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=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED autolearn=ham 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 805FCC04AB5 for ; Thu, 6 Jun 2019 08:03:39 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 5728F206BB for ; Thu, 6 Jun 2019 08:03:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="AE5MrLtR"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=marvell.com header.i=@marvell.com header.b="pdSJvebr"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=marvell.onmicrosoft.com header.i=@marvell.onmicrosoft.com header.b="dnMSIisq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5728F206BB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=marvell.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Content-ID:In-Reply-To: References:Message-ID:Date:Subject:To:From:Reply-To:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=zcTMMihBEClK/UC/BPFtSgtusX5RwbvupYTbTsxoaWA=; b=AE5MrLtRfM4GSx 4aREPhN54A93CG1ePTaEONKp0pGTg+UglgBLTj+B18HMzriZzC2E8V4P50iYWQxQ3dXsHBkLg1Ht+ 5OfhoWzc58ora0zQ1XlANP96IEVWyS9BcBKads0tPwYipLEWWmUvjVDUImzsQJTDhiv8QwLtGhvNc aZhRO1FpiSQLuRmBJsTwTD7ANFaqo6hzD/QKn+HJoUc0zO3/y1UyISv3DJ9zdXVysXs/AYX8Ogfzp Ye2aeTJuYHrWGHsCxTTEPxhAiNLdTFtKVE0KMvN2kJiYr3JM7V1wB2EYrRg02hFf8B6U3vo5qUQM1 TKji7cgF4BeWy/Gi/NRw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hYnN4-00019B-65; Thu, 06 Jun 2019 08:03:38 +0000 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hYnN1-00017W-Ix for linux-arm-kernel@lists.infradead.org; Thu, 06 Jun 2019 08:03:37 +0000 Received: from pps.filterd (m0045851.ppops.net [127.0.0.1]) by mx0b-0016f401.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x56815em030473; Thu, 6 Jun 2019 01:03:31 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=marvell.com; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : content-id : content-transfer-encoding : mime-version; s=pfpt0818; bh=tSTOVvQ1mAWagoaWboJkfjzIFNrg7rzULkPK4Im436s=; b=pdSJvebrjSYa6omKUxAIaa9nuxvbzOjETlTRX9LueLaUHdvHBKj1UNkyzPGH2RJuTq7D ko7LFNlcunz6cDTzXZXEUPuUzSYeSNwF6keW09UfO3NhqJOOTFtVewluhtGYEsS8kTVL kvt0ErgyAAMxXMokOqHveV9h0Zxfvm7lIgexjOZ84+uUJ47WVrgyLsDwyD/0A7tuP+v7 46YEldEqi4LjF1yMIu+mERzOqrldjZrF9NenRI7zIKIlNaMva5LxumkvmDmpQ1EujzBL xAmkyJubZwNMAlquvqnKYKM4TZOL84Pt6PsI7Okq5d32qkYDeaOWuF1eZlSxk7xE3aUI hA== Received: from sc-exch02.marvell.com ([199.233.58.182]) by mx0b-0016f401.pphosted.com with ESMTP id 2sxthegwqw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Thu, 06 Jun 2019 01:03:30 -0700 Received: from SC-EXCH02.marvell.com (10.93.176.82) by SC-EXCH02.marvell.com (10.93.176.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 6 Jun 2019 01:03:29 -0700 Received: from NAM04-SN1-obe.outbound.protection.outlook.com (104.47.44.55) by SC-EXCH02.marvell.com (10.93.176.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3 via Frontend Transport; Thu, 6 Jun 2019 01:03:29 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=marvell.onmicrosoft.com; s=selector2-marvell-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=tSTOVvQ1mAWagoaWboJkfjzIFNrg7rzULkPK4Im436s=; b=dnMSIisquh7tCLbh6wmWTCjWV/AN7o0myqpFvR8Dh0MaIO1/+3fTR/pn5vPnBkZQuQYwQzeu9a0s1+NK7TPKVyM/3QR1S2svIkZTMyM2obcwdSAIDFUyGkWR3EsxyEViTtHwqdAbKB+RFg8MULRsHfknRQo+nEofU4t+IH/ojuM= Received: from DM5PR18MB1578.namprd18.prod.outlook.com (10.175.224.136) by DM5PR18MB1274.namprd18.prod.outlook.com (10.173.213.140) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1965.14; Thu, 6 Jun 2019 08:03:28 +0000 Received: from DM5PR18MB1578.namprd18.prod.outlook.com ([fe80::e42c:8f1f:ac4d:c16e]) by DM5PR18MB1578.namprd18.prod.outlook.com ([fe80::e42c:8f1f:ac4d:c16e%6]) with mapi id 15.20.1965.011; Thu, 6 Jun 2019 08:03:28 +0000 From: Jan Glauber To: Linus Torvalds Subject: Re: [PATCH] lockref: Limit number of cmpxchg loop retries Thread-Topic: [PATCH] lockref: Limit number of cmpxchg loop retries Thread-Index: AQHVHD5S/Fy6pcse0E6tWtS4S5X27w== Date: Thu, 6 Jun 2019 08:03:27 +0000 Message-ID: <20190606080317.GA10606@hc> References: <20190605134849.28108-1-jglauber@marvell.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: VI1PR0501CA0027.eurprd05.prod.outlook.com (2603:10a6:800:60::13) To DM5PR18MB1578.namprd18.prod.outlook.com (2603:10b6:3:14d::8) x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [78.43.112.85] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 8efe314f-1f10-4603-c912-08d6ea5574c1 x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600148)(711020)(4605104)(1401327)(2017052603328)(7193020); SRVR:DM5PR18MB1274; x-ms-traffictypediagnostic: DM5PR18MB1274: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:6430; x-forefront-prvs: 00603B7EEF x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(7916004)(396003)(136003)(366004)(346002)(376002)(39860400002)(199004)(189003)(1076003)(68736007)(26005)(478600001)(4744005)(66066001)(8936002)(86362001)(4326008)(5660300002)(76176011)(66556008)(53936002)(2906002)(186003)(14454004)(3846002)(6116002)(476003)(486006)(6246003)(11346002)(25786009)(9686003)(6512007)(446003)(256004)(6916009)(316002)(14444005)(71190400001)(71200400001)(107886003)(6436002)(66446008)(66946007)(33716001)(66476007)(73956011)(64756008)(53546011)(6506007)(52116002)(386003)(99286004)(102836004)(229853002)(33656002)(305945005)(8676002)(54906003)(7736002)(81166006)(81156014)(6486002)(40753002)(133343001); DIR:OUT; SFP:1101; SCL:1; SRVR:DM5PR18MB1274; H:DM5PR18MB1578.namprd18.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1; received-spf: None (protection.outlook.com: marvell.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: gMHOnDx/6LzIM9HHdKwMFGZhpEiCQ2PeH2vg2AqQxCdID1jP5LEHlX6TfW+AjXNjqdm+QIIYBdJ0dA9x1syusmLJQCMbzweh96pflB6psZ4kDmO9nKyz5RuTBeesfwI1b6vBVgf+0/p1CjBWKtwpBCRdBH9qWLrG3DlZILd1Pu2O3CY86JgiBN+aiZXYfdTiM/SgbG0iiPC2cKLrCbOjgp1wdDvVLC/b2DxnqNEsBGqTkCJqcj6+kcTWb5/D0+bTnpIrd3QkymdwpXkqKmHkW2ePzzcCigV4YkXn4LqjOdhp1D/U3KZzvln3/gPRaY74rVJAmdmAlIfF8wabilUu/VIhk4C/Hg936OWhGLWcOoSOIsEmSO05frZJwmKpThAO7DAQx0cqvMIOVWIv7y0qp8dc064QAr9tP774SzLjhTI= Content-ID: <4EDECC1AD149F64AA2F5FC6090A1140B@namprd18.prod.outlook.com> MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 8efe314f-1f10-4603-c912-08d6ea5574c1 X-MS-Exchange-CrossTenant-originalarrivaltime: 06 Jun 2019 08:03:27.8636 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 70e1fb47-1155-421d-87fc-2e58f638b6e0 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: jglauber@marvell.com X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR18MB1274 X-OriginatorOrg: marvell.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-06-06_06:, , signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190606_010335_887312_25ECB02D X-CRM114-Status: GOOD ( 16.31 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , Will Deacon , Linux List Kernel Mailing , Jayachandran Chandrasekharan Nair , Jan Glauber , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jun 05, 2019 at 01:16:46PM -0700, Linus Torvalds wrote: > On Wed, Jun 5, 2019 at 6:49 AM Jan Glauber wrote: > > > > Add an upper bound to the loop to force the fallback to spinlocks > > after some time. A retry value of 100 should not impact any hardware > > that does not have this issue. > > > > With the retry limit the performance of an open-close testcase > > improved between 60-70% on ThunderX2. > > Btw, did you do any kind of performance analysis across different > retry limit values? I tried 15/50/100/200/500, results were largely identical up to 100. For SMT=4 a higher retry value might be better, but unless we can add a sysctl value 100 looked like a good compromise to me. --Jan > I'm perfectly happy to just pick a random number and '100' looks fine > to me, so this is mainly out of curiosity. > > Linus _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel