network connection 1000Mbps doesn't reach 1000Mbps

Yes, I’m using tcp, I think is the default now in NFS. Actually, when I use UDP, I have a warning “Using NFS over UDP can cause data corruption.”.
But using UDP is slightly faster than TCP, more or less 10-20% faster


Unless NFS itself for some reason is imposing a layer of window buffering above TCP, if you’re implementing TCP transport the proper TCP algorithm should have made that adjustment automatically for you. If you re-ran your tests using something like “Scalable TCP” or “TCP Westwood+” would probably be recommended… On my default 11.3, the algorthm is Cubic which is described in my reference article as “less aggressive” adapting to less than normal conditions such as yours.


I wonder if using jumbo frames may also help?
Gigabit Ethernet Jumbo Frames