From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6A1CC35FFF for ; Fri, 21 Mar 2025 09:15:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2D03A280002; Fri, 21 Mar 2025 05:15:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 27F71280001; Fri, 21 Mar 2025 05:15:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 12119280002; Fri, 21 Mar 2025 05:15:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id E8375280001 for ; Fri, 21 Mar 2025 05:15:04 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 950A4AADFC for ; Fri, 21 Mar 2025 09:15:05 +0000 (UTC) X-FDA: 83244998970.18.A68B9E4 Received: from mailout1.w1.samsung.com (mailout1.w1.samsung.com [210.118.77.11]) by imf13.hostedemail.com (Postfix) with ESMTP id F3E6A20005 for ; Fri, 21 Mar 2025 09:15:01 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=samsung.com header.s=mail20170921 header.b=og2LnBpv; spf=pass (imf13.hostedemail.com: domain of da.gomez@samsung.com designates 210.118.77.11 as permitted sender) smtp.mailfrom=da.gomez@samsung.com; dmarc=pass (policy=none) header.from=samsung.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1742548503; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kNAM1R1HcAsH6Vhbw1Rvoo09UepNnwwrLKDhYROZtMs=; b=8Ja5EkbKh9c/3dAiwZp6FC16cXeCCZvxlr2Cyy7rwOTgnehHWwL8+i3OO2DjJagZOaOhmQ YQaGkK71WidSKLk5qxgA7kv6ioWpBvNVmsARRaRQgCoQoNM+wqyIZk3WPG3MhERg61pa7n Xa3RcuJt53qOxIhhV2yR6Nz7fen4kbw= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=samsung.com header.s=mail20170921 header.b=og2LnBpv; spf=pass (imf13.hostedemail.com: domain of da.gomez@samsung.com designates 210.118.77.11 as permitted sender) smtp.mailfrom=da.gomez@samsung.com; dmarc=pass (policy=none) header.from=samsung.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1742548503; a=rsa-sha256; cv=none; b=6UCZoQu7lzQ2W/eoxuGoDXSnDiW3jcepz1ufX3Af0uxswpgcimfC2aFFdbk9ZVw11KjbeQ Dp507MXew6mBcUgc5kiCuSpGxIWAeOXwS509y4IZdlOGWHpq5H0Bdx5LJNJTYypp5A/NzU xQoc8d74S87f9Z5OD6A12z9WFSQadsM= Received: from eucas1p2.samsung.com (unknown [182.198.249.207]) by mailout1.w1.samsung.com (KnoxPortal) with ESMTP id 20250321091500euoutp01e61cb1cfbd6c97a4d989497f046f9719~uxqDx-iqL0262402624euoutp017 for ; Fri, 21 Mar 2025 09:15:00 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout1.w1.samsung.com 20250321091500euoutp01e61cb1cfbd6c97a4d989497f046f9719~uxqDx-iqL0262402624euoutp017 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1742548500; bh=kNAM1R1HcAsH6Vhbw1Rvoo09UepNnwwrLKDhYROZtMs=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=og2LnBpvtYUY/ZknVs6KONvWUXuUdOrDz1tKHxNH9BHJoutvdNryp8vPhK9KlzF2Y BzE5BzUY8Evo2Cj6n4ZxUudWXgU7dwSIgmH5QxQIkyKyBkV75/PbsJ8pYHjP2iyJS+ 2boBQI0Hz4wDf4L9qOujjl7QMDV8QZpUic0j38Cc= Received: from eusmges1new.samsung.com (unknown [203.254.199.242]) by eucas1p1.samsung.com (KnoxPortal) with ESMTP id 20250321091459eucas1p161e141aa7326845f1bd9e2d2345d072a~uxqDVWd-U0991209912eucas1p1I; Fri, 21 Mar 2025 09:14:59 +0000 (GMT) Received: from eucas1p1.samsung.com ( [182.198.249.206]) by eusmges1new.samsung.com (EUCPMTA) with SMTP id 3A.DA.20821.31E2DD76; Fri, 21 Mar 2025 09:14:59 +0000 (GMT) Received: from eusmtrp2.samsung.com (unknown [182.198.249.139]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20250321091459eucas1p2e32e6d201c819fdcfcc04ec5988bf5fa~uxqCrjfcY1991019910eucas1p2D; Fri, 21 Mar 2025 09:14:59 +0000 (GMT) Received: from eusmgms2.samsung.com (unknown [182.198.249.180]) by eusmtrp2.samsung.com (KnoxPortal) with ESMTP id 20250321091459eusmtrp21e04f8d44751e75c856195435f1ee123~uxqCqsEIf3051730517eusmtrp2N; Fri, 21 Mar 2025 09:14:59 +0000 (GMT) X-AuditID: cbfec7f2-b09c370000005155-80-67dd2e13770f Received: from eusmtip2.samsung.com ( [203.254.199.222]) by eusmgms2.samsung.com (EUCPMTA) with SMTP id B8.FA.19654.31E2DD76; Fri, 21 Mar 2025 09:14:59 +0000 (GMT) Received: from CAMSPWEXC02.scsc.local (unknown [106.1.227.4]) by eusmtip2.samsung.com (KnoxPortal) with ESMTPA id 20250321091458eusmtip224f3efd4955992c1c0175a9ab9d54c60~uxqCdXX4I2797827978eusmtip2h; Fri, 21 Mar 2025 09:14:58 +0000 (GMT) Received: from localhost (106.110.32.87) by CAMSPWEXC02.scsc.local (106.1.227.4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.1118.40; Fri, 21 Mar 2025 09:14:58 +0000 Date: Fri, 21 Mar 2025 10:14:58 +0100 From: Daniel Gomez To: Christoph Hellwig CC: Daniel Gomez , Luis Chamberlain , , , , , , , , , , , , , , , , , , Subject: Re: [LSF/MM/BPF TOPIC] breaking the 512 KiB IO boundary on x86_64 Message-ID: <20250321091458.rpnwezqjb2t7lwhy@AALNPWDAGOMEZ1.aal.scsc.local> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250320145449.GA14191@lst.de> X-Originating-IP: [106.110.32.87] X-ClientProxiedBy: CAMSVWEXC01.scsc.local (106.1.227.71) To CAMSPWEXC02.scsc.local (106.1.227.4) X-Brightmail-Tracker: H4sIAAAAAAAAA01Se0xTVxjfuff29rZJ8drWeYDOxBrJgFnxNU6c2zRblquYZdP9sTFfRe+K Aar2tviMY06x4gxSiUoVh408BAFbgYCUoi0PARFjDYK1TA0khKqMwjasSEe5LPO/3+v7zvdL DoVLXwgiqJ1aPavTqlOVpJioaXl9b5FM5dXEXa5chMq82STyufwAvT2bgqpa+gBy94chu8WE oatlzRi6H6gF6MSF60JkcnYDlBsoxFHD41hkb2gjUN+1oAA5fA046jk9ANDtdqMQVfiGCfRm /CK5Wsb0376EMe0WyNSZvUKmq89KMDdKYhh3p4GxlZ4gGZvfJGTO9BQDpr43g2RGBh5PBToO MqO2ed9IEsWrdrCpO9NZ3eLPtomTR4/lC3Y7xPueWsdBBsimsgBFQXo5fFXOZgExJaVLAKwP Vgh4MgZgb7+F5MkogM67g1OOaHpiosMzYxQDWJ0zgvPED+Bwlgvw5BmAF12/YaFHCHohzBib FZom6WjoaLMJQ1hOK+HAUOd0HqePErCrbJQMGTJ6HXww3DiNJXQCPOXLxHg8G7bl9RMhjNMf wYJ6Pxnaj9ORsHiSCsmiKfl5UaWQv3Q+PJ9zleB7JsFfBqd7QtovgvbWgJDXv4SFvpV8XAaH WqtmRhUwWPc7xuMU2PmPHfBYDyf/DBA8/gQGy70z+hpYm/tEwK8Mgz0vZ/NHhkFTzTmclyXQ mCnl01GwrO8FcRosML9Ty/xOLfP/tQoAXgrmsgYuTcNyS7TsXhWnTuMMWo1q+640G5j6kB2T rf5akD80onICjAJOAClcKZfIjR6NVLJDvf8Aq9u1VWdIZTkniKQI5VyJpfGYRkpr1Ho2hWV3 s7r/XIwSRWRg+enxsV/9qBgcqv7i+KpIiStHpM+OeeiOj1lesPRjeRJzjbOS5d41yOqa83Zj V15cTdgRh2Gh1l2nftP9w9mTdU0lfzg2F5WAI/M2hPfkzu9WBNq/l21VfG0/rGmJqHjvjuiD Z7Oo4/cyG3M3rPiWM8YZ89dvwj9MvbMyYVtjeF7CRHO0uffRmJvDSO5mIM1zaMvnzGSi+rLW a0rX/Sw5E33pVzoqztL8UrFxde/5TQderdOPH0rcXIo/lY4Xva6S3xJVpuc4kh9lNZ2MTTr4 01/VV0a2xNuTo5KQPuo74BkTPlQV7rFeXxZ+9P1Pr5yK/FumlzNNEwFqcE/w8F1PwtoCJcEl q5fE4DpO/S+PVpdN/wMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupmleLIzCtJLcpLzFFi42I5/e/4PV1hvbvpBse62CxW3+1ns3h9+BOj xd9p2RZbjt1jtLj8hM9iz6JJTBYrVx9lsrjwawejRefsDewWkw5dY7SY8msps8XeW9oWe/ae ZLG4t+Y/q8W+13uZLW5MeMpocfBUB7vFutfvWSx+/5jD5iDs8eTgPCaPU4skPHbOusvucf7e RhaPzSu0PC6fLfXYtKqTzWPTp0nsHpNvLGf02H2zgc3j49NbQAWnqz0+b5IL4I3SsynKLy1J VcjILy6xVYo2tDDSM7S00DMysdQzNDaPtTIyVdK3s0lJzcksSy3St0vQy/jcOpe1YB9XxYON PxgbGPs5uhg5OSQETCT+nL7N1sXIxSEksJRR4ljvBRaIhIzExi9XWSFsYYk/17rYQGwhgQ+M Ekf/q0PYDxklfp/L6GLk4GARUJVo+MIPEmYT0JTYd3ITO4gtIqAk8fTVWUaQ+cwCLSwSp9ZP YwRJCAt4SVx6vx9sJq+At0Tv6zYmiCPeM0psenURKiEocXLmE7CDmAV0JBbs/sQGsoxZQFpi +T+wBziBwo+WrWeHuFNRYsbElVD3J0kcbZ7HOoFReBaSSbOQTJqFMGkBI/MqRpHU0uLc9Nxi I73ixNzi0rx0veT83E2MwFSx7djPLTsYV776qHeIkYmD8RCjBAezkgivSMftdCHelMTKqtSi /Pii0pzU4kOMpsCgmMgsJZqcD0xWeSXxhmYGpoYmZpYGppZmxkrivGxXzqcJCaQnlqRmp6YW pBbB9DFxcEo1MDksEmWauj3I+5PTjl/pf1V93Kzr+kz27J0lUuO+1FNtQdOZTfnPt0xJMVTS bd+5rUCYx/a758SHTJHfmdcbPN146PkTvs/rjxjIWl/YsaHhiN7jhB8rbpcYF68579Pc8Fjj v8eTHwZi16XWy006smVq8h+9cNG1C08u2PfJYUeyZnjMISb1XbrHv7Muqerj414RZa2SePNi 4JO+qCjuu5Oz9z+4tGuSXDpzlKCwksWFPRsWWk/fM03O6cvvT1XmlbJG705kTE/MzT4dtMXe 88+3xuMbyu71u7Ptbtx3SXNFINMnv4WCqh8TXvUVfluvW9r0k9dm/TYhnc2Tqj/xPkvKj6nl zO2376rRzeD6HqLEUpyRaKjFXFScCACniP5TngMAAA== X-CMS-MailID: 20250321091459eucas1p2e32e6d201c819fdcfcc04ec5988bf5fa X-Msg-Generator: CA X-RootMTR: 20250320145500eucas1p121d971c1fae20628b9716bbac197d84f X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20250320145500eucas1p121d971c1fae20628b9716bbac197d84f References: <20250320145449.GA14191@lst.de> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: F3E6A20005 X-Stat-Signature: 6tzxj41sywn6gfz915e4bak1pijoe6ee X-HE-Tag: 1742548501-388375 X-HE-Meta: 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 98o8Na0e Z5rB4gCwmOCcmtCtowOD8s1x+t4HhPm74RUtRjLDe/ZTXvwoJo78LlzAyjEeVS/mtC9V2O1EYzkI6UF7+NusoTfhKz+/9BkOdJ6kRLRwU3/qUbnusC+6r0n7ngFnMtLLncOEDGa/Hiji94CRjAoCjihSBi5RxEgHZg2qqkZ5Z1lO9lVXFDMYc8VoLjRXh/84f5bb85GEzQGnFvrXYm2f5q/EdHY0jHkPtH25NL8i++0BHci4BPPbXrDyBPrfSTO0/QwfvogeyAiMUFJRxsHYhjXrh7zMvYq/pYtRPhwUGYUQlb5WrlyrjYTG2oVdSVVuBMry+inCOb4VxuLDEofitx5Nngun4RBpkiZkYhb1642SNqhcSQd8TJR2mdg== 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 03:54:49PM +0100, Christoph Hellwig wrote: > On Thu, Mar 20, 2025 at 02:47:22PM +0100, Daniel Gomez wrote: > > On Thu, Mar 20, 2025 at 04:41:11AM +0100, Luis Chamberlain wrote: > > > We've been constrained to a max single 512 KiB IO for a while now on x86_64. > > > This is due to the number of DMA segments and the segment size. With LBS the > > > segments can be much bigger without using huge pages, and so on a 64 KiB > > > block size filesystem you can now see 2 MiB IOs when using buffered IO. > > > > Actually up to 8 MiB I/O with 64k filesystem block size with buffered I/O > > as we can describe up to 128 segments at 64k size. > > Block layer segments are in no way limited to the logical block size. You are right but that was not what I meant. I'll use a 16 KiB fs example as with 64 KiB you hit the current NVMe 8 MiB driver limit (NVME_MAX_KB_SZ): "on a 16 KiB block size filesystem, using buffered I/O will always allow at least 2 MiB I/O, though higher I/O may be possible". And yes, we can do 8 MiB I/O with direct I/O as well. It's just not reliable unless huge pages are used. The maximum reliable supported I/O size is 512 KiB. With buffered I/O, a larger fs block size guarantees a specific upper limit, i.e 2 MiB for 16 KiB, 4 MiB for 32 KiB and 8 MiB for 64 KiB.