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Mon, 16 Mar 2026 04:09:35 -0700 (PDT) X-Received: by 2002:a05:600c:a4a:b0:47f:f952:d207 with SMTP id 5b1f17b1804b1-485566facc8mr211848875e9.19.1773659374904; Mon, 16 Mar 2026 04:09:34 -0700 (PDT) Received: from [192.168.88.32] ([216.128.11.95]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48541aa73dasm1212991845e9.2.2026.03.16.04.09.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Mar 2026 04:09:34 -0700 (PDT) Message-ID: Date: Mon, 16 Mar 2026 12:09:32 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v2 00/14] tcp: preserve receive-window accounting across ratio drift To: atwellwea@gmail.com, netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, edumazet@google.com, ncardwell@google.com Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mptcp@lists.linux.dev, dsahern@kernel.org, horms@kernel.org, kuniyu@google.com, andrew+netdev@lunn.ch, willemdebruijn.kernel@gmail.com, jasowang@redhat.com, skhan@linuxfoundation.org, corbet@lwn.net, matttbe@kernel.org, martineau@kernel.org, geliang@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, 0x7f454c46@gmail.com References: <20260314201348.1786972-1-atwellwea@gmail.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20260314201348.1786972-1-atwellwea@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/14/26 9:13 PM, atwellwea@gmail.com wrote: > From: Wesley Atwell > > This series keeps sender-visible TCP receive-window accounting tied to the > scaling basis that was in force when the window was advertised, even if > later receive-side truesize inflation lowers scaling_ratio or the live > receive window retracts below the largest right edge already exposed to the > sender. > > After the receive-window retraction changes, the receive path needs to keep > track of two related pieces of sender-visible state: > > 1. the live advertised receive window > 2. the maximum advertised right edge and the basis it was exposed with > > This repost snapshots both, uses them to repair receive-buffer backing when > ratio drift would otherwise strand sender-visible space, extends > TCP_REPAIR_WINDOW so repair/restore can round-trip the new state, and adds > truesize-drift coverage through TUN packetdrill tests and netdevsim-based > selftests. The series is IMHO significantly not trivial. Can the end-user meet the relevant condition in practice? How? What is the net benefit in practice? Is that observable under usual conditions or require exceptional circumstances? I think we need a strong motivation to merge this kind of changes. /P