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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742477399; bh=blquli6rY0AiE+Vj/Xq3yIzJvhxk3Y2KmzfSno2Oyg0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=USWFXwAL+jliQWyJALPWV+ylDzrxzMujgditOImK1xKbtXiUIcwCtpIc4LyI9ZBj/ AgBFdz2LaQw8FUtN1hlNsp3+eHp0ULFiyhWf+Vvk0ERkJBKTQaQ4xmBTGyIhbWEuBE 5mh8X1/dr9Um1qBjygk1k+Herayh57umOk1vVQHs2jLSUDJRgSMl/7MkcwchxUgSFA InulU32kl6HjWdlPHQO2nmx6IoubsdEcTiVTQZjIjQGvznluAXSqGYQRDQi1aHZe1i zUz63ZqXhcwtcrGYGTumvTuEcXRZU0UBUF3uEQP2j+iGQd46EdquJEaTArfESnHzdG zLETVi+x5UQtA== Date: Thu, 20 Mar 2025 14:29:56 +0100 From: Daniel Gomez To: Matthew Wilcox Cc: Luis Chamberlain , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, lsf-pc@lists.linux-foundation.org, david@fromorbit.com, leon@kernel.org, hch@lst.de, kbusch@kernel.org, sagi@grimberg.me, axboe@kernel.dk, joro@8bytes.org, brauner@kernel.org, hare@suse.de, djwong@kernel.org, john.g.garry@oracle.com, ritesh.list@gmail.com, p.raghav@samsung.com, gost.dev@samsung.com, da.gomez@samsung.com Subject: Re: [LSF/MM/BPF TOPIC] breaking the 512 KiB IO boundary on x86_64 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 31C8814000D X-Stat-Signature: zrjpmqe79imhdas8mbr6wxdrd1edqzkz X-Rspamd-Server: rspam06 X-HE-Tag: 1742477400-835439 X-HE-Meta: U2FsdGVkX18ktRWvtBcjqYaCFOErzueUavF3V9e/296VolJ0zANBlnrIqnH4if0CpDmUswa1rN5w1LVTPVyQXSzCIEBEW5t2UA+/GQrjLfye9o8d6rYBmcvvwYqD8avGjt7qAcbACFMOhdBq9cQkENiKG3h3LIa9ikwLRB+HV+y1RnV0RQsjeccmPZkIJfOufV5SLSW+aX5rgYqGMDRH6n5Cz/lOugHXiFlCCjDPiPBvZ+jTPcixpDNdtMEcB9PeCL+40wgI608mMmV4Nm7sM8wSN0mIfxjHggl3FZJzy6sLZsAMwiwpJDNrOdWsf6gyYOyCg6u6BYhnzg+ATSBrQ3GrXDub3Sp3/FDdbn2xb5W4+f2WT0Ulc1LdKPIr0xO9eW8/IfNPHJfiz/5dj1O1tISvUy1S0usrANuieQ8rTgfwnifvtEuhPHSe/9C9cTrxaAzUiYY03k28zPT6HtQ+aZurYGsAqx7wJPslcnrFeMD/EEkxa+UuAp0RE2g+nyv1V0OGNtlhA7fM8WSbQIq1XRcO4UKjwZ4Vicjuu+S6hSLvNSD0fMWg1WNe3mFP6bmfxjVc2i3qsY72wfHOyA61tcYpFlsFEAckpOGmRzTdZyA8QP0TVpPfq9o//aIr0TTR3sVGHEdGGv7RNAtYMH6uhRShQt+sjZhf+nC8klCDJhTELKREF7cswh+Z/kkkOjg6hcU2+inutizdKJ8gPt0Vo+XeQ2pC5uB12U5kHRtWuS8wifadyywljegetlq1XbCVYe3gY0O56mNKpY5es9qLgiB6Mp7+kcmYkpKztcUziTlpFEDkpA7jvrI59SBLsvhnuVSGdJevF5bfBb+3zRXW1u5M6ti0guGVMRtdMy3cS8Ur/cPkrVxyaNMs6d4i8H1W7/o8cTGTGDZoTpQfO53RlaCa3bsgND35THjPstQgLPvAjsnxdoRBcOJxDWK/QTd8v9E5K4a2OWAKo9Trw69 9WBM/OA0 soXZlPg04g42miptGhcWass72UpWU3WZDHP0JCvHPcHF2BOkgt4mDar/qFP92QTvxXY3jibyEQSBVDFTfWhC3djxegOlHZ1HaGgZEpDrj7esAe0bdAcUjsu6/fcPXfUL2RxJG4xC64M2FNd4dkBBvC1fTE01lgwb4Uqk+T2PHyvakVNshWrDc/kk7QB52OMNKfVnpcE+89hMFqIJRD/kHb3DEWjTrxA+O8ut7n2wU5u/0jK6VJH5Jk0buSXnnrxyWBH/JKMC8/ec2L7H5S6/NPlmPvnHGnzaxcxtLUtj/6IJG9MosfkTVLmlBVZSu5WrlQ9ookNg1swTTsMomwSoVDrHmwBTskPA9f40VC82dVlekCGLmJwlMlnAxUzDgfebqAYhICuUBjXqy1lg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 20, 2025 at 12:11:47PM +0100, Matthew Wilcox wrote: > On Thu, Mar 20, 2025 at 04:41:11AM -0700, Luis Chamberlain wrote: > > We've been constrained to a max single 512 KiB IO for a while now on x86_64. > ... > > It does beg a few questions: > > > > - How are we computing the new max single IO anyway? Are we really > > bounded only by what devices support? > > - Do we believe this is the step in the right direction? > > - Is 2 MiB a sensible max block sector size limit for the next few years? > > - What other considerations should we have? > > - Do we want something more deterministic for large folios for direct IO? > > Is the 512KiB limit one that real programs actually hit? Would we > see any benefit from increasing it? A high end NVMe device has a > bandwidth limit around 10GB/s, so that's reached around 20k IOPS, > which is almost laughably low. Current devices do more than that. A quick search gives me 14GB/s and 2.5M IOPS for gen5 devices: https://semiconductor.samsung.com/ssd/enterprise-ssd/pm1743/ An gen6 goes even further. Daniel