider to use tap interfaces in packetdrill.
  • D28822 improves PRR. rscheff@ will do some testing, rrs@ and tuexen@ will review.
  • While working on allowing BBLog being used as a replacement of trpt, tuexen@ figured out that trpt is broken in several ways in stable/13. After a short discussion is was decided that it is better to document this brokenness than to fix it by direct commits in the stable/13 branch. tuexen@ will add a note to the trpt man-page.

Ongoing Longer Term Projects

  • rscheff@ is improving AccECN code: D36303.
  • D23230 is implementing ECN++.
  • tuexen@ wants to write a tool which dumps the BBLog information of a TCP endpoint from a life system or a core. Using kvm_read() has drawbacks as glebius@ pointed out, using a python kgdb script may be an alternative. An alternative is to write a python kgdb script which pumps data into tcplog_dumper. This would allow to minimize code duplication. @glebius will try to work on this soon.
  • glebius@ and markj@ are improving the inp code and as part of this work will make the transport protocols inp code agnostic.
  • thj@ describes a problem related to SYN-ACK retransmissions occurring in a setup using jails and epairs. There seem to be a 1 second pause.

Next Meeting

23 February 2023 @ 1500 UTC

  • transportprotocols/09february2023.txt
  • Last modified: 2023/02/21 17:52
  • by MichaelTuexen