ParaProf: A Portable, Extensible, and Scalable Tool for Parallel Performance Profile Analysis. This paper presents the design, implementation, and application of ParaProf, a portable, extensible, and scalable tool for parallel performance profile analysis. ParaProf attempts to offer “best of breed” capabilities to performance analysts – those inherited from a rich history of single processor profilers and those being pioneered in parallel tools research. We present ParaProf as a parallel profile analysis framework that can be retargeted and extended as required. ParaProf’s design and operation is discussed, and its novel support for large-scale parallel analysis demonstrated with a 512-processor application profile generated using the TAU performance system.