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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: AQHUqCh6wdyUqgFwnkq9Kum4KiJL8KWnFauAgAHfdvCABvLRQA== Date: Tue, 15 Jan 2019 06:33:36 +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: 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: [193.47.165.251] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; DB7PR05MB5241; 6:Jq8puEjFitYHcFXSo9QzPHBUGi+DbVHNScCet3YlwNwvcUwhumx/esGMDr4jV5jK7jGhqPT+K4DS1gTpWNOjizQT4tm7ZueTP/1O6FgpX3vCfRAlYCtngYdWJ2nFNCyyJ94jh/prm/aLxy0LANfJCD3kDjVoMpddnPyt80jDh5pSMH80VY6DJAR0H1NfbJtgvwqzAZQHnN4SmA+wVWKgD/taCwP7WgX7W7QsUeL2sSbOaARfD7raxwLWas+lDk7UXW7cNcR/y/Ohxz290pecJUAXOGbl+OnuYMw40fITtX0y1XW/BhP33L0cJUyDfXj10QxyPi6iNhhs46oWEm5aSV+it75DCXm4eRwJF1Pg7iV1RGu8NYruY/D5jfpvbDHpnglWsV8+ZvaiUF063YNbGYk1/VcIziD4FS9geJcwklT4Pql9NHS2Q8g8i7q1ttpWI4UcvbnnbgyHTZrPEbMadQ==; 5:B6D3ch7B+zY97S7bnDH8ONn7x+zxJk6SxZmYWHRnWVlirBlB65mhYfsKhJktujzCjvxgvPNU/YXC/p4htvIJldQqpXOs9iTCn64PxtIWoURq0tVe5P0W1uS268sfvZAcuBo7y1Htjvg+PROSJCkoAV2APj59ganpVSLOfBLbndxLfYS+9Ixm1q8UDQKbCU0Ppro0rkO25VjDog2SMjq1mA==; 7:Xq3kOMQ7PnWOT+myjKK0YG+IN1kFn6xXheNrpnYZQE2IBxbmpimzaFGYll7GnxY9OSdk2mGXGtfRaBJSmYod6lO+0qweJNfnDvWjdDgDl6FwjkPXKoWnczXZ/SU4Yo/59StNv2tG0hf+3NJEapwCsA== x-ms-exchange-antispam-srfa-diagnostics: SOS; x-ms-office365-filtering-correlation-id: a1e24d16-536a-4be2-1917-08d67ab360f2 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:DB7PR05MB5241; x-ms-traffictypediagnostic: DB7PR05MB5241: x-microsoft-antispam-prvs: x-forefront-prvs: 0918748D70 x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(366004)(346002)(396003)(39860400002)(136003)(376002)(199004)(189003)(25786009)(68736007)(86362001)(39060400002)(4326008)(71200400001)(71190400001)(97736004)(102836004)(9686003)(66066001)(54906003)(110136005)(6506007)(186003)(6246003)(107886003)(478600001)(2906002)(6306002)(53936002)(5660300001)(7416002)(8676002)(81166006)(81156014)(7736002)(14454004)(55016002)(3846002)(305945005)(8936002)(6436002)(6116002)(76176011)(7696005)(316002)(33656002)(26005)(256004)(93886005)(99286004)(476003)(105586002)(966005)(74316002)(11346002)(446003)(106356001)(229853002)(486006); DIR:OUT; SFP:1101; SCL:1; SRVR:DB7PR05MB5241; H:DB7PR05MB4426.eurprd05.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX: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: NZnjpcBEkuCMTSg4zoN3fAMF0Xn/qeiozeV0IKmj3IUMfQdGVuWKlojbERt6GyJ1jXCunbR5dnSqQWn1EyK8kqofeUqLypElSSxJsHUfP/YhgEMJM1ejvd3e9Aji4Kywtm1esNZMvcMsSApRU2dx50Dq4TJyrmUZaZo4p00EoSCHqhX0y9qHHhPp2xgcRbm9Bzs7y1LvI4zeOx8QNEUi418ntcUsc7+o8ZaHTFwof0TDFhgkEtWVgqbxEujZa8nix41nKw6Gg5ZVrI9Lnvkfn4fgRDWzu3ulklIoH0Y5tVclxT/cXdGXlfWEJGlwrpgPJ9mhG3KyGxRarzhLlju2yZ8W52pIrv/XAf6szspCKrLVsgMbSsknFClI7xSTtpJittk2vYw/QIK6KkXYH7uKcBD8YjO1C5I0jf/HrA+Tbek= 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: a1e24d16-536a-4be2-1917-08d67ab360f2 X-MS-Exchange-CrossTenant-originalarrivaltime: 15 Jan 2019 06:33:36.2936 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR05MB5241 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: Tue, 15 Jan 2019 06:33:39 -0000 Thursday, January 10, 2019 10:37 PM, Shahaf Shuler: > Subject: RE: [dpdk-dev] [PATCH v2] net/virtio: add platform memory > ordering feature support >=20 > 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 > > > > 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. > > > > Linux driver doesn't avoid it either. >=20 > I understand v3 was merged but still would like to continue the discuss a= nd > make sure all is clear and agreed. >=20 > Form patch [1] description it is very clear why we need the rte_smp_mb() > barrier. > However I am not sure why this barrier is interoperate into rte_mb in cas= e of > vDPA. In vDPA case, both read of the user ring and write of the avail in= dex > are for local cached memory. > The only write which is to uncachable memory (device memory) is the notif= y > itself. >=20 > As I mentioned, there is a need to have a store fence before doing the > notify, but from different reasons. So vDPA use case and need Is a bit > different than what presented in [1]. Any answer? It is pity if we add redundant barriers which will degrade the driver perfo= rmance.=20 >=20 > [1] > https://patches.dpdk.org/patch/49545/ >=20 > > > > -- > > MST