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Virtual switches are a key elements within the new paradigms of Software Defined Networking (SDN) and Network Function Virtualization (NFV). Unlike proprietary networking appliances, virtual switches come with a high level of flexibility in the management of their physical resources such as the number of CPU cores, their allocation to the switching function, and the capacities of the RX queues, which...
Data with vastly different access characteristics is efficiently stored in multi-tiered storage systems. A cost-effective way to retain large volumes of infrequently accessed data is to store it on tape. Steady developments in tape technology deliver ever increasing storage capacities at low cost. This has established tape as a viable solution to cope with the extreme data growth in the context of...
Messages traversing a network commonly experience waiting times due to sharing the forwarding resources. During those times, the crossed systems must provide sufficient buffer space for queueing messages. Network Calculus (NC) is a mathematical methodology for bounding flow delays and system buffer requirements. The accuracy of these performance bounds depends mainly on two factors: the principles...
The Wireless Network after Next (WNaN) radio is a multi-transceiver multi-frequency mobile ad-hoc network system that features four independent frequency agile transceivers and uses a variation of Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA). Utilizing WNaN's multiple transceivers, dynamic frequency assignment algorithm, and varying the hello packet interval can help alleviate the increased...
Probabilistic I/O automata (PIOAs) provide a modelling framework that is well suited for describing and analyzing distributed and concurrent systems. They incorporate a notion of probabilistic choice as well as a notion of composition that allows one to construct a PIOA for a composite system from a collection of simpler PIOAs representing the components. Differently from other probabilistic models,...
We evaluate the performance of a cloud system using ahysteresis queueing system with phase-type and batch arrivals. To represent the dynamic allocation of the resources, the hysteresis queueactivates and deactivates the virtual machines according to the threshold values of the queue length. We suppose a variable traffic intensity as the client requests (or jobs) arrive by batches, and follow a phase-type...
In this paper, we study the dynamics of coupled speed scaling systems, in which service rate is a function of system occupancy. We focus on both Processor Sharing (PS) and Shortest Remaining Processing Time (SRPT) as scheduling disciplines, and study their speed scaling dynamics under heavy load. Using a combination of Markov chain analysis and discrete-event simulation, we identify several important...
Network densification is currently seen as one ofthe key techniques enabling Radio Access Networks (RANs) tomeet the performance and functional requirements of the 5Gparadigm in urban areas. Avoiding the connection of small cellsto the power grid facilitates their deployment and reduces bothcapital and operational expenditures (CAPEX and OPEX). Inthis paper, we propose an approach to enable net-Zero...
In cloud computing, multiple servers are consolidated into a physical machine in order to reduce the cost of deploying the servers. Guaranteeing the service level objective (SLO) of each server is one of the most important factors in a virtualization system. Particularly, isolating the I/O resources among VMs competing for a shared storage system is challenging. Recently, use of flash based Solid...
There is a lack of support for explicit synchronization in GPUs between the streaming multiprocessors (SMs) adversely impacts the performance of the GPUs to efficiently perform inter-block communication. In this paper, we present several approaches to inter-block synchronization using explicit/implicit CPU-based and dynamic parallelism (DP) mechanisms. Although this topic has been addressed in previous...
The ability to execute the original source code for network protocols and applications within a network simulation environment frees the simulation modeler from the time consuming task of having to create, test and debug models representing these applications. This work extends the functionality of the Direct Code Execution (DCE) framework of ns-3 by incorporating the ability to call NVIDIA CUDA kernels...
In wireless ad hoc networks (WANETs), collaboration among nodes is usually inefficient and the network is vulnerable to various attacks. Although some intrusion detection systems (IDSs) and reputation strategies have been proposed to enhance the network's robustness, the significant power consumption they cause will reduce the networks' lifetime. In this paper, we propose a power-efficient mechanism...
We present TerrainLOS, an outdoor propagation model that uses Digital Elevation Models to determine whether two nodes can communicate. We have implemented TerrainLOS in the sensor network simulator COOJA and used it to evaluate how the roughness of terrain, which we classify using Average Cumulative Visibility, affects the number of edges, connectedness, latency, and power of a network. We compare...
Since game applications have spilled over on the modern mobile platforms equipped with Multiprocessor Systemon-Chips and highlighted the power consumption and battery life problem of these platforms, reducing the game power for mobile devices becomes meaningful. The design of independent CPU-GPU power managements in contemporary platforms results in power consumption waste due to the failure of consideration...
Target tracking with the wireless sensors networks is to detect and locate a target on its entire path through a region of interest. This application arouses interest in the world of research for its many fields of use. Wireless sensor networks, thanks to their versatility, can be used in many hostile environments and inaccessible to humans. However, with a limited energy, they cannot remain permanently...
Predicting memory occupancy during the execution of large-scale analytical workloads becomes critical for in-memory databases. In particular, probabilistic performance measures for such systems are of interest, but difficult to model with analytical methods due to the highly variable threading levels in corresponding workloads. Since literature with queueing theoretic background largely ignores the...
Reverse proxies are key performance elements of a content distribution network (CDN) and operate as intermediaries between client and upstream (or origin) server traffic. A typical reverse proxy server aims to distribute user workload, more or less equally, among multiple upstream servers. To keep the pace with the growing demand for content, CDNs regularly expand their capacity by adding extra upstream...
Memory access tracing is aprogram analysis technique with many different applications, ranging from architectural simulation to (on-line) data placement optimization and security enforcement. In this article we propose a memory access tracing approach based on static x86 binary instrumentation. Unlike non-selective schemes, whichinstrument all the memory access instructions, our proposal selectively...
A major drawback of mobile devices is limited battery life. Apps that use graphics are especially energy greedy and developers must invest significant effort to make such apps energy efficient. We propose a novel static optimization technique for eliminating drawing commands to produce energy-efficient apps. The key insight we exploit is that the static analysis is able to predict future behavior...
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