From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) (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 A4795383A5 for ; Mon, 14 Apr 2025 19:47:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=205.220.165.32 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744660064; cv=fail; b=MxqlGHnbRMGk1osWSu/t2PUYUlVh6NCuWEu1L1fZTjkoFnS1TxCewtOd691RoRHH/j+aePIJPlNCvlrEFK+XoVAp2kCAIcZlhWKu4O7/YgBttLFneGNTx78FIfxOStxf6Im1dDLtGuYgXwc45Zk03TycYUmNlOH0yxgRMhCNtP8= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744660064; c=relaxed/simple; bh=e2m+zlnnV63qsvpzBf/xpGrLA7wr7pBwgHShBUd7XLE=; h=References:From:To:Cc:Subject:In-reply-to:Date:Message-ID: Content-Type:MIME-Version; b=Q7ge7SDrUAEasXB4gW2jRPIqZaPMeZjC27DKR1tIPei5ZmExOLFkE8YgQ0vHLbxG1vTG7UnLcIWEKDYRC7a7gDCldAxIcSLUNSW0NAKlJ1Z+8u7X11QX4JBdanLhRLuWtl+XZPxNDE9x97hipc92AXY64JohIunN9aosdV5SwAE= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=SFkquTGh; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b=aqrIyDeh; arc=fail smtp.client-ip=205.220.165.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="SFkquTGh"; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b="aqrIyDeh" Received: from pps.filterd (m0246627.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 53EHW1JF027755; Mon, 14 Apr 2025 19:46:46 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=corp-2023-11-20; bh=eRXksl8rK3rY33vxFg wTXG2XDNkHHd2AcroSQ6bECX0=; b=SFkquTGhv0kati6iuPJLUXGU9M7Cxe78QN 8ytMSNYbQpIlL7LMxmlw6zkFOdAXwtx+X08NomxClZ8tShmyvKNrzCs1h5K7f46n 5fij5TIUn1ogE914WiK0lHsCoDGFJNd9N7esUWxvxFw1ZCtJYG7G3Zvd2nUay6sk 3CKP5uPas0SOxFg9kVib1rGfQTh2JPu/D2b3jrX7e6nz/rzajqK6d8LuMin+YRst 6cXEWQgfwKSYNRVnlbCJWHi0J3vM7HOFaioqMHVlsw3M6YP2B0EQoDzZlxVRNdC6 +fjxKO8k5OljzsBUZUjDB4Cwgx7AejAOfYjQSQF+R3IFjepmuDlQ== Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.appoci.oracle.com [138.1.114.2]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 4616uf09s7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 14 Apr 2025 19:46:46 +0000 (GMT) Received: from pps.filterd (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (8.18.1.2/8.18.1.2) with ESMTP id 53EJH4s2009250; Mon, 14 Apr 2025 19:46:45 GMT Received: from byapr05cu005.outbound.protection.outlook.com (mail-westusazlp17010002.outbound.protection.outlook.com [40.93.1.2]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 460d3gyeu9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 14 Apr 2025 19:46:45 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=TW1bOcXnSoTacPengCfCRXI1dlp6tGWnK/iQuYPN/kqSJhnM+pZAse9mt6vCqQpoOimVAUDQa8IJI5wbDEf+bkdjftlQz8GtHI23acFR6FVLcZzFeqkHEukL+9KWWuJ3cgbwuAB8twslwGEatjvq66MxvRGd44K3vEsGCkMqZbiUiJimRIE+1Bw6IsdZVyYiPM9PaRf99Y9yACgzru53LYmOn4pm9gIDWRNVjtuyBrprNq6LYykcOS7VtLUx/bqCsyWLGoPZRg1QEfPh58hnkByl0HKwWGerlv6L+r/rq9tH379zSPF4tH0yysp0hsZ0W4fISJOIFQYtYX+4F3WbVA== 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=eRXksl8rK3rY33vxFgwTXG2XDNkHHd2AcroSQ6bECX0=; b=BeJl6jbg6rmdOV3OsZn47JUorH52sL5nZWhvEbn/7Rwrr9aXd+mbtdSLXspGNAFXYTOWBubUkPQo+E3rFY+4+y5cnZ2hLFyb03GxCe+bjspV+u8Pdx6gMVO4jqmxT4DVY51hBQ3oaik0LFtk8LztjUqPKPkK/zvTy9yYnvydXJTYqoqCRt5SxfY627rHr3qXSdDOqf2HjAz2KXQuIzXWWxc8lXSKnLRCDZMAHlU3yGImxAr5qBOb7TutlZ3uFn/lEq2GvNdIZaZWR/FkHkO/egj34hRN5PD+ptgk2tncpQEUXETNZVD98FyitSTv+ugYinzAF/QTF0aQBbMJWC5Aiw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=eRXksl8rK3rY33vxFgwTXG2XDNkHHd2AcroSQ6bECX0=; b=aqrIyDehlWElEA6d2z7C1H2Z7O8AeydhwZyNIJCqJoetzEroBs/1xPVoR19mNWbQV1KI6rfyYYEIo8q6dDA1LfJ1DzrPGagIP7ArJYNbMPOXqp9Rls5C+Fn9oWAWl5EP8sq7OuRGg8IGQc6233y3ls5aVk0Y/QAgkGkM75GUses= Received: from CO6PR10MB5409.namprd10.prod.outlook.com (2603:10b6:5:357::14) by IA1PR10MB7141.namprd10.prod.outlook.com (2603:10b6:208:3fd::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8632.32; Mon, 14 Apr 2025 19:46:42 +0000 Received: from CO6PR10MB5409.namprd10.prod.outlook.com ([fe80::25a9:32c2:a7b0:de9e]) by CO6PR10MB5409.namprd10.prod.outlook.com ([fe80::25a9:32c2:a7b0:de9e%5]) with mapi id 15.20.8632.030; Mon, 14 Apr 2025 19:46:41 +0000 References: <20250414034607.762653-1-ankur.a.arora@oracle.com> <20250414034607.762653-2-ankur.a.arora@oracle.com> <20250414110259.GF5600@noisy.programming.kicks-ass.net> User-agent: mu4e 1.4.10; emacs 27.2 From: Ankur Arora To: Peter Zijlstra Cc: Ingo Molnar , Ankur Arora , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, luto@kernel.org, paulmck@kernel.org, rostedt@goodmis.org, tglx@linutronix.de, willy@infradead.org, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com Subject: Re: [PATCH v3 1/4] x86/clear_page: extend clear_page*() for multi-page clearing In-reply-to: <20250414110259.GF5600@noisy.programming.kicks-ass.net> Date: Mon, 14 Apr 2025 12:46:40 -0700 Message-ID: <878qo234rj.fsf@oracle.com> Content-Type: text/plain X-ClientProxiedBy: MW4PR03CA0040.namprd03.prod.outlook.com (2603:10b6:303:8e::15) To CO6PR10MB5409.namprd10.prod.outlook.com (2603:10b6:5:357::14) 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: CO6PR10MB5409:EE_|IA1PR10MB7141:EE_ X-MS-Office365-Filtering-Correlation-Id: 5758ddb6-4dfa-442a-7586-08dd7b8d1441 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|7416014|1800799024|7053199007; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?392LUhoB8yXuCkKpWg6HvoSZjG8x6RuDbvs0jLQsWUach78Ra7Ng44oQ9Lcp?= =?us-ascii?Q?tvrhdG78FScqjb3pG25cJMAtMrCf5JzDzWFpFbN7eCJ/B2Hg+mdcbRNd2yz7?= =?us-ascii?Q?Hr5Fjm8sMSQn5+r8/JqPCF8VtzD9OVyqtlvv1H2bfbdmD2jUoDBx0oZUN2E5?= =?us-ascii?Q?rdbF1cVenx305aRzP5OOHWUKh22oOS2nXzbgYq0l4rjeWIboTTShGHBRQUuf?= =?us-ascii?Q?Wq9C6MX1fZ1UNZBKDdTuLYL4s1JRofCy/cWG89mjBfb1VHKX1fsWd5IU+/wo?= =?us-ascii?Q?vZaub9Re+w49aw/sjwu3jUMIMkAJ7DezN+q6usM/iLg4ripOATF2ql/QPA4z?= =?us-ascii?Q?5TtDifjv1vzQJHzDKfRGeiP0ycNAdGJo6crcg4ZFr6eIhQq0lk5gnDsRx0uc?= =?us-ascii?Q?KslZDy2wIwgFsi1Z+dvhhcqa2ergx0m+j994L5wslyaroa70tDbyIvKTS849?= =?us-ascii?Q?C7VXU8pfZ1I8CTXH4ZL0SHIYfi4Cr8RpkKjYVcG2WO5UfRT/covvMByuSKNW?= =?us-ascii?Q?+8zz4xC6VuYsDUgqCn/S+U5AckA4IxH9RI60iAv+W1fr/lk9RZnuFgUUZvcb?= =?us-ascii?Q?r1YPf6N/KZzc02BJJAxSkug7K9x2Y/o0gb9jcuyfDCjI3tDZz+z1D/rrIRFm?= =?us-ascii?Q?iAMagxKdhsqFNsEMfw+WRpvdwNB7BYgUN3pYjDbf2drvmZHhBDQhiXz6PeXV?= =?us-ascii?Q?t2N3J33jb4M2TRf8VWI8vb4G++vDEnlJQZureEUGM8lMTaFbkpjSrD9uiKxQ?= =?us-ascii?Q?r4bexqxy54Eora4UAwY0QsxuTZaXNr0eqSNZCF//heualoJkO9Akgx0PEodD?= =?us-ascii?Q?cgS7F69+FQy1RJy0PMldHnBhj+ftRcpRhSKg3J+Oei4Vg9kLTpODSqwjpbbF?= =?us-ascii?Q?LcFhRkFH9B3MIgOUMm7Fd6KUo/cw9lb1k2RhxgIot0t4oCGakgs/7TExA1ph?= =?us-ascii?Q?YvcQvLhkxp+RiAmIdQshwYrT89vu7i2Dk05+cZHhjGD1lqWTQpMgNl8jB3Nj?= =?us-ascii?Q?whN7k59ro6+uJ2CkVIjg8ua/iiFBSTAhrgu6iQ6cvcZPvYUsTBb5dnKzbN88?= =?us-ascii?Q?5cAR3Fnk7Sfz88dVtJZC/3upNXwA/W2P9GP1+JLP34t8TB742Wen4m+lQK1v?= =?us-ascii?Q?Xv3vXG9P/VswqKHvosxb+np8SeISnBdQl2GwXCqrvUzn4Bm4Ccl3rEUVv339?= =?us-ascii?Q?lKf2Z4C8MPtyndZiZaQjDhb2zblqZNg/e98I3RHj9J6XoRQcecsVSTZCD62L?= =?us-ascii?Q?NA2Nlaiw6DDH3tqNDUo85qFPPavWoIfaawQ+lIyzGFDSAGfiLo4PhVZHCOvv?= =?us-ascii?Q?TSB8hqnNAQ4t1zce7hPhKvKRzhMbonpGLLCrUZu7eSr/vYl1R5mT1qUwWUTe?= =?us-ascii?Q?/5G3XusOjHOR6h1ancqV85olnun+KOCWnHi8eFQyj9MevYrvoA=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CO6PR10MB5409.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(366016)(7416014)(1800799024)(7053199007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Tw7v8lquzkZuufAwqb/aFMzat0Iq+shybKF8a3VEti8wlB/PZLbgEfIKJv3p?= =?us-ascii?Q?IScc3eTPT82NGh2NlEByzURD4rotqNrWtA/ilPRYp6VgNBGh2WdZsPgSLUEH?= =?us-ascii?Q?GQ3zCtqhrHA2wl81i2qyuTSeZeczSNtSyzJPTp+QJGVqoODEO1GrQVg5pDRk?= =?us-ascii?Q?C5Sa9n+C90IFNKrZ235beC0Tj6co+R1HumB6C4bmlcodC/ECYqJpYzzeFORq?= =?us-ascii?Q?1JwDFhOSv9CiP414Vag4oFkeRSctI61Dp9kp4pCp/Kt/JgAf9ux7k2dbXndU?= =?us-ascii?Q?L732l9zGg5i7LFWWNgJo/nyHOEptUknmKnQxrppJPityGytpvTrBd5nPRGN/?= =?us-ascii?Q?8/4MboaVOJsIEYlFxvVmVrNhQiUanYBRrfG/lkoKLi8PIfrqYQPDTFwkc74L?= =?us-ascii?Q?Eu9F7K8bvugNCXtzaZLDUwa/fVm7KCNtnAjqoHEZFePt8m1v191+DgTTaQ4K?= =?us-ascii?Q?xN5WaSRRKiXsON8SR+Nj2y6vEPHsGsw3H/zMsVFJasZM/mjpen5+NIJvoST/?= =?us-ascii?Q?hz9BXjalpbtW6GY+MWTjor6/mESllw1GkTQKiVB/ZrZwrvRrBfT3efwG2lRf?= =?us-ascii?Q?d+Ie3zAOCVH55lKAiQ5kSXBcLpEX0jPjX0fOE+JfStG9ZQILERPJr2zkWcZl?= =?us-ascii?Q?kWTf98W4FDDgIpRMnq3wka4VoWo/sFiIxPhGR7X6hXi8oV7oazYJMw8yQrzn?= =?us-ascii?Q?Gnur22ooBgh4u0PyFlgB4TCgdVUgYOpp2KqPGl880BM0MCerqgSmv5VjsMTz?= =?us-ascii?Q?9mfyDz5y46RvqNW9gsxkXT6/Bcrr9MR0ub7UsAkABVTbLnzzt7khdZFHrFoZ?= =?us-ascii?Q?Z5PdMGhsLVhHxXRzvo3naxoMJD1Ym1IyzGJUFlfpQuGRZ9Cc4+Mkf6F/Pcdr?= =?us-ascii?Q?glCS7u4LeJvFimGnplP8wFasMw5xUVhelgDB2Q4AH6uQ6HE2x0s8UyGTNdbB?= =?us-ascii?Q?iGa/AiUiLRbg8aydhuZ5Mdlcns7YQO5XnqpvEm8wbUlFVcrk0MaU/63Pm/kX?= =?us-ascii?Q?QF6ixgpTr4E3dKSbEkTPVXutmIInzpDyC9UqwhgFnECBl7hlmpMl+38/3sn/?= =?us-ascii?Q?DGIaUCXhqxgdpuRBV5WvXrAqemdLnJeM6KiFiwsMQaCYOwFNoH4B2uO7geBZ?= =?us-ascii?Q?PZSjVtKpMhTXOYb6FF3+GGQK/oKu6zlgri6/uwtO1/ejuHEutZfMD8uV+KDs?= =?us-ascii?Q?dJ5yUfxmSfrz7ZBYMSrGQhltmlZiUo/djuddsAzhhlWADfzqWdI0tgN0P8Rn?= =?us-ascii?Q?0ot3YcZU2HfpWf0eyih8OzpnonxU1N6j3J4AGQwa52IM1gb4HJxACUaLetdZ?= =?us-ascii?Q?RydEEyx7deBUtKCNxVGleU4d4fXXGw7rZn+wWsqVUOefsR1QqrwPt/LScxa3?= =?us-ascii?Q?/L62WHG2J/ViNc6A9yUoJ5i2UOLgdUaMVnCUS44p7QGMWx3ktLmC074cAMIQ?= =?us-ascii?Q?dWg46sJQKmFcXgtoN0182mnGBwsCWBE52Z4vJJtZG3gJBr11qwAJPS4cr/gI?= =?us-ascii?Q?sDrm5uLLnp1ALqrzFV6A4nM9bWr9ISFNFXtwREFWPBQXCldxGOAnwab/2N6L?= =?us-ascii?Q?PuihLVePkuWghLgoiXfZzBKQWO5vD5XwAQrBeBLpJ2J0L7LQF1b57mCipq9J?= =?us-ascii?Q?tw=3D=3D?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5758ddb6-4dfa-442a-7586-08dd7b8d1441 X-MS-Exchange-CrossTenant-AuthSource: CO6PR10MB5409.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Apr 2025 19:46:41.8466 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 9Ie8j7RKC+Fr6zXG44AwnH6kxxCpV2i5o6yhlJ0uloevEjQDrYiJPzSfitxQQdR5Srpfa7KCv4p7DYLKwHx2fDQpnKTKyIta8EJaNOB0cSg= X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR10MB7141 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-04-14_07,2025-04-10_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 phishscore=0 suspectscore=0 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2502280000 definitions=main-2504140143 X-Proofpoint-GUID: Vu3yTvd5ZxH0RkXKZhMxr7jqZ-2QDQGw X-Proofpoint-ORIG-GUID: Vu3yTvd5ZxH0RkXKZhMxr7jqZ-2QDQGw Peter Zijlstra writes: > On Mon, Apr 14, 2025 at 08:32:29AM +0200, Ingo Molnar wrote: [ ... ] >> > -SYM_TYPED_FUNC_START(clear_page_orig) >> > +/* >> > + * Original page zeroing loop. >> > + * Input: >> > + * %rdi - destination >> > + * %esi - length >> > + * >> > + * Clobbers: %rax, %rcx, %rflags >> > + */ >> > +SYM_TYPED_FUNC_START(clear_pages_orig) >> > + movl %esi, %ecx >> > xorl %eax,%eax >> > - movl $4096/64,%ecx >> > + shrl $6,%ecx >> >> So if the natural input parameter is RCX, why is this function using >> RSI as the input 'length' parameter? Causes unnecessary register >> shuffling. > > This symbol is written as a C function with C calling convention, even > though it is only meant to be called from that clear_page() alternative. > > If we want to go change all this, then we should go do the same we do > for __clear_user() and write it thusly: > > asm volatile(ALTERNATIVE("rep stosb", > "call rep_stos_alternative", ALT_NOT(X86_FEATURE_FSRS) > : "+c" (size), "+D" (addr), ASM_CALL_CONSTRAINT > : "a" (0)) > > And forget about all those clear_page_*() thingies. Yeah, this makes sense. We don't call any of the clear_pages_*() variants from anywhere else. clear_pages_rep() and clear_pages_erms() are trivial enough to be inlined in the ALTERNATIVE as well. Thanks! -- ankur