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tcp: make the maximum number of retransmissions tunable per VNET
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Authored by rscheff on Jun 5 2023, 5:51 PM.
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imp
melifaro

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cc
rrs
jtl
tuexen
glebius
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transport
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rG43b117f88f30: tcp: make the maximum number of retransmissions tunable per VNET
Summary

With Windows (TcpMaxDataRetransmissions) and Linux (tcp_retries2)
there is precedent that sometimes it is useful to restrict the
maximum number of retransmissions sent - as each of these will
be sent after an exponentially increasing interval.

This adds that same capability on a per-VNet basis to FreeBSD.

Diff Detail

Repository
rG FreeBSD src repository
Lint
Lint Passed
Unit
No Test Coverage
Build Status
Buildable 51929
Build 48820: arc lint + arc unit

Event Timeline

rscheff created this revision.Jun 5 2023, 5:51 PM
Herald added a reviewer: transport. · View Herald TranscriptJun 5 2023, 5:51 PM
Herald added subscribers: melifaro, imp. · View Herald Transcript
rscheff requested review of this revision.Jun 5 2023, 5:51 PM
Harbormaster completed remote builds in B51907: Diff 122856.Jun 5 2023, 5:51 PM
tuexen added inline comments.Jun 5 2023, 7:14 PM
sys/netinet/tcp_timer.c
224

Maybe something like "maximum number of consecutive timer based retransmissions"?

517

What happens if the sysctl variable is changed during the existence of a TCP connection?

rscheff updated this revision to Diff 122865.Jun 5 2023, 8:39 PM
  • deal with V_tcp_retries reduced while in a RTO sequence
Harbormaster completed remote builds in B51910: Diff 122865.Jun 5 2023, 8:39 PM
rscheff updated this revision to Diff 122866.Jun 5 2023, 8:43 PM
rscheff marked an inline comment as done.
  • better short description
Harbormaster completed remote builds in B51911: Diff 122866.Jun 5 2023, 8:43 PM
rscheff marked an inline comment as done.Jun 5 2023, 8:43 PM
cc added inline comments.Jun 5 2023, 9:24 PM
share/man/man4/tcp.4
37

Back to the future? Shall be Jun?

sys/netinet/tcp_timer.c
224

Maybe something like "maximum number of consecutive timer based retransmissions"?

+1

rscheff updated this revision to Diff 122876.Jun 6 2023, 8:20 AM
  • man date proper month
Harbormaster completed remote builds in B51919: Diff 122876.Jun 6 2023, 8:20 AM
rscheff marked 2 inline comments as done.Jun 6 2023, 8:21 AM
cc accepted this revision as: cc.Jun 6 2023, 12:24 PM
cc added inline comments.
sys/netinet/tcp_timer.c
226

Remove this extra empty line. And I am OK with the rest of the change.

rscheff updated this revision to Diff 122893.Jun 6 2023, 1:08 PM
  • fix whitespace
Harbormaster completed remote builds in B51929: Diff 122893.Jun 6 2023, 1:08 PM
tuexen accepted this revision.Jun 6 2023, 8:17 PM
This revision is now accepted and ready to land.Jun 6 2023, 8:17 PM
rscheff closed this revision.Jun 6 2023, 9:58 PM
rscheff added a commit: rG43b117f88f30: tcp: make the maximum number of retransmissions tunable per VNET.

Revision Contents
Changeset List

PathSize
share/
man/
man4/
5 lines
sys/
netinet/
2 lines
tcp_stacks/
8 lines
8 lines
30 lines
2 lines

Diff 122893

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share/man/man4/tcp.4

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sys/netinet/tcp_output.c

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sys/netinet/tcp_stacks/bbr.c

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sys/netinet/tcp_stacks/rack.c

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sys/netinet/tcp_timer.c

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sys/netinet/tcp_var.h

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