The latency cost of blocking is significant compared to round
trip ping-pong time. Spin briefly on rsockets before calling
into the kernel and blocking.
The time to spin before blocking is read from an rsocket
configuration file %sysconfig%/rdma/rsocket/polling_time. This
is user adjustable or may be set automatically by ibacm.
As a completely unintentional side effect, this just happens to
improve application performance in benchmarks, like netpipe,
significantly. ;)