Question Intel X550-T1 NIC on Windows gives very low throughput / slow transfer speed ?

[flobernd]

Hi there,

I recently added a Intel X550-T1 NIC to my Windows machine. Now after doing some tests I noticed the throughput is only about 2.5 GBits/s (using iperf3 for testing).

Same test performed using an Ubuntu Live Boot Stick yielded me a throughput of about 9 GBits/s.

Things I tried to improve:

1. Completely re-installed Windows
2. Installed the latest driver for the X550-T1 (from the Intel website)

What as well catched my mind: If I run the test with the loopback interface (localhost) as the target server, I only get the same poor throughput of about 2.5 GBits/s. All my Debian VMs and as well a Windows Server 2019 VM (on an ESXi host) are showing between 40-100 GBits/s in the same test.

Can anybody help me out please?

Btw. googling the problem showed up some more people with this issue and they state that the performance became bad after they did the 2004 update . I’m currently running the latest 20H2.

Best regards

 

[kanewolf]

Please use the correct notation. You don't get 9GB/s on a 10gigbit network card. You get 10Gb/s. Incorrect notation can be the problem. Mixing bits/s and bytes/s. can cause many of the "slow" throughput complaints.
No operating system will show 100GB/s with a 10 gigabit network.

Since this seems like a Windows issue, have you checked the Windows AutoTune setting -- https://www.ghacks.net/2016/08/05/windows-10-limiting-internet-speed/
Also, since this is a multi-speed adapter, you should validate your link rate. It is possible that your NIC is negotiating to a 2.5Gb/s link rate.

 

[flobernd]

All measurements in Gbits!

I tested with disabled, normal and experimental auto-tune. Disabled was even slower a lot and the normal/experimental ones did not make any difference.

I tested the loopback speeds on a different Win10 Pro machine and was able to get about 4.5Gbits/s. Strange think: This machine is a lot less powerful.