NERSCPowering Scientific Discovery Since 1974

Nicholas Wright

Nicholas (Nick) James Wright , Ph.D.
Group Lead
Advanced Technologies Group
Phone: (510) 486-5730
Fax: (510) 486-6459
1 Cyclotron Road.
Mailstop: 59-4010A
Berkeley, CA 94720 US

Biographical Sketch

Nick Wright focuses on evaluating future technologies for potential application in scientific computing. He also works on performance measurement and optimization and is particuarly involved in investigating performance optimization for the multicore-era. Before moving to NERSC, he was a member of the Performance Modeling and Characterization (PMaC) group at the San Diego Supercomputing Center. He earned both his undergraduate and doctoral degrees in chemistry at the University of Durham in England.

Journal Articles

Hongzhang Shan, J. Wright, Shalf, A. Yelick, Wagner, Nathan Wichmann, "A preliminary evaluation of the hardware acceleration of Cray Gemini interconnect for PGAS languages and comparison with MPI", SIGMETRICS Performance Evaluation Review, 2012, 40:92-98,

Lavanya Ramakrishnan, Richard Canon, Muriki, Sakrejda, Nicholas J. Wright, "Evaluating Interconnect and Virtualization Performance forHigh Performance Computing", SIGMETRICS Performance Evaluation Review, 2012, 40:55-60,

K. Fuerlinger, N.J. Wright, D. Skinner, "Performance analysis and workload characterization with ipm", Tools for High Performance Computing 2009, January 1, 2010, 31--38,

K. Fuerlinger, N.J. Wright, D. Skinner, C. Klausecker, D. Kranzlmueller, "Effective Holistic Performance Measurement at Petascale Using IPM", Competence in High Performance Computing 2010, January 1, 2010, 15--26,

B. R. de Supinski, S. Alam, D. H. Bailey, L., C. Daley, A. Dubey, T., D. Gunter, P. D. Hovland, H., K. Karavanic, G. Marin, J., S. Moore, B. Norris, L., C. Olschanowsky, P. C. Roth, M., S. Shende, A. Snavely, Spear, M. Tikir, J. Vetter, P. Worley, N. Wright, "Modeling the Office of Science ten year facilities plan: The PERI Architecture Tiger Team", Journal of Physics: Conference Series, 2009, 180:012039,

Conference Papers

Shane Snyder, Philip Carns, Kevin Harms, Robert Ross, Glenn K. Lockwood, Nicholas J. Wright, "Modular HPC I/O characterization with Darshan", Proceedings of the 5th Workshop on Extreme-Scale Programming Tools (ESPT'16), Salt Lake City, UT, November 13, 2016, 9-17, doi: 10.1109/ESPT.2016.9

Contemporary high-performance computing (HPC) applications encompass a broad range of distinct I/O strategies and are often executed on a number of different compute platforms in their lifetime. These large-scale HPC platforms employ increasingly complex I/O subsystems to provide a suitable level of I/O performance to applications. Tuning I/O workloads for such a system is nontrivial, and the results generally are not portable to other HPC systems. I/O profiling tools can help to address this challenge, but most existing tools only instrument specific components within the I/O subsystem that provide a limited perspective on I/O performance. The increasing diversity of scientific applications and computing platforms calls for greater flexibility and scope in I/O characterization.

In this work, we consider how the I/O profiling tool Darshan can be improved to allow for more flexible, comprehensive instru- mentation of current and future HPC I/O workloads.We evaluate the performance and scalability of our design to ensure that it is lightweight enough for full-time deployment on production HPC systems. We also present two case studies illustrating how a more comprehensive instrumentation of application I/O workloads can enable insights into I/O behavior that were not previously possible. Our results indicate that Darshan’s modu- lar instrumentation methods can provide valuable feedback to both users and system administrators, while imposing negligible overheads on user applications.

W. Bhimji, D. Bard, M. Romanus, D. Paul, A. Ovsyannikov, B. Friesen, M. Bryson, J. Correa, G. K. Lockwood, V. Tsulaia, S. Byna, S. Farrell, D. Gursoy, C. Daley, V. Beckner, B. Van Straalen, D. Trebotich, C. Tull, G. Weber, N. J. Wright, K. Antypas, Prabhat, "Accelerating Science with the NERSC Burst Buffer Early User Program", Cray User Group, May 11, 2016, LBNL LBNL-1005736,

NVRAM-based Burst Buffers are an important part of the emerging HPC storage landscape. The National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory recently installed one of the first Burst Buffer systems as part of its new Cori supercomputer, collaborating with Cray on the development of the DataWarp software. NERSC has a diverse user base comprised of over 6500 users in 700 different projects spanning a wide variety of scientific computing applications. The use-cases of the Burst Buffer at NERSC are therefore also considerable and diverse. We describe here performance measurements and lessons learned from the Burst Buffer Early User Program at NERSC, which selected a number of research projects to gain early access to the Burst Buffer and exercise its capability to enable new scientific advancements. To the best of our knowledge this is the first time a Burst Buffer has been stressed at scale by diverse, real user workloads and therefore these lessons will be of considerable benefit to shaping the developing use of Burst Buffers at HPC centers.

C.S. Daley, L. Ramakrishnan, S. Dosanjh, N.J. Wright, "Analyses of Scientific Workflows for Effective Use of Future Architectures", The 6th International Workshop on Big Data Analytics: Challenges, and Opportunities (BDAC-15), 2015,

Yu Jung Lo, Samuel Williams, Brian Van Straalen, Terry J. Ligocki,Matthew J. Cordery, Nicholas J. Wright, Mary W. Hall, Leonid Oliker, "Roofline Model Toolkit: A Practical Tool for Architectural and Program Analysis", SC'14, November 16, 2014,

Brian Austin, Nicholas Wright, "Measurement and interpretation of microbenchmark and application energy use on the Cray XC30", Proceedings of the 2nd International Workshop on Energy Efficient Supercomputing, November 2014,

M. J. Cordery, B. Austin, H. J. Wasserman, C. S. Daley, N. J. Wright, S. D. Hammond, D. Doerfler, "Analysis of Cray XC30 Performance using Trinity-NERSC-8 benchmarks and comparison with Cray XE6 and IBM BG/Q", SC'13, November 11, 2013,

Hongzhang Shan, Brian Austin, Wibe De Jong, Leonid Oliker, Nicholas Wright, Edoardo Apra, "Performance Tuning of Fock Matrix and Two-Electron Integral Calculations for NWChem on Leading HPC Platforms", SC'13, November 11, 2013,

Zhengji Zhao, Katie Antypas, Nicholas J Wright, "Effects of Hyper-Threading on the NERSC workload on Edison", 2013 Cray User Group Meeting, May 9, 2013,

Brian Austin, Matthew Cordery, Harvey Wasserman, Nicholas J. Wright, "Performance Measurements of the NERSC Cray Cascade System", 2013 Cray User Group Meeting, May 9, 2013,

Andrew Uselton, Nicholas J. Wright, "A file system utilization metric for I/O characterization", 2013 Cray User Group Conference, Napa, CA, 2013,

Hongzhang Shan, Brian Austin, Nicholas Wright, Erich Strohmaier, John Shalf, Katherine Yelick, "Accelerating Applications at Scale Using One-Sided Communication", The 6th Conference on Partitioned Global Address Programming Models, Santa Barbara, CA, October 10, 2012,

Lavanya Ramakrishnan, Richard Shane Canon, Krishna Muriki, Iwona Sakrejda, and Nicholas J. Wright., "Evaluating Interconnect and Virtualization Performance for High Performance Computing", Proceedings of 2nd International Workshop on Performance Modeling, Benchmarking and Simulation of High Performance Computing Systems (PMBS11), 2011,

In this paper we detail benchmarking results that characterize the virtualization overhead and its impact on performance. We also examine the performance of various interconnect technologies with a view to understanding the performance impacts of various choices. Our results show that virtualization can have a significant impact upon performance, with at least a 60% performance penalty. We also show that less capable interconnect technologies can have a significant impact upon performance of typical HPC applications. We also evaluate the performance of the Amazon Cluster compute instance and show that it performs approximately equivalently to a 10G Ethernet cluster at low core counts.

Zhengji Zhao and Nick Wright, "Performance of Density Functional Theory codes on Cray XE6", A paper presented in the Cray User Group meeting, May 23-26, 2011, Fairbanks, Alaska., May 24, 2011,

K. Furlinger, N.J. Wright, D. Skinner, "Comprehensive Performance Monitoring for GPU Cluster Systems", Parallel and Distributed Processing Workshops and Phd Forum (IPDPSW), 2011 IEEE International Symposium on, 2011, 1377--1386,

Praveen Narayanan, Alice Koniges, Leonid Oliker, Robert Preissl, Samuel Williams, Nicholas J Wright, Maxim Umansky, Xueqiao Xu, Benjamin Dudson, Stephane Ethier, Weixing Wang, Jeff Candy, John R. Cary, "Performance Characterization for Fusion Co-design Applications", Proceedings of CUG, 2011,

Neal Master, Matthew Andrews, Jason Hick, Shane Canon, Nicholas J. Wright, "Performance Analysis of Commodity and Enterprise Class Flash Devices", Petascale Data Storage Workshop (PDSW), November 2010,

Keith R. Jackson, Ramakrishnan, Muriki, Canon, Cholia, Shalf, J. Wasserman, Nicholas J. Wright, "Performance Analysis of High Performance Computing Applications on the Amazon Web Services Cloud", CloudCom, January 1, 2010, 159-168,

Hongzhang Shan, Haoqiang Jin, Karl Fuerlinger, Alice Koniges, Nicholas J Wright, "Analyzing the effect of different programming models upon performance and memory usage on cray xt5 platforms", CUG2010, Edinburgh, Scotland, 2010,

Andrew Uselton, Howison, J. Wright, Skinner, Keen, Shalf, L. Karavanic, Leonid Oliker, "Parallel I/O performance: From events to ensembles", IPDPS, 2010, 1-11,

Karl F\ urlinger, J. Wright, David Skinner, "Effective Performance Measurement at Petascale Using IPM", ICPADS, January 1, 2010, 373-380,

N.J. Wright, S. Smallen, C.M. Olschanowsky, J. Hayes, A. Snavely, "Measuring and Understanding Variation in Benchmark Performance", DoD High Performance Computing Modernization Program Users Group Conference (HPCMP-UGC), 2009, 2009, 438 -443,

Wayne Pfeiffer, Nicholas J. Wright, "Modeling and predicting application performance on parallel computers using HPC challenge benchmarks", IPDPS, 2008, 1-12,

John Michalakes, Hacker, Loft, O. McCracken, Snavely, J. Wright, E. Spelce, C. Gorda, Robert Walkup, "WRF nature run", SC, 2007, 59,

Book Chapters

Sudip Dosanjh, Shane Canon, Jack Deslippe, Kjiersten Fagnan, Richard Gerber, Lisa Gerhardt, Jason Hick, Douglas Jacobsen, David Skinner, Nicholas J. Wright, "Extreme Data Science at the National Energy Research Scientific Computing (NERSC) Center", Proceedings of International Conference on Parallel Programming – ParCo 2013, ( March 26, 2014)

Lavanya Ramakrishnan, Adam Scovel, Iwona Sakrejda, Susan Coghlan, Shane Canon, Anping Liu, Devarshi Ghoshal, Krishna Muriki, Nicholas J. Wright, "Magellan - A Testbed to Explore Cloud Computing for Science", On the Road to Exascale Computing: Contemporary Architectures in High Performance Computing, (Chapman & Hall/CRC Press: 2013)

Lavanya Ramakrishnan, Adam Scovel, Iwona Sakrejda, Susan Coghlan, Shane Canon, Anping Liu, Devarshi Ghoshal, Krishna Muriki and Nicholas J. Wright, "CAMP", On the Road to Exascale Computing: Contemporary Architectures in High Performance Computing, (Chapman & Hall/CRC Press: January 1, 2013)


Nick Wright, NERSC Initiative: Preparing Applications for Exascale, February 12, 2013,

Zhengji Zhao and Nick Wright, Performance of Density Functional Theory codes on Cray XE6, A talk in Cray User Group meeting 2011, May 23-26, 2011, Fairbanks, Alaska., May 23, 2011,


K. Antypas, B.A Austin, T.L. Butler, R.A. Gerber, C.L Whitney, N.J. Wright, W. Yang, Z Zhao, "NERSC Workload Analysis on Hopper", Report, October 17, 2014, LBNL 6804E,