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([2620:10d:c090:400::5:f31c]) by smtp.gmail.com with ESMTPSA id f6sm2941403pgd.61.2021.04.15.06.59.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Apr 2021 06:59:53 -0700 (PDT) Subject: Re: [RFC] io_uring: submit even with overflow backlog To: Pavel Begunkov , io-uring@vger.kernel.org References: <0933f5027f3b7b7eea8a7ece353db9c516816b1b.1618489868.git.asml.silence@gmail.com> From: Jens Axboe Message-ID: Date: Thu, 15 Apr 2021 07:59:52 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <0933f5027f3b7b7eea8a7ece353db9c516816b1b.1618489868.git.asml.silence@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 4/15/21 6:40 AM, Pavel Begunkov wrote: > Not submitting when have requests in overflow backlog looks artificial, > and limits users for no clear purpose, especially since requests with > resources are now not locked into it but it consists for a small memory > area. Remove the restriction. > > Signed-off-by: Pavel Begunkov > --- > > Mainly for discussion. It breaks several tests, and so in theory > userspace, but can't think this restriction not being just a > nuisance to the userspace. IMHO much more convenient to allow it, > userspace can take care of it itself if needed, but for those > who don't care and use rings in parallel (e.g. different threads > for submission and completion), it will be hell of a synchronisation. I think we can kill it, with the main change enabling that being the cgroup memory accounting. This was kind of a safe guard to avoid having silly cases just go way overboard, but I do agree that this is really up to the application to manage. And it may have an easier time doing so without -EBUSY on overflow being set on submit. -- Jens Axboe