Toward Implementing Robust Support for Portals 4 Networks in MPICH

The Portals 4 network specification is a low-levelAPI for high-performance networks developed by Sandia National Laboratories, Intel Corporation, and the University of NewMexico. Portals 4 is specifically designed to support both the MPIand PGAS programming models efficiently by providing building blocks upon which to implement their particular features. In this paper we discuss our ongoing efforts to add efficient and robust support for Portals 4 networks inside MPICH, and we describe how the API semantics influenced our design. In particular, we found the lack of reliability guarantees from the Portals4 layer challenging to address. To tackle this situation, we implemented an intermediate layer - Rportals (reliable Portals), which modularizes the reliability functionality within our Portals network module for MPICH. In this paper we present theRportals design and its performance impact.