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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4601f2dcae2sm35545066f8f.6.2026.06.06.03.22.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 06 Jun 2026 03:22:53 -0700 (PDT) Date: Sat, 6 Jun 2026 11:22:52 +0100 From: David Laight To: Stefan Metzmacher Cc: Linus Torvalds , Andy Lutomirski , 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, pfalcato@suse.de, viro@zeniv.linux.org.uk, willy@infradead.org Subject: Re: [PATCH 0/3] vmsplice: make vmsplice a trivial wrapper for preadv2/pwritev2 Message-ID: <20260606112252.3c70bad6@pumpkin> In-Reply-To: <634c8ae2-3f1c-46b1-b002-1e2ac797dd80@samba.org> References: <20260602225426.122258-1-safinaskar@gmail.com> <512d948f-7883-4d8c-b2c5-a777e70ca975@samba.org> <20260605131942.4584728e@pumpkin> <634c8ae2-3f1c-46b1-b002-1e2ac797dd80@samba.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: E28594000D X-Stat-Signature: 78t6eijrqha764ys968n8938igfxrab5 X-HE-Tag: 1780741375-822160 X-HE-Meta: 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 PMoRYgZT mJj6W2uhDA8SMVFC6nAzgUypOS+bR3PDRIr1av87RJhR3ukVOWEQuNsygUTRfk1AvNvEdiCR5SJZ1Pre56EIVUr9DLskun/NsyCVhd9djN/ZKxqwlnmkh2JAISPcu3kBmU9vUxWcXrs9SS3QhScl6DyF4y0qRYoMVMw5xPguV9XVlI2Hdkg2wEeR3Nsq2OVaZG4etlUlQgvul9BndE4Ct7hTv2BH5Fg7gG2LV7NWFfIyokQPQt7cfJmnnHDZLn+JpD8bpvMooHAqQYMwKhTpiyml4yyhBD62JbnThEMDLtrYIeVpPO7R3ZtvUNXXwZoBaencIrup4utBfQuPeIH0DWCbwpgclCn9vZ22y1NUZQzbYqF8K5SMTFtNT29ymyh/tEehnjeeZwxP2AzbMKdgn0fcTPnXmOqjr4a1LmoV7a3OdpGQJj4ae3L9slDXAgXTfjNa9AHeMfnBCvlMbRQrU5+GF7hJF2Dcerg6UN4UalFmbf38= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 5 Jun 2026 17:20:34 +0200 Stefan Metzmacher wrote: > Hi David, > > >>> So sendfile() as a concept (whether you use combinations of splice() > >>> system calls or the sendfile system call itsefl) isn't necessarily > >>> only about the zero-copy, it's really also about avoiding the user > >>> space memory management. > >> > >> I don't think so. Ok, maybe for webservers just serving tiny > >> html files, that's true. But for me with Samba it's really the > >> copy_to/from_iter() that is the major factor. > > > > Is that copy also doing the ip checksum? > > Not in my tests. I guess there's offload in the network hardware > for this. There will be, it is just whether the syscall checksum is actually being suppressed. -- David > > At least at the syscall layer of sendmsg() there's no checksuming > happening. > > metze >