ConnectX-3 - Upload speeds slower on Windows 10 than Ubuntu 18.10

I’m experiencing a strange issue - I have a fiber connection that is rated at 1.5 Gbps download, 940 Mbps upload. When I run a speed test on my Windows 10 machine with a Mellanox ConnectX-3 card, the upload tops out at ~800 Mbps, whereas running under Ubuntu 18.10, I get closer to ~900 almost every time. Are there any setting I can tweak under Windows to optimize the upload speed? The download speed is more consistent across operating systems, although still has a slight edge under Ubuntu.

I should also mention that on the exact same machine, if I run a speed test using the built-in Gigabit Ethernet adapter connected to the same switch, it reaches speeds of ~940 Mbps on the upload no problem.



I don’t know what upload /download test you are using, neither do I know if you run on the top of RDMA or simply TCP/UDP traffic but the upload & download to a file issue sounds to me more like storage read/write test. What I would suggest you to do is 1. Approach mellanox website, download & install Melannox driver (WinOF v5.50) 2. Download and read the Driver’s “user-manual” that will guide you how to set HW & FW “performance-tuning"of CX_3 adapter 3. Next, use Microsoft “NTttcp”` tool to measure first the “network-performance” between the 2x End-to-Dnd Mellanox CX-3 adapter. Ensure you get optimum performance. For example, if your adapter has a sped-rate of 10Gb/s - see that you get at least ~8-9Gb/s bandwidth 4. if all above is as expected, and you still get upload/download low performance, then I suggest you liaise with Miicrosoft & the storage vendor to get their advice if & how you can enhance it 5. as for Linux vs. Windows - it depends whether you have “fine-tuned” both OS in terms of the sw & hw” parameters, if you have harnessed all CPU / cores resources etc… Read more on this in Mellanox Windows & LInux driver’s user manuals