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Thu, 26 Apr 2018 22:26:36 +0000 From: "Wu, Xiaoban" To: "users@dpdk.org" Thread-Topic: Interesting considerate but annoying behavior of MLX5 driver Thread-Index: AQHT3arn+5BHs4kFF0y+3oUgfrSmWg== Date: Thu, 26 Apr 2018 22:26:36 +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=Xiaoban_Wu@student.uml.edu; x-originating-ip: [129.63.5.158] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; DM5PR02MB2460; 7:cF7VQGLZoJJw5jjna83txZhd4wk9B7UGPPwvG4IFk7qwtgcQDOFjMcQUXVk0vSkJn1dBL+wagTNXdZ1+2kDlGPC0J/ZCf+5kigJu7XlSp5ZHxBB5hdKQJr+XylFosLXA++X5zkLwm5mwX4syjnNkGNKzHdmt0c1VTDrontL5/a1Ha0br66+E8vWZT6m4xiSeCT+XUPnzSJ7U7QZRViIEDZEdfa3O65u9p+Xeth0sIIVovZ/Mvp/8OgljqspGFdCz x-ms-exchange-antispam-srfa-diagnostics: SOS; x-microsoft-antispam: UriScan:; BCL:0; PCL:0; RULEID:(7020095)(4652020)(8989080)(5600026)(4534165)(4627221)(201703031133081)(201702281549075)(8990040)(2017052603328)(7153060)(7193020); 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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: [dpdk-users] Interesting considerate but annoying behavior of MLX5 driver X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Apr 2018 22:26:38 -0000 Dear All, I have two Dell PowerEdge R740 servers A and B running with ubuntu 16.04, e= ach one has a Mellanox MCX556A-ECAT NIC installed on the PCIe x16 slot. And= , the two NICs are directly connected back to back with a copper cable. On server A, it runs a RX program which runs a function to process and anal= yze the received packets. On server B, it runs a packet-gen program which g= enerates and sends packets out. They are both compiled with dpdk-17.11 Now the interesting thing is that on server B, it is kind of smart and cons= iderate enough to automatically adjust its TX throughput according to how f= ast server A processes the packets. If server A processes the packets faste= r, then server B sends packets with a higher throughput. Similarly, if serv= er A processes the packets slower, then server B sends packets with a lower= throughput. Please note that once the program on server B starts, it is ne= ver interrupted by any way. However, I think the server B should send out the packets with a constant t= hroughput no matter how fast server A processes the packets. Does anybody else notice this interesting behavior of MLX5 driver? Can anyb= ody help me disable this feature permanently? Thanks very much for your hel= p. Best wishes, Xiaoban