135 research outputs found
Corporate influence and the academic computer science discipline. [4: CMU]
Prosopographical work on the four major centers for computer
research in the United States has now been conducted, resulting in big
questions about the independence of, so called, computer science
Metascheduling of HPC Jobs in Day-Ahead Electricity Markets
High performance grid computing is a key enabler of large scale collaborative
computational science. With the promise of exascale computing, high performance
grid systems are expected to incur electricity bills that grow super-linearly
over time. In order to achieve cost effectiveness in these systems, it is
essential for the scheduling algorithms to exploit electricity price
variations, both in space and time, that are prevalent in the dynamic
electricity price markets. In this paper, we present a metascheduling algorithm
to optimize the placement of jobs in a compute grid which consumes electricity
from the day-ahead wholesale market. We formulate the scheduling problem as a
Minimum Cost Maximum Flow problem and leverage queue waiting time and
electricity price predictions to accurately estimate the cost of job execution
at a system. Using trace based simulation with real and synthetic workload
traces, and real electricity price data sets, we demonstrate our approach on
two currently operational grids, XSEDE and NorduGrid. Our experimental setup
collectively constitute more than 433K processors spread across 58 compute
systems in 17 geographically distributed locations. Experiments show that our
approach simultaneously optimizes the total electricity cost and the average
response time of the grid, without being unfair to users of the local batch
systems.Comment: Appears in IEEE Transactions on Parallel and Distributed System
Formal Verification of Synchronisation, Gossip and Environmental Effects for Wireless Sensor Networks
The Internet of Things (IoT) promises a revolution in the monitoring and control of a wide range of applications, from urban water supply networks and precision agriculture food production, to vehicle connectivity and healthcare monitoring. For applications in such critical areas, control software and protocols for IoT systems must be verified to be both robust and reliable. Two of the largest obstacles to robustness and reliability in IoT systems are effects on the hardware caused by environmental conditions, and the choice of parameters used by the protocol. In this paper we use probabilistic model checking to verify that a synchronisation and dissemination protocol for Wireless Sensor Networks (WSNs) is correct with respect to its requirements, and is not adversely affected by the environment. We show how the protocol can be converted into a logical model and then analysed using the probabilistic model-checker, PRISM. Using this approach we prove under which circumstances the protocol is guaranteed to synchronise all nodes and disseminate new information to all nodes. We also examine the bounds on synchronisation as the environment changes the performance of the hardware clock, and investigate the scalability constraints of this approach
Formal verification of synchronisation, gossip and environmental effects for wireless sensor networks
The Internet of Things (IoT) promises a revolution in the monitoring and control of a wide range of applications, from urban water supply networks and precision agriculture food production, to vehicle connectivity and healthcare monitoring. For applications in such critical areas, control software and protocols for IoT systems must be verified to be both robust and reliable. Two of the largest obstacles to robustness and reliability in IoT systems are effects on the hardware caused by environmental conditions, and the choice of parameters used by the protocol. In this paper we use probabilistic model checking to verify that a synchronisation and dissemination protocol for Wireless Sensor Networks (WSNs) is correct with respect to its requirements, and is not adversely affected by the environment. We show how the protocol can be converted into a logical model and then analysed using the probabilistic model-checker, PRISM. Using this approach we prove under which circumstances the protocol is guaranteed to synchronise all nodes and disseminate new information to all nodes. We also examine the bounds on synchronisation as the environment changes the performance of the hardware clock, and investigate the scalability constraints of this approach. © 2019 Universitatsbibliothek TU Berlin
Security supportive energy-aware scheduling and energy policies for cloud environments
Cloud computing (CC) systems are the most popular computational environments for providing elastic
and scalable services on a massive scale. The nature of such systems often results in energy-related
problems that have to be solved for sustainability, cost reduction, and environment protection.
In this paper we defined and developed a set of performance and energy-aware strategies for resource
allocation, task scheduling, and for the hibernation of virtual machines. The idea behind this model is to
combine energy and performance-aware scheduling policies in order to hibernate those virtual machines
that operate in idle state. The efficiency achieved by applying the proposed models has been tested using
a realistic large-scale CC system simulator. Obtained results show that a balance between low energy
consumption and short makespan can be achieved.
Several security constraints may be considered in this model. Each security constraint is characterized
by: (a) Security Demands (SD) of tasks; and (b) Trust Levels (TL) provided by virtual machines. SD and TL
are computed during the scheduling process in order to provide proper security services.
Experimental results show that the proposed solution reduces up to 45% of the energy consumption
of the CC system. Such significant improvement was achieved by the combination of an energy-aware
scheduler with energy-efficiency policies focused on the hibernation of VMs.COST Action IC140
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