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b=EYt4jGOFf5LyezMTLV9dtf2WymLahWZzOV9zIlsR/s0qVRxpHXAAirSEbS46iArUz 3jFo9xc18HpY/AIlMplWvxVe2GOAw49DmR+mT+asEMqWykbJ3kaGZxjmXlhW4c8Ors EW/vIn7AffpcwBX08cwjSweCluQTp3Sevfta9TJlQ7MM6F7ZVYwEsQy2HTUikfeGFa xQZRg7I4AP/QtUfwHSQZfCZmhKiph4Mdhz2KEt6agP6Meih8rA58vz+GsKjWNqY2AQ pEIH9ry/aBOAEjUXK0Ra/KnN1Fh7TD8mTUn2t3uUQKfwGWOkiN7vTRf9U+IHj5k+B0 fFWYzzBA9yA4Q== Date: Wed, 3 Jun 2026 11:14:52 -0700 From: Jakub Kicinski To: Pedro Falcato Cc: Andy Lutomirski , Linus Torvalds , Askar Safin , akpm@linux-foundation.org, axboe@kernel.dk, brauner@kernel.org, david@kernel.org, dhowells@redhat.com, hch@infradead.org, jack@suse.cz, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, miklos@szeredi.hu, netdev@vger.kernel.org, patches@lists.linux.dev, viro@zeniv.linux.org.uk, willy@infradead.org Subject: Re: [PATCH 0/3] vmsplice: make vmsplice a trivial wrapper for preadv2/pwritev2 Message-ID: <20260603111452.7e7bb17c@kernel.org> In-Reply-To: References: <20260602225426.122258-1-safinaskar@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 3D5A84000D X-Rspam-User: X-Stat-Signature: umuhrcwuknp11exowihtwrqionenehb3 X-Rspamd-Server: rspam08 X-HE-Tag: 1780510495-932892 X-HE-Meta: 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 z+dVKW4P 2VFQE/LvXoQx6VOjbqm6oiNyjaLINVLphQidH2Rg4LMxavo2f+8GI7XmMu8FGi/T0LZeApKEZM5Bh1mAYb7ZkRXBhvziwxTxyXyzezqyj+BMaj9FUvDCLdpECOITNn2b23ouHvxsPXVf6TzJvu0Q/BnHyUD2boPjLZpV+zv1teocy3BKjAy4bLW+IlNspOsWidYc3EmCP9C7d9GgrYk58bnnvZxb6eP29KaG7k6r4ssYkBzWeXOOCUsdEFoR3mB7GM48jEcVnjNOmQnu1LZwuvfjN8g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 3 Jun 2026 12:43:54 +0100 Pedro Falcato wrote: > > Am I understanding correctly that this will completely break zerocopy > > sendfile? sendfile is, internally, splice-to-a-secret-per-task-pipe > > and then splice to the socket. How much to people care? These days, > > a lot of high-bandwidth network senders are sending encrypted data, > > which is not zerocopy frompagecache. But there are surely some users > > You can do zerocopy from the page cache, even with TLS on top, by having > your (fancy) NIC do TLS offloading for you. See https://people.freebsd.org/~gallatin/talks/euro2019-ktls.pdf. > Linux works similarly. Slide 26 is particularly interesting. > (No KTLS I assume is using simple sendmsg()'s from user memory, SW TLS > and NIC KTLS are both sendfile(), per the slides) FTR this datapoint should come with the caveat that kTLS _offload_ does not support TLS 1.3 today. So how much that configuration is used in practice is unclear.