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Sat, 11 Feb 2023 04:35:29 +0900 (KST) Received: from green5 (unknown [107.110.206.5]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20230210193527epsmtip291a6ffd0fa6cef23f4a44ad4dcc62cc6~CjZ_PeVcI3022730227epsmtip2O; Fri, 10 Feb 2023 19:35:27 +0000 (GMT) Date: Sat, 11 Feb 2023 01:04:59 +0530 From: Kanchan Joshi To: Bart Van Assche Cc: lsf-pc@lists.linux-foundation.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, io-uring@vger.kernel.org, axboe@kernel.dk, hch@lst.de, kbusch@kernel.org, ming.lei@redhat.com Subject: Re: [LSF/MM/BPF ATTEND][LSF/MM/BPF Topic] Non-block IO Message-ID: <20230210193459.GA9184@green5> MIME-Version: 1.0 In-Reply-To: <69443f85-5e16-e3db-23e9-caf915881c92@acm.org> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrHJsWRmVeSWpSXmKPExsWy7bCmum7TnGfJBj92cVisvtvPZjHtw09m i5WrjzJZvGs9x2Ix6dA1Rou9t7Qt5i97ym6x7/VeZotDk5uZHDg9Ll/x9rh8ttRj06pONo/N S+o9Jt9Yzuix+2YDm8f7fVfZPD5vkgvgiMq2yUhNTEktUkjNS85PycxLt1XyDo53jjc1MzDU NbS0MFdSyEvMTbVVcvEJ0HXLzAG6TUmhLDGnFCgUkFhcrKRvZ1OUX1qSqpCRX1xiq5RakJJT YFKgV5yYW1yal66Xl1piZWhgYGQKVJiQnTFp8xe2gldcFXNnP2ZuYJzC2cXIySEhYCJxovkN axcjF4eQwG5GiZ4p3SwgCSGBT4wSD28pQdifGSXe3TeHaXh87R4TRMMuRol1WxZCOU8YJfoW nGYDqWIRUJVYd20zYxcjBwebgKbEhcmlIGERAQ2Jbw+Ws4DUMwscZZTY8/4tWL2wgL3Eidvz GUFsXgEtiedHTzFD2IISJ2c+AbuIU8BaYuvEW+wgtqiAssSBbceZIC7awiFxbaYzhO0i8XfN ZEYIW1ji1fEt7BC2lMTL/jYoO1ni0sxzUL0lEo/3HISy7SVaT/WD7WUWyJDYt/w0E4TNJ9H7 +wkTyC8SArwSHW1CEOWKEvcmPWWFsMUlHs5YAmV7SLzc+4ANEib7GCUm3nzJPoFRbhaSd2Yh WQFhW0l0fmhihbDlJZq3zmaeBbSOWUBaYvk/DghTU2L9Lv0FjGyrGCVTC4pz01OLTQsM81LL 4dGdnJ+7iRGccLU8dzDeffBB7xAjEwfjIUYJDmYlEd5Km2fJQrwpiZVVqUX58UWlOanFhxhN gVE1kVlKNDkfmPLzSuINTSwNTMzMzEwsjc0MlcR51W1PJgsJpCeWpGanphakFsH0MXFwSjUw lbi0cl3fdknjzW/HQsaC+UsrFnT0P7l87eOTFzc/iGXEv7KxqXXN2dw5OXGZul++o/YM5pyf k+dHyCWGZR38167I8qZjx9sPbYtmNEX/YOi+fG7vunb9JLUixY+hwfMPfy9lni48O8Kw0e0Z g73PUZY+zbuiD8xC21Zv+sHM7d125NDKh5V95zKnZ857O8voRljT5/xtul756RZnvjL4Tfa+ 4fr9aY64QW1jxoKetrOhN+WKV2so9xhU+Kte9Nl3Rn/+DnHGoCrJa3MTn1x8sLMywVOuKWJb UMaGCNGuol1OzJrujC92bPZhmrk4YofP17wLOYt+Red8YOx6FKqvYXqz4N7hxrfHopcf5GFT YinOSDTUYi4qTgQAEjM62UEEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupikeLIzCtJLcpLzFFi42LZdlhJXrdxzrNkg+2nZC1W3+1ns5j24Sez xcrVR5ks3rWeY7GYdOgao8XeW9oW85c9ZbfY93ovs8Whyc1MDpwel694e1w+W+qxaVUnm8fm JfUek28sZ/TYfbOBzeP9vqtsHp83yQVwRHHZpKTmZJalFunbJXBlfLx7iq3gN3vF1zc9TA2M h9i6GDk5JARMJB5fu8cEYgsJ7GCU+N/hBBEXl2i+9oMdwhaWWPnvOZDNBVTziFFixr5msASL gKrEumubGbsYOTjYBDQlLkwuBQmLCGhIfHuwnAWknlngKKNE14dLzCAJYQF7iRO35zOC2LwC WhLPj55ihhi6j1Hiy42rzBAJQYmTM5+wgNjMAmYS8zY/ZAZZwCwgLbH8HwdEWF6ieetssHJO AWuJrRNvgd0jKqAscWDbcaYJjEKzkEyahWTSLIRJs5BMWsDIsopRMrWgODc9t9iwwCgvtVyv ODG3uDQvXS85P3cTIzi6tLR2MO5Z9UHvECMTB+MhRgkOZiUR3kqbZ8lCvCmJlVWpRfnxRaU5 qcWHGKU5WJTEeS90nYwXEkhPLEnNTk0tSC2CyTJxcEo1MNWkf/z98/nG409VT0d9d3afPuno g1/cn+4cT0xbsefstNpj2lbrbx+eudiRuffa17llfQf3VjYmr1j57tfWnfvs1H+UVOaKCJ0x KUu6fM7OxjJocUzy4dQ5BvMW527IyTp0QkdlRePP1A0bz8Xp70pLX1U7e6oQi47s1UsnL945 uWfz/N9nSqKs+HOnqVf9kGX23q76QnxS3CXxk3+/mZm1nf9W5rNGin/vybg9AosnlUxLNlsr /PaGxeEDP6Jsv1Xt15P+NsnicH0a57cnf1Q6V//8Y/OB+9uJ3V0fuj98LZ6U7d54IeXFKc4V t8vP7fB8csms8XKWuG6qsEyvXX1Ez8fTTacvnDHST+l7wS5rpMRSnJFoqMVcVJwIAPwYw7Ed AwAA X-CMS-MailID: 20230210193529epcas5p29956db1ace003a9a8cce0f192139797d X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----KU2CxbTk4.ftA7vvsvzLW4bt.-m_7jRTbTuK1k18jgDVn8pS=_54827_" CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20230210180226epcas5p1bd2e1150de067f8af61de2bbf571594d References: <20230210180033.321377-1-joshi.k@samsung.com> <69443f85-5e16-e3db-23e9-caf915881c92@acm.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230210_113539_041462_3CEA0BE8 X-CRM114-Status: GOOD ( 12.19 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org ------KU2CxbTk4.ftA7vvsvzLW4bt.-m_7jRTbTuK1k18jgDVn8pS=_54827_ Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Content-Disposition: inline On Fri, Feb 10, 2023 at 10:18:08AM -0800, Bart Van Assche wrote: >On 2/10/23 10:00, Kanchan Joshi wrote: >>3. DMA cost: is high in presence of IOMMU. Keith posted the work[1], >>with block IO path, last year. I imagine plumbing to get a bit simpler >>with passthrough-only support. But what are the other things that must >>be sorted out to have progress on moving DMA cost out of the fast path? > >Are performance numbers available? Around 55% decline when I checked last (6.1-rcX kernel). 512b randread IOPS with optane, on AMD ryzen 9 box - when iommu is set to lazy (default config)= 3.1M when iommmu is disabled or in passthrough mode = 4.9M >Isn't IOMMU cost something that has already been solved? From https://www.usenix.org/system/files/conference/atc15/atc15-paper-peleg.pdf: >"Evaluation of our designs under Linux shows that (1) >they achieve 88.5%–100% of the performance obtained >without an IOMMU". Since above numbers are more recent than the paper, this is yet to be solved. ------KU2CxbTk4.ftA7vvsvzLW4bt.-m_7jRTbTuK1k18jgDVn8pS=_54827_ Content-Type: text/plain; charset="utf-8" ------KU2CxbTk4.ftA7vvsvzLW4bt.-m_7jRTbTuK1k18jgDVn8pS=_54827_--