William Jalby started his career first at INRIA as a researcher then joined University of Illinois (CEDAR project), after which he was appointed Associate Professor at University of RENNES, before joining University of Versailles as a Full Professor. His research interests are focused on memory system analysis and optimization, compilers and parallelism. Most of his research has been carried out in close collaboration with hardware suppliers (Fujitsu, Bull and INTEL), tools developers (JSC, TUD, University of Oregon, CAPS Entreprise) and application developers both from research (CEA, EDF, CNRS) and Industry (ESI, MAGMAsoft, Dassault, GNS, RECOM). Since 2004, he has been the Director of a joint Lab (ITACA) between CEA DAM and UVSQ focusing on code optimization techniques. In 2010, he was appointed as CTO of the Exascale Computing Research (ECR) Lab and is leading research in parallel performance tools and optimization.