"Sequentiality is an illusion"
Kevin Skadron
Professor and Department Chair, Computer Science 

Department of Computer Science
School of Engineering and Applied Science
University of Virginia
85 Engineer's Way, Rice Hall, Box 400740
Charlottesville, VA 22904-4740

Office: Rice 521
Phone: (434) 982-2042
Fax: (434) 982-2214

Email for departmental/chair matters: deptchair@cs.virginia.edu
Email for personal matters: skadron@cs.virginia.edu



(classes | bio | note to grad-student/summer-intern applicants | research summary | selected publications | software)

  Areas of Interest

 Computer architecture and computational science, especially pertaining to multi-core and multi-threaded chip architectures, CPU/GPU convergence, and novel heterogeneous processor organizations; architectures for managing power, temperature, and reliability; applications of control theory to computer architecture; and architectural modeling and simulation methodology.

  Classes

 Current courses:
  • Fall 2013, CS 6190:  Computer Science Perspectives

Prior undergraduate courses taught - highlights:

Prior graduate courses taught - highlights:


 Biographical Sketch

 Kevin Skadron has been on the faculty at University of Virginia since 1999. He received his B.S. in Electrical and Computer Engineering and B.A. in Economics from Rice University in 1994, and his Ph.D. in Computer Science from Princeton University in 1999. He spent the 2007-08 academic year on sabbatical at NVIDIA Research. He became department chair in 2012. 

Skadron is the recipient of the 2011 ACM SIGARCH Maurice Wilkes Award, a Distinguished Scientist in the ACM, and a Fellow of the IEEE.  For the year 2003-04, he was named a University of Virginia Teaching Fellow.  Among other professional activities, he is co-founder and editorial board member of  IEEE Computer Architecture Letters, for which he served as associate editor-in-chief from 2001-2009 and editor-in chief from 2010-2012; and he is a member of the technical advisory board of Gradient-DA.  He has served on the editorial board of IEEE Micro from 2004-2012 and as co-founder/co-editor (with Kevin Rudd) of its "Prolegomena" column, as secretary-treasurer of ACM's SIGARCH from 2007-2011, as technical program co-chair of PACT 2006, general co-chair for PACT 2002 and MICRO-37,  co-organizer of the Workshop on Temperature Aware Computer Systems, and on numerous technical program committees.


Note to postdoc, graduate student and summer-intern applicants

 International summer-intern requests: Due to visa complexities, UVA generally does not allow undergraduate summer interns from abroad.  I get a very large number of these requests; please understand that I generally cannot respond personally.

Inquiries from prospective graduate students: Due to the large number of these inquiries, please understand that I am not able to respond to form letters.  But I am always happy to discuss mutual research interests!  Potential applicants may also want to read more about my advising philosophy.

  Research

 I currently direct the LAVA lab (Laboratory for Computer Architecture at Virginia).  My research currently focuses on how to design multicore architectures in the presence of severe physical constraints, especially thermal, power delivery, process variations, and wear-out. We are chiefly focusing on these issues in the context of asymmetric and heterogeneous designs, which provide the best balance between high single-thread performance and high throughput for parallel tasks.  Support for asymmetry is also becoming essential as process variations (chiefly "process tilt") create performance and power asymmetry even in organizations that were originally designed to be symmetric (see our DATE'07 paper).  To address these challenges, we are taking a variety of approaches:

We are also one of the first groups to explore the use of graphics processors (GPUs) for general-purpose computing (are GPUs for you?) and the first to develop an architectural simulation infrastructure-Qsilver-for performance, power, and thermal studies.  In addition to exploring the implications of heterogeneous organizations combining CPUs, GPUs, and other processor types, we are exploring how the massive parallelism of the GPU and its novel SIMD and memory organization can most effectively be used.  To address these questions, we are pursuing a variety of investigations, such as:

  • Developing the Rodinia benchmark suite of applications with both optimized GPU and multicore-CPU implementations of a diverse set of applications  (see our IISWC'10, IISWC'09 and JPDC'08 papers and ASPLOS 2010 tutorial) -- also look for the upcoming SPEC HPG accelerator benchmark suite
  • Support for cache-conscious data layout for heterogeneous systems (SC'11)
  • Exploring how to most effectively use texture, constant, per-block shared memory, and other features that GPUs and GPU languages such as CUDA provide (e.g., see our ACM Queue'08, JPDC'08, IPDPS'09, and ICS'09/IJPP'11 papers)
  • Developing new techniques to make SIMD architectures more effective in the presence of irregular data structures or irregular parallelism (see our ISCA'10 and SC'09 papers)
  • Comparing GPU and FPGA efficiency for diverse application characteristics (e.g. our SASP'08 paper)
  • Developing new programming abstractions to simplify GPU programming (e.g. our ICS'09/IJPP'11 and WOLFHPC'11 papers)
  • Developing new dynamic analysis techniques for GPU programs (e.g. our STMCS'08 and PMEA'09 papers)

Our work uses a variety of tools, from native GPU implementations using CUDA, Brook, OpenCL and MATLAB to simulation tools, chiefly M5 and our VF2 extensions for multicore, multi-threading, SIMD, and asymmetric organizations; our Genetically Programmed Response Surfaces Toolkit; and of course HotLeakage and HotSpot.

In prior work, my group has:

These research projects have stimulated several innovations in our computer architecture courses, including the development of a Microprocessor Survey Course (also described in a paper at SIGCSE) and the use of CUDA to teach both concurrency and parallel architecture.

This work is currently supported by the National Science Foundation under grant nos. EF-1124931 and CCF-1116673; by DARPA MTO (PERFECT program) under contract HR0011-13-C-0022; by DARPA IIO (VMR program) under contract FA8750-12-C-0181; by C-FAR, one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA; by the UVA WICAT Center; and equipment donations and extended loans from NVIDIA, AMD, and Hewlett Packard.

Prior support has come from the National Science Foundation under grant nos. ITR-0082671, CCR-0133634 (CAREER), CCR-0105626, EIA-0224434, DOS-0306404, CCF-0429765, CNS-0509245, CNS-0551630 (CRI), IIS-0612049, CNS-0615277, CCF-0903471 (MCDA), and CNS-0916908 (ARRA); the Army Research Office under grant no. W911NF-04-1-0288; the Semiconductor Research Corporation under task no. 1607, 1972 and 2042; grants from AMD Research, Intel Research, NVIDIA Research, NEC Labs, IBM Research;  and an Excellence Award from the University of Virginia Fund for Excellence in Science and Technology (FEST).  Additional support has been provided by William A. Ballard Fellowships for John W. Haskins and David Tarjan, a University of Virginia Award for Excellence in Scholarship in the Sciences & Engineering for David Tarjan and Jiayuan Meng, an ATI graduate fellowship for Jeremy Sheaffer, an NVIDIA Ph.D. fellowship for Jiayuan Meng, and a GRC/AMD Ph.D. fellowship for Michael Boyer.

Please note that any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the funding agencies.

Current Graduate Students:

  • Lukasz Szafaryn
  • Jack Wadden
  • Liang Wang
  • Runjie Zhang (co-advised with Mircea Stan)

LAVA alumni - postdocs, graduate students, undergraduate students

Other links:

  Selected Publications

Please note that papers linked here represent author preprints.   The official, published version must be obtained from the publisher's website or the published print copy.  This material is presented here to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each document's copyright terms. In most cases, these works may not be reposted without the explicit permission of the copyright holder. Permission is given to make digital or hard copies of all or part of this material without fee for personal or classroom use, provided that the copies are not made or distributed for profit or commercial advantage, and that copies bear the appropriate copyright notice and the full bibliographic citation on the first page.  Copyrights for components of this work owned by others must also be honored. To copy otherwise, to republish, to post on servers, to redistribute to lists, etc. requires specific permission and/or a fee.  In particular, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the copyright owner.

Please note further that any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsoring agencies, employers, or publishers.



Recent Highlights

  • (power delivery, IR drop) K. Wang, R. Zhang, B. H. Meyer, K. Skadron, and M. R. Stan. "Walking Pads: Fast Power-Supply Pad-Placement Optimization." In Proceedings of the ACM/IEEE Asia and South Pacific Design Automation Conference (ASP-DAC), Jan. 2014, to appear.

  • (heterogeneous architecture, dark silicon) L. Wang and K. Skadron. "Implications of the Power Wall: Dim Cores and Reconfigurable Logic." IEEE Micro special issue on Dark Silicon, to appear.  (preprint pdf)

  • (gpgpu, accelerators, manycore, heterogeneous architecture, benchmarks) S. Che. B. M. Beckmann, S. K. Reinhardt, and K. Skadron, "R-Graph: A Characterization of GPGPU Graph Applications, In Proceedings of the IEEE International Symposium on Workload Characterization (IISWC), Sept. 2013, to appear.

  • (gpgpu, accelerators, manycore, heterogeneous architecture, programming models and frameworks) L. Szafaryn, T. Gamblin, B. R. de Supinski, and K. Skadron. "Trellis: Portability Across Architectures with a High-level Framework." Elsevier Journal of Parallel and Distributed Computing, to appear. (preprint pdf)

  • (performance prediction, gpgpu, accelerators, manycore, heterogeneous architecture, benchmarks) S. Che and K. Skadron.  "BenchFriend: Correlating the Performance of GPU Benchmarks." Sage International Journal of High Performance Computing Applications (IJHPCA), to appear. (preprint pdf)

  • (reliability) L. Szafaryn, B. H. Meyer, and K. Skadron. "Evaluating the Overheads of Soft Error Protection Mechanisms in the Context of Multi-bit Errors at the Scope of a Processor Core." IEEE Micro special issue on Reliability Aware Design, 33(4):56-65, July-Aug. 2013. (preprint pdf)

  • (CPU-GPU load balancing) M. Boyer, K. Skadron, S. Che, N. Jayasena. "Load Balancing in a Changing World: Dealing with Heterogeneity and Performance Variability. In Proceedings of the ACM Conference on Computing Frontiers, May 2013. (pdf)

  • (floorplanning, thermal, power delivery) G. Faust, R. Zhang, K. Skadron, M.R. Stan, and B. Meyer. "ArchFP: Rapid Prototyping of pre-RTL Floorplans." In Proceedings of the IFIP/IEEE International Conference on Very Large Scale Integration (VLSI-SoC), Oct. 2012, to appear. (ArchFP software)

  • (SIMD, cache, branch divergence) J. Meng, J. W. Sheaffer, and K. Skadron.  "Robust SIMD: Dynamically Adapted SIMD Width and Multi-Threading Depth."  In Proceedings of the IEEE International Parallel & Distributed Processing Symposium (IPDPS), May 2012, to appear. (pdf) 

  • (datacenter co-scheduling, cache) J. Mars, L. Tang, R. Hundt, K. Skadron, and M. L. Soffa.  "BubbleUp: Increasing Sensible Co-locations for Improved Utilization in Modern Warehouse Scale Computers."   In Proceedings of the ACM/IEEE International Symposium on Microarchitecture (MICRO), Dec. 2011. (pdf)  Also to appear in IEEE Micro "Top Picks from 2011 Architecture Conferences."

  • (thermal) K. Sankaranarayanan, B. H. Meyer, W. Huang, R. J. Ribando, H. Haj-Hajiri, M. R. Stan, and K. Skadron.  "Architectural Implications of Spatial Thermal Filtering."  Elsevier Integration, the VLSI Journal, 46(1):44-56, Jan. 2013. DOI 10.1016/j.vlsi.2011.12.002 (preprint pdf)

  • (gpgpu, accelerators, heterogeneous architecture, memory, performance portability) S. Che, J. W. Sheaffer, and K. Skadron.  "Dymaxion: Optimizing Memory Access Patterns for Heterogeneous Systems."  In Proceedings of the ACM/IEEE International Conference for High Performance Computing, Networking, Storage and Analysis (SC), Nov. 2011. (pdf)

  • (reliability, fault tolerance, redundant execution) B. Meyer, B. Calhoun, J. Lach, and K. Skadron.  "Cost-effective Safety and Fault Localization using Distributed Temporal Redundancy."  In Proceedings of the ACM/IEEE International Conference on Compilers, Architectures, and Synthesis for Embedded Systems (CASES), Oct. 2011. (pdf)

  • (thermal, power, scaling, dark silicon) W. Huang, K. Rajamani, M. R. Stan, and K. Skadron.  "Scaling with Design Constraints – Predicting the Future of Big Chips."  IEEE Micro special issue on Big Chips, 31(4):16-29, July/Aug. 2011, DOI 10.1109/MM.2011.42. (preprint pdf)

Highlights from Prior Work

  • (manycore, GPU architecture, power) M. Gebhart, D. R. Johnson, D. Tarjan, S. W. Keckler, W. J. Dally, E. Lindholm, and K. Skadron. "Energy-efficient Mechanisms for Managing Thread Context in Throughput Processors."  In Proceedings of the ACM/IEEE International Symposium on Computer Architecture (ISCA), June 2011. (pdf)

  • (gpgpu, accelerators, manycore, heterogeneous architecture, benchmarks) S. Che, J. W. Sheaffer, M. Boyer, L. G. Szafaryn, L. Wang, and K. Skadron.  "A Characterization of the Rodinia Benchmark Suite with Comparison to Contemporary CMP Workloads."  In Proceedings of the IEEE International Symposium on Workload Characterization (IISWC), Dec. 2010. (pdf)

  • (manycore, dynamic cores) M. Boyer, D. Tarjan, K. Skadron.  “Federation: Boosting Per-Thread Performance of Throughput-Oriented Manycore Architectures.”  ACM Transactions on Architecture and Code Optimization (TACO), 7(4):1-38, Dec. 2010, DOI 10.1145/1880043.1880046. (preprint pdf)

  • (manycore, cache, coherence) D. Tarjan and K. Skadron.  "The Sharing Tracker: Using Ideas from Cache Coherence Hardware to Reduce Off-Chip Memory Traffic with Non-Coherent Caches."  In Proceedings of the ACM/IEEE International Conference for High Performance Computing, Networking, Storage and Analysis (SC), Nov. 2010. (pdf)

  • (SIMD, cache, branch divergence) J. Meng, D. Tarjan, and K. Skadron.  "Dynamic Warp Subdivision for Integrated Branch and Memory Divergence Tolerance."  In Proceedings of the 37th ACM/IEEE International Symposium on Computer Architecture, June 2010. (pdf)

  • (manycore, cache, coherence) J. Meng and K. Skadron “Avoiding Cache Thrashing due to Private Data Placement in Last-Level Cache for Manycore Scaling.”  In Proceedings of the IEEE International Conference on Computer Design (ICCD), pp. 282-88, Oct. 2009. (pdf)

  • (power, real-time, control theory) T. Horvath and K. Skadron.  "Multi-mode Energy Management for Multi-tier Server Clusters."  In Proceedings of the ACM/IEEE/IFIP International Conference on Parallel Architectures and Compilation Techniques (PACT), pp. 270-79, Oct. 2008.  (preprint pdf)

  • (thermal) W. Huang, K. Sankaranarayanan, K. Skadron, R. J. Ribando, and M. R. Stan.  "Accurate, Pre-RTL Temperature-Aware Processor Design Using a Parameterized, Geometric Thermal Model."  IEEE Transactions on Computers, 57(9):1277-88, Sept. 2008, DOI 10.1109/TC.2008.64. (pdf)

  • (gpgpu, fpga, accelerators, heterogeneous architecture) S. Che, J. Li, J. W. Sheaffer, K. Skadron, and J. Lach. “Accelerating Compute Intensive Applications with GPUs and FPGAs.” In Proceedings of the IEEE Symposium on Application Specific Processors (SASP), pp. 101-07, June 2008. (pdf)

  • (simulation methodology) H. Cook and K. Skadron. “Predictive Design Space Exploration Using Genetically Programmed Response Surfaces.” In Proceedings of the 45th ACM/IEEE Conference on Design Automation (DAC), June 2008. (pdf)

  • (gpgpu) J. Nickolls, I. Buck, M. Garland, K. Skadron.  “Scalable Parallel Programming with CUDA.”  ACM Queue, 6(2):40-53, Mar.-Apr. 2008.  DOI 10.1145/1365490.1365500 (pdf)

  • (power, branch prediction) S. W. Chung and K. Skadron.  “On-Demand Solution to Minimize I-Cache Leakage Energy with Maintaining Performance.”  IEEE Transactions on Computers, 57(1):7-24, Jan. 2008, DOI 10.1109/TC.2007.70770. (pdf)

  • (graphics architecture, reliability) J. Sheaffer, D. Luebke, and K. Skadron. “A Hardware Redundancy and Recovery Mechanism for Reliable Scientific Computation on Graphics Processors.” In Proceedings of Eurographics/ACM Graphics Hardware 2007 (GH), pp. 55-64, Aug. 2007. (pdf)

  • (parameter variations, multicore, thermal, power, leakage) E. Humenay, D. Tarjan, and K. Skadron.  "Impact of Process Variations on Multicore Performance Symmetry."  In Proceedings of the 2007 Conference on Design, Automation and Test in Europe (DATE), pp. 1653-58, Apr. 2007.  (pdf)

  • (reliability, thermal) Z. Lu, W. Huang, M. Stan, K. Skadron, and J. Lach.  “Interconnect Lifetime Prediction for Reliability-Aware Systems.”  IEEE Transactions on VLSI Systems, 15(2):159-72, Feb. 2007.  (pdf)

  • (branch prediction, trace cache, power) M. Co, D. A.B. Weikle, and K. Skadron. "Evaluating Trace Cache Energy Efficiency." ACM Transactions on Architecture and Code Optimization (TACO), 3(4):450-76, Dec. 2006. (Abstract | pdf)

  • (power, multimedia, real-time) Z. Lu, J. Lach, K. Skadron, and M. R. Stan. “Design and Implementation of an Energy Efficient Multimedia Playback System.” In Proceedings of the 40th Asilomar Conference on Signals, Systems and Computers, Oct. 2006. (pdf)

  • (graphics architecture, reliability) J. W. Sheaffer, D. P. Luebke, and K. Skadron. “The Visual Vulnerability Spectrum: Characterizing Architectural Vulnerability for Graphics Hardware.” In Proceedings of Eurographics/ACM Graphics Hardware 2006 (GH), pp. 9-16, Sept. 2006. (pdf)

  • (thermal) S. W. Chung and K. Skadron. “Using on-Chip Event Counters for High-Resolution, Real-Time Temperature Measurements.” In Proceedings of the IEEE/ASME Tenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM), June 2006. (pdf)

  • (power) Z. Lu, Y. Zhang, M. R. Stan, J. Lach, and K. Skadron.  “Procrastinating Voltage Scheduling with Discrete Frequency Sets.”   In Proceedings of the 2004 Design, Automation and Test in Europe Conference (DATE), pp. 456-61, Mar. 2006.  (pdf)

  • (multi-core architecture, power, thermal) Y. Li, B. C. Lee, D. Brooks, Z. Hu, and K. Skadron.  "CMP Design Space Exploration Subject to Physical Constraints."  In Proceedings of the Twelfth IEEE International Symposium on High Performance Computer Architecture (HPCA), pp. 15-26, Feb. 2006. (pdf)

  • (power) V. Narayanan and K. Skadron.  "Architectural/System Design and Optimization," in "CAD Algorithms, Methods and Tools For Low-Power Circuits and Systems," E. Macii ed. IEEE Council on Electronic Design Automation (C-EDA) Technology Survey, Jan. 2006.  (IEEE Xplore link)

  • (thermal) K. Sankaranarayanan, S. Velusamy, M.R. Stan, and K. Skadron.  "A Case for Thermal-Aware Floorplanning at the Microarchitectural Level."  The Journal of Instruction-Level Parallelism, vol. 7, Oct. 2005, http://www.jilp.org/vol7/. (pdf)

  • (branch prediction) D. Tarjan and K. Skadron. “Merging Path and Gshare Indexing in Perceptron Branch Prediction.” ACM Transactions on Architecture and Code Optimization, Sept. 2005, 2(3):280-300. (pdf)

  • (power, thermal) Y. Li, M. Hempstead, P. Mauro, D. Brooks, Z. Hu, and K. Skadron. “Power and Thermal Effects of SRAM vs. Latch­Mux Design.” In Proceedings of the ACM/IEEE 2005 International Symposium on Low-Power Electronics Design (ISLPED), pp. 173-178, Aug. 2005.  (pdf)

  • (thermal, security) P. Dadvar and K. Skadron.  “Potential Thermal Security Risks.”  In Proceedings of the IEEE Semiconductor Thermal Measurement, Modeling, and Management Symposium (Semi-Therm 21), pp. 229-34, Mar. 2005.  (pdf)

  • (thermal, graphics architecture) J. W. Sheaffer, K. Skadron, and D. P. Luebke.  “Studying Thermal Management for Graphics-Processor Architectures.”  In Proceedings of the 2005 IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS), Mar. 2005.  (pdf | Qsilver software home page)

  • (thermal) K. Skadron, K. Sankaranarayanan, S. Velusamy, D. Tarjan, M.R. Stan, and W. Huang.  “Temperature-Aware Microarchitecture: Modeling and Implementation.”  ACM Transactions on Architecture and Code Optimization, 1(1):94-125, Mar. 2004.  (pdf)

  • (leakage power) Y. Li, D. Parikh, Y. Zhang, K. Sankaranarayanan, M. R. Stan, and K. Skadron.  “State-Preserving vs. Non-State-Preserving Leakage Control in Caches.”  In Proceedings of the 2004 Design, Automation and Test in Europe (DATE) Conference, pp. 22-27, Feb. 2004.  (pdf) [HotLeakage software home page]

  • (power, real-time) V. Sharma, A. Thomas, T. Abdelzaher, Z. Lu, and K. Skadron.  “Power-Aware QoS Management on Web Servers.”  In Proceedings of the 24th International Real-Time Systems Symposium, pp. 63-72, Dec. 2003. (pdf) (Best student paper!)

  • (branch prediction) Z. Lu, J. Lach, M. Stan, and K. Skadron.  “Alloyed Branch History: Combining Global and Local Branch History for Robust Performance,” International Journal of Parallel Programming, Kluwer, 31(2):137-77, Apr. 2003.  (pdf | Abstract)

  • (write buffers) K. Skadron and D.W. Clark. "Design Issues and Tradeoffs for Write Buffers." In Proceedings of the Third International Symposium on High-Performance Computer Architecture, pp. 144-55, February 1997. (postscript | pdf | abstract)


Complete list of Skadron's publications

  Software Releases

Last updated: 24 Sept. 2013
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