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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51001C54EBD for ; Mon, 9 Jan 2023 13:32:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236602AbjAINcp (ORCPT ); Mon, 9 Jan 2023 08:32:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237011AbjAINcN (ORCPT ); Mon, 9 Jan 2023 08:32:13 -0500 Received: from NAM10-MW2-obe.outbound.protection.outlook.com (mail-mw2nam10on2057.outbound.protection.outlook.com [40.107.94.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B3331EEFD for ; Mon, 9 Jan 2023 05:32:02 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=Du161CwoMI2Zngk3jXL6rcZbWM6PJkcSarOxqBqNx7tNl3lmk/1HSRRLWUWvz7Qcq+ly1q+cU/rEV9N2LXwUoq7YYgKMlrA4BfU1LLX0GJr1ahXMBF2feX9rJlpyeYqR/bXEM0xYC6eA44J2l+x6cqBPlDdzMbAAyaq/qctLo5fg7OqHsLfMh7+BQeURMeRK6iOWF4XKaR94OiDtdkL125BQqc7ivxZelxcBerMGL+7RBB1WdY/65IF+uobeTDuTjfERdoCmzZedudUBo7UXWnPNPmS+WAb/wjGmjdxoFzGwHXkZDheaN85Y4kPKPbzchR0EKy7Lt+o7gJYQp6A0Vg== 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=w0J4LimSn8ZUbTM5j1NedghnIFosV0mMEZMKi+xnnuo=; b=G0p3KiEdOJ8RMYWZACrE3s9kZxg5FSxJZUdWcU4Hh8IPkDkg3Y1k6m+IjTGkL6eFl3fhW0NInPKlDQeETCwvlHL8Q8CY7q7aB/4Fubwh5CF0DCsCRJe/M3eiokMzfNazhS5I386hOzPu1tCH5b1Z6K3dlQWbdsxB5bqlpAbTfJCyZCP+hf4efZWO9m42FnvIUtzjaEZJKiSRrmx+rIhY+UQyCCIGdhsTS2ztqEw7mLXfE9x/3OjGBeQDeYwDIDTkJPteYYlsTQOZcdkavqs1RCe9Lr2DUgsOBlHunrIIVXG5Sw7yVJgFa5jmQyL92xmIGJkmqvMJkH0R4XrH9TPM5Q== 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=w0J4LimSn8ZUbTM5j1NedghnIFosV0mMEZMKi+xnnuo=; b=Ui9bhrsLPXwBv5xegBrB9hmcoCKeQKUKlgmLuWgYlnvWZa5wgOZ95p5ry85J5QWGj36QxA5DDD9NRJJLwnxnVTOQdwXAqJ7mLSk18w5Lxiuml+bb2Zp42dz3XI3/ORw0kBuOE1MLa1i18ls0CCwzk2X9XdgtxpHlvUY0Rq/fBsnvkvqh97/0ya87LuGZ1vuQDT8N6Gb/0tXqrteRtJsfZkNGoWHJj/HF7ex3DCWuhb1nzPV7Mo3tzLJxYi6addiIaUMoiH83qeO5wlIcW4Q/Vqum0aaPzXaF8rxUmJJGMpQ1qHi1smhCEps+ZjCSPJdQwC7VXc3w2tGbsfqdN6Xi/w== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from SJ1PR12MB6075.namprd12.prod.outlook.com (2603:10b6:a03:45e::8) by CH0PR12MB5074.namprd12.prod.outlook.com (2603:10b6:610:e1::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5986.18; Mon, 9 Jan 2023 13:32:00 +0000 Received: from SJ1PR12MB6075.namprd12.prod.outlook.com ([fe80::6d66:a4bb:4018:3c70]) by SJ1PR12MB6075.namprd12.prod.outlook.com ([fe80::6d66:a4bb:4018:3c70%6]) with mapi id 15.20.5986.018; Mon, 9 Jan 2023 13:32:00 +0000 From: Aurelien Aptel To: linux-nvme@lists.infradead.org, netdev@vger.kernel.org, sagi@grimberg.me, hch@lst.de, kbusch@kernel.org, axboe@fb.com, chaitanyak@nvidia.com, davem@davemloft.net, kuba@kernel.org, Alexander Viro Cc: Ben Ben-Ishay , Aurelien Aptel , aurelien.aptel@gmail.com, smalin@nvidia.com, malin1024@gmail.com, ogerlitz@nvidia.com, yorayz@nvidia.com, borisp@nvidia.com Subject: [PATCH v8 05/25] iov_iter: skip copy if src == dst for direct data placement Date: Mon, 9 Jan 2023 15:30:56 +0200 Message-Id: <20230109133116.20801-6-aaptel@nvidia.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230109133116.20801-1-aaptel@nvidia.com> References: <20230109133116.20801-1-aaptel@nvidia.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: FR3P281CA0146.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:95::18) To SJ1PR12MB6075.namprd12.prod.outlook.com (2603:10b6:a03:45e::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PR12MB6075:EE_|CH0PR12MB5074:EE_ X-MS-Office365-Filtering-Correlation-Id: a62ae4ec-ffb2-45c1-f19a-08daf245e31a 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:SJ1PR12MB6075.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230022)(4636009)(136003)(396003)(366004)(376002)(346002)(39860400002)(451199015)(1076003)(316002)(5660300002)(7416002)(26005)(6512007)(186003)(6486002)(478600001)(2616005)(41300700001)(6916009)(54906003)(4326008)(66556008)(66946007)(66476007)(8676002)(8936002)(83380400001)(86362001)(36756003)(6666004)(107886003)(6506007)(38100700002)(921005)(2906002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Z5qb0eeyrMmIIblwb1+qKXmH0CDL6G6e3pVFwm0AfHFGjDZzANrJdQzKHVQB?= =?us-ascii?Q?ALHAk3rYmG2DczyRaFyH35kR5InA+N4g44fZHo5fwXWKPutYOFKz/KRYuvSS?= =?us-ascii?Q?UqpucESisg4qxxjsreVzE0UmEH2zHFkohwYf9sebZOFUh9FKG4JhtJOCXqt4?= =?us-ascii?Q?AKImIbUe6/SUTrFAQK2eL8f9DC92KZ2CrUvVGBsZSSroNg4sHqo08h0CEcTN?= =?us-ascii?Q?ocxCuCqfzm0I02v2DE04IJfWoVGp7Z97xTWxaT0FIyujSY0EW77s5ZCsPavh?= =?us-ascii?Q?wZGEl9FV3gltD7h/Wdwmw//nmgLcTzanwl9JbC257d/HvC4LgZCiASf/WXL+?= =?us-ascii?Q?gzt4+V3nCdyQBpHyiI9nqbFeveuiq6Z2MFmZDDnoTI3vebgM52G0K+zsqK0O?= =?us-ascii?Q?SoyQQ+59x1bap4mFHsH3rzWBLz0wn7EOdAMaP1qlmu3+UUV+4LAWnELMEgmU?= =?us-ascii?Q?rwc9NrOmlnpqubnSytcCruURUeiFAxkhhTO/IRP++yLl5W3qqmLMoYmfNaw+?= =?us-ascii?Q?quU++/za38M1Z1slm4cle9adabfgdio5hUtKOZcq3bwUTo07GuHA8/DpbAIP?= =?us-ascii?Q?o+CjW8aAmyQ4m3mpate93sScdObZvaSxXUmTGDJkcb7HV1m76I0nqUmS2zCh?= =?us-ascii?Q?Yhs0UP3sMvYNck8Dy/4h32ihQIqWAzlOt7LaVzXAsZ5f6I++4/5FQ/usrK9n?= =?us-ascii?Q?STnnvWzeqrxysSkJ3dJNsD0BeFG0crbz4UzmCrgMUfsKFFQZYrVcdL7XfzXz?= =?us-ascii?Q?y9INe+lvg/L+eMA+GEIIwIdyv63Gke0TZ2l47yZKhR/39RAejHiGWEGlRu0Z?= =?us-ascii?Q?BsARrDiHW2WT2i/zCAIjTYIJnoo0OxzLAPx6LvPwmgfFLSms9Pm4lEYQyPUU?= =?us-ascii?Q?Nh3Vf/MN9/zhLKRYMomSJfnh8VHlYL+gVoJR2FYGWRqPGOXX5tWKol94BZ87?= =?us-ascii?Q?e2aDVu/rTIxs/IdGRy2MziXAFGW/AP5UV0PPgThp5y8Orsufmnp3ogNkWFH+?= =?us-ascii?Q?4Rfm5UgAV3cpP9F+q35lqB9sKJoqNP2fO+6ibFSJqxuZVkqpPAS4NF8H8l3E?= =?us-ascii?Q?azCHBKPp1gBK+H+uxdOICEge0frTR+39J8pEv+jrXX+qfCXXm6c269O27FwW?= =?us-ascii?Q?mq/mo0MB/eqFkNfoKbJMhmw9gnwYO0q3DW7H+kv16sayUPP6g4lJ7pxvnd/k?= =?us-ascii?Q?0tQcn+XGdJMIx12P0LjS4H4oD/p+hgvfg/ntX9a++43GCwsLErbgGjhBLYB4?= =?us-ascii?Q?d4fL2Acg5fvXEFfhgWgagthe5WP6FJ+OHrumgJse3pxuWL8PqSGfqvkZdlIf?= =?us-ascii?Q?hoW2O/ZlwiGoIhV6Beq5YRmYdu2FjP28lp92+T88qVRnUmRIY8ZYSDJw47ID?= =?us-ascii?Q?MDBm3J/P8Ohm/QApTzq1txKF85maYKllq08loG7kj4d0x42xFwZGuV0tf6yE?= =?us-ascii?Q?LW6LU941AbikG8G0JSPhfVYH/0EELJHE6HfTqVp3vpTJt41FVx0IbRVRpbY+?= =?us-ascii?Q?3QQjUZKd3sMgeWU7wZV0iAlHj3/C3GFW9sHGpzA3BvWydEZZfULCGIia6SdY?= =?us-ascii?Q?OEDt7W+6ES+7wTYqwE8LOXgXqh97qnQCYwJGp1Fz?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: a62ae4ec-ffb2-45c1-f19a-08daf245e31a X-MS-Exchange-CrossTenant-AuthSource: SJ1PR12MB6075.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Jan 2023 13:32:00.4142 (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: 6Ht4u3bP7Poru4mt27VAbMQc4mEpzutvXev76iZlCqgqeZjGXvSZ+9tfWA9/kzmRoBSQnltIFknND2rSg1nqiw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR12MB5074 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Ben Ben-Ishay When using direct data placement (DDP) the NIC could write the payload directly into the destination buffer and constructs SKBs such that they point to this data. To skip copies when SKB data already resides in the destination buffer we check if (src == dst), and skip the copy when it's true. Signed-off-by: Ben Ben-Ishay Signed-off-by: Boris Pismenny Signed-off-by: Or Gerlitz Signed-off-by: Yoray Zack Signed-off-by: Shai Malin Signed-off-by: Aurelien Aptel Reviewed-by: Chaitanya Kulkarni --- lib/iov_iter.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index f9a3ff37ecd1..2df634bb6d27 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -526,9 +526,15 @@ size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) return copy_pipe_to_iter(addr, bytes, i); if (user_backed_iter(i)) might_fault(); + /* + * When using direct data placement (DDP) the hardware writes + * data directly to the destination buffer, and constructs + * IOVs such that they point to this data. + * Thus, when the src == dst we skip the memcpy. + */ iterate_and_advance(i, bytes, base, len, off, copyout(base, addr + off, len), - memcpy(base, addr + off, len) + (base != addr + off) && memcpy(base, addr + off, len) ) return bytes; -- 2.31.1