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[133.18.180.162]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b3b5ba8426sm7208003c88.23.2026.11.10.08.49.18 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 10 Nov 2026 08:49:22 -0800 (PST) Content-Type: text/plain; charset=us-ascii X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3901.100.1.1.12\)) Subject: Re: [PATCH net-next v3 3/4] selftests/net: packetdrill: add TCP black hole detection test From: Esko Mobius In-Reply-To: Date: Wed, 11 Nov 2026 00:49:06 +0800 Cc: davem@davemloft.net, edumazet@kernel.org, pabeni@redhat.com, shuah@kernel.org, kuniyu@google.com, horms@kernel.org, kuba@kernel.org, netdev@vger.kernel.org, panweiping3@gmail.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <18B3E417-AC3D-4A70-88BD-4ADA9003ACAF@gmail.com> References: <20261110-mtu-probing-series-v3-0-dedfab25d641@gmail.com> <20261110-mtu-probing-series-v3-3-dedfab25d641@gmail.com> To: Neal Cardwell X-Mailer: Apple Mail (2.3901.100.1.1.12) > 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=3D1` Thanks, Neal. That makes sense. I renamed this case and added a test that only sets tcp_mtu_probing=3D1 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=