Slow network performance on WinNAT due to receive segment coalescing (RSC)

[mback2k]

As mentioned in docker/for-win#698 Docker for Windows (including Windows Server / Docker EE) can experience slow network performance with WinNAT due to receive segment coalescing (RSC).

I was able to reproduce the issue by having a long-running container that regularly does a git clone of the curl repository. After disabling RSC on all available network adapters, I no longer experienced slow network performance. Even just a regular curl download of large files (>1 GB) caused this issue.

Therefore I would like to suggest to disable RSC via hcsshim on the host adapter everytime a virtual network switch is created for use with Docker.

[daschott]

This issue should no longer be applicable to WinNAT on RS5 and above.

[weidi]

This issue should no longer be applicable to WinNAT on RS5 and above.

This issue is still there in Server 2022, was able to fix it by disabling RSC
Get-NetAdapterRsc | Disable-NetAdapterRsc
Improved download speed from ~15MB/s to 200MB/s

[jankap]

This issue should no longer be applicable to WinNAT on RS5 and above.

This issue is still there in Server 2022, was able to fix it by disabling RSC Get-NetAdapterRsc | Disable-NetAdapterRsc Improved download speed from ~15MB/s to 200MB/s

Same here, from 100 KiB/s (!) to 30 MiB/s inside a Windows Docker container. That's from "unusable" to host-performance.