Hi Ivan,
I've done test for nic_bridge, and I've updated page with results http://ksyslabs.org/doku.php?id=genode_network_perfomance#nic_bridge_test
thanks for posting the results. One thing left me wondering: In the last scenario, the roles of both L4Linux instances look entirely symmetric. How can it be that the benchmark produces different results when swapping the roles of both instances? Are both instances configured identically? In particular, do they have the same amount of RAM configured? I'm asking because we observed that the TCP parameters of the Linux TCP/IP stack depend on the memory available to Linux.
Apart from that, your measurement seems to support my presumption that the driver is the bottleneck. Even with two Linux instances running and the overhead introduced by the indirection via nic_bridge, the throughput stays in the same order as native Linux.
Do you share my interpretation? If so, it would be worthwhile to focus the investigation on the driver.
Cheers Norman