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Displaying 1-50 out of 157 total
Reducing False Sharing and Improving Spatial Locality in a Unified Compilation Framework
Found in: IEEE Transactions on Parallel and Distributed Systems
By Mahmut Kandemir, Alok Choudhary, J. Ramanujam, Prith Banerjee
Issue Date:April 2003
pp. 337-354
<p><b>Abstract</b>—The performance of applications on large shared-memory multiprocessors with coherent caches depends on the interaction between the granularity of data sharing, the size of the coherence unit, and the spatial locality ex...
 
Exploring concentration and channel slicing in on-chip network router
Found in: Networks-on-Chip, International Symposium on
By Prabhat Kumar, Yan Pan, John Kim, Gokhan Memik, Alok Choudhary
Issue Date:May 2009
pp. 276-285
Sharing on-chip network resources efficiently is critical in the design of a cost-efficient network on-chip (NoC). Concentration has been proposed for on-chip networks but the trade-off in concentration implementation and performance has not been well unde...
 
Noncontiguous I/O Accesses Through MPI-IO
Found in: Cluster Computing and the Grid, IEEE International Symposium on
By Avery Ching, Alok Choudhary, Kenin Coloma, Wei-keng Liao, Robert Ross, William Gropp
Issue Date:May 2003
pp. 104
I/O performance remains a weakness of parallel computing systems today. While this weakness is partly attributed to rapid advances in other system components, I/O interfaces available to programmers and the I/O methods supported by file systems have tradit...
 
Fpga Hardware Synthesis From Matlab
Found in: VLSI Design, International Conference on
By Malay Haldar, Anshuman Nayak, Alok Choudhary, Prith Banerjee, Nagraj Shenoy
Issue Date:January 2001
pp. 299
Field Programmable Gate Arrays (FPGAs) have been recently used as an effective platform for implementing many image/signal processing applications. MATLAB is one of the most popular languages to model image/signal processing applications. We present the MA...
 
Integrating Parallel File I/O and Database Support for High-Performance Scientific Data Management
Found in: SC Conference
By Jaechun No, Rajeev Thakur, Alok Choudhary
Issue Date:November 2000
pp. 57
Many scientific applications have large I/O requirements, in terms of both the size of data and the number of files or data sets. Management, storage, efficient access, and analysis of this data present an extremely challenging task. Traditionally, two dif...
 
Implementation and Evaluation of Prefetching in the Intel Paragon Parallel File System
Found in: Parallel Processing Symposium, International
By Meenakshi Arunachalam, Alok Choudhary, Brad Rullman
Issue Date:April 1996
pp. 554
The significant difference between the speeds of the I/O system (e.g. disks) and compute processors in parallel systems creates a bottleneck that lowers the performance of an application that does a considerable amount of disk accesses. A major portion of ...
 
Supporting Irregular Distributions Using Data-Parallel Languages
Found in: IEEE Concurrency
By Ravi Ponnusamy, Yuan-Shin Hwang, Raja Das, Joel H. Saltz, Alok Choudhary, Geoffrey Fox
Issue Date:March 1995
pp. 12-24
This article presents methods that make it possible to efficiently support irregular problems using data-parallel languages. The approach involves the use of a portable, compiler-independent, runtime support library called CHAOS. The CHAOS runtime support ...
 
The Impact of Dynamic Directories on Multicore Interconnects
Found in: Computer
By Matthew Schuchhardt,Abhishek Das,Nikos Hardavellas,Gokhan Memik,Alok Choudhary
Issue Date:October 2013
pp. 32-39
A large fraction of on-chip multicore interconnect traffic originates not from actual data transfers but from communication between the cores to maintain data coherence. Co-locating directories near their shared data eliminates many interconnect traversals...
 
IOPin: Runtime Profiling of Parallel I/O in HPC Systems
Found in: 2012 SC Companion: High Performance Computing, Networking, Storage and Analysis (SCC)
By Seong Jo Kim,Seung Woo Son,Wei-keng Liao,Mahmut Kandemir,Rajeev Thakur,Alok Choudhary
Issue Date:November 2012
pp. 18-23
Abstract -- Many I/O- and data-intensive scientific applications use parallel I/O software to access files in high performance. On modern parallel machines, the I/O software consists of several layers, including high-level libraries such as Parallel netCDF...
 
A new scalable parallel DBSCAN algorithm using the disjoint-set data structure
Found in: 2012 SC - International Conference for High Performance Computing, Networking, Storage and Analysis
By Md. Mostofa Ali Patwary,Diana Palsetia,Ankit Agrawal,Wei-keng Liao,Fredrik Manne,Alok Choudhary
Issue Date:November 2012
pp. 1-11
DBSCAN is a well-known density based clustering algorithm capable of discovering arbitrary shaped clusters and eliminating noise data. However, parallelization of Dbscan is challenging as it exhibits an inherent sequential data access order. Moreover, exis...
 
On the path to sustainable, scalable, and energy-efficient data analytics: Challenges, promises, and future directions
Found in: 2012 International Green Computing Conference (IGCC)
By Sriram Lakshminarasimhan,Prabhat Kumar, Wei-keng Liao,Alok Choudhary,Vipin Kumar,Nagiza F. Samatova
Issue Date:June 2012
pp. 1-6
As scientific data is reaching exascale, scalable and energy efficient data analytics is quickly becoming a top notch priority. Yet, a sustainable solution to this problem is hampered by a number of technical challenges that get exacerbated with the emergi...
 
Supporting computational data model representation with high-performance I/O in parallel netCDF
Found in: High-Performance Computing, International Conference on
By Kui Gao,Chen Jin,Alok Choudhary,Wei-keng Liao
Issue Date:December 2011
pp. 1-10
Parallel computational scientific applications have been described by their computation and communication patterns. From a storage and I/O perspective, these applications can also be grouped into separate data models based on the way data is organized and ...
 
Twitter Trending Topic Classification
Found in: Data Mining Workshops, International Conference on
By Kathy Lee,Diana Palsetia,Ramanathan Narayanan,Md. Mostofa Ali Patwary,Ankit Agrawal,Alok Choudhary
Issue Date:December 2011
pp. 251-258
With the increasing popularity of microblogging sites, we are in the era of information explosion. As of June 2011, about 200 million tweets are being generated everyday. Although Twitter provides a list of most popular topics people tweet about known as T...
 
Community Dynamics and Analysis of Decadal Trends in Climate Data
Found in: Data Mining Workshops, International Conference on
By William Hendrix,Isaac K. Tetteh,Ankit Agrawal,Fredrick Semazzi,Wei-keng Liao,Alok Choudhary
Issue Date:December 2011
pp. 9-14
The application of complex networks to study complex phenomena, including the Internet, social networks, food networks, and others, has seen a growing interest in recent years. In particular, the use of complex networks and network theory to analyze the be...
 
SES: Sentiment Elicitation System for Social Media Data
Found in: Data Mining Workshops, International Conference on
By Kunpeng Zhang,Yu Cheng,Yusheng Xie,Daniel Honbo,Ankit Agrawal,Diana Palsetia,Kathy Lee,Wei-keng Liao,Alok Choudhary
Issue Date:December 2011
pp. 129-136
Social Media is becoming major and popular technological platform that allows users discussing and sharing information. Information is generated and managed through either computer or mobile devices by one person and consumed by many other persons. Most of...
 
Identifying HotSpots in Lung Cancer Data Using Association Rule Mining
Found in: Data Mining Workshops, International Conference on
By Ankit Agrawal,Alok Choudhary
Issue Date:December 2011
pp. 995-1002
We analyze the lung cancer data available from the SEER program with the aim of identifying hotspots using association rule mining techniques. A subset of 13 patient attributes from the SEER data were recently linked with the survival outcome using predict...
 
Learning to Group Web Text Incorporating Prior Information
Found in: Data Mining Workshops, International Conference on
By Yu Cheng,Kunpeng Zhang,Yusheng Xie,Ankit Agrawal,Wei-keng Liao,Alok Choudhary
Issue Date:December 2011
pp. 212-219
Clustering similar items for web text has become increasingly important in many Web and Information Retrieval applications. For several kinds of web text data, it is much easier to obtain some external information other than textual features which can be u...
 
Poll: A Citation Text Based System for Identifying High-Impact Contributions of an Article
Found in: Data Mining Workshops, International Conference on
By Lalith Polepeddi,Ankit Agrawal,Alok Choudhary
Issue Date:December 2011
pp. 965-968
The body of scientific literature is growing yearly, presenting new challenges in accurate retrieval of relevant publications. Citation sentences stand to be a useful way to concisely represent the main contributions of a publication. In this paper, we pre...
 
Delegation-Based I/O Mechanism for High Performance Computing Systems
Found in: IEEE Transactions on Parallel and Distributed Systems
By Arifa Nisar,Wei-Keng Liao,Alok Choudhary
Issue Date:February 2012
pp. 271-279
Massively parallel applications often require periodic data checkpointing for program restart and post-run data analysis. Although high performance computing systems provide massive parallelism and computing power to fulfill the crucial requirements of the...
 
Achieving Target MTTF by Duplicating Reliability-Critical Components in High Performance Computing Systems
Found in: Parallel and Distributed Processing Workshops and PhD Forum, 2011 IEEE International Symposium on
By Nithin Nakka,Alok Choudhary,Gary Grider,John Bent,James Nunez,Satsangat Khalsa
Issue Date:May 2011
pp. 1567-1576
Mean Time To failure, MTTF, is a commonly accepted metric for reliability. In this paper we present a novel approach to achieve the desired MTTF with minimum redundancy. We analyze the failure behavior of large scale systems using failure logs collected by...
 
High Performance Data Mining Using R on Heterogeneous Platforms
Found in: Parallel and Distributed Processing Workshops and PhD Forum, 2011 IEEE International Symposium on
By Prabhat Kumar,Berkin Ozisikyilmaz,Wei-Keng Liao,Gokhan Memik,Alok Choudhary
Issue Date:May 2011
pp. 1720-1729
The exponential increase in the generation and collection of data has led us in a new era of data analysis and information extraction. Conventional systems based on general-purpose processors are unable to keep pace with the heavy computational requirement...
 
Sensitive and Specific Identification of Protein Complexes in
Found in: Parallel and Distributed Processing Workshops and PhD Forum, 2011 IEEE International Symposium on
By William Hendrix,Tatiana Karpinets,Byung-Hoon Park,Eric Schendel,Alok Choudhary,Nagiza F. Samatova
Issue Date:May 2011
pp. 512-522
High-throughput mass-spectrometry technology has enabled genome-scale discovery of protein-protein interactions. Yet, computational inference of protein interaction networks and their functional modules from large-scale pull-down data is challenging. Over-...
 
Predicting Node Failure in High Performance Computing Systems from Failure and Usage Logs
Found in: Parallel and Distributed Processing Workshops and PhD Forum, 2011 IEEE International Symposium on
By Nithin Nakka,Ankit Agrawal,Alok Choudhary
Issue Date:May 2011
pp. 1557-1566
In this paper, we apply data mining classification schemes to predict failures in a high performance computer system. Failure and Usage data logs collected on supercomputing clusters at Los Alamos National Laboratory (LANL) were used to extract instances o...
 
Enabling active storage on parallel I/O software stacks
Found in: Mass Storage Systems and Technologies, IEEE / NASA Goddard Conference on
By Seung Woo Son, Samuel Lang, Philip Carns, Robert Ross, Rajeev Thakur, Berkin Ozisikyilmaz, Prabhat Kumar, Wei-Keng Liao, Alok Choudhary
Issue Date:May 2010
pp. 1-12
As data sizes continue to increase, the concept of active storage is well fitted for many data analysis kernels. Nevertheless, while this concept has been investigated and deployed in a number of forms, enabling it from the parallel I/O software stack has ...
 
Sensing, Triggers and Mobile (Meta)Data
Found in: Mobile Data Management, IEEE International Conference on
By Goce Trajcevski, Alok Choudhary, Peter Scheuermann
Issue Date:May 2010
pp. 331-335
Processing spatio-temporal queries pertaining to the whereabouts of a large number of mobile entities has traditionally been the topic of the Moving Objects Databases (MOD)research. More recently, due to the advances in sensing and communication technologi...
 
Uncertain Range Queries for Necklaces
Found in: Mobile Data Management, IEEE International Conference on
By Goce Trajcevski, Alok Choudhary, Ouri Wolfson, Li Ye, Gang Li
Issue Date:May 2010
pp. 199-208
We address the problem of efficient processing of spatio-temporal range queries for moving objects whose whereabouts in time are not known exactly. The fundamental question tackled by such queries is, given a spatial region and a temporal interval, retriev...
 
pFANGS: Parallel high speed sequence mapping for Next Generation 454-roche Sequencing reads
Found in: Parallel and Distributed Processing Workshops and PhD Forum, 2011 IEEE International Symposium on
By Sanchit Misra,Ramanathan Narayanan, Wei-keng Liao,Alok Choudhary,Simon Lin
Issue Date:April 2010
pp. 1-8
Millions of DNA sequences (reads) are generated by Next Generation Sequencing machines everyday. There is a need for high performance algorithms to map these sequences to the reference genome to identify single nucleotide polymorphisms or rare transcripts ...
 
AHPIOS: An MPI-Based Ad Hoc Parallel I/O System
Found in: Parallel and Distributed Systems, International Conference on
By Florin Isaila, Javier Garcia Blas, Jesus Carretero, Wei-keng Liao, Alok Choudhary
Issue Date:December 2008
pp. 253-260
This paper presents the design and implementation of a portable ad-hoc parallel I/O system (AHPIOS). AHPIOS virtualizes on-demand available distributed storage resources and allows the files to be striped over several storage devices. Additionally, the des...
 
Evaluating the effects of cache redundancy on profit
Found in: Microarchitecture, IEEE/ACM International Symposium on
By Abhishek Das, Berkin Ozisikyilmaz, Serkan Ozdemir, Gokhan Memik, Joseph Zambreno, Alok Choudhary
Issue Date:November 2008
pp. 388-398
Previous works in computer architecture have mostly neglected revenue and/or profit, key factors driving any design decision. In this paper, we evaluate architectural techniques to optimize for revenue/profit. The continual trend of technology scaling and ...
 
Scaling parallel I/O performance through I/O delegate and caching system
Found in: SC Conference
By Arifa Nisar, Wei-keng Liao, Alok Choudhary
Issue Date:November 2008
pp. 1-12
Increasingly complex scientific applications require massive parallelism to achieve the goals of fidelity and high computational performance. Such applications periodically offload checkpointing data to file system for post-processing and program resumptio...
 
Dynamically adapting file domain partitioning methods for collective I/O based on underlying parallel file system locking protocols
Found in: SC Conference
By Wei-keng Liao, Alok Choudhary
Issue Date:November 2008
pp. 1-12
Collective I/O, such as that provided in MPI-IO, enables process collaboration among a group of processes for greater I/O parallelism. Its implementation involves file domain partitioning, and having the right partitioning is a key to achieving high-perfor...
 
Temperature-aware test scheduling for multiprocessor systems-on-chip
Found in: Computer-Aided Design, International Conference on
By David R. Bild, Sanchit Misra, Thidapat Chantemy, Prabhat Kumar, Robert P. Dick, X. Sharon Huy, Li Shangz, Alok Choudhary
Issue Date:November 2008
pp. 59-66
Increasing power densities due to process scaling, combined with high switching activity and poor cooling environments during testing, have the potential to result in high integrated circuit (IC) temperatures. This has the potential to damage ICs and cause...
 
Machine Learning Models to Predict Performance of Computer System Design Alternatives
Found in: Parallel Processing, International Conference on
By Berkin Ozisikyilmaz, Gokhan Memik, Alok Choudhary
Issue Date:September 2008
pp. 495-502
Computer manufacturers spend a huge amount of time, resources, and money in designing new systems and newer configurations, and their ability to reduce costs, charge competitive prices, and gain market share depends on how good these systems perform. In th...
 
Microarchitectures for Managing Chip Revenues under Process Variations
Found in: IEEE Computer Architecture Letters
By Abhishek Das, Serkan Ozdemir, Gokhan Memik, Joseph Zambreno, Alok Choudhary
Issue Date:January 2008
pp. 5-8
As transistor feature sizes continue to shrink intothe sub-90nm range and beyond, the effects of process variationson critical path delay and chip yields have amplified. A commonconcept to remedy the effects of variation is speed-binning, bywhich chips fro...
 
An Efficient FPGA Implementation of Principle Component Analysis based Network Intrusion Detection System
Found in: Design, Automation and Test in Europe Conference and Exhibition
By Abhishek Das, Sanchit Misra, Sumeet Joshi, Joseph Zambreno, Gokhan Memik, Alok Choudhary
Issue Date:March 2008
pp. 1160-1165
Modern Network Intrsuion Detection Systems (NIDSs) use anomaly detection to capture malicious attacks. Since such connections are described by large set of dimensions, processing these huge amounts of network data becomes extremely slow. To solve this time...
 
Operating System Controlled Processor-Memory Bus Encryption
Found in: Design, Automation and Test in Europe Conference and Exhibition
By Xi Chen, Robert P. Dick, Alok Choudhary
Issue Date:March 2008
pp. 1154-1159
Unencrypted data appearing on the processor-memory bus can result in security violations, e.g., allowing attackers to gather keys to financial accounts and personal data. Although on-chip bus encryption hardware can solve this problem, it requires hardware...
 
Using MPI file caching to improve parallel write performance for large-scale scientific applications
Found in: 2007 SC - International conference for High Performance Computing, Networking, Storage and Analysis
By Wei-keng Liao,Avery Ching,Kenin Coloma,Arifa Nisar,Alok Choudhary,Jacqueline Chen,Ramanan Sankaran,Scott Klasky
Issue Date:November 2007
pp. 1-11
Typical large-scale scientific applications periodically write checkpoint files to save the computational state throughout execution. Existing parallel file systems improve such write-only I/O patterns through the use of client-side file caching and write-...
 
Noncontiguous locking techniques for parallel file systems
Found in: SC Conference
By Avery Ching, Wei-keng Liao, Alok Choudhary, Robert Ross, Lee Ward
Issue Date:November 2007
pp. 1-12
Many parallel scientific applications use high-level I/O APIs that offer atomic I/O capabilities. Atomic I/O in current parallel file systems is often slow when multiple processes simultaneously access interleaved, shared files. Current atomic I/O solution...
 
Microarchitectures for Managing Chip Revenues under Process Variations
Found in: IEEE Computer Architecture Letters
By Abhishek Das, Serkan Ozdemir, Gokhan Memik, Joseph Zambreno, Alok Choudhary
Issue Date:July 2007
pp. 29-32
As transistor feature sizes continue to shrink intothe sub-90nm range and beyond, the effects of process variationson critical path delay and chip yields have amplified. A commonconcept to remedy the effects of variation is speed-binning, bywhich chips fro...
 
Compiler-Directed Energy Optimization for Parallel Disk Based Systems
Found in: IEEE Transactions on Parallel and Distributed Systems
By Seung Woo Son, Guangyu Chen, Ozcan Ozturk, Mahmut Kandemir, Alok Choudhary
Issue Date:September 2007
pp. 1241-1257
Disk subsystem is known to be a major contributor to overall power consumption of high-end parallel systems. Past research proposed several architectural level techniques to reduce disk power by taking advantage of idle periods experienced by disks. While ...
 
Improving MPI Independent Write Performance Using A Two-Stage Write-Behind Buffering Method
Found in: Parallel and Distributed Processing Symposium, International
By Wei-keng Liao, Avery Ching, Kenin Coloma, Alok Choudhary, Mahmut Kandemir
Issue Date:March 2007
pp. 295
Many large-scale production applications often have very long executions times and require periodic data check-points in order to save the state of the computation for program restart and/or tracing application progress. These write-only operations often d...
 
An Implementation and Evaluation of Client-Side File Caching for MPI-IO
Found in: Parallel and Distributed Processing Symposium, International
By Wei-keng Liao, Avery Ching, Kenin Coloma, Alok Choudhary, Lee Ward
Issue Date:March 2007
pp. 49
Client-side file caching has long been recognized as a file system enhancement to reduce the amount of data transfer between application processes and I/O servers. However, caching also introduces cache coherence problems when a file is simultaneously acce...
 
Scalable Design and Implementations for MPI Parallel Overlapping I/O
Found in: IEEE Transactions on Parallel and Distributed Systems
By Wei-keng Liao, Kenin Coloma, Alok Choudhary, Lee Ward, Eric Russell, Neil Pundit
Issue Date:November 2006
pp. 1264-1276
<p><b>Abstract</b>—We investigate the Message Passing Interface Input/Output (MPI I/O) implementation issues for two overlapping access patterns: the overlaps among processes within a single I/O operation and the overlaps across a sequenc...
 
Design and Evaluation of Database Layouts for MEMS-Based Storage Systems
Found in: Database Engineering and Applications Symposium, International
By Jayaprakash Pisharath, Wei-keng Liao, Alok Choudhary
Issue Date:July 2005
pp. 263-272
MEMS-based storage systems have recently generated significant interest due to their potential to be faster and more efficient than disks, while providing the non-volatility property. Designing data layouts for these devices is a challenging, important and...
 
Design of a Hardware Accelerator for Density Based Clustering Applications
Found in: Application-Specific Systems, Architectures and Processors, IEEE International Conference on
By Jayaprakash Pisharath, Alok Choudhary
Issue Date:July 2005
pp. 101-106
<p>Data mining is beginning to be widely used in various application fields. Density based clustering algorithms perform data mining by grouping high-density regions of points to form clusters. In recent years, the data sizes and the problem complexi...
 
Exploiting Multi-Grained Parallelism in Reconfigurable SBC Architectures
Found in: Field-Programmable Custom Computing Machines, Annual IEEE Symposium on
By Joseph Zambreno, Dan Honbo, Alok Choudhary
Issue Date:April 2005
pp. 333-334
In recent years, reconfigurable technology has emerged as a popular choice for implementing various types of cryptographic functions. Nevertheless, an insufficient amount effort has been placed into fully exploiting the tremendous amounts of parallelism in...
   
A Window-Based Approach to Retrieving Memory-Resident Data for Query Execution
Found in: Database Engineering and Applications Symposium, International
By Jayaprakash Pisharath, Alok Choudhary, Mahmut Kandemir
Issue Date:July 2004
pp. 283-288
Memory-resident databases are gaining popularity. In this paper, we present a data-centric approach to optimize multiple queries issued to a memory-resident database. Our approach involves a bottom-up methodology that reuses each block of data in a table t...
 
Scalable High-level Caching for Parallel I/O
Found in: Parallel and Distributed Processing Symposium, International
By Kenin Coloma, Alok Choudhary, Wei-keng Liao, Lee Ward, Eric Russell, Neil Pundit
Issue Date:April 2004
pp. 96b
<p>In order for I/O systems to achieve high performance in a parallel environment, they must either sacrifice client-side file caching, or keep caching and deal with complex coherency issues. The most common technique for dealing with cache coherency...
 
Flexible Software Protection Using Hardware/Software Codesign Techniques
Found in: Design, Automation and Test in Europe Conference and Exhibition
By Joseph Zambreno, Alok Choudhary, Rahul Simha, Bhagirath Narahari
Issue Date:February 2004
pp. 10636
A strong level of trust in the software running on an embedded processor is a prerequisite for its widespread deployment in any high-risk system. The expanding field of software protection attempts to address the key steps used by hackers in attacking a so...
 
Data Windows: A Data-Centric Approach for Query Execution in Memory-Resident Databases
Found in: Design, Automation and Test in Europe Conference and Exhibition
By Jayaprakash Pisharath, Alok Choudhary, Mahmut Kandemir
Issue Date:February 2004
pp. 21352
Structured embedded databases are currently becoming an integrated part of embedded systems, thus, enabling higher standards in system automation. These embedded databases are typically memory resident. In this paper, we present a data-centric approach cal...
   
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