On the efficiency of several VM provisioning strategies for workflows with multi-threaded tasks on clouds

Cloud computing promises the delivery of on-demand pay-per-use access to unlimited resources. Using these resources requires more than a simple access to them as most clients have certain constraints in terms of cost and time that need to be fulfilled. Therefore certain scheduling heuristics have been devised to optimize the placement of client tasks on allocated virtual machines. The applications can be roughly divided in two categories: independent bag-of-tasks and workflows. In this paper we focus on the latter and investigate a less studied problem, i.e., the effect the virtual machine allocation policy has on the scheduling outcome. For this we look at how workflow structure, execution time, virtual machine instance type affect the efficiency of the provisioning method when cost and makespan are considered. To aid our study we devised a mathematical model for cost and makespan in case single or multiple instance types are used. While the model allows us to determine the boundaries for two of our extreme methods, the complexity of workflow applications calls for a more experimental approach to determine the general relation. For this purpose we considered synthetically generated workflows that cover a wide range of possible cases. Results have shown the need for probabilistic selection methods in case small and heterogeneous execution times are used, while for large homogeneous ones the best algorithm is clearly noticed. Several other conclusions regarding the efficiency of powerful instance types as compared to weaker ones, and of dynamic methods against static ones are also made

Client-side resource management on the cloud: survey and future directions

Cloud computing and how to bridge the gap between various providers is getting increasing attention. In this context, efficiently scheduling tasks on heterogeneous resources is of extreme importance. The state-of-the-art for this field has been continuously growing during the last years and has reached a point in which a comprehensive overview indicating current solutions and ongoing challenges is of extreme importance for researchers. This paper aims to offer this analysis from a client-side scheduling perspective in which emphasis is not put on physical resource selection but on task to virtual machine mappings and virtual machine allocation. It provides a taxonomy for the current state-of-the-art and a unified model concerning the various metrics and goals used throughout literature. This model is designed to be sufficiently generic, extensible, and comprehensive to support most of the future work in the field. Several promising research directions and existing challenges are described

Single Node On-Line Simulation of MPI Applications with SMPI

Simulation is a popular approach for predicting the performance of MPI applications for platforms that are not at one’s disposal. It is also a way to teach the principles of parallel programming and high-performance computing to students without access to a parallel computer. In this work we present SMPI, a simulator for MPI applications that uses on-line simulation, i.e., the application is executed but part of the execution takes place within a simulation component. SMPI simulations account for network contention in a fast and scalable manner. SMPI also implements an original and validated piece-wise linear model for data transfer times between cluster nodes. Finally SMPI simulations of large-scale applications on large-scale platforms can be executed on a single node thanks to techniques to reduce the simulation’s compute time and memory footprint. These contributions are validated via a large set of experiments in which SMPI is compared to popular MPI implementations with a view to assess its accuracy, scalability, and speed

Refinement of data parallel programs in Pei

Parallel programs mainly differ from sequential ones in that they include geometrical aspects involved by the hardware architecture. We present in this paper the Pei formalism, which enables to take into account both the geometrical and functional aspects of programs. It provides a refinement calculus mainly used to transform the geometrical characteristics of parallel programs, and we show how it may apply on data parallel programs, in particular for data alignments. Keywords Data fields, Data-parallelism, Program transformation, Refinement. 1 INTRODUCTION Parallel programming is a major challenge for handling efficient computations. It involves two technological issues: a program expressed in some dedicated language which supports a parallel programming model, and a computer and the parallel execution model it implements. Ideally the programming language should be architecture independent whereas the computations efficiency requires a strong-related architecture implementation. ..