Intel 10-Gigabit X540-AT2 (rev 01) Bandwidth Not as spec

[TRANG2]

Hello Intel,

We have purchased 3pcs of Intel Corporation Ethernet Controller 10-Gigabit X540-AT2 (rev 01).

We have connected this to our HP Desktops in the PCI Express slot(PCI bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor PCI Express x16 Controller (rev 06)).

Now when we run iperf tool to measure the bandwidth we found that when dual port are used to tx/rx we see total bandwidth as 1st port @~4Gbits/sec and 2nd port @~5Gbits/sec total for 2 ports(port1 + port2) @~9Gbits/sec

When we use only 1 port we see 9Gbps bandwidth.

But as the product spec details from the link (https://ark.intel.com/products/58954/Intel-Ethernet-Converged-Network-Adapter-X540-T2 Intel® Ethernet Converged Network Adapter X540-T2 Product Specifications ) as per port 10Gbps.

Please help us to reach the bandwidth as mentioned in the product spec. Means are we doing something wrong or any configuration in the driver that we need do.

Attachments shows how we are connected and tests performed with the results.

Thanks in advance.

[TRANG2]

Hello Daniel,

This sounds interesting, Can you please share the driver used for this test, along with the configuration.

i.e any arguments passed during the driver insertion.

Thanks and Regrads,

Trilokesh Rangam.

[idata]

Hello Rangam,

Thank you for the reply. We used the 4.2.1-k and 5.3.7 drivers. The adapters were set to their default settings with nothing modified.Best regards,Daniel D

[TRANG2]

Hello Daniel,

Can you please describe the commands used to test the bandwidth in detail.

Thanks,

Trilokesh Rangam.

[TRANG2]

Hello Daniel,

It would be a great help if you can provide us some screenshots.

[idata]

Hello Rangam,

Command used was iperf -c 192.168.x.x from the X540 ports.

I have attached 3 screenshots to show the command used and resulting iperf output.

Please let me know if you have any questions.

Best regards,

Daniel D

[LMeze]

Trilokesh Rangam,

As far as I know, if you have two interfaces on the same network 192.168.1.x, then the Linux kernel is just going to pick one interface to send traffic for that network.

[idata]

Hello Rangam,

Have you tried using different subnets on the connected ports as Fielious suggested? We will try iperf using a single subnet. We have been using different subnets for the ports in our previous tests.Thank you for the information Fielious. Best regards,Daniel D

[idata]

Hello Rangam,

We were able to replicate your scenario in the lab using a similar subnet for all ports and iperf3. Please try this scenario using different subnets for each pair of ports. Does this improve the throughput? Screenshots are attached. Please let us know if you have any questions.

Best regards,

Daniel D

[idata]

Hello Rangam,

Please let us know if you need anymore assistance. We were able to replicate your issue. Using similar subnets on each interface may cause throughput issues. If you have any other questions please let us know.Best regards,Daniel D

[TRANG2]

Hello David,

Thanks for the support, we are able to see the results as you mentioned with different subnets.

Thanks,

Trilokesh Rangam.

[idata]

Hello Rangam,

Glad you were able to get the desired results. If you have any other questions please do not hesitate to contact us.Best regards,Daniel D