Existing MPI Applications Research Articles

Exploiting Offload-Enabled Network Interfaces

Network interface cards are one of the key components to achieve efficient parallel performance. In the past, they have gained new functionalities, such as lossless transmission and remote direct memory access, that are now ubiquitous in high-performance systems. Prototypes of next-generation network cards now offer new features that facilitate device programming. In this article, the authors discuss an abstract machine model for offloading architectures. They used the Portals 4 network interface to implement the proposed abstraction model, and they present two microbenchmarks to show the effects of fully offloaded collective communications. They then propose the concept of persistent offloaded operations that can reduce the creation/offloading overhead, and they discuss a possible extension to the current Portals 4 interface to enable their support. The results obtained show how this work can be used to accelerate existing MPI applications.

Portable, MPI-interoperable coarray fortran

The past decade has seen the advent of a number of parallel programming models such as Coarray Fortran (CAF), Unified Parallel C, X10, and Chapel. Despite the productivity gains promised by these models, most parallel scientific applications still rely on MPI as their data movement model. One reason for this trend is that it is hard for users to incrementally adopt these new programming models in existing MPI applications. Because each model use its own runtime system, they duplicate resources and are potentially error-prone. Such independent runtime systems were deemed necessary because MPI was considered insufficient in the past to play this role for these languages. The recently released MPI-3, however, adds several new capabilities that now provide all of the functionality needed to act as a runtime, including a much more comprehensive one-sided communication framework. In this paper, we investigate how MPI-3 can form a runtime system for one example programming model, CAF, with a broader goal of enabling a single application to use both MPI and CAF with the highest level of interoperability.

MagPIe

Writing parallel applications for computational grids is a challenging task. To achieve good performance, algorithms designed for local area networks must be adapted to the differences in link speeds. An important class of algorithms are collective operations, such as broadcast and reduce. We have developed M AG PI E , a library of collective communication operations optimized for wide area systems. M AG PI E 's algorithms send the minimal amount of data over the slow wide area links, and only incur a single wide area latency. Using our system, existing MPI applications can be run unmodified on geographically distributed systems. On moderate cluster sizes, using a wide area latency of 10 milliseconds and a bandwidth of 1 MByte/s, M AG PI E executes operations up to 10 times faster than MPICH, a widely used MPI implementation; application kernels improve by up to a factor of 4. Due to the structure of our algorithms, M AG PI E 's advantage increases for higher wide area latencies.