From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751510AbeBTVOg (ORCPT ); Tue, 20 Feb 2018 16:14:36 -0500 Received: from esa6.hgst.iphmx.com ([216.71.154.45]:10792 "EHLO esa6.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750799AbeBTVOd (ORCPT ); Tue, 20 Feb 2018 16:14:33 -0500 X-IronPort-AV: E=Sophos;i="5.46,541,1511798400"; d="scan'208";a="72312794" From: Bart Van Assche To: "jgg@ziepe.ca" , "arnd@arndb.de" , "dledford@redhat.com" CC: Bart Van Assche , "linux-kernel@vger.kernel.org" , "leonro@mellanox.com" , "linux-rdma@vger.kernel.org" , "sagi@grimberg.me" Subject: Re: [PATCH] RDMA/core: reduce IB_POLL_BATCH constant Thread-Topic: [PATCH] RDMA/core: reduce IB_POLL_BATCH constant Thread-Index: AQHTqo22g3e0rzeB4kWE08COXa55qKOtynkA Date: Tue, 20 Feb 2018 21:14:29 +0000 Message-ID: <1519161268.3737.12.camel@wdc.com> References: <20180220205924.2035765-1-arnd@arndb.de> In-Reply-To: <20180220205924.2035765-1-arnd@arndb.de> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Bart.VanAssche@wdc.com; x-originating-ip: [12.250.207.42] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;CY1PR0401MB1631;7:OCtmtY8y+iL1tQC9aXYAKwW0aaoGa2/0c91c8NaEu/xsWo9AHf3kOE9KllJlJsNf38hmYrndgihp1A4WG+WnqZJqnk6t7tO5raohULUJgxz6Dp/x7TkNbqVvuKCiYVnZpwYC1tu/dVV4h5VwFrfPWCRYh8LYt9kui7rCsYqFgQ3cEL4yOhS3UuRTckgJ9X/zWN4i923vAvsHEUSTnvOR5Hbxixyvj2bi7nNH1rXqPdFwrVeVL4qHKE4fqy3IFgrQ;20:7K68mqKp44GZGU1VM2CdZ12+WSf8lCKzo48DxEmnSvx2IdIMidLZGbLii+FsBoYUZZ/tr4jsNVpP5syTP5TQ4Q5yzuS7afm11n3tUZuH5fdOzaLYYyE960RIdHklmOiX/Eg8V2Ag1LfL3NF5bKuB/a2pHPxHbQCqAXfLN81SYMM= x-ms-exchange-antispam-srfa-diagnostics: SSOS;SSOR; x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 7b50bb5e-bd35-4aef-046e-08d578a6ee57 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603307)(7153060)(7193020);SRVR:CY1PR0401MB1631; x-ms-traffictypediagnostic: CY1PR0401MB1631: wdcipoutbound: EOP-TRUE x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:; x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(6040501)(2401047)(8121501046)(5005006)(93006095)(93001095)(3231101)(944501161)(3002001)(10201501046)(6055026)(6041288)(20161123562045)(20161123564045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123558120)(20161123560045)(6072148)(201708071742011);SRVR:CY1PR0401MB1631;BCL:0;PCL:0;RULEID:;SRVR:CY1PR0401MB1631; x-forefront-prvs: 05891FB07F x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39380400002)(39860400002)(346002)(366004)(396003)(376002)(377424004)(189003)(199004)(8936002)(3280700002)(6436002)(36756003)(103116003)(53936002)(66066001)(6512007)(2906002)(3846002)(6116002)(68736007)(6246003)(6486002)(2900100001)(305945005)(106356001)(4326008)(7736002)(2501003)(81156014)(105586002)(5660300001)(25786009)(97736004)(76176011)(86362001)(8676002)(2201001)(26005)(77096007)(186003)(6506007)(54906003)(3660700001)(110136005)(229853002)(316002)(81166006)(99286004)(478600001)(72206003)(14454004)(2950100002)(102836004);DIR:OUT;SFP:1102;SCL:1;SRVR:CY1PR0401MB1631;H:CY1PR0401MB1536.namprd04.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; x-microsoft-antispam-message-info: PuuH+Koz7mDf68WDuL2hwIx8QNuUU2OmH4RPTLpHRor14I0ykKU3oFr+0NVVvPKSdyzH5Vmt8tDgfV8Z8Zq4Q5o40f3LErqwHBD5TCArDICCCbvRe09vR48/1EeEbPkvKO+cpLhBOeIPGT2oi3EHaxg4KHis6r2HyTaSk5/p0LM= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-ID: <427F65363C83344EBF4BA933C493CAE4@namprd04.prod.outlook.com> MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7b50bb5e-bd35-4aef-046e-08d578a6ee57 X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Feb 2018 21:14:29.9971 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY1PR0401MB1631 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w1KLEeuJ017608 On Tue, 2018-02-20 at 21:59 +0100, Arnd Bergmann wrote: > /* # of WCs to poll for with a single call to ib_poll_cq */ > -#define IB_POLL_BATCH 16 > +#define IB_POLL_BATCH 8 The purpose of batch polling is to minimize contention on the cq spinlock. Reducing the IB_POLL_BATCH constant may affect performance negatively. Has the performance impact of this change been verified for all affected drivers (ib_srp, ib_srpt, ib_iser, ib_isert, NVMeOF, NVMeOF target, SMB Direct, NFS over RDMA, ...)? Bart.