[Cake] Long-RTT broken again

[Toke Høiland-Jørgensen]

Jonathan Morton <chromatix99 at gmail.com> writes:

> Okay, that seems to be working somewhat better now.  I’m still not
> getting 100Mbps throughput in either direction, but now it seems to be
> because the receive windows won’t open far enough - there’s enough
> buffering to prevent any packet loss.

Yeah, Linux is window limited at these BDPs with the default settings.
Try these sysctls on both sides:

net.core.rmem_max=16777216
net.core.wmem_max=16777216
net.ipv4.tcp_rmem = 4096 87380 104857600
net.ipv4.tcp_wmem = 4096 16384 104857600

-Toke