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AJvYcCUr+8tUmwXmem/zJlnO1Sw6JphOGcOjgbM/Va24eF2wVXuGrmTrBQD0LMyvgJvdGV2NFmiKoFvvtx88H5qJzaF66tW+nsfixkpD/VSb X-Gm-Message-State: AOJu0YxMPe7KLsB1tUi4+yFazowzyKEZLYjvp90gn1Cn0e75/25RmDv2 vvp1dPN+FXlll8TUzzWMeOx4f/PHlXAyu0m45VVDszTUMOgUQzjikEAjHo6eZVg= X-Google-Smtp-Source: AGHT+IElFKMAHk+SOA6w9kBY0nmgmx2P2dLSXK7tM7Mw9hlbm3C7RcjZHbgY1CFKwd2m+Z5N0UwVTA== X-Received: by 2002:a05:6808:21a9:b0:3c3:be3e:aaa6 with SMTP id be41-20020a05680821a900b003c3be3eaaa6mr11077672oib.0.1711424367798; Mon, 25 Mar 2024 20:39:27 -0700 (PDT) Received: from [192.168.201.244] ([50.234.116.5]) by smtp.gmail.com with ESMTPSA id ka5-20020a056a00938500b006eab499fb50sm1053889pfb.128.2024.03.25.20.39.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Mar 2024 20:39:27 -0700 (PDT) Message-ID: Date: Mon, 25 Mar 2024 21:39:25 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: io_uring: releasing CPU resources when polling Content-Language: en-US To: Xue Cc: asml.silence@gmail.com, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, peiwei.li@samsung.com, joshi.k@samsung.com, kundan.kumar@samsung.com, anuj20.g@samsung.com, wenwen.chen@samsung.com, ruyi.zhang@samsung.com, xiaobing.li@samsung.com, cliang01.li@samsung.com References: <20240318090017.3959252-1-xue01.he@samsung.com> <20240326032331.1003213-1-xue01.he@samsung.com> From: Jens Axboe In-Reply-To: <20240326032331.1003213-1-xue01.he@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/25/24 9:23 PM, Xue wrote: > Hi, > > I hope this message finds you well. > > I'm waiting to follow up on the patch I submitted on 3.18, > titled "io_uring: releasing CPU resources when polling". > > I haven't received feedback yet and wondering if you had > a chance to look at it. Any guidance or suggestions you could > provide would be greatly appreciated. I did take a look at it, and I have to be honest - I don't like it at all. It's a lot of expensive code in the fast path, for a problem that should not really exist. The system is misconfigured if you're doing polled IO for devices that don't have a poll queue. At some point the block layer returned -EOPNOTSUPP for that, and honestly I think that's a MUCH better solution than adding expensive code in the fast path for something that is really a badly configured setup. -- Jens Axboe