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Fri, 20 Oct 2017 01:18:19 +0000 From: Yongseok Koh To: "dev@dpdk.org" Thread-Topic: Requirement of minimum Rx burst size for PMDs Thread-Index: AQHTSUFQdbnbefauokyRffJ/1Z0bUg== Date: Fri, 20 Oct 2017 01:18:18 +0000 Message-ID: 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=yskoh@mellanox.com; x-originating-ip: [209.116.155.178] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; VI1PR0501MB2045; 6:mSoP9IQByQY2dINvm8ewhDpTSMV8sZyUGt0s48/5AVsI5qOphGKKozxUph6PXyoc573X1ouJ93IRRa2dmy6m+ojnVHcELe05o2ltjc8XEJ8PsfsOxEPn6GhLZzCFBmcC1zuHKCLumR6oCElFQJHxNTbsloVNkRQkNO0+keyIpdA2HiRtE8zLD8qRgzxMkHqtEwIkGI5Dfp81kpCTKLrBo+WIGZGXGV+R1O+KJr/BERPkAiZkNA3+EG+0z7Cp16UcPPF3LLbZzgwRKE5Dz9wkvN83DL5ZGyu0jdkmq8fiBeckz53vs1rwomOvoHEcJIoTj85P3gm+D4yb1j08h//rBg==; 5:EMStDc5UPVuKK0jfb3uBMU8aKakGR9DoGvC1tR+Bi5yvIP7YBjLUE64iAbZBQf4Q1r8iQrP9bvB7i0WmSeyQ9NyCMLCnZd1WluwREHxGf//YOJRcuhAlidxkN5eXdNRF523OGo5ian+EHIsaBYrC6g==; 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charset="us-ascii" Content-ID: <7C1E54F296402B48BCDFDA40556086FD@eurprd05.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Oct 2017 01:18:19.0124 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0501MB2045 Subject: [dpdk-dev] Requirement of minimum Rx burst size for PMDs 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: Fri, 20 Oct 2017 01:18:21 -0000 Hi, In some rx_burst functions, especially for vectorized ones (e.g. i40e_rxtx_= vec* or mlx5_rxtx_vec*), there's actually a requirement of min burst size. As it manipulates 4 packets simultaneously in a loop, if nb_pkts of rte_eth_rx_burst() is less than 4, it just returns without sending a packet= . One way to handle it could be falling back to regular rx_burst in such case= s but the burst size isn't a fixed/static parameter but applications can dynamica= lly change it when it polls a device. So, it might not be a good option. Therefore, how about adding min_rx/tx_burst_sz in struct rte_eth_dev_info a= nd have PMDs fill it in on dev_ops->dev_infos_get() so as to make apps comply = with it. Because the max size of a burst can be handled well by PMD, it may not be necessary. Thoughts? Thanks, Yongseok