Modelling of Communication in Unified Parallel and Distributed Computing Environment

Abstract

In modelling of sequential computers and algorithms, communication delay has often been ignored. Later, in modelling of parallel computers and parallel algorithms based on shared memory, it was supposed that the influence of communication is lower compared to computation complexity. It was supposed that, in better cases, communication delay is included in analysed computation complexity. However, a different situation can occur in high performance processors (CPU) or simplified CPUs called cores within the parallel computing node (multiprocessor/ multicore SMP). The similar case could occur in the multiple use of high performing computing nodes as the building computing nodes of modern parallel computers NOW (network of workstations) or Grid module (network of NOW modules). However, if complex problem are intended to be solved in a parallel way (parallel algorithm), they generate additional communication steps which correspond to inter process communication (IPC) among the decomposed parts (parallel processes) of the given solved problem. In general, it can be said that any parallel algorithm (PA) consists of created parallel processes having sequential character and IPC communication. Therefore, the increased role of IPC communication has been analysed in this paper through the analytical modelling of IPC complexity (number of communication steps) in a similar way as the one used to analyse computation complexity in sequential algorithms or parallel processes). Based on the defined communication parameters and the extensions of the complexity theory to PA, a unique modelling approach was developed to model the communication complexity of all existing parallel computers and PA. The secondary problem is to model critical parts of IPC influence for PA performance and that, at first, in minimisation of IPC steps of decomposed parallel processes and secondly at whole performance optimisation of the PA. The achieved results showed, from the user’s point of view, the important influence of modelling IPC complexity in PA on the illustrated real examples.
Copyright © 2018 Praise Worthy Prize - All rights reserved.