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AJvYcCWzkxfvWa+VEFH1N/kEtZdIXdrPeAQ5jlZWqRRliUEtEpM0tHsAQbY9szcyJS2NAY/hIj5tOR2bjA==@kvack.org X-Gm-Message-State: AOJu0YxDkK88MHwWelDQFSU6JFOLXHHxWoU8+E+B3Z9m5ZnBKZxz9rVM h6ViIvBUCI9H7auHImigRDBJK2Svf36hWLSc9N5FAHsWv7SUlP2GtCHOXY3YjNK2KA8OuZ9VkcK J2Vdbod18EgV3bb6ENh49aTfxKdJVqa6TwPYp6pkM X-Gm-Gg: ASbGncsLup3J3mvhG7/SHyA5Tg1Ix+02JL0rstrTvee5KFfF/YXslqRlBDWKHTAKH/m zX6O7Gv+O/QMVX+pkevutikrU7rngbZIJlA7GZ9NfPS9TKHIQw3sYrZyA6ziL755jZOGVceu3o7 OF+fDVzrp/7PNTGNE7u3BsoqbQFoXINXvGOWP+g6N64aTT X-Google-Smtp-Source: AGHT+IEZUo2qBBR9yZ8J8CWB7wPiYJhomLFn0SMyc3wIzCJ11kpp39ohznAmygfJ0IG/GUGi77IY7bYTMNdUf1wHq7Q= X-Received: by 2002:a17:902:e747:b0:216:7aaa:4c5f with SMTP id d9443c01a7336-236024df8e3mr312825ad.3.1749151840320; Thu, 05 Jun 2025 12:30:40 -0700 (PDT) MIME-Version: 1.0 References: <770012.1748618092@warthog.procyon.org.uk> <1098853.1749051265@warthog.procyon.org.uk> <1099957.1749052763@warthog.procyon.org.uk> In-Reply-To: <1099957.1749052763@warthog.procyon.org.uk> From: Mina Almasry Date: Thu, 5 Jun 2025 12:30:26 -0700 X-Gm-Features: AX0GCFtaQpHTxx8RriEcyQWAS8xO0zGQ8-djOws2dAzyDrQGK3gSIIJKsqf3Vq4 Message-ID: Subject: Re: Device mem changes vs pinning/zerocopy changes To: David Howells Cc: willy@infradead.org, hch@infradead.org, Jakub Kicinski , Eric Dumazet , netdev@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: C9C1680004 X-Stat-Signature: ip9dqusnk77uf8oeeugmt1wwqe3i41wb X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1749151841-908133 X-HE-Meta: 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 iQvGIP5W BSyLAhPzbvRCwMzDVHrP5wxT2F1d7qFMucekosZph7tIfyEl/Z0NZdCHvbwPL0koUPk8jZmC8KH55U0dfgLSegaUt4TwWs0w61xbvVYzdnfeksPHEsUospIxdyskqmmrARJl1tp1LCADfowtSZt4HuIokcfQ2Cu9zDY3v8Kz8wOLQtVbx4vq+xZI1ob2+g9HPLe6v6nY2z0ZA1VaNT3wCkPFYsw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jun 4, 2025 at 8:59=E2=80=AFAM David Howells = wrote: > > (Apologies, I accidentally sent the incomplete email) > > > I think you need to modify the existing sk_buff. I think adding > > a new struct and migrating the entire net stack to use that is a bit > > too ambitious. But up to you. Just my 2 cents here. > > It may come down to that, and if it does, we'll need to handle frags > differently. Basically, for zerocopy, the following will all apply or co= me to > apply sometime in the future: > > (1) We're going to be getting arrays of {physaddr,len} from the higher > layers. I think Christoph's idea is that this makes DMA mapping eas= ier. > We will need to retain this. > I would punt this to a follow up project. Currently the net stack uses pages extensively; replacing them with scatterlist-like {physaddr, len} sounds like a huge undertaking. Especially with the conversion to netmem_desc happening in parallel with Byungchul's series. Just my 2 cents. --=20 Thanks, Mina