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 A01C6C433EF for ; Mon, 14 Feb 2022 12:04:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352356AbiBNMEE (ORCPT ); Mon, 14 Feb 2022 07:04:04 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:33126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352297AbiBNMDy (ORCPT ); Mon, 14 Feb 2022 07:03:54 -0500 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31CFBD9C for ; Mon, 14 Feb 2022 04:03:47 -0800 (PST) Received: from pps.filterd (m0246629.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 21EBfExE031159; Mon, 14 Feb 2022 12:03:44 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : content-transfer-encoding : content-type : mime-version; s=corp-2021-07-09; bh=i72Zuk4HngpHHy83v0BKVClagpOwW0ASOJv7kdB+Xdo=; b=s1Ck9TAZ9iW1PkV66CtzFtt29xEAUS1LtlniyHhehhtIKJe/dWn0G/4IPiQGDqUvLX3C ijH4QNkM4EAafz8Sdag86ZMtgKWlrB7Lh1tcyzzxWX36R/FegK8gck1P5KZNDHetAKf8 sFdJj1rCiofGexxd7qd+qkERct4QUy0rUcAvc32dNlEb2Cx4iuOHUmcKeIy+2mAItUIE Jt/m99XmzQ7sc9cTFqJlAtt1trn3ljK3m1a+A0rbOb1jblmtZY9+K3Fjngvx9ftDS4GX TPmlcsAs3Mmqqlz5YH+fNbL3SFSxuv3G1wkSJNAoYGDOYst7jUmeU//Mk8fTbONLRtQl yA== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by mx0b-00069f02.pphosted.com with ESMTP id 3e64sbv32a-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 14 Feb 2022 12:03:44 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.1.2/8.16.1.2) with SMTP id 21EBuM0C184636; Mon, 14 Feb 2022 12:03:42 GMT Received: from nam12-bn8-obe.outbound.protection.outlook.com (mail-bn8nam12lp2175.outbound.protection.outlook.com [104.47.55.175]) by userp3030.oracle.com with ESMTP id 3e620vusue-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 14 Feb 2022 12:03:42 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=k/qR6rZ60X57zG62xFyRv12WK0OP1M4sqX+L507IuIBccq0otR/wFU7wXTY+TBcoVeXFmB04vRDRiCAVFoTMcFrwpWNlHPN/98SpQoyJAOc62TvuxFuDmSJQCMPrGLyskEMinLMNoYVPW2AZS2IwGMNeUgybpSt6z7OXZMEXGghJs9w7JmZ+Tfh7bWxnssgJ5nZM9Rn07DyD/zqo4iKvMhGbVTJqXMK36d9t0zteRPFZcf69VY0W2W6yRDwekexiYWcKX730qMw9ZjtN4KKxmkR9rLkoA4y8jZf/HieTGxn8xj4kPpTmj/xvju0uNAb7SZ1Y0liwRvJJnzgoYMFe8A== 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=i72Zuk4HngpHHy83v0BKVClagpOwW0ASOJv7kdB+Xdo=; b=KIOSMSxnS30r7QgzSZUdRsNW86fgO8qUJIuA/3rMgMk0iDnIZ4LzZaKlHvFbsT7smJ5uIAV+EjRMJ07Zlje0Ke/TXy77Wed0mdVXLIIxHdZvd6tF66aEejXpV5wtJPqS8QCRrBr+fD8lDPzwyyx3MV3gckXKq+u+CJ/NDsUptyLN63LAZEGRjARpwESZMPc+OBIlWNajthKByKoISh+ghdlwkvbvhGW2OHAM3jv8jXXOBiXeKy3BFBfUQiKy2MTnYLm7J+ivb6KQmiLvzwQqHl1oBzhxrPSkoZDwmcpCaJJh2yKCnUwZXuFmubRy+uTwZFI76nNjxu2sQVmt1DsEsw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=none; dmarc=none; dkim=none; 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=i72Zuk4HngpHHy83v0BKVClagpOwW0ASOJv7kdB+Xdo=; b=YBIdVVWaVBl8biNpbJ8eHv22ntRSeYVWOnIec0pot0z1jgvWgPqqIn+l1vtllvq5hi6Ah149fZARL6l0hLq1dL2ILZc3L9v3p6nYVj1rG2uIgHA0l7pxksDpnAh4RHu3vEAWIe0pA8hm/o+Cg41Kz/+Ti2yiXYVs2TriTtKWVyQ= Received: from CO1PR10MB4468.namprd10.prod.outlook.com (2603:10b6:303:6c::24) by BN8PR10MB3538.namprd10.prod.outlook.com (2603:10b6:408:b3::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4975.17; Mon, 14 Feb 2022 12:03:40 +0000 Received: from CO1PR10MB4468.namprd10.prod.outlook.com ([fe80::a5d1:ed4:5ab6:e9b1]) by CO1PR10MB4468.namprd10.prod.outlook.com ([fe80::a5d1:ed4:5ab6:e9b1%4]) with mapi id 15.20.4975.019; Mon, 14 Feb 2022 12:03:40 +0000 From: Imran Khan To: tj@kernel.org, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH v6 3/7] kernfs: Introduce hashed spinlocks to replace global kernfs_open_node_lock. Date: Mon, 14 Feb 2022 23:03:18 +1100 Message-Id: <20220214120322.2402628-4-imran.f.khan@oracle.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220214120322.2402628-1-imran.f.khan@oracle.com> References: <20220214120322.2402628-1-imran.f.khan@oracle.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: SY2PR01CA0016.ausprd01.prod.outlook.com (2603:10c6:1:14::28) To CO1PR10MB4468.namprd10.prod.outlook.com (2603:10b6:303:6c::24) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9a753bf1-d98f-475d-3749-08d9efb209f0 X-MS-TrafficTypeDiagnostic: BN8PR10MB3538:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; 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:CO1PR10MB4468.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(366004)(38350700002)(66946007)(316002)(38100700002)(2616005)(36756003)(6486002)(66556008)(4326008)(66476007)(103116003)(186003)(1076003)(26005)(6666004)(6512007)(2906002)(86362001)(508600001)(52116002)(83380400001)(5660300002)(8936002)(6506007)(8676002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?IAsOmEEFKV7/QsX9kABJqAuW0Ns5qTpJXE+GLSJcJi2ftHP+a2SuUu+Im5Ia?= =?us-ascii?Q?+DjzktnOXv33ZzUFuvJaKC6ohmnFyhEHfmfhKs6krhadg9f756pGUyhwTFcf?= =?us-ascii?Q?zHLkX4+cg+1o7hS9XKyV/2ChfGumzW3jRxW5UA3pd2aICkCZwcf+DLkzuC4f?= =?us-ascii?Q?qOSFKWeRdjLM15uDC7JTTl2c39SupOmHYCb+52nPWnh9WHepFSe73V9Hky5u?= =?us-ascii?Q?UzLXKsKOV8geYKnwdvfRyyz0XRVNsXQGwODnd+Gh5yscyi+A901CxLZfM+Av?= =?us-ascii?Q?jtWePLX09VdXSzlDKn49pPw5u8kAPSmGbWq1uQBgTUDR4GEqP3m+IxHO16nj?= =?us-ascii?Q?34YL7aLdJquIOQP9B9Pq5BX3WrBkhwYPL2TGnDR10aSLCc6oFmhYRHhADCak?= =?us-ascii?Q?cXYPSS0jwr+A7aoGJRY2A9sKtqfDif4fmsUNL3o28+2VvEb4qtG32YhP8qq7?= =?us-ascii?Q?yGrYl9w7DoJPTja0ICAm/mFHmbMUi1WsNyapoltYMY6tEJPyt6njvxP6/NKP?= =?us-ascii?Q?hgLM5dhJWV7R6dRgevK/Uq4aHY3AD69UYfrmqltiqAtzmri6ASjMxDJpJ8LG?= =?us-ascii?Q?PtyPJ0S9L/rntYcEjwAiLjT54i+3jjaiaqTVAF2fkHRiBU4OKvZwz18EwxOW?= =?us-ascii?Q?sbtJN7wvDVIrGIo9aGErhlQ8/X/gyiAeV6Hz6iRZT3wwpqXVIdeFXceiTCO5?= =?us-ascii?Q?w8TIysh+RMlNZgN52iLv+V0+UA+9YirOX6Ra99Sn1PrStvpd759hEqeJtl4c?= =?us-ascii?Q?+prNtCW5qYWzYPfcrbqZ3F9WFBICnvrsAQvXQ/GBs4zsD9e+Puxd+uP/hiet?= =?us-ascii?Q?Qnm7JPxE19jFWI7Ij8XEQSA/CMXbfZAy+uM4rf6kHOwPtbOaG9RjIi4RfOfE?= =?us-ascii?Q?5oZxVrAnKR+90V1qdL20WBGKbLhWrkulffDgXeTK7831WWrnPYPLZy/mz41S?= =?us-ascii?Q?yFxSwNsQdAOlqSlq0R8hNpHN3pSPMIHFBIv7H8BWkwN72msimyemUhPlo2LK?= =?us-ascii?Q?EqGb2dFYnR1b7B7ePzzyn3Q7Y1kEfun0dL9nc0krWuRYWT3STQjrzuaMRocm?= =?us-ascii?Q?shHDQzosQei0+LpVeG6fdVcXxNMHgTXVbzeZhy7exHcwH2KDVuhblPh0kyvR?= =?us-ascii?Q?yh6Waj6OiDzwJ+OJKySgd0xzKDZ4WK9LDltWWDiNRfH6505HtzaJzIWiIiCt?= =?us-ascii?Q?8GbQ8O8DaOQj07FRPeGIhbVwUYNEDFfvnYRnVBTpF49xBZWyePPI/hJGQqKb?= =?us-ascii?Q?NlmO2e5FLS0LANGvX4N2ElJFvBa5JYYyP2KVnbR5ii9KOoaERkfxNxWKlMl6?= =?us-ascii?Q?HXnxpC0LiN/SzXE6P/ew+6fMqFii0KC24v4C4BxFAiNr4z5tuL5v/fN7yxfD?= =?us-ascii?Q?sflmrjvq5rWVlC4DqWqQ2VGm1+MPzgFG67wUdk+Cl+nMi69gFkgY9TfaEkGU?= =?us-ascii?Q?94PmmKWNID+ZQFxjTrDXAgxzlBc2BEBEHvLv0gyBuF2amrtaBejVnrR3P2sU?= =?us-ascii?Q?s4k8HMvX0bFCpxedRAgnIpRllXiO/EQDCSRAoGmEZ9HCYpVsaG0MY0nZs+/x?= =?us-ascii?Q?wt06T4qrT7eUZYyHE0cPPQFlIqSkZb5QIE5P3ZwzuRBI/8ZwTu7ZAlbXTzzp?= =?us-ascii?Q?RPiSGeBZUawYKisobj6hhYY=3D?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9a753bf1-d98f-475d-3749-08d9efb209f0 X-MS-Exchange-CrossTenant-AuthSource: CO1PR10MB4468.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Feb 2022 12:03:40.0840 (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: gS4vAMKIZPqHgYftqhVxizp5IDD3ICt54M7Ie3t0wp3CPMHQ11jbG1UabKka7yW34zyK9KBvIGI3/Zr0gxIwlQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR10MB3538 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10257 signatures=673431 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 mlxlogscore=999 bulkscore=0 spamscore=0 adultscore=0 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202140073 X-Proofpoint-GUID: NEBi6_SOzdKV8jckaolFRbUMMHo3s76e X-Proofpoint-ORIG-GUID: NEBi6_SOzdKV8jckaolFRbUMMHo3s76e Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In current kernfs design a single spinlock, kernfs_open_node_lock, protects the kernfs_node->attr.open i.e kernfs_open_node instances corresponding to a sysfs attribute. So even if different tasks are opening or closing different sysfs files they can contend on this spinlock. The contention is more apparent in large scale systems with few hundred CPUs where most of the CPUs have running tasks that are opening, accessing or closing sysfs files at any point of time. Using hashed spinlocks in place of a single global spinlock, can significantly reduce contention around global spinlock and hence provide better scalability. Moreover as these hashed spinlocks are not part of kernfs_node objects we will not see any singnificant change in memory utilization of kernfs based file systems like sysfs, cgroupfs etc. This patch introduces hashed spinlocks that can be used in place of above mentioned global spinlock. It also provides interfaces needed to use hashed spinlocks. The next patch makes use of these interfaces and replaces global spinlock with hashed ones. Signed-off-by: Imran Khan --- fs/kernfs/kernfs-internal.h | 20 ++++++++++++++++++++ fs/kernfs/mount.c | 4 +++- include/linux/kernfs.h | 11 +++++++++-- 3 files changed, 32 insertions(+), 3 deletions(-) diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index 03e983953eda4..593395f325a18 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -170,4 +170,24 @@ static inline struct mutex *kernfs_open_file_mutex_lock(struct kernfs_node *kn) return lock; } +static inline spinlock_t * +kernfs_open_node_spinlock_ptr(struct kernfs_node *kn) +{ + int idx = hash_ptr(kn, NR_KERNFS_LOCK_BITS); + + return &kernfs_locks->open_node_locks[idx].lock; +} + +static inline spinlock_t * +kernfs_open_node_spinlock(struct kernfs_node *kn) +{ + spinlock_t *lock; + + lock = kernfs_open_node_spinlock_ptr(kn); + + spin_lock_irq(lock); + + return lock; +} + #endif /* __KERNFS_INTERNAL_H */ diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index fa3fa22c95b21..809b738739b18 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -395,8 +395,10 @@ void __init kernfs_lock_init(void) kernfs_locks = kmalloc(sizeof(struct kernfs_global_locks), GFP_KERNEL); WARN_ON(!kernfs_locks); - for (count = 0; count < NR_KERNFS_LOCKS; count++) + for (count = 0; count < NR_KERNFS_LOCKS; count++) { mutex_init(&kernfs_locks->open_file_mutex[count].lock); + spin_lock_init(&kernfs_locks->open_node_locks[count].lock); + } } void __init kernfs_init(void) diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 3f72d38d48e31..7ee0595b315a2 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -19,6 +19,7 @@ #include #include #include +#include struct file; struct dentry; @@ -75,20 +76,26 @@ struct kernfs_iattrs; * kernfs_open_file. * kernfs_open_files are chained at kernfs_open_node->files, which is * protected by kernfs_open_file_mutex.lock. + * + * kernfs_node->attr.open points to kernfs_open_node. attr.open is + * protected by kernfs_open_node_lock.lock. */ - struct kernfs_open_file_mutex { struct mutex lock; } ____cacheline_aligned_in_smp; +struct kernfs_open_node_lock { + spinlock_t lock; +} ____cacheline_aligned_in_smp; + /* * To reduce possible contention in sysfs access, arising due to single * locks, use an array of locks and use kernfs_node object address as * hash keys to get the index of these locks. */ - struct kernfs_global_locks { struct kernfs_open_file_mutex open_file_mutex[NR_KERNFS_LOCKS]; + struct kernfs_open_node_lock open_node_locks[NR_KERNFS_LOCKS]; }; enum kernfs_node_type { -- 2.30.2