NERSCPowering Scientific Discovery Since 1974

Iwona Sakrejda

Iwona Sakrejda , Ph.D.
Technology Integration Group
National Energy Research Scientific Computing Center
Phone: (510) 486-4078
Fax: (510) 486-4316
Lawrence Berkeley National Laboratory
1 Cyclotron Road
Mail Stop 943-256
Berkeley, CA 94720 US

Biographical Sketch

Iwona Sakrejda earned her Ph.D in particle physics from the Institute of Nuclear Physics in Krakow, Poland. She worked at CERN, BNL and LBNL with several relativistic heavy ion experiments specializing in event reconstruction and gaining experience in a variety of programming languages (FORTRAN, c, C++), operating systems, visualization for HENP experiments, and user support. For five years before joining NERSC, Iwona led a team that wrote the core software for the STAR TPC, one of the largest detectors looking for quark-gluon plasma at the Relativistic Heavy Ion Collider at BNL.

Journal Articles

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,

I. Sakrejda, others, "Global features of heavy ion collisions from the NA36", January 1, 1997,

Conference Papers

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.

Lavanya Ramakrishnan, Piotr T. Zbiegel, Scott Campbell, Rick Bradshaw, Richard Shane Canon, Susan Coghlan, Iwona Sakrejda, Narayan Desai, Tina Declerck, Anping Liu, "Magellan: Experiences from a Science Cloud", Proceedings of the 2nd International Workshop on Scientific Cloud Computing, ACM ScienceCloud '11, Boulder, Colorado, and New York, NY, 2011, 49 - 58,


Eric Hjort, Larry Pezzaglia, Iwona Sakrejda, PDSF at NERSC: Site Report, A talk at the HEPiX Spring 2012 Workshop, Prague, Czech Republic, April 24, 2012,

PDSF is a commodity Linux cluster at NERSC which has been in continuous operation since 1996. This talk will provide a status update on the PDSF system and summarize recent changes at NERSC. Highlighted PDSF changes include the conversion to xCAT-managed netboot node images, the ongoing deployment of Scientific Linux 6, and the introduction of XRootD for STAR.


Katherine Yelick, Susan Coghlan, Brent Draney, Richard Shane Canon, Lavanya Ramakrishnan, Adam Scovel, Iwona Sakrejda, Anping Liu, Scott Campbell, Piotr T. Zbiegiel, Tina Declerck, Paul Rich, "The Magellan Report on Cloud Computing for Science", U.S. Department of Energy Office of Science, Office of Advanced Scientific Computing Research (ASCR), December 2011,