Hi. Got a headscratcher here, I’m getting some odd iperf results on my windows machine. I have 3 systems with 100Gb network adapters with a mellanox switch in between, from a linux machine to my NAS I can get 97Gb both ways with iperf, but from my windows machine I get ~85 from my desktop to either the NAS or the linux machine, but only 15Gb down, from either the linux or NAS machine. The 3 way testing means I know the switch does the right things, and I know that both the NAS and linux machine can do bidirectonal high speed, so it’s something in the windows networking I suspect.
I’ve tried window sizes on the iperf command, which doesn’t seem to have changed anything, and I’ve tried changing the receive buffers in the mellenox device settings from 256 to 2048 to match the send buffers, but no joy. Wondering what else there is to try with the windows networking that might improve the down speed, any suggestions greatfully received.
For info, the NAS is an Epyc 7352 with 128GB Ram and a connectx5 ex, the linux machine is a threadripper 3960x with 64GB Ram and a connectx4, the windows machine is a threadripper 7970x with 128GB ram and a connectx 5.