Abstract: The C++ DASH template library provides distributed data container for Partitioned Global Address Space (PGAS)-like programming. Because DASH is new and under development no debugger is capable to handle the parallel processes or access/modify container elements in a convenient way. This paper describes how the DASH library has to be extended to interrupt the start-up process to connect a debugger with all started processes and to enable the debugger for accessing and modifying DASH container elements. Furthermore, an GDB extension to output well formatted DASH container information is presented.

Abstract: The advent of multicore and manycore processors, including GPUs, in the customer market encouraged developers to focus on extraction of parallelism. While it is true that parallelism can deliver performance boosts, parallelization is also very complex and error-prone task. Many applications are still sequential, or dominated by sequential sections. Modern micro-architectures have become extremely complex, and they usually do a very good job at executing fast a given sequence of instructions. When they occasionally fail, however, the penalty may be severe. Pathological behaviors often have their roots in very low-level implementation details of the micro-architecture, hardly available to the programmer. We argue that the impact of these low-level features on performance has been overlooked, often relegated to experts. We show that a few metrics can be easily defined to help assess the overall performance of an applications, and quickly diagnose a problem. Finally we illustrate our claim with a simple prototype, along with several use cases.

Abstract: Dimensional analysis is a well known technique for checking the consistency of equations involving physical quantities, constituting a kind of type system. Various type systems for dimensional analysis, and its refinement to units-of-measure, have been proposed. In this paper, we detail the design and implementation of a units-of-measure system for Fortran, implemented as a pre-processor. Our system is designed to aid adding units to existing code base: units may be polymorphic and can be inferred. Furthermore, we introduce a technique for reporting to the user a set of critical variables}which should be explicitly annotated with units to get the maximum amount of unit information with the minimal number of explicit declarations. This aids adoption of our type system to existing code bases, of which there are many in computational science projects.