Suggestions for preset watermark settings based on upload speed

[hunkydunk]

I cannot find a clear articulation for the following settings anywhere, but assume they are important settings to change in order to maximize high speed upload.

send_buffer_watermark
send_buffer_low_watermark

Can someone suggest values for high performance 1Gbp/s upload?

In addition, I suggest to help configuration and maximize performance, provide any:
i) documentation of examples/suggested values based on some common upload connection speeds e.g. (100mbps / 1Gbps / 10Gbps)
ii) within client offer templates or preset values based on connection speed

[Seeker2]

Those values also depend on connection latency/pingtimes.
A longer round trip needs a larger buffer to prevent the buffer running empty...the low watermark is to keep some leeway against that, but may not be enough in worst-case situations.
VPNs/proxies can add to the latency/pingtimes even if the delay is purely cpu-based.