From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from SA9PR02CU001.outbound.protection.outlook.com (mail-southcentralusazon11013059.outbound.protection.outlook.com [40.93.196.59]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1658F41CB31 for ; Tue, 4 Aug 2026 16:19:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.196.59 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785860365; cv=fail; b=ixaTM6SoFzdKdatbvH7eKjeTwVV5s4z7jbVI+UiKZCxj//5se8uNo4h7NALPMvNtOWvMOsT3Lvx5N1jxfbungqND3Ya+TWy2fRzjBuCIKKIlE6aOmTG6wYZtQCl9XIDVBOo7oN/f/7rIIzNP3hAS07Q2TKUklWsqnSWGWa0QCXs= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785860365; c=relaxed/simple; bh=PBo6e4XSwAp2f5KYf3J5r0VIHjVb9vpf0Ijg/0PpKh8=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=a7JnhjXlQPGv8+f4PRls1AK8pAzLaN/70dMx91XEkVBT5Uiw1kNN8pspx8HI0nDii+Pa1Jc4jfWrtz3mCPomJJEzCuMIrxgeaidZahYQ5MrrPG5GyvOkm2C+3ZXNXb0Ln1RqSfOuFkvJp8RFCKr8Ix8lFBWOqi1ojJSTPFrQXfg= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=OV+cyEuZ; arc=fail smtp.client-ip=40.93.196.59 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="OV+cyEuZ" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=NkiimqAXMrC96QxsmVuNVWVNkM89BJNx6Wy6Hu1x38BkWhuo2RQVXiuXGbywuoJ9+0oPev0mKfl8MU7yR+rXjW0ne+UORGTokyH4blTy74l+LMAS2AJNT2J9KRMRKpdXQCjTeAHvhz5o3+pkrIV3iE+9Y7SlLDRv90GuewH9AWatgqQj5vNRV7iAieG+/OcuiY4bkbW251NVu3Ag59UT0bZ74MiuJSQBvzyOgwTOpdM+UXn/cPc3VgZl8TRk1X73b5hy47lrb8BO/XrNIYsL829Dh+R2wVnPeeRNNQE8JQbjbnMQ3zFJcuyHgMObdvl1yqy4YS/s/4VKpx0nLol12g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=QT+k7pp+Wz2QAJGVnLyVEomFbV5EW+H7sDIR5+cNg8E=; b=DqK7rJeYQ9dOh/4tAODZFbulyJVU29f2hCaUTSvrdCdMupryqCGpLVNY8xTjKGrZvSlcVAfK+lcTC9XZSKa1NjcVq2ij8RPgs16Uc3QpWD1XbTFQTgQwdcwa24W0ExDEvQmdsVPNFm9vK14BvjJHRHQ0F0HPI9WZJCQKZMUT+gm/nPla6QJ9xBIejLcn7t/4xntSTXt+d2wj2cIVXYTu3DV5mtDbisWUbZKMAgflGBFAIKUfiPLpplgw6pDY7ENxoZ5o32v/7xV+NdtNDMn7/+ny/ZV2YQP3YQNoSHDGw/+tsI2GmFzC5ktfPsmnWMJ4cP0tlMWxKMtXAe/WrogS9A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=QT+k7pp+Wz2QAJGVnLyVEomFbV5EW+H7sDIR5+cNg8E=; b=OV+cyEuZpWUQTkgPtKsA79k5l9hidTh4I0D62nsLrj5KJ84eKCja5arppJ3XtLtdISKlY+r7oV2ui8qNq6es3ytYjjlYSzSLhPtyuQpKB+Y13DBOZGXX0dOdpcHOjoKGIkMTC6mt1uiQWlzJKiqG9Y8iL87KPBnCmhC9cmD8weSQUKmX+PhpVlE1rn2cteFTuAbeLFFvF3iFUFDC3HzG7KRllVCLfBKHnroxBP4B8hk8aFzAysno+dSZmqQSi3tAbNEkrLcGO1+4PJTRBjAtTBbgp4f4ZKBBzK4T212Evrvqvwio+5CY0mjY5h0a20hZa/rr+/vO/tzVp7IIf41Bvg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from LV8PR12MB9620.namprd12.prod.outlook.com (2603:10b6:408:2a1::19) by SA5PPFB9BA66B77.namprd12.prod.outlook.com (2603:10b6:80f:fc04::8df) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.292.15; Tue, 4 Aug 2026 16:19:20 +0000 Received: from LV8PR12MB9620.namprd12.prod.outlook.com ([fe80::299d:f5e0:3550:1528]) by LV8PR12MB9620.namprd12.prod.outlook.com ([fe80::299d:f5e0:3550:1528%4]) with mapi id 15.21.0292.015; Tue, 4 Aug 2026 16:19:20 +0000 Date: Tue, 4 Aug 2026 13:19:18 -0300 From: Jason Gunthorpe To: Nicolin Chen Cc: Will Deacon , Kiryl Shutsemau , Robin Murphy , Joerg Roedel , Pranjal Shrivastava , Breno Leitao , Kyle McMartin , Usama Arif , linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] iommu/arm-smmu-v3: Shrink command/event/PRI queues in kdump kernel Message-ID: <20260804161918.GG27883@nvidia.com> References: <20260706084708.8072-1-kas@kernel.org> <20260804141704.GB27883@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: YT4PR01CA0397.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:108::16) To LV8PR12MB9620.namprd12.prod.outlook.com (2603:10b6:408:2a1::19) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV8PR12MB9620:EE_|SA5PPFB9BA66B77:EE_ X-MS-Office365-Filtering-Correlation-Id: 3ce8d5ab-3119-4e2a-ac80-08def2442316 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|23010399003|1800799024|376014|10067099003|11063799006|4143699003|6133799003|56012099006|18002099003|22082099003; X-Microsoft-Antispam-Message-Info: w0Abjm6gpOIjZYQ/szGSZoY2kN7n/MGJFEJJuwD3qMt7a7NHVZYnwlFTDvlAd0N3vXw0CZnFxEBHdL0hfa3A69p/5t8hxt2sj5TPLPdfrpaOnpqskhqA7WpG3CZSzi+H/qkHQw9J+sw9AF2+Dwy9QzFoP1/P0qFfdv75AO4ewFTfNrSUTpGzd6D6u+O4rNvXmaihPjiaMOPxMicBPcPpfLI11t/9D3BXGcllzrp0dsJxb04IDLskBFJZSC0kieHkvRPgKeOmyhxl61IqFZs1JN/xJyptx4UKlceolgoEnd7+Oo199QgtemmgirNLDueL/IvNCrY5McAazlv2seCQdgd0D9nc4ep1z3fD/PnAKX58biNGgVuEVENB8E68But6AhdUqEsR38hkAOxJzGRpn5YIJ5+xPjpJhCAzjlAsQwiB+awB5wCh64p/pM36rD3IbrXM2VG3ApkUdptsxyJwwrwOfZUBuXhuBUwA2Orpsb0mbvXs6ZVBYDM2J64yp9XJZ9xJGFQkK7KjODaQzfysT82XRRNFTBr01cTrFVJhncJZy91P1IQN1Ca5X39Df0Pif6Go8mxwuCFTFbLel6jrvPzhROCiNf+iszdIAmGc5aUBfcprnoH+NQFV00cnwwozbsi999m9Xlewr3zmidv6z5lzoCS5mw3pvn49gJz4RLw= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:LV8PR12MB9620.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(23010399003)(1800799024)(376014)(10067099003)(11063799006)(4143699003)(6133799003)(56012099006)(18002099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?gdofpCLQel58K//BXth3Tvv0rJxPkh7NFJYROUP85GROsKJZJEJjjKo3w1mM?= =?us-ascii?Q?7G4+yLmyavCaSnI/hVjpHbItlREcE5xRfTFJT40BKtrMHYnv4b4ODdgYDHHB?= =?us-ascii?Q?FthEp7i67nV+VLZ0nuLk0Gz3/4yFs1eOKnm4IubiYAKnzkzcjJi71JGaNXHr?= =?us-ascii?Q?JZnEGKRscOhk7ah0qiRuvdmm2/nJuBF3jfS6B/4o91MrjCy2Y2CLUIBIgVMy?= =?us-ascii?Q?8APvt0YSurko/JS8WntUJHcCpOjXNHB2hbR/+fbY/L1xXbPmVzMgHxC+43GX?= =?us-ascii?Q?jdcWQyXQJs72VncUQIAk8zsKqfa8Fac1EiNLRTM5R5/2RjHKZLftFFhyqDss?= =?us-ascii?Q?ISeEWcuFbSH3l/SwE0QXy5klexTRa/dJrmP1Gadc33yZkryJ3HG+BmgOW5Ac?= =?us-ascii?Q?05enLSJV7AHY95W7UHGeKnXbChUHFKQE5dSgHDPv9USE6Zoy2eoXyRWKBpVb?= =?us-ascii?Q?Wg/5PrC3q0TP5dv4UILB5HrHaw/Af8+HhFNOQakhfqoMeQtYf9BEtMA2X1Fd?= =?us-ascii?Q?Q5OA1oor8qisQCTNkIONhkMkgwiY0iNgEI77Xs4vebTkWcHzpDiU7xT2KVMo?= =?us-ascii?Q?LqudwJ1zluyAu4K8UCKvV3zjXRM/P7BiQyrOBpPU75s4KOGvLlih8iltiq++?= =?us-ascii?Q?tecJgSSroaREzdm6hlYkY/ff+jValaRFDknPknEpyTMuHoLXS9kCIs9ioWdi?= =?us-ascii?Q?MsotuFCclRg3TiCSId87ALAquPl0tM+HhNQvkVWi+BGQm9QltAKBsgDRZvCd?= =?us-ascii?Q?bPQ00djAqvQs2b8Bsgtm7fJMaZfQslS/G1/UdZUGaQ+T/9kz17TaxhKeoAJD?= =?us-ascii?Q?MFmSF2qC+DcRnpAhV4xwYQG+s9M6SfV5lL4LmP8L1o8wwocFkNvtjnCHgoQ9?= =?us-ascii?Q?FtI26kgzDmnJyEjc80t6wvTO1487Mz4Ls7q0oPu/zciutdpIhiH8pvQYWdzI?= =?us-ascii?Q?eP2daqVogmRp1M5Sm62KEErkZvcH6fIKxQ3ENGKk8VDxS3ew/yI53UynnsXp?= =?us-ascii?Q?A1Wa3Ai7A74ULl2njxRks7Y33RslfD4KyadDvsrZ503bNt/4vI0pxCr1Koby?= =?us-ascii?Q?xcd95+tze8f+OaquqUIVQojxXIdi73Hz77tEjBwVNalGyxud0+/uYxCYLQDN?= =?us-ascii?Q?P09mOtfPctBGPBkjidTaUYaAktsw0YBy5GsfWpez1UY7UTbCVri052Ed2q1T?= =?us-ascii?Q?OD04bT3SLs39pAi58itbs/JZdQY8YU9TBR9/05zCvJmldqmmC8VjBnDaBrjz?= =?us-ascii?Q?aXZTIW7dGuFShQVFs6sJSg9ykuWp98gV4M9tpaLBj3hYEAD8nKp2dLd1alrV?= =?us-ascii?Q?v1QMHj+IBxExDUhWPy+LvlYTofKhM0/XUp1gzB/Mw94dqOV6uaS0wb0k5XsX?= =?us-ascii?Q?l3P/T3KsRiPFh1y8qWyYIZpfQlWzk4rAzC5FVvyQykm/WLNMDiQxdyvG8xHs?= =?us-ascii?Q?FoQyJ+i7H/Krk5KPWueXWjE/AzirUIWkf7MJYOMP2dSnNHV5GBtd67NCpzFp?= =?us-ascii?Q?K+ipkiu6UfvRw1Y1HdPm4q9szsNB0ajvgxhVX8PUBuP17RyDJUmyy7M56fLb?= =?us-ascii?Q?Kxm5Kq3fesnPoskiqOQwnCuBOYaH2fDp1Az7T0SAhK3G1F84mRN4kStIwlRr?= =?us-ascii?Q?cbueDxY7BLwuUijJqa2bZK1pDCofqVdv5MKy66iHePhSwurXOIajAOF0Uthf?= =?us-ascii?Q?Kvs5h/99sqQ4uhODeho6IzKFrRKuVuMwZDlTkcWyxBxFFTb/Qsh7PHGFE+dx?= =?us-ascii?Q?BXw3bT800A=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 3ce8d5ab-3119-4e2a-ac80-08def2442316 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Aug 2026 16:19:19.4655 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 4Hzizuf6sSw8RdmQHdiGjOwhRLhT0SyfEh0dbzNQ1UuR0jQOWSVAO+/TpZpLfOKQ X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA5PPFB9BA66B77 On Tue, Aug 04, 2026 at 09:04:32AM -0700, Nicolin Chen wrote: > On Tue, Aug 04, 2026 at 11:17:04AM -0300, Jason Gunthorpe wrote: > > On Tue, Aug 04, 2026 at 03:02:46PM +0100, Will Deacon wrote: > > > > Would skipping their allocation when is_kdump_kernel() be acceptable on > > > > its own, or would you rather see it done differently? > > > > > > With Nicolin's patch, we can just avoid allocating the priq and the evtq > > > entirely in the kdump case. We can then add a cmdline option to control > > > the maximum size of the cmdq, which is useful regardless of kdump. > > > > I would still prefer kdump do this re-sizing automatically, even if we > > do add a commandline. It makes it easire to deploy than having to know > > secret command lines :\ > > > > So functionally I still think this patch is fine, though yes it points > > out more things in Nicolin's work too. > > I will send a v10 of mine, to skip the EVTQ/PRIQ allocations. I think Robin's point is to structure the v10 so you introduce a bunch of tunables, including something like 0 size to disable a feature. Then have kdump default those tunables to the right thing Jason