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[24.6.151.244]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-227811b2aefsm21875045ad.109.2025.03.21.13.30.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Mar 2025 13:30:46 -0700 (PDT) Date: Fri, 21 Mar 2025 13:30:43 -0700 From: Joe Damato To: 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 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-arch@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 09:36:34AM -0700, Joe Damato wrote: > 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. I think what added to my confusion here was this bit, Jens: > > As far as the bit about plumbing only the splice bits, sorry if I'm > > being dense here, do you mean plumbing the error queue through to > > splice only and dropping sendfile2? > > > > That is an option. Then the apps currently using sendfile could use > > splice instead and get completion notifications on the error queue. > > That would probably work and be less work than rewriting to use > > iouring, but probably a bit more work than using a new syscall. > > Yep I thought I was explicitly asking if adding SPLICE_F_ZC and plumbing through the error queue notifications was OK and your response here ("Yep") suggested to me that it would be a suitable path to consider. I take it from your other responses, though, that I was mistaken.