Re: [PATCH net-next v3 3/4] selftests/net: packetdrill: add TCP black hole detection test

[Esko Mobius]

> So I'd suggest renaming this case to be something like
> tcp_mtu_probing_blackhole_no_tlp_retries1_is_1.pkt.
>
> Then I'd suggest creating a test like this, but with only the following setting:
>
> `./defaults.sh
> sysctl -q net.ipv4.tcp_mtu_probing=1`

Thanks, Neal. That makes sense.

I renamed this case and added a test that only sets tcp_mtu_probing=1
on top of defaults.sh. With the default settings, the TLP and the first
three RTO retransmissions keep the full size. The fourth RTO falls back
to tcp_base_mss, about 4.8 seconds after the original transmission.

The new test passes in all three IP modes on x86_64 KVM. v4 has both
tests.

Thanks,
Yongjian