Thursday, August 5, 2021

Windows Server 2019/2020 @ 25Gbps?

We upgraded some equipment to 25Gbps and our Linux boxes will hit 23Gbps all day, no tweaks. Our Windows Servers (mix of 2019 and 2022 for pre-testing) can't seem to break 15Gbps.

The machines are all high clock-speed Epyc Rome 2 (equivalent of Ryzen Zen 2) as well as a Ryzen Zen 3 workstation. Mellanox CX4 cards. Fiber. Using iperf3 for testing.

I don't think it's a CPU issue, as running multiple streams in parallel doesn't improve throughput, each stream just decreases so the cumulative is 13-14Gbps.

Does anyone have any suggestions for improving performance on Windows? I went through this way back in the day with Server 2012/2016 and 10Gbps, but have largely forgotten everything I did.

edit: disabling virtual machines queues and setting the TCP Windowing to "experimental" did the trick.



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