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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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Details

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
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Lint Passed
Unit
No Test Coverage
Build Status
Buildable 51929
Build 48820: arc lint + arc unit

Event Timeline

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?

  • deal with V_tcp_retries reduced while in a RTO sequence
rscheff marked an inline comment as done.
  • better short description
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

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.

This revision is now accepted and ready to land.Jun 6 2023, 8:17 PM