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Zhang Y.,University of Pittsburgh | Yang J.,University of Pittsburgh | Li W.,University of Pittsburgh | Wang L.,Nanjing University | Jin L.,Nvidia Inc.
Journal of Network and Computer Applications | Year: 2010

Wireless sensor networks have recently emerged as a promising computing model for many civilian and military applications. Sensor nodes in such a network are subject to varying forms of attacks since they are left unattended after deployment. Compromised nodes can, for example, tamper with legitimate reports or inject false reports in order to either distract the user from reaching the right decision or deplete the precious energy of relay nodes. Most of the current designs take the en-network detection approach: misbehaved nodes are detected by their neighboring watchdog nodes; false reports are detected and dropped by trusted en-route relay nodes, etc. However en-network designs are insufficient to defend collaborative attacks when many compromised nodes collude with each other in the network. In this paper we propose COOL, a COmpromised nOde Locator for detecting and locating compromised nodes once they misbehave in the network. It is based on the observation that for a well-behaved sensor node, the set of outgoing messages should be equal to the set of incoming and locally generated or dropped messages. However, comparing the message sets for different nodes is not enough to identify attacks as their sanity is unknown. We exploit a proven collision-resilient hashing scheme, termed incremental hashing, to sign the incoming, outgoing and locally generated/dropped message sets. The hash values are then sent to the sink for trusted comparisons. We discuss how to securely collect these hash values and then confidently locate compromised nodes. The scheme can also be combined with existing en-route false report filtering schemes to achieve both early false report dropping and accurate compromised nodes isolation. Through identifying and excluding compromised nodes, the COOL protocol prevents further damages from these nodes and forms a reliable and energy-conserving sensor network. © 2009 Elsevier Ltd. All rights reserved.

Butt S.,Rutgers University | Butt S.,Nvidia Inc. | Ganapathy V.,Rutgers University | Srivastava A.,AT&T
Proceedings of the 5th ACM Symposium on Cloud Computing, SOCC 2014 | Year: 2014

Self-service Cloud Computing (SSC) [7] is a recently-proposed model to improve the security and privacy of client data on public cloud platforms. It prevents cloud operators from snooping on or modifying client VMs and provides clients the flexibility to deploy security services, such as VM introspection tools, on their own VMs. SSC achieves these goals by modifying the hypervisor privilege model. This paper focuses on the unique challenges involved in building a control plane for an SSC-based cloud platform. The control plane is the layer that facilitates interaction between hosts in the cloud infrastructure as well as between the client and the cloud. We describe a number of novel features in SSC's control plane, such as its ability to allow specification of VM dependencies, flexible deployment of network middleboxes, and new VM migration protocols. We report on our design and implementation of SSC's control plane, and present experimental evaluation of services implemented atop the control plane. Copyright © 2014 by the Association for Computing Machinery, Inc. (ACM).

Patel K.,Nvidia Inc. | Annavaram M.,University of Southern California | Pedram M.,University of Southern California
IEEE Transactions on Computers | Year: 2013

Due to prohibitive cost of data center setup and maintenance, many small-scale businesses rely on hosting centers to provide the cloud infrastructure to run their workloads. Hosting centers host services of the clients on their behalf and guarantee quality of service as defined by service level agreements (SLAs.) To reduce energy consumption and to maximize profit it is critical to optimally allocate resources to meet client SLAs. Optimal allocation is a nontrivial task due to 1) resource heterogeneity where energy consumption of a client task varies depending on the allocated resources 2) lack of energy proportionality where energy cost for a task varies based on server utilization. In this paper, we introduce a generalized Network Flow-based Resource Allocation framework, called NFRA, for energy minimization and profit maximization. NFRA provides a unified framework to model profit maximization under a wide range of SLAs. We will demonstrate the simplicity of this unified framework by deriving optimal resource allocations for three different SLAs. We derive workload demands and server energy consumption data from SPECWeb2009 benchmark results to demonstrate the efficiency of NFRA framework. © 1968-2012 IEEE.

Arora A.,Indian Institute of Technology Delhi | Harne M.,Nvidia Inc. | Sultan H.,Indian Institute of Technology Delhi | Bagaria A.,Indian Institute of Technology Delhi | Sarangi S.R.,Indian Institute of Technology Delhi
IEEE Transactions on Parallel and Distributed Systems | Year: 2015

NUCA caches have traditionally been proposed as a solution for mitigating wire delays, and delays introduced due to complex networks on chip. Traditional approaches have reported significant performance gains with intelligent block placement, location, replication, and migration schemes. In this paper, we propose a novel approach in this space, called FP-NUCA. It differs from conventional approaches, and relies on a novel method of co-designing the last level cache and the network on chip. We artificially constrain the communication pattern in the NUCA cache such that all the messages travel along a few predefined paths (fast paths) for each set of banks. We leverage this communication pattern by designing a new type of NOC router called the Freeze router, which augments a regular router by adding a layer of circuitry that gates the clock of the regular router when there is a fast path message waiting to be transmitted. Messages along the fast path do not require buffering, switching, or routing. We incorporate a bank predictor with our novel NOC for reducing the number of messages, and resultant energy consumption. We compare our performance with state of the art protocols, and report speedups of up to 31 percent (mean: 6.3 percent), and ED2 reduction up to 46 percent (mean: 10.4 percent) for a suite of Splash and Parsec benchmarks. We implement the Freeze router in VHDL and show that the additional fast path logic has minimal area and timing overheads. © 2014 IEEE.

Catania V.,University of Catania | Patti D.,University of Catania | Palesi M.,University of Catania | Spadaccini A.,University of Catania | Fazzino F.,Nvidia Inc.
WSEAS Transactions on Information Science and Applications | Year: 2014

Instruction-set Simulators (ISS) are commonly used in any computer architecture course as primary tools for supporting the teaching activity. Although there are several simulation platforms for educational purposes, the lack of an unified and integrated platform often forces educators to use a range of heterogeneous tools to cover the different topics of the syllabus. This paper presents EduMIPS64 a free, visual, and platform-independent MIPS64 Instruction-Set Simulator designed as a learning aid for topics like instruction pipelining, hazard detection and resolution, exception handling, interrupts, and memory hierarchies. Its dual execution mode - stand-alone application and web applet - allows for inclusion in distance learning courses. Copyright © 2014 - All Rights Reserved.

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