Search

An introduction is presented in which the editors discuss various reports within the issue on topics including parallel programming, parallel computers, and CPU/GPU multi-core architectures.

Parallel programming has proved to be an effective technique to increase the performance of computationally intensive applications. However, writing parallel programs is not easy, and activities such as debugging are usually hard and time consuming. To cope with these difficulties, skeletal parallel programming has been widely explored in recent years with very promising results. However, prototypal skeletal systems developed so far tend to be rather inflexible and difficult to adapt to many practical parallelization scenarios. For instance, many systems restrict all the substructures of an application being encapsulated together in term of possibly nested skeletons, which may be cumbersome when parallelizing some large and complex applications. Moreover, it is usually difficult to share resources among different skeleton instances and to reuse the same instance of a skeleton in different parts of the code. This paper reports on the current status of the OcamIP3I (2.0) system, which sensibly changes the skeletal model of the previous versions, making it more usable and flexible. In particular, we describe the new skeletons, the new skeletal execution model as well as related issues on design and implementation. [ABSTRACT FROM AUTHOR]

The paper presents a parallel programming methodology that ensures easy programming, efficiency and portability of programs to different machines belonging to the class of the general-purpose, distributed-memory, MIMD architectures. The methodology is based on the definition of a new, high-level, explicitly parallel language, called P3L, and of a set of static tools that automatically adapt the program features for each target architecture. P3L does not require programmers to specify process activations, the actual parallelism degree, scheduling, or interprocess communications, i.e. all those features that need to be adjusted to harness each specific target machine. Parallelism is on the other hand, expressed in a structured and qualitative way, by hierarchical composition of a restricted set of language constructs, corresponding to those forms of parallelism that are frequently encountered in parallel applications, and that can be efficiently implemented. The efficient portability of P3L applications is guaranteed by the compiler along with the novel structure of the support. The compiler automatically adapts the program features for each specific architecture, using the costs (in terms of performance) of the low-level mechanisms exported by the architecture itself, In our methodology, these costs, along with other features of the architecture, are viewed through an abstract machine, whose interface is used by the compiler to produce the final object code. [ABSTRACT FROM AUTHOR]