The client max_rpcs_in_flight parameter is often tuned to try and get better performance from clients with large bandwidth-delay products. Unfortunately, people are less familiar with tuning the LNET peer credits values, and this results in the Lustre layer trying to send RPCs concurrently that will never go on the wire at the same time.

It would make sense to increase the LNET peer credits when the max_rpcs_in_flight is increased above the current value, so that users get the behaviour that they expect.