Hello Mohammad,
I am still getting same small numbers for the throughput when testing the network performance for the Raspberry pi with the TCP_STREAM,
the small TCP window size you observed seems to be the limiting factor. But I have no idea why the TCP connection throttles the window parameters in this way.
Have you tried any of the following experiments to encircle the problem?
* Different host machine * Different OS on your host machine. You mentioned that the problem does not occur when running OpenBSD in a VM on the host machine. How is the behavior when running OpenBSD natively on the host machine? * Different network equipment (network cables, switch) * Different Raspberry Pi * Different power supply for the Raspberry Pi * Performing the netperf test with Raspian
could you tell me please what you use in the client machine side,
We run our nightly tests on Ubuntu 12.04.4 LTS (GNU/Linux 3.2.0-67-generic x86_64).
Have you tried to follow (and possibly instrument) the lwIP code that is involved in the TCP parameter negotiation?
Cheers Norman