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Harding" CC: Andrew Morton , Matthew Wilcox , Alexander Viro , "Christoph Hellwig" , Pekka Enberg , "David Rientjes" , Joonsoo Kim , Christopher Lameter , Miklos Szeredi , Andreas Dilger , Waiman Long , "Tycho Andersen" , Theodore Ts'o , Andi Kleen , David Chinner , Nick Piggin , Rik van Riel , Hugh Dickins , Jonathan Corbet , "linux-mm@kvack.org" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC PATCH v5 13/16] slub: Enable balancing slabs across nodes Thread-Topic: [RFC PATCH v5 13/16] slub: Enable balancing slabs across nodes Thread-Index: AQHVDs7ctVwmY1mfWEGms02f+3BxA6Z0xI6A Date: Tue, 21 May 2019 01:04:10 +0000 Message-ID: <20190521010404.GB9552@tower.DHCP.thefacebook.com> References: <20190520054017.32299-1-tobin@kernel.org> <20190520054017.32299-14-tobin@kernel.org> In-Reply-To: <20190520054017.32299-14-tobin@kernel.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: MWHPR1201CA0013.namprd12.prod.outlook.com (2603:10b6:301:4a::23) To BYAPR15MB2631.namprd15.prod.outlook.com (2603:10b6:a03:152::24) x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [2620:10d:c090:200::3:a985] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 862a72bd-6b3a-44a5-c236-08d6dd883b6c x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600141)(711020)(4605104)(2017052603328)(7193020);SRVR:BYAPR15MB2405; x-ms-traffictypediagnostic: BYAPR15MB2405: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:9508; x-forefront-prvs: 0044C17179 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(136003)(346002)(376002)(366004)(39860400002)(396003)(199004)(189003)(486006)(66946007)(2906002)(66476007)(46003)(66556008)(73956011)(64756008)(186003)(66446008)(81166006)(33656002)(446003)(11346002)(68736007)(8936002)(81156014)(8676002)(476003)(305945005)(6436002)(229853002)(6916009)(5660300002)(7736002)(9686003)(6512007)(6486002)(1076003)(4744005)(102836004)(478600001)(7416002)(14454004)(6116002)(256004)(76176011)(53936002)(71200400001)(71190400001)(25786009)(4326008)(52116002)(86362001)(54906003)(6246003)(6506007)(99286004)(316002)(386003);DIR:OUT;SFP:1102;SCL:1;SRVR:BYAPR15MB2405;H:BYAPR15MB2631.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: JjhJmYGMPkjH1z5jP878WPyQf2fbLbmFr6sqILpUMvAQjlukyOV2Dv5lTgY4vNACrM1TCll3/fBNJO46xbdfVCp3Jtg9Dd/OAByjGn3YnKlztJDMAnoYjwBOtdkY6OH3dwAPqBYg1qGmH/BiqeJC98ng0IHwxwGXtCW1JNflZ9VTy2ueNql+eOwDHZHN1qrTGt3h9QuXQ6BUEo+lhq5Dols5+VLZddMwnkNBwaTVKbKhDeYoE3D+rCjGfkziRg44ophKBKMGOlMU0dtP3ECyLMQvN/jI2bON9lsfZIxEjvcQyBzVfkwpSajFmSbkuKBcxAfEl26jikcwvZ1O/nWuBcjUqx50WAm9evexyyMFzw0mmd65DDSyOmPRGH3Cl/Da/DGNI/kj1Aqdy+E38yaHYVjMdvT0lZxGEUpMxmEDImE= Content-Type: text/plain; charset="us-ascii" Content-ID: <9D0C93632F69DC48947AE33B016879D1@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 862a72bd-6b3a-44a5-c236-08d6dd883b6c X-MS-Exchange-CrossTenant-originalarrivaltime: 21 May 2019 01:04:10.7884 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2405 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-20_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=578 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905210004 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 20, 2019 at 03:40:14PM +1000, Tobin C. Harding wrote: > We have just implemented Slab Movable Objects (SMO). On NUMA systems > slabs can become unbalanced i.e. many slabs on one node while other > nodes have few slabs. Using SMO we can balance the slabs across all > the nodes. >=20 > The algorithm used is as follows: >=20 > 1. Move all objects to node 0 (this has the effect of defragmenting the > cache). This already sounds dangerous (or costly). Can't it be done without cross-node data moves? >=20 > 2. Calculate the desired number of slabs for each node (this is done > using the approximation nr_slabs / nr_nodes). So that on this step only (actual data size - desired data size) has to be moved? Thanks!