The PMBS15 workshop is concerned with the comparison of high-performance computer systems through performance modeling, benchmarking or through the use of tools such as simulators. We are particularly interested in research which reports the ability to measure and make tradeoffs in software/hardware co-design to improve sustained application performance. We are also keen to capture the assessment of future systems, for example through work that ensures continued application scalability through peta- and exa-scale systems. The aim of this workshop is to bring together researchers, from industry and academia, concerned with the qualitative and quantitative evaluation and modeling of high-performance computing systems. Authors are invited to submit novel research in all areas of performance modeling, benchmarking and simulation, and we welcome research that brings together current theory and practice. We recognize that the coverage of the term performance has broadened to include power consumption and reliability,and that performance modeling is practiced through analytical methods and approaches based on software tools and simulators.