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([2a0d:3344:2712:7e10:4d59:d956:544f:d65c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47114428dbfsm14301785e9.5.2025.10.16.02.17.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Oct 2025 02:17:09 -0700 (PDT) Message-ID: <98342f21-08c8-46de-9309-d58dfc44d0a0@redhat.com> Date: Thu, 16 Oct 2025 11:17:06 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 net-next 02/13] gro: flushing when CWR is set negatively affects AccECN To: chia-yu.chang@nokia-bell-labs.com, edumazet@google.com, linux-doc@vger.kernel.org, corbet@lwn.net, horms@kernel.org, dsahern@kernel.org, kuniyu@amazon.com, bpf@vger.kernel.org, netdev@vger.kernel.org, dave.taht@gmail.com, jhs@mojatatu.com, kuba@kernel.org, stephen@networkplumber.org, xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net, andrew+netdev@lunn.ch, donald.hunter@gmail.com, ast@fiberby.net, liuhangbin@gmail.com, shuah@kernel.org, linux-kselftest@vger.kernel.org, ij@kernel.org, ncardwell@google.com, koen.de_schepper@nokia-bell-labs.com, g.white@cablelabs.com, ingemar.s.johansson@ericsson.com, mirja.kuehlewind@ericsson.com, cheshire@apple.com, rs.ietf@gmx.at, Jason_Livingood@comcast.com, vidhi_goel@apple.com References: <20251013170331.63539-1-chia-yu.chang@nokia-bell-labs.com> <20251013170331.63539-3-chia-yu.chang@nokia-bell-labs.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20251013170331.63539-3-chia-yu.chang@nokia-bell-labs.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 10/13/25 7:03 PM, chia-yu.chang@nokia-bell-labs.com wrote: > From: Ilpo Järvinen > > As AccECN may keep CWR bit asserted due to different > interpretation of the bit, flushing with GRO because of > CWR may effectively disable GRO until AccECN counter > field changes such that CWR-bit becomes 0. > > There is no harm done from not immediately forwarding the > CWR'ed segment with RFC3168 ECN. I guess this change could introduce additional latency for RFC3168 notification, which sounds not good. On the flip side adding too much AccECN logic to GRO (i.e. to allow aggregation only for AccECN enabled flows) looks overkill. @Eric: WDYT? Thanks, Paolo