3,157 research outputs found
Investigation of the applicability of a functional programming model to fault-tolerant parallel processing for knowledge-based systems
In a fault-tolerant parallel computer, a functional programming model can facilitate distributed checkpointing, error recovery, load balancing, and graceful degradation. Such a model has been implemented on the Draper Fault-Tolerant Parallel Processor (FTPP). When used in conjunction with the FTPP's fault detection and masking capabilities, this implementation results in a graceful degradation of system performance after faults. Three graceful degradation algorithms have been implemented and are presented. A user interface has been implemented which requires minimal cognitive overhead by the application programmer, masking such complexities as the system's redundancy, distributed nature, variable complement of processing resources, load balancing, fault occurrence and recovery. This user interface is described and its use demonstrated. The applicability of the functional programming style to the Activation Framework, a paradigm for intelligent systems, is then briefly described
Evaluating load balancing policies for performance and energy-efficiency
Nowadays, more and more increasingly hard computations are performed in
challenging fields like weather forecasting, oil and gas exploration, and
cryptanalysis. Many of such computations can be implemented using a computer
cluster with a large number of servers. Incoming computation requests are then,
via a so-called load balancing policy, distributed over the servers to ensure
optimal performance. Additionally, being able to switch-off some servers during
low period of workload, gives potential to reduced energy consumption.
Therefore, load balancing forms, albeit indirectly, a trade-off between
performance and energy consumption. In this paper, we introduce a syntax for
load-balancing policies to dynamically select a server for each request based
on relevant criteria, including the number of jobs queued in servers, power
states of servers, and transition delays between power states of servers. To
evaluate many policies, we implement two load balancers in: (i) iDSL, a
language and tool-chain for evaluating service-oriented systems, and (ii) a
simulation framework in AnyLogic. Both implementations are successfully
validated by comparison of the results.Comment: In Proceedings QAPL'16, arXiv:1610.0769
Bounding the execution time of parallel applications on unrelated multiprocessors
Heterogeneous multiprocessors, that consist of processor types with different execution capabilities, are critical today, and in future, to offer high performance and high energy efficiency. In order to use them in hard real-time systems to support parallel processing, a tight estimation of the upper bound on the completion time (WCET) of parallel applications is needed. This paper presents, for the first time, a closed-form solution for the calculation of the WCET for task-based parallel applications modeled as directed acyclic-graphs (DAG) using the general unrelated multiprocessor model that is capable of modeling a wide range of heterogeneous multiprocessor platforms. The paper contributes with a polynomial time algorithm to calculate the WCET (i.e., makespan) for the unrelated model. In addition, it presents simulation results that are based on modeling a set of representative OpenMP task-based parallel applications from the BOTS benchmark suite
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