The Sockets Direct Protocol (SDP), which was designed to provide an RDMA alternative to TCP over InfiniBand networks, is known to suffer from performance degradation on more recent kernels such as UEK R4u2 and later. There is no active development on this protocol.

Although the library for this protocol is still available for this kernel, support is limited. You should consider using TCP on top of IP over InfiniBand as a more stable alternative. (Bug ID 22354885)