Abstract
This paper describes how the NewMadeleine communication library has been integrated within the MPICH2 MPI implementation and the benefits brought. NewMadeleine is integrated as a Nemesis network module but the upper layers and in particular the CH3 layer has been modified. By doing so, we allow NewMadeleine to fully deliver its performance to an MPI application. NewMadeleine features sophisticated strategies for sending messages and natively supports multirail network configurations, even heterogeneous ones. It also uses a software element called PIOMan that uses multithreading in order to enhance reactivity and create more efficient progress engines. We show various results that prove that NewMadeleine is indeed well suited as a low-level communication library for building MPI implementations.