P 3 T is an interactive performance estimator that assists users in performance tuning of scientific Fortran programs. It detects performance bottlenecks in the program, identifies the causes of performance problems, and guides the user in selecting effective program transformations in order to gain performance. Four of the most critical performance aspects of parallel programs are estimated: load balance, cache locality, communication and computation overhead. P 3 T is an integrated tool of the Vienna Fortran Compilation System, which enables the estimator to aggressively exploit considerable knowledge about the compiler's analysis information and code restructuring strategies. We evaluate existing features and describe substantial enhancements in three key areas: graphical user interface, performance parameters and input programs. P 3 T 0 s graphical user interface directs the user to bottlenecks in a computation that prevent the program from performing well. In addition, it...

. Performance evaluation studies are to be an integral part of the design and tuning of parallel applications. Their structure and their behavior are the dominating factors. We propose a hierarchical approach to the systematic characterization of the workload of a parallel system, to be kept as modular and flexible as possible. The methodology is based on three different, but related, layers: the application, the algorithm, and the routine layer. For each of these layers different characteristics representing functional, sequential, parallel, and quantitative descriptions have been identified. Taking also architectural and mapping features into consideration, the hierarchical workload characterization can be used for any type of performance studies. 1 Introduction The main reason to use parallel systems is to get more performance, i.e. either to be able to solve larger problems or to solve given problems in shorter time. So, in fact, performance is the driving force to deve...

The CAPSE (Computer Aided Parallel Software Engineering) environment aims to assist a perfor-mance oriented parallel program development approach by integrating tools for performance prediction in the design phase, analytical or simulation based perfor-mance analysis in the detailed specification and coding phase, and finally monitoring in the testing and cor-rection phase. In this work, the N-MAP tool as part of the CAPSE environment is presented. N-MAP covers the crucial aspect of performance prediction to support a perfor-mance oriented, incremental development process of parallel applications such that implementation design choices can be investigated far ahead of the full coding of the application. Methodologically, N-MAP in an automatic parse and translate step generates a simu-lation program from a skeletal SPMD program, with which the programmer expresses just the constituent and performance critical program parts, subject to an incremental refinement. The simulated execution of the SPMD skeleton supports a variety of performance studies. We demonstrate the use and performance of the N-MAP tool by developing a linear system solver for the CM-5. 1

Programming languages based solely upon plain textual representations inherit the textual linearization drawback. When writing parallel programs this shortcoming places an additional burden on the programmer because the most interesting parts of a parallel system are not linear. The bunch of existing visualization systems justifies the overall need for graphical methods in parallel programming. We argue that graphical support for all phases -- namely program development, analysis and visualization -- results in a more useful programming environment than a textual language supplemented by a set of isolated visualization tools. We describe the rationale for a visual parallel language and its use through all phases of program development in the Meander programming environment. 1 Introduction The overall goal of the Meander project is to provide a helpful programming environment for explicit parallel programming of distributed memory machines. Parallel programming is harder than writing ...

. In the development of e#cient parallel applications, reliable performance predictions are essential. However, many performance modelling formalisms, such as queueing networks, are not directly suitable for modelling parallel applications, while for other formalisms the analysis is too expensive. We present a methodology for performance modelling of parallel processing systems #Glamis#, based on extended queueing networks, aiming to overcome these problems. The methodology yields reliable performance predictions for a class of parallel machines and programs at relatively low #polynomial time# analysis cost. Additional reductions of analysis cost are obtained by exploiting inherent replications in parallel systems. 1 Introduction Performance predictions of a parallel program running on a parallel machine can be of great importance in a number of situations. A #rst application is the decision which one from a range of parallel machines is most suitable for a given applicatio...

We address the problem of performance prediction for parallel programs executed on clusters of heterogeneous workstations on which resource contention is present. We develop a methodology for the construction of performance models whose analysis allows the estimation of the execution time of these programs. We use Timed Petri Nets to represent the behavior of parallel programs, and a contention model based on queueing theory to quantify the effects of resource contention on the execution time of the application processes. Our methodology is demonstrated through the construction of the model of an example program, which is also used to validate the predictions against measured execution times obtained by executing the program on two different clusters of workstations. 1 Introduction Clusters of workstations are increasingly being used as costeffective parallel computing platforms, but their effective exploitation requires consideration of many of the research problems already addresse...

. Petri nets with an explicit notion of time have proven to be a good modelling tool for the qualitative and quantitative study of asynchronous concurrent systems with parallelism, synchronization and resource sharing. The formalism could be successfully applied in performance modelling and evaluation of concurrent programs, parallel systems and mappings among the two. However, performance models of realistic systems are in general very costly to evaluate. In this work we develop a Time Warp based distributed discrete event simulation scheme to accelerate the evaluation of timed Petri net performance models. The particular model structure that typically results from performance modelling of parallel systems explicitly provides partitioning possibilities which are very cumbersome to identify in general Petri net models. With our implementations of a distributed simulation engine running on an Intel iPSC/860 multiprocessor we show that real speedup over sequential simulation model evalua...

Performance is often a key factor in determining the success of a parallel software system. Performance evaluation...

this paper, we give a sketch of the Meander language as well as an example program in section 2, discuss the important topic how to manage complex graphical specifications in section 3, provide an overview of the current functionality of our system (section 4) and close with some comments on future plans w.r.t. Meander. 2. The Meander Language

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