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([2a01:4b00:bd21:4f00:7cc6:d3ca:494:116c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-434af6b2a61sm55266f8f.20.2026.01.14.08.04.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Jan 2026 08:04:59 -0800 (PST) Message-ID: Date: Wed, 14 Jan 2026 16:04:56 +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 liburing 1/1] man: add io_uring_register_region.3 From: Pavel Begunkov To: Jens Axboe , Gabriel Krisman Bertazi Cc: io-uring@vger.kernel.org References: <6ba5f1669bfe047ed790ee47c37ca63fd65b05de.1768334542.git.asml.silence@gmail.com> <87ldi12o91.fsf@mailhost.krisman.be> <9f032fbc-f461-4243-9561-2ce7407041f1@gmail.com> <5f026b78-870f-4cfd-b78b-a805ca48264b@gmail.com> Content-Language: en-US In-Reply-To: <5f026b78-870f-4cfd-b78b-a805ca48264b@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/14/26 14:54, Pavel Begunkov wrote: > On 1/14/26 14:42, Pavel Begunkov wrote: >> On 1/13/26 22:37, Jens Axboe wrote: >>> On 1/13/26 2:31 PM, Gabriel Krisman Bertazi wrote: >>>> Pavel Begunkov writes: >>>> >>>>> Describe the region API. As it was created for a bunch of ideas in mind, >>>>> it doesn't go into details about wait argument passing, which I assume >>>>> will be a separate page the region description can refer to. >>>>> >>>> >>>> Hey, Pavel. >>> >>> I did a bunch of spelling and phrasing fixups when applying, can you >>> take a look at the repo and send a patch for the others? Thanks! >> >> "Upon successful completion, the memory region may then be used, for >> example, to pass waiting parameters to the io_uring_enter(2) system >> call in a more efficient manner as it avoids copying wait related data >> for each wait event." >> >> Doesn't matter much, but this change is somewhat misleading. Both copy >> args same number of times (i.e. unsafe_get_user() instead of >> copy_from_user()), which is why I was a bit vague with that >> "in an efficient manner". > > Hmm, actually the normal / non-registered way does make an extra > copy, even though it doesn't have to. And the compiler is smart enough to optimise it out since it's all on stack. -- Pavel Begunkov