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[204.195.96.226]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-71ec13336f1sm6761899b3a.81.2024.10.23.14.09.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Oct 2024 14:09:48 -0700 (PDT) Date: Wed, 23 Oct 2024 14:09:46 -0700 From: Stephen Hemminger To: Ilpo =?UTF-8?B?SsOkcnZpbmVu?= Cc: chia-yu.chang@nokia-bell-labs.com, netdev@vger.kernel.org, dsahern@gmail.com, davem@davemloft.net, jhs@mojatatu.com, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, dsahern@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, Olga Albisser , Oliver Tilmans , Bob Briscoe , Henrik Steen Subject: Re: [PATCH v2 iproute2-next 1/1] tc: add dualpi2 scheduler module Message-ID: <20241023140946.2f6f66ce@hermes.local> In-Reply-To: <76bef0ad-2d27-aa2b-fe5e-02ab5c752793@kernel.org> References: <20241023110434.65194-1-chia-yu.chang@nokia-bell-labs.com> <20241023110434.65194-2-chia-yu.chang@nokia-bell-labs.com> <20241023085217.5ae0ea40@hermes.local> <76bef0ad-2d27-aa2b-fe5e-02ab5c752793@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Wed, 23 Oct 2024 22:47:00 +0300 (EEST) Ilpo J=C3=A4rvinen wrote: > On Wed, 23 Oct 2024, Stephen Hemminger wrote: >=20 > > On Wed, 23 Oct 2024 13:04:34 +0200 > > chia-yu.chang@nokia-bell-labs.com wrote: > > =20 > > > + * DualPI Improved with a Square (dualpi2): > > > + * - Supports congestion controls that comply with the Prague requir= ements > > > + * in RFC9331 (e.g. TCP-Prague) > > > + * - Supports coupled dual-queue with PI2 as defined in RFC9332 > > > + * - =20 > >=20 > > It is awkward that dualPI is referencing a variant of TCP congestion > > control that is not supported by Linux. Why has Nokia not upstreamed > > TCP Prague? > > > > I would say if dualpi2 only makes sense with TCP Prague then the conges= tion > > control must be upstreamed first? =20 >=20 > Hi Stephen, >=20 > In any order, there'll be similar chicken and egg problems from the=20 > perspective of the first comer. >=20 > The intention is to upstream Dual PI2, TCP support for AccECN (+ the L4S= =20 > identifier support), and TCP Prague. The patches are only sent in smaller= =20 > subsets to not overwhelm netdev and all of them are available here right= =20 > from the start: >=20 > https://github.com/L4STeam/linux-net-next/commits/upstream_l4steam/ >=20 > ...As you can see, TCP Prague is among them. >=20 > While any of those 3 main components can be used without the others due t= o=20 > how the L4S framework is architected, the practical benefits are largely= =20 > realized when all the components are there (and enabled which is another= =20 > big step upstreaming alone won't address anyway). So in that sense, it=20 > doesn't matter much which of them comes first and which last, but it=20 > explains why they tend to crossreference the others [*]. >=20 > Implementation wise, L4S identifier support bits are required by the TCP= =20 > Prague patch so TCP support for AccECN/L4S has to be upstreamed before TC= P=20 > Prague. Dual PI2 does not have similar implementation dependencies to the= =20 > other main components (AFAIK) but if you insist on including it last, I=20 > don't see big problem with that. >=20 >=20 > [*] There's leeway within L4S framework so that Dual PI2 or TCP Prague=20 > could be replaced by something else that just meets the requirements. >=20 Understood, just want to make sure that we don't end up with some component accepted and another necessary and related piece gets rejected by kernel co= mmunity.