The Real-Time Message Passing Interface (MPI/RT) is an emerging real-time communications middleware standard for distributed real-time applications. The Message Passing Interface (MPI) is the de facto standard for high performance parallel application development. In this thesis, we describe how MPI/RT with best effort quality of service can be used as an alternative for MPI. Mercury Computer Systems' RACE embedded parallel computer is used as the platform for comparison of design and performance of these two standards. The main advantages MPI/RT has over MPI are its explicit support for communication channels and its emphasis on early binding. Design and implementation of best effort MPI/RT on Mercury is described and its performance is compared with MPI in order to illustrate how MPI/RT features allow implementations to exploit the underlying platform more optimally. The results for the benchmarks show that MPI/RT outperforms MPI in almost all cases examined.

Distributed real-time applications require support from the underlying middleware to meet the strict requirements for jitter, latency, and bandwidth. While most existing middleware standards such as MPI do not support Quality of Service (QoS), the MPI/RT standard supports QoS in addition to striving for high performance. This thesis presents HARE, the first known implementation of a subset of the MPI/RT 1.1 standard with time-driven QoS support. This thesis proves the following hypothesis: It is possible to achieve zero-sided communication (a model of communication characterized by the absence of any explicit per-message transfer calls by any of the participating sides) in a real-time environment using a QoS contract between an application and message-passing middleware. Furthermore, it is shown that the performance and predictability of a time-driven task using zero-sided communication is better than that of a best-effort task. The hypothesis is validated through compact MPI/RT application programs that achieve zero-sided communication.