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[82.132.219.237]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aa20e045270sm561214266b.146.2024.11.18.09.44.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Nov 2024 09:44:13 -0800 (PST) Message-ID: <4f5ef808-aef0-40dd-b3c8-c34977de58d2@gmail.com> Date: Mon, 18 Nov 2024 17:45:02 +0000 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 06/11] io_uring: introduce attributes for read/write and PI support To: Christoph Hellwig Cc: Anuj Gupta , axboe@kernel.dk, kbusch@kernel.org, martin.petersen@oracle.com, anuj1072538@gmail.com, brauner@kernel.org, jack@suse.cz, viro@zeniv.linux.org.uk, io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, gost.dev@samsung.com, linux-scsi@vger.kernel.org, vishak.g@samsung.com, linux-fsdevel@vger.kernel.org, Kanchan Joshi References: <20241114104517.51726-1-anuj20.g@samsung.com> <20241114104517.51726-7-anuj20.g@samsung.com> <20241118125029.GB27505@lst.de> <2a98aa33-121b-46ed-b4ae-e4049179819a@gmail.com> <20241118170329.GA14956@lst.de> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20241118170329.GA14956@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/18/24 17:03, Christoph Hellwig wrote: > On Mon, Nov 18, 2024 at 04:59:22PM +0000, Pavel Begunkov wrote: >>> >>> Can we please stop overdesigning the f**k out of this? Really, >> >> Please stop it, it doesn't add weight to your argument. The design >> requirement has never changed, at least not during this patchset >> iterations. > > That's what you think because you are overdesigning the hell out of > it. And at least for me that rings every single alarm bell about > horrible interface design. Well, and that's what you think, terribly incorrectly as far as I can say. >>> either we're fine using the space in the extended SQE, or >>> we're fine using a separate opcode, or if we really have to just >>> make it uring_cmd. But stop making thing being extensible for >>> the sake of being extensible. >> >> It's asked to be extendible because there is a good chance it'll need to >> be extended, and no, I'm not suggesting anyone to implement the entire >> thing, only PI bits is fine. > > Extensibility as in having reserved fields that can be checked for > is one thing. "Extensibility" by adding indirections over indirections I don't know where you found indirections over indirections. > without a concrete use case is another thing. And we're deep into the > latter phase now. > >> And no, it doesn't have to be "this or that" while there are other >> options suggested for consideration. And the problem with the SQE128 >> option is not even about SQE128 but how it's placed inside, i.e. >> at a fixed spot. >> >> Do we have technical arguments against the direction in the last >> suggestion? > > Yes. It adds completely pointless indirections and variable offsets. One indirection, and there are no variable offsets while PI remains the only user around. > How do you expect people to actually use that sanely without > introducing bugs left right and center? I've just given you an example how the user space can look like, I have absolutely no idea what you're talking about. > I really don't get why you want to make an I/O fast path as complicated > as possible. Exactly, _fast path_. PI-only handling is very simple, I don't buy that "complicated". If we'd need to add more without an API expecting that, that'll mean a yet another forest of never ending checks in the fast path effecting all users. -- Pavel Begunkov