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[24.6.151.244]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22780f39772sm19205225ad.25.2025.03.21.09.36.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Mar 2025 09:36:38 -0700 (PDT) Date: Fri, 21 Mar 2025 09:36:34 -0700 From: Joe Damato To: Jens Axboe Cc: Christoph Hellwig , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, asml.silence@gmail.com, linux-fsdevel@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, horms@kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, kuba@kernel.org, shuah@kernel.org, sdf@fomichev.me, mingo@redhat.com, arnd@arndb.de, brauner@kernel.org, akpm@linux-foundation.org, tglx@linutronix.de, jolsa@kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC -next 00/10] Add ZC notifications to splice and sendfile Message-ID: Mail-Followup-To: Joe Damato , Jens Axboe , Christoph Hellwig , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, asml.silence@gmail.com, linux-fsdevel@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, horms@kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, kuba@kernel.org, shuah@kernel.org, sdf@fomichev.me, mingo@redhat.com, arnd@arndb.de, brauner@kernel.org, akpm@linux-foundation.org, tglx@linutronix.de, jolsa@kernel.org, linux-kselftest@vger.kernel.org References: <2d68bc91-c22c-4b48-a06d-fa9ec06dfb25@kernel.dk> <19e3056c-2f7b-4f41-9c40-98955c4a9ed3@kernel.dk> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Mar 21, 2025 at 05:14:59AM -0600, Jens Axboe wrote: > On 3/20/25 11:56 PM, Christoph Hellwig wrote: > >> I don't know the entire historical context, but I presume sendmsg > >> did that because there was no other mechanism at the time. > > > > At least aio had been around for about 15 years at the point, but > > networking folks tend to be pretty insular and reinvent things. > > Yep... > > >> It seems like Jens suggested that plumbing this through for splice > >> was a possibility, but sounds like you disagree. > > > > Yes, very strongly. > > And that is very much not what I suggested, fwiw. Your earlier message said: If the answer is "because splice", then it would seem saner to plumb up those bits only. Would be much simpler too... wherein I interpreted "plumb those bits" to mean plumbing the error queue notifications on TX completions. My sincere apologies that I misunderstood your prior message and/or misconstrued what you said -- it was not clear to me what you meant. It is clear to me now, though, that adding a flag to splice as previously proposed and extending sendfile based on the SO_ZEROCOPY sock flag being set are both unacceptable solutions. If you happen to have a suggestion of some piece of code that I should read (other than the iouring implementation) to inform how I might build an RFCv2, I would appreciate the pointer. Thanks for your time and energy, Joe