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 X-Spam-Level: X-Spam-Status: No, score=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC04AC433ED for ; Tue, 4 May 2021 00:02:09 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4911A61185 for ; Tue, 4 May 2021 00:02:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4911A61185 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:CC:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=eaoY0nw3iWIpsNkIku9bp87ZucuCUfxJZ5U3bp4ojXE=; b=SqFGP3USM6WW0IwoNNzP8mfD2 JElPCRoMBVbbEG0gae252nzk08jN3i0MepevxlVqr7bKUFIsgbok1M9F0uqn6Ozy4ssW7GhaJBfyt S0kepdnKEvWanpLjzVUQkghl4SW6UgNMU7YEkarmscbdq7ONWNt7zCgmXZ4+iUQVNJ5aFYu9C0f46 8hm+G384yPHQw6McJ5FAgvePd3dXP/IScPXYT04n30Jh/oIyW/DREE5uRb8Q5S3hGnLw1hnExdpmM ZKSflC8go/7CZ3105ZpS3MC6BCanuvzmPJVOAcyLTfXHrolGOxYOKQN0GdyVNnC+ioWqopo4Mnfaq qGbUDihdQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1ldiVX-00F4yR-Oh; Tue, 04 May 2021 00:01:47 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1ldiVT-00F4xx-7x for linux-nvme@desiato.infradead.org; Tue, 04 May 2021 00:01:45 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:CC:To: Subject:Sender:Reply-To:Content-ID:Content-Description; bh=G/cKLKtzFGu2aBmD9V1JWghE6lhzzVpZbjGGqXGgfDE=; b=Ef7KzQExwjysf5zE1uzO4ZUkvw NyAR4E7Rp1ANonpgZdUdo3Hdi/jFvRbgMw91krMoaaTvzG1Qvij0cXSy91+teZmO74g2tY53otPL7 t7WbgGQd0MyyyOF4ImTVVsNt2+4UJE7db/dBF+zYgOdldtE2VCdbyJpEsV7ZzKPVZ7rzojsMJHbUb XnGeglFFcLrE/qkM8JAwSLIOVHjM0Wi5nUoLFUjLjwii8xi2YBkKmqJNuAgjPyaFlOgoOtAOP29xq pQaDbWMP7CmTzuQgtBX8l9BNzIh5fXwPoQoSnNvJelclti7eLe4NJLhNLG/6tMg2rcR0JrlFpf0/2 1NW4Tc5w==; Received: from mail-bn1nam07on2074.outbound.protection.outlook.com ([40.107.212.74] helo=NAM02-BN1-obe.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1ldiVQ-003Z82-GY for linux-nvme@lists.infradead.org; Tue, 04 May 2021 00:01:41 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=CQ349dalfFZlLLUKAv+RmQPoKi+23fNIQgQS2ofOamHpPKizm7dnKrisFHG1LB3ubk9IdMId+FwsComDQbU79wlfh4/Zpp+6rwTae3MdFSa7f/KlDCZ1s8A40nVKjPW9ZoUlkpifT2VcZQxj03nYz/ZHv38u/hrci0yHy2Rr2WywuquGiwqx4YRVMr/mRdKkxsAAECgirXqJ3AFLG//yGBFQzoY7Z/6Iz+/LFBEbCLM2iKAqVLBNcV9k/xJNoEFkXsVTDmaiim0s7TLAvPIAaTvYSYOSRvXv33K8bhSaFEC2RoNV06hWLZfTakDWNrjbFgE36JdWWGYdUXPBDixpMA== 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-SenderADCheck; bh=G/cKLKtzFGu2aBmD9V1JWghE6lhzzVpZbjGGqXGgfDE=; b=k5dcz9/T4tpG5GqOJOtrV1I8j77yaPzkGmCEwGKAwoaZFTvETmDvNdy8RdHn3IYz/tfvjI4AwRi5YwiPjmvxFK6j4iN6imKr+6gpq7vV2cP16SaQKheVDftNsyCCbfIbKlSO8e2DdR1R/IoSS5OqvAsbu/yJRfAmkV5GOClL6sEeRtNeOCxS9qVF4kUFmxbAK7C0HXx6+e+iRzEsOYDSb+MyUyNY/RDz5dDfg6vPtnAoxotoVkUmUdF4K0Y6WWtK6IFLHnmoAskwvQ9d+tPZkJMx644fK/6dFHXI772ndGZWrrQUkbq+KF68E99UT3jbUS82xK7EmRhNkKIKfsYXAg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 216.228.112.34) smtp.rcpttodomain=raithlin.com smtp.mailfrom=nvidia.com; dmarc=pass (p=none sp=none pct=100) action=none header.from=nvidia.com; dkim=none (message not signed); 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=G/cKLKtzFGu2aBmD9V1JWghE6lhzzVpZbjGGqXGgfDE=; b=jJ3JtgOsZ8NdK38ie1C/LhBT5lRufdPnz5NSvkEbrYT4JI3vO9GIgBeR3JRhNZhzJeatAhI9ayAIZ6iuAiINzGzyUP+v3NO5+DNdpECxNi7fG5sR3OfynMROkukDho+yd3EdflRpyrywD38cYSQpZXb3W7+p9jG2vSurHcVlFUAE5ZdKmEqKSAu0Kn+1IF9ULvgdbbIU6P5x+57G6QEqh+eau6iZ+4mPLs5ESA7iyeJDCNFH6S+hTaA341K1q7eSCYAlhB3roWrr9niNae6sZL2FTJVHxjDt2ZH3nZSGZCjbs8Dz3icvxNitctTzEVZ/Mqh1lEYPovTbufFhDVYM3w== Received: from BN6PR18CA0011.namprd18.prod.outlook.com (2603:10b6:404:121::21) by DM6PR12MB4419.namprd12.prod.outlook.com (2603:10b6:5:2aa::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4087.25; Tue, 4 May 2021 00:01:32 +0000 Received: from BN8NAM11FT068.eop-nam11.prod.protection.outlook.com (2603:10b6:404:121:cafe::50) by BN6PR18CA0011.outlook.office365.com (2603:10b6:404:121::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4087.25 via Frontend Transport; Tue, 4 May 2021 00:01:32 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 216.228.112.34) smtp.mailfrom=nvidia.com; raithlin.com; dkim=none (message not signed) header.d=none;raithlin.com; dmarc=pass action=none header.from=nvidia.com; Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates 216.228.112.34 as permitted sender) receiver=protection.outlook.com; client-ip=216.228.112.34; helo=mail.nvidia.com; Received: from mail.nvidia.com (216.228.112.34) by BN8NAM11FT068.mail.protection.outlook.com (10.13.177.69) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.4087.27 via Frontend Transport; Tue, 4 May 2021 00:01:32 +0000 Received: from [10.2.50.162] (172.20.145.6) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 4 May 2021 00:01:30 +0000 Subject: Re: [PATCH 09/16] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg To: Logan Gunthorpe , , , , , , CC: Stephen Bates , Christoph Hellwig , Dan Williams , Jason Gunthorpe , =?UTF-8?Q?Christian_K=c3=b6nig?= , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy References: <20210408170123.8788-1-logang@deltatee.com> <20210408170123.8788-10-logang@deltatee.com> <37fa46c7-2c24-1808-16e9-e543f4601279@nvidia.com> <8de928ab-2842-dac9-07ad-a098124f791f@deltatee.com> From: John Hubbard Message-ID: <2a08b685-53c1-3ee4-0ce1-315554d63685@nvidia.com> Date: Mon, 3 May 2021 17:01:29 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <8de928ab-2842-dac9-07ad-a098124f791f@deltatee.com> Content-Language: en-US X-Originating-IP: [172.20.145.6] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 0813dd7d-b8d3-4a4a-ab1e-08d90e8fc688 X-MS-TrafficTypeDiagnostic: DM6PR12MB4419: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:5516; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.112.34; CTRY:US; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:mail.nvidia.com; PTR:schybrid03.nvidia.com; CAT:NONE; SFS:(4636009)(376002)(136003)(39860400002)(346002)(396003)(46966006)(36840700001)(110136005)(316002)(2906002)(336012)(36860700001)(426003)(7416002)(8676002)(83380400001)(47076005)(31696002)(86362001)(4326008)(26005)(7636003)(82310400003)(5660300002)(8936002)(478600001)(31686004)(16576012)(70586007)(36756003)(70206006)(186003)(16526019)(356005)(36906005)(2616005)(82740400003)(54906003)(53546011)(43740500002)(2101003); DIR:OUT; SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 May 2021 00:01:32.1844 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 0813dd7d-b8d3-4a4a-ab1e-08d90e8fc688 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a; Ip=[216.228.112.34]; Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT068.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4419 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210503_170140_565734_F2393DA1 X-CRM114-Status: GOOD ( 18.27 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 5/3/21 10:04 AM, Logan Gunthorpe wrote: > Oops missed a comment: > > On 2021-05-02 5:28 p.m., John Hubbard wrote: >>> int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, >>> enum dma_data_direction dir, unsigned long attrs) >>> { >>> - int i; >>> + struct pci_p2pdma_map_state p2pdma_state = {}; >> >> Is it worth putting this stuff on the stack--is there a noticeable >> performance improvement from caching the state? Because if it's >> invisible, then simplicity is better. I suspect you're right, and that >> it *is* worth it, but it's good to know for real. > > I haven't measured it (it would be hard to measure), but I think it's > fairly clear here. Without the state, xa_load() would need to be called > on *every* page in an SGL that maps only P2PDMA memory from one device. > With the state, it only needs to be called once. xa_load() is cheap, but > it is not that cheap. OK, thanks for spelling it out for me. :) > > There's essentially the same optimization in get_user_pages for > ZONE_DEVICE pages. So, if it is necessary there, it should be necessary > here. > Right, that's a pretty solid example. thanks, -- John Hubbard NVIDIA _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme