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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0194DC76196 for ; Fri, 31 Mar 2023 03:37:03 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 58C6D10F0D1; Fri, 31 Mar 2023 03:37:00 +0000 (UTC) Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2BBFD10E009; Fri, 31 Mar 2023 03:36:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1680233817; x=1711769817; h=date:from:to:cc:subject:message-id:references: in-reply-to:mime-version; bh=ITeIKSCZb2ML9jNy4q96p8GX9m674UHPjhUZb6Aif/g=; b=Rso0WoKugcSh6DG5hEZSpglAxb7HdkpVEya13K31GELWdXAqtjCCVOuk EsgJ2PQZcJdJTv/QESQI2/73ygtw4BLtLclOB5zIYUxIW4v80rtHAuhzp siEK1yQ1mHE+M2M4ifdKLqfag+UXItMMttB52Lvz3u/ouEDrixNIuuA+j wCKeOnp3zo3lgw5YDPmS/M+x7sR9ywsnrjQwo1mwyn2TUkHTX+D9JkLDb cVuVBLjxXL4Rn6jLdDYLNg6SKnkmq0Om9jKqO+n83W9lrEzexsaT8dGmF fzkogIyzBU7lNBM7SivW5KU68CwDunwtXJXBkQBxtWTaUpqQOWHq/B/uf g==; X-IronPort-AV: E=McAfee;i="6600,9927,10665"; a="369132307" X-IronPort-AV: E=Sophos;i="5.98,306,1673942400"; d="scan'208";a="369132307" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Mar 2023 20:36:56 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10665"; a="795945664" X-IronPort-AV: E=Sophos;i="5.98,306,1673942400"; d="scan'208";a="795945664" Received: from orsmsx603.amr.corp.intel.com ([10.22.229.16]) by fmsmga002.fm.intel.com with ESMTP; 30 Mar 2023 20:36:56 -0700 Received: from orsmsx610.amr.corp.intel.com (10.22.229.23) by ORSMSX603.amr.corp.intel.com (10.22.229.16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Thu, 30 Mar 2023 20:36:55 -0700 Received: from ORSEDG602.ED.cps.intel.com (10.7.248.7) 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 15.1.2507.21 via Frontend Transport; Thu, 30 Mar 2023 20:36:55 -0700 Received: from NAM12-BN8-obe.outbound.protection.outlook.com (104.47.55.172) by edgegateway.intel.com (134.134.137.103) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.21; Thu, 30 Mar 2023 20:36:54 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=AKjZneCUOCxJa4V/aOpc8BpV2FEvRrZbcL3x8h5Tvgejcj4oD0ZxMUqSh1HlVLug/oofYGpAvgoIZfKScYZjcvvTpGZuPsLcVwNJ8DHZBZ9H1x/FFvM7Zm8aNSIKsuw7fADwIaHA45+vC2jsZ7tbDVTUtgM0D3UPH10fm9Ddrg4TjrTkELDhdzh8z7gDRQcqSBJzUMyF3DoGVLoTrkO6cq3+7EUD+84wvyP73wDJOFkfhR/Svkn68rgX5edhaFcWkNCmSXpiYSEZ/E2cAEVEPxF3t8PPMpQAEvZ2HMXbNaPkkxuEq6FJxTNs1Eg3A5QlmukI2Ib0aqeBbvMOvYcv4g== 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=l9rVXGSjG479BtmK2inO00NUHDmZ08YV+7vJmpcFYbE=; b=FGdjZXyXUEijsd6uBtC7snvQ9P8wz3I5SbMMfdu/IrREec2ro/1eMmysYebHtdmIbkv2aKZ0O+UsIa/am7rOTe9pTJ6PIcq+V4AQyfAA9MIPRY1h6XVBDcEi43iDRP6BRowrc5WP1L6X21ZtoQp1evMIPgueB9pZtoIRivQ1V6Mu1HToU+zLEuxD0ZJ4Q/jyvJACAo1vPG9BFh0lvEXYlhZjnXRM1WDk+IcLMxqpvnpWoQhg0pPQb3lkvTiMvxDEhHD0PYZwkdI2E6bcEZckzH2976eZaY5qB0urfIFXubh5zxie0356jb5aE+TPXE9MNKOSTQI6lgkMNx7+CfIkZA== 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 SA1PR11MB6733.namprd11.prod.outlook.com (2603:10b6:806:25c::17) by BL3PR11MB6411.namprd11.prod.outlook.com (2603:10b6:208:3ba::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6156.22; Fri, 31 Mar 2023 03:36:49 +0000 Received: from SA1PR11MB6733.namprd11.prod.outlook.com ([fe80::c5b2:6996:5aee:91db]) by SA1PR11MB6733.namprd11.prod.outlook.com ([fe80::c5b2:6996:5aee:91db%5]) with mapi id 15.20.6222.033; Fri, 31 Mar 2023 03:36:49 +0000 Date: Thu, 30 Mar 2023 20:36:44 -0700 From: Ira Weiny To: Zhao Liu , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter , Matthew Auld , Thomas =?iso-8859-1?Q?Hellstr=F6m?= , Nirmoy Das , Maarten Lankhorst , Chris Wilson , Christian =?iso-8859-1?Q?K=F6nig?= , , , Message-ID: <6426554c3db9a_375f7e294af@iweiny-mobl.notmuch> References: <20230329073220.3982460-1-zhao1.liu@linux.intel.com> <20230329073220.3982460-9-zhao1.liu@linux.intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20230329073220.3982460-9-zhao1.liu@linux.intel.com> X-ClientProxiedBy: BY3PR05CA0029.namprd05.prod.outlook.com (2603:10b6:a03:254::34) To SA1PR11MB6733.namprd11.prod.outlook.com (2603:10b6:806:25c::17) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA1PR11MB6733:EE_|BL3PR11MB6411:EE_ X-MS-Office365-Filtering-Correlation-Id: b01cc12b-6b1c-44c3-1924-08db319928a5 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr 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:SA1PR11MB6733.namprd11.prod.outlook.com; PTR:; CAT:NONE; SFS:(13230028)(346002)(136003)(366004)(376002)(39860400002)(396003)(451199021)(26005)(66946007)(9686003)(921005)(7416002)(8936002)(6486002)(83380400001)(6506007)(41300700001)(66476007)(316002)(2906002)(38100700002)(54906003)(5660300002)(6512007)(478600001)(86362001)(186003)(44832011)(6666004)(66556008)(966005)(82960400001)(8676002)(110136005)(4326008); DIR:OUT; SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?zNVHNJctuHkkDWe0lKDFm+AZSt8f/aSe0WfX0bYsKsRiAbdE/PkKZTrBH55B?= =?us-ascii?Q?boBsCG9WVAry6apmf6mMhUYv5SGg02673HMsF6tDs8UBz60b09EFFgjxv9d6?= =?us-ascii?Q?i1WFao+YwqqFoWZgpayKV0NR0tnVRUVyn0Olt1KZnoL6Z16gN+FXjoEpHV3E?= =?us-ascii?Q?0EWy3wzpSMDdzOOraZhartchuKLG6IEbPIcyONLGfp47Hi1v3tSjsJRUXBek?= =?us-ascii?Q?4+8mNEhe3IWx3wo6HDompUuPCbSSP6kFB+URng3sS3kWdbMxLeuj5n1coNP8?= =?us-ascii?Q?r1LsgDw+VE8gsOY/WT8IJz8OeIaDW6ZdWgMAkdSaHyEoGAYumRFZvKGidB/1?= =?us-ascii?Q?kZloObge0/PczNrsNrcZk01b/0sA9/U1foDy8Y5n5LQfmdQERNhzF74ZY/VW?= =?us-ascii?Q?TtJ+ZPzMUr3saIy/LFqsGtjLJWUH77mdIUwqxvGj/1TWLXXqQDDb8tztsMiI?= =?us-ascii?Q?Udxltf7tQ8ueXEBGaVtftJCP9bRzmnVde1XbGlHMKLQbLkuT5YMP64T4uM26?= =?us-ascii?Q?L0Oxu/gTWozADlG+pJ61hTO0cafhdM2jbJNBrzBsF0XRboI65GUCUL6k/842?= =?us-ascii?Q?zty4hcnzeQksrFt2BgHtWmLXXAtEAgi0uVhITkzcK9rFrgonewqjWQilH3Th?= =?us-ascii?Q?SEEJGPZA1x21cQEDFYssDN83TBC1Ze+RgOmOZqn3JiwlGz67nsnHHAu2DDNk?= =?us-ascii?Q?zg1XlGZifB77lbEuicLFc6XRs0GkTEtuUMUYKZt6QCE14zM0BcbuoB6vYl6P?= =?us-ascii?Q?T1WAr7YQRZ150H0SCEhEDhACZdBQsRCJXfOHbBt0TlrKeQ16EFJE5LC10/uy?= =?us-ascii?Q?uRZsx8uSlTJXDKBb5BEytWwMz9bPgOvF/CF+bCzCFlVUEGUf35EqT3Vzv0+I?= =?us-ascii?Q?F8se9QYGVszfnLhBm0g8lYbBDJ5hC2IoanWZ2pqT8uVywjGgqnIKxjIYD1f0?= =?us-ascii?Q?3ope22w2AbQlchu29CK0DH9Pmi8vFxQ9qOYZb3k24EFsX0L05R44hIFplfyJ?= =?us-ascii?Q?Uaq7l8LxVI3ORjKtzLr9oyxM53PhBw/xJS9atwKeetZEVyFJcLJZrwZbaA0s?= =?us-ascii?Q?kqnoIT8J+zfOvLFIhSFQsGyNmtbHln8VhNvJFp3lHfZj67ON0BAryEZujXFm?= =?us-ascii?Q?jcAW9GdEJKC3JdUCdiCsTirsmZAP9uhafZPJujFk4BBO5B5MSS7V3oZPLDHp?= =?us-ascii?Q?GRgIZM6PH/V3oRRAZG7dnHryCchp9TEkxMOCJ+k1MySRAoG55aJQ1pl92EoQ?= =?us-ascii?Q?BlzbPslAJYsCLLNfnquJa333xC4HQMGHEp2mnqB/uQabaP6k9rTRdmZy+/PA?= =?us-ascii?Q?+QlEKS4lkTWVElHmbCOc8hyhT3UTlrMVH9/FxzdLXXNHL4o0/NGjJvi5ip4v?= =?us-ascii?Q?P16PCQpbF++WceYxMlBq53dorh2vsQoORT5rkPnQ3MZEPMTkymYMutR35+7K?= =?us-ascii?Q?UnG0ozJAmc/4Nt7cokEVoly7KKMyx3z4pO3siMvvp4YB9ku41IMJuJ0aoRGz?= =?us-ascii?Q?2leGSVeLg4l+4r4LCPsicE3q1n2Ut/jE1GuCeKvO84N9o11VCsvR2ZOthT1M?= =?us-ascii?Q?5iTKjzn9X9vQMx0nu2QK3/8zabAIBWdDhElUhZJQ?= X-MS-Exchange-CrossTenant-Network-Message-Id: b01cc12b-6b1c-44c3-1924-08db319928a5 X-MS-Exchange-CrossTenant-AuthSource: SA1PR11MB6733.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Mar 2023 03:36:48.7428 (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: Q3zBTSqK0GlvSmDc3ftQ11OuHn5dizsrMvIEgF0N8NGH3D2Uo3sKH2O4EZvu3uCgehIR0U8j1PfjEE9i/+Ll9w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR11MB6411 X-OriginatorOrg: intel.com Subject: Re: [Intel-gfx] [PATCH v2 8/9] drm/i915: Use kmap_local_page() in i915_cmd_parser.c X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Fabio M . De Francesco" , Ira Weiny , Zhao Liu , Zhenyu Wang , Dave Hansen Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Zhao Liu wrote: > From: Zhao Liu > > The use of kmap_atomic() is being deprecated in favor of > kmap_local_page()[1], and this patch converts the call from > kmap_atomic() to kmap_local_page(). > > The main difference between atomic and local mappings is that local > mappings doesn't disable page faults or preemption (the preemption is > disabled for !PREEMPT_RT case, otherwise it only disables migration). > > With kmap_local_page(), we can avoid the often unwanted side effect of > unnecessary page faults and preemption disables. > > There're 2 reasons why function copy_batch() doesn't need to disable > pagefaults and preemption for mapping: > > 1. The flush operation is safe. In i915_cmd_parser.c, copy_batch() calls > drm_clflush_virt_range() to use CLFLUSHOPT or WBINVD to flush. > Since CLFLUSHOPT is global on x86 and WBINVD is called on each cpu > in drm_clflush_virt_range(), the flush operation is global. > > 2. Any context switch caused by preemption or page faults (page fault > may cause sleep) doesn't affect the validity of local mapping. > > Therefore, copy_batch() is a function where the use of > kmap_local_page() in place of kmap_atomic() is correctly suited. > > Convert the calls of kmap_atomic() / kunmap_atomic() to > kmap_local_page() / kunmap_local(). > > [1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com > > v2: > * Dropped hot plug related description since it has nothing to do with > kmap_local_page(). > * No code change since v1, and added description of the motivation of > using kmap_local_page(). > > Suggested-by: Dave Hansen > Suggested-by: Ira Weiny Reviewed-by: Ira Weiny