20April2023 [FreeBSD WIKI]

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====== Attendees ======
  * glebius@
  * rscheff@
  * rrs@
  * tuexen@
  * cc@

====== 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: [[https://reviews.freebsd.org/D38436|D38436]].
  * ''%%netstat%%'' does not support reading connection information from a core file anymore. tuexen@ will document that in the man-page. This has been committed as [[https://reviews.freebsd.org/D39610|D39610]]. A corresponding cleanup for the source code is under review: [[https://reviews.freebsd.org/D39688|D39688]].
  * 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. Setting the ''%%sysctl%%'' variable ''%%kern.timecounter.alloweddeviation%%'' to zero allows the timers to run of very precisely, which is useful when running ''%%packetdrill%%''. However, it affects the overall system performance.
  * 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 [[https://reviews.freebsd.org/D37437|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.
  * [[https://reviews.freebsd.org/D28822|D28822]] improves PRR. rrs@ and tuexen@ will review.
  * [[https://reviews.freebsd.org/D39299|D39299]] improves compliance to [[https://www.rfc-editor.org/rfc/rfc6675|RFC 6675]] with regard to the ''%%isLost%%'' variable. rrs@ and cc@ will review it.
  * 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. tuexen@ will commit a fix by direct commits in the stable/13 branch and will add a note to the ''%%trpt%%'' man-page that ''%%trpt%%'' is deprecated and will be removed in %%FreeBSD%% 14. The change is under review: [[https://reviews.freebsd.org/D39436|D39436]].
  * tuexen@ will try to improve the error handling in PRU functions to allow the reporting of more error cases and put it up for review. glebius@ will review it and make sure it works with the recent changes in the inp/tcb area. A patch is under review: [[https://reviews.freebsd.org/D39591|D39591]]. glebius@ suggests to move the constants from ''%%in_ktrace.h%%'' to a separate file. He will provide a patch and tuexen@ will review it and update D39591.
  * Make ''%%sysctl%%''-variable ''%%net.inet.tcp.functions_default%%'' per vnet or fib? tuexen@ will implement the vnet support after rrs@ gets updates for stack swiching in. This was committed as [[https://reviews.freebsd.org/D39516|D39516]]. If possible, it will be MFCed to stable/13.
  * cc@ is planing to improve siftr.
  * glebius@ is separating the tcpcbs and the inps. markj@ will then improve the handling of vnets.

====== Ongoing Longer Term Projects ======
  * rscheff@ is improving %%AccECN%% code: [[https://reviews.freebsd.org/D36303|D36303]]. rrs@ will review it and implement it for the rack stack.
  * [[https://reviews.freebsd.org/D23230|D23230]] is implementing ECN++. rrs@ will review it.
  * 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.

====== Next Meeting ======
04 May 2023 @ 1500 UTC