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Mon, 09 Jun 2025 10:47:35 -0700 (PDT) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: In-Reply-To: From: Neal Cardwell Date: Mon, 9 Jun 2025 13:47:18 -0400 X-Gm-Features: AX0GCFuGJcKJ-J9f2xRRct5K93_iCG5bcN1NRi-VaRiq6LhKOmm5riw3G799aoc Message-ID: Subject: Re: Re: [EXT] Re: tcp: socket stuck with zero receive window after SACK To: Simon Campion Cc: netdev@vger.kernel.org, Eric Dumazet , Yuchung Cheng , Kevin Yang , Jon Maloy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Jun 3, 2025 at 3:27=E2=80=AFAM Simon Campion wrote: > > > I agree it will take a while to gather more confidence that the issue > > is gone for your workload with net.ipv4.tcp_shrink_window=3D0. > > To confirm, it's been over a week since we set > net.ipv4.tcp_shrink_window=3D0, and so far we haven't seen an issue with > TCP connections being stuck with a zero window and an empty recv-q. > So, it looks like the problem is either entirely gone or occurs much > less frequently with net.ipv4.tcp_shrink_window=3D0. > > We also attempted to reproduce the issue with a program that sends > data over a TCP connection but leaves out the first N bytes. > Unfortunately, we haven't been able to reproduce the issue so far, > even with net.ipv4.tcp_shrink_window=3D1 and with a system under memory > pressure. Thanks for the detailed update! Those are very useful data points. best regards, neal