From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <dev-bounces@dpdk.org> Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id A659C426D0; Fri, 6 Oct 2023 14:20:09 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 8A5014067B; Fri, 6 Oct 2023 14:20:09 +0200 (CEST) Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.20]) by mails.dpdk.org (Postfix) with ESMTP id E28624014F for <dev@dpdk.org>; Fri, 6 Oct 2023 14:20:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696594808; x=1728130808; h=date:from:to:cc:subject:message-id:references: content-transfer-encoding:in-reply-to:mime-version; bh=nf5Lwcle1Jl5HXALq0AQLyTArJPTgOT6j3Ig2SFSfl0=; b=JhVLOcZfADJhCUrlIyG++KNudc+zh2s+RYZ7PtqGHbEUmsydKcQh3ltk MCPNTK7MpmifOUKE1qewwILy2bRJjIoQ6DXfDGTx6H6VEbNrBmT5bLski AcmrHybkOgkBBPPgZi+S4GPvIdSrngH/Fai4R4tJkP5Lmqiy3vqr37PaE xIxubLIbbs4VffZTtlctd8Urdd5WtjB0L3wAArILC6cHJYRa/kIggBXmv R3wqYDp6+VrDfgy9z4SFZQXi4ML2De4Po9pIvgOxEGLZ6YrnSieFKqYso LCuMBkeqJQZSMQ+sFAVM5pLV58Rt4Unm47YTL+qM60GY9QxhzXlfATY9+ w==; X-IronPort-AV: E=McAfee;i="6600,9927,10854"; a="374085795" X-IronPort-AV: E=Sophos;i="6.03,204,1694761200"; d="scan'208";a="374085795" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Oct 2023 05:20:07 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10854"; a="999314780" X-IronPort-AV: E=Sophos;i="6.03,204,1694761200"; d="scan'208";a="999314780" Received: from orsmsx602.amr.corp.intel.com ([10.22.229.15]) by fmsmga006.fm.intel.com with ESMTP/TLS/AES256-GCM-SHA384; 06 Oct 2023 05:20:06 -0700 Received: from orsmsx610.amr.corp.intel.com (10.22.229.23) by ORSMSX602.amr.corp.intel.com (10.22.229.15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.32; Fri, 6 Oct 2023 05:20:06 -0700 Received: from orsedg603.ED.cps.intel.com (10.7.248.4) by orsmsx610.amr.corp.intel.com (10.22.229.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.32 via Frontend Transport; Fri, 6 Oct 2023 05:20:06 -0700 Received: from NAM11-BN8-obe.outbound.protection.outlook.com (104.47.58.169) by edgegateway.intel.com (134.134.137.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.32; Fri, 6 Oct 2023 05:20:05 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=PPuaf14fuPByhsoQEQ+muAFg3G9LO3A4sq8ROh4yUNZ0xj3fMVMGsNlmPv8C9N8SQThWGGz8DZ8NEfOwMBUkS/iY9oI+AQkMlh+jP1NbnZ8GZVEm9d2i2rEVkAzW/D2CbpOww5gCAuiQwK2HqamQHANUXZnO9LFAm4Ffuyh7jzV448XsAzm2AqqiEW5nDl4JTxTjW3z6+BMLyecyABdLjgKN+AXouxBp9++PrbNSWI+ZGZ2Q+/rFLib9wRrSncBKBDxITxZm02r40H/EF0jw+nXYe63n65rP2kEXtBxvyUaDxRdePBUR2cx/+Ri9sN1+pQgrNzTS1M46e6+RGFtT0A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; 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=tWzLeaAf/s2fuiOT510vpaZL8BoDn0r40tx29TQKt60=; b=nEdXJOSWUbYVbewl/bukMNqzywNZqyb/0IDJoupp1mQLuTKg+q9sKUZ/y9U5GT43upmMK9ZJrIV65pPxTv7eWT38XtqGzMy8+8FNFpBaMheBxo7tO3FRrMRPolY8U+oC1xRL1F/8Q3e+CUwiNieEqcg7miWNKNW7tV6ZeAolmzX4OhY+NthXIj4oiKlAwrRRyzyI/jFQR0lQnBtD3S6uvkA89Wxwomq2H+Pm0Hjv2HeKkZ6aaffDrrY0EpISHyt35LFtSmM/ZK8l6eeHHRIzfvMXuS5rietJR7eZGWGAy9UTpDJ60X4AAMrEz46N3zBb/NEe+5U99YW/OVlBtbsIUg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from CY8PR11MB7290.namprd11.prod.outlook.com (2603:10b6:930:9a::6) by SA1PR11MB8326.namprd11.prod.outlook.com (2603:10b6:806:379::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6792.23; Fri, 6 Oct 2023 12:20:04 +0000 Received: from CY8PR11MB7290.namprd11.prod.outlook.com ([fe80::1049:683e:132f:e690]) by CY8PR11MB7290.namprd11.prod.outlook.com ([fe80::1049:683e:132f:e690%7]) with mapi id 15.20.6838.028; Fri, 6 Oct 2023 12:20:03 +0000 Date: Fri, 6 Oct 2023 13:19:58 +0100 From: Bruce Richardson <bruce.richardson@intel.com> To: Mattias =?iso-8859-1?Q?R=F6nnblom?= <hofors@lysator.liu.se> CC: <dev@dpdk.org>, Jerin Jacob <jerinj@marvell.com> Subject: Re: [RFC PATCH] eventdev: ensure 16-byte alignment for events Message-ID: <ZR/7buT5KgDV0ecv@bricha3-MOBL.ger.corp.intel.com> References: <20231005115101.12276-1-bruce.richardson@intel.com> <fcd11d73-d098-4734-9540-944aff73ed71@lysator.liu.se> Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <fcd11d73-d098-4734-9540-944aff73ed71@lysator.liu.se> X-ClientProxiedBy: DUZPR01CA0230.eurprd01.prod.exchangelabs.com (2603:10a6:10:4b4::7) To CY8PR11MB7290.namprd11.prod.outlook.com (2603:10b6:930:9a::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY8PR11MB7290:EE_|SA1PR11MB8326:EE_ X-MS-Office365-Filtering-Correlation-Id: df156076-c07e-4b93-1517-08dbc66691bb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:CY8PR11MB7290.namprd11.prod.outlook.com; PTR:; CAT:NONE; SFS:(13230031)(366004)(376002)(136003)(39860400002)(396003)(346002)(230922051799003)(186009)(451199024)(64100799003)(1800799009)(8676002)(296002)(66946007)(316002)(83380400001)(6916009)(26005)(66476007)(5660300002)(86362001)(6506007)(66574015)(53546011)(6486002)(2906002)(8936002)(41300700001)(38100700002)(6666004)(44832011)(6512007)(66556008)(4326008)(478600001)(82960400001); DIR:OUT; SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?iso-8859-1?Q?95j7FERemyDnjl0JDz2wbIAC9TXeH1d3AywcJIjdyLVm/iTkkRmv1qWMi9?= =?iso-8859-1?Q?JMwF5orO/knYmyaanDzYew4lwlkUPJPuDRT0/yScdW61ggR0YBB1H12qBj?= =?iso-8859-1?Q?go+7mwouVZt0ouhqsqOj/a31FjAp4uTehYncxqq3j+Zg1et7fHF/JRW0kL?= =?iso-8859-1?Q?7XARwIt2m2ubuDs5o13OUBkmBRi5S4iV6JUrwJbhK4Bx3+gwSe584cX5u8?= =?iso-8859-1?Q?iEUu2e4NchFlo0CdPW9sNNi8euT6+FsDB2q2MIzM7G6P8x5ZaY8vS6bxi5?= =?iso-8859-1?Q?SstWc6fmIeaMd+3GAoyRqBl46LMQ9+vAdoHPTzYONCUqVqBprwXr46cPuk?= =?iso-8859-1?Q?p/g6lbS/R6WvvwTaLlBo71izU21mSNXX/0ULF2a33hjsID5xxh9aLcFniY?= =?iso-8859-1?Q?7VM5CzYvgujz5Xg25Hfjx9Oh9XMnU8S+53M/l7pOkwdCveS1CyatsWOD6i?= =?iso-8859-1?Q?7VPzl0lnteDWBOMh6LI0AQ614npup+iC90Vl1Ot/5VdQaANmgWOrtiz2tU?= =?iso-8859-1?Q?cvnSIoShCcs+U/gDP0VVj6OO8cJPLWpiq1h0Wg57UY8X57Eouz7gMOW9/K?= =?iso-8859-1?Q?w9a2wVTv71TZU1v2t7mVGD2KFO2MJW575twYm7FH36ISXF2jA/XtSmuksC?= =?iso-8859-1?Q?Fvu5YqgjpCNZ5fNDMhES0SzR6YNR0AvzE8ZZC8gRyVMSaNFVzbvH5yrrZt?= =?iso-8859-1?Q?hVN2C3+10Us+DT2H9MZbdKNo9otF4/6uzMl1pQdN7cYA2exR/wVeGYEzAK?= =?iso-8859-1?Q?B1u2zbtZbRhdKyh6qZ0b+coHKUQGwa6xky6VAXiS+7AprryL/TtQNi5mfv?= =?iso-8859-1?Q?Qm5i0bPbpgOyyxs3WFP9+veilxjgBFqAu8puIszXz+ykSzyXcl/B81+LNY?= =?iso-8859-1?Q?rHNMhWi02HHkwzQTm+HT+GAFdE8T3sphRofaspJVc0DTdao4KapRzPAgRc?= =?iso-8859-1?Q?5cIj4ie+M45r45IKSMEdoLzrpl+PXWnLk+GYSAQ3/cHgc0VCGkzaWhwRQZ?= =?iso-8859-1?Q?2nAk6BgqEvYfus+eDNO5auP+rAdZG+BQEgXs+UP3DEXrB4Mfvy+uCFy0Uw?= =?iso-8859-1?Q?xDWeDSF2zJNGQDChwoFEox3zylaDxkb/QjPB1NL06iS3srSPhXiIyxBnwr?= =?iso-8859-1?Q?Jc+FQBplWuZvz017iNijloeaQKiHyH6jek1sSskfqZq98OxKaerc1Ykhv9?= =?iso-8859-1?Q?/4MOSimLDZQOY9+EDueya/h4L/lp+PQ9ZYf5m7o0XrURvY45DZNmQyqXoK?= =?iso-8859-1?Q?nO+vg/8Y3DtiORql0qUirK+cew4TdTT19ja3wfIJDWAqWoVuRxXRpOcYt3?= =?iso-8859-1?Q?3hHOB/Q+uzbqv/ULBhLEsDth1iKDNlRLZowDQ1wpXTFFhbulSN0rv/Lu1S?= =?iso-8859-1?Q?1NileOMP3Pw8kN71twZAe1DnIFAfa/hN0JAyCJzadb0RswLqxn+FNAYa5D?= =?iso-8859-1?Q?8EyJNrxY2ZLxM/nUpC/tOUpKx+2gLPX3LwyKNMmgW4j/ZmErjMUSJYL9EU?= =?iso-8859-1?Q?X78+W4gaIsfcxVWn+oxG6ZOaC0gvEh5awV6tl2FsJfjWChnG4We61DUh4U?= =?iso-8859-1?Q?9BKj+s/kH+Ss/znyt8jZgFGb6yvVZrKVx9iOfgQnlBmHkgodeo39en7VQW?= =?iso-8859-1?Q?TP8/dCd3Z0yHXHc0zskPSeDFd7jeonx6KcEZr42t+717PNe/ZKI+j0+w?= =?iso-8859-1?Q?=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: df156076-c07e-4b93-1517-08dbc66691bb X-MS-Exchange-CrossTenant-AuthSource: CY8PR11MB7290.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Oct 2023 12:20:03.9244 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: FmQ81Adwm+RTunuXLkxnyk8gjhmnkos5iNII5viXMDnvHgokzwJJl560HoNm3gXnh6r510LC48KGuG9vqVS81lr8cwLE/rwDWWESkk8C+ts= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR11MB8326 X-OriginatorOrg: intel.com X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> Errors-To: dev-bounces@dpdk.org On Fri, Oct 06, 2023 at 02:15:00PM +0200, Mattias Rönnblom wrote: > On 2023-10-05 13:51, Bruce Richardson wrote: > > The event structure in DPDK is 16-bytes in size, and events are > > regularly passed as parameters directly rather than being passed as > > pointers. > > When are events passed by-value, rather than by-reference? There are no such > examples in the public eventdev API. > > To help compiler optimize correctly, we can explicitly request > > 16-byte alignment for events, which means that we should be able > > to do aligned vector loads/stores (e.g. with SSE or Neon) when working > > with those events. > > > > That change is both helping and sabotaging the optimizer's work. Now every > stack allocation needs to be 2-byte aligned - in DPDK code, and in the > application. > > The effect this change has on an eventdev app using DSW is a ~3 cycle/event > performance degradation on an AMD Zen 3 system, and a ~4 cycle/event > performance degradation on a Skylake-generation Intel CPU. > Thanks for checking - this is the sort of feedback needed alright. In SW eventdev we copy events around alot without using pointers, so I felt that alignment would be helpful to avoid issues with events spanning cachelines. However, since it has negative impacts, I'm quite happy to drop the idea, and keep things as they are. I'll mark the change as rejected in patchwork. /Bruce