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Tsirkin" , Ilya Maximets CC: "dev@dpdk.org" , Maxime Coquelin , Xiao Wang , "jfreimann@redhat.com" , Tiwei Bie , Zhihong Wang , Jason Wang , "xiaolong.ye@intel.com" , "alejandro.lucero@netronome.com" , Daniel Marcovitch Thread-Topic: [dpdk-dev] [PATCH v2] net/virtio: add platform memory ordering feature support Thread-Index: AQHUqCh6wdyUqgFwnkq9Kum4KiJL8KWnFauAgAHfdvA= Date: Thu, 10 Jan 2019 20:36:45 +0000 Message-ID: References: <20181214153812.3878-1-i.maximets@samsung.com> <20181226163712.31596-1-i.maximets@samsung.com> <2832c88f-9b43-997c-5937-ef5ae6482fd5@samsung.com> <20190109104855-mutt-send-email-mst@kernel.org> In-Reply-To: <20190109104855-mutt-send-email-mst@kernel.org> 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=shahafs@mellanox.com; x-originating-ip: [31.154.10.105] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; DB7PR05MB5082; 6:PerQAPk6pnSw7NEwAY1g8IkRjYxT+RaLuD98DXyFDoCkja2eQeHLJhODvr4YK1027c2n+czlSTjQPWpgSma3ptrJx9ZkulSvP0mt1Zx/aoYOF/Sw3XW5oN2kacpDhDiX3VRemdgFbQRvXCXC0sDdYLRY6NICqTwrDeVx94oCwkg6fdpdF3vvPouCbNZSg34HzjxUG/dqp0HKsk7+KOGrOJ0IATAHxXdtIllMyMelDTXQSlXcaTX9sK3dD+8Vgm/QZFuc2uv7jmDpJHxun4WBLPZU/HWkvv/eQZwFqPFGWQVWh1VjOU9dzDmW6SFasPEgZEv5S5IdGjwtFFH+/5SgBnrRq74FXAr/oLYJ/1Tb31QZwchYw2fHZJUcs+SC4oPBxUXwBSzbWB+PKuYjHzdLvIS2j4KTBc4k7I8WtYe4AwOMMSXjyDyg24jufjEgENcGjjpxf45VGJjuC3KadoaFUA==; 5:M7EBHErysZ4vOh/tdPQ/2jkmWQhCtXFYJP6wlWJ6At5E9Fgez7PkVGmhVEjuqQM/PLNNNd0hJWu9FqJlWRQx994fcGlxsDouMxhaDXdkpqd2//OyMpzgmqUrt7qtja7+GSw/GW1D2ii39jWNAYQ6CR1tn6M1nMPgPfzYaPOm22EdzVtUxnXAI7IsSNCBdoxeMezmb/xBjZUYZQjOZMWDXg==; 7:PcJwMl/mUtSCG9YZrKnUPgA2IIr3Wnk/5eCKoHUa6CdDzubBLA20fzuDlvzNNb1K9ukuvJDvHjc52WhVzQ4O06VWSRz8Ozx3/xSaHDsY5lATTST+zr9WWlQxPQl5dHqV4JZYlxBOx7gkrdoxdOGMhg== x-ms-exchange-antispam-srfa-diagnostics: SOS; x-ms-office365-filtering-correlation-id: e84c5711-2035-4b27-1fb1-08d6773b5649 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600109)(711020)(4618075)(2017052603328)(7153060)(7193020); SRVR:DB7PR05MB5082; x-ms-traffictypediagnostic: DB7PR05MB5082: x-microsoft-antispam-prvs: x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:(8211001083)(3230021)(908002)(999002)(5005026)(6040522)(8220060)(2401047)(8121501046)(3002001)(3231475)(944501520)(52105112)(93006095)(93001095)(10201501046)(6055026)(6041310)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123558120)(20161123560045)(20161123562045)(20161123564045)(201708071742011)(7699051)(76991095); SRVR:DB7PR05MB5082; BCL:0; PCL:0; RULEID:; SRVR:DB7PR05MB5082; x-forefront-prvs: 0913EA1D60 x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(346002)(366004)(376002)(39860400002)(396003)(136003)(189003)(199004)(81156014)(8936002)(81166006)(86362001)(107886003)(305945005)(33656002)(53936002)(478600001)(26005)(14454004)(106356001)(68736007)(8676002)(486006)(966005)(25786009)(7736002)(4326008)(102836004)(39060400002)(186003)(6246003)(105586002)(9686003)(256004)(66066001)(6306002)(6116002)(6506007)(11346002)(5660300001)(446003)(97736004)(7696005)(7416002)(3846002)(476003)(110136005)(2906002)(55016002)(54906003)(316002)(71190400001)(71200400001)(99286004)(93886005)(6436002)(74316002)(76176011)(229853002); DIR:OUT; SFP:1101; SCL:1; SRVR:DB7PR05MB5082; H:DB7PR05MB4426.eurprd05.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; MX:1; A:1; received-spf: None (protection.outlook.com: mellanox.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: c2h6ckHKM3DO7qt7Ah2iS/xQG8qt7U9pzQD1uSKSMv1EjaHwk9W4XABg309vC/88sL+ZgTexm7kZOtowydSAsl1f+IbUfeEhXbFapLawu04J8JWV8UWlstwnZqkhZSOiRfUG9B+oiWAewTnQUtC/re0HWvMPIfh2dvaCAbcLjrlxBafPvu4WRYsQMMQWLw6u7xqm9CeXN9Cmynvpjpj73oV3gATv5SiBGcXg5LIHjF5WUDzvc75vWZhuhlzX3vU2g8L5tf9d1rFT2P+6dZIfWges7l/8IeU03nM6FLWTtEsYUSvpw8yVaCUcxKJSN3jZ spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: e84c5711-2035-4b27-1fb1-08d6773b5649 X-MS-Exchange-CrossTenant-originalarrivaltime: 10 Jan 2019 20:36:45.2641 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR05MB5082 Subject: Re: [dpdk-dev] [PATCH v2] net/virtio: add platform memory ordering feature support X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Jan 2019 20:36:48 -0000 Wednesday, January 9, 2019 5:50 PM, Michael S. Tsirkin: > alejandro.lucero@netronome.com; Daniel Marcovitch > > Subject: Re: [dpdk-dev] [PATCH v2] net/virtio: add platform memory > ordering feature support >=20 > On Wed, Jan 09, 2019 at 05:34:38PM +0300, Ilya Maximets wrote: > > virtio_mb() is really heavy. I'd like to avoid it somehow, but I don't > > know how to do this yet. >=20 > Linux driver doesn't avoid it either. I understand v3 was merged but still would like to continue the discuss and= make sure all is clear and agreed. Form patch [1] description it is very clear why we need the rte_smp_mb() ba= rrier. However I am not sure why this barrier is interoperate into rte_mb in case = of vDPA. In vDPA case, both read of the user ring and write of the avail i= ndex are for local cached memory.=20 The only write which is to uncachable memory (device memory) is the notify = itself.=20 As I mentioned, there is a need to have a store fence before doing the noti= fy, but from different reasons. So vDPA use case and need Is a bit differen= t than what presented in [1]. [1] https://patches.dpdk.org/patch/49545/ >=20 > -- > MST