DescriptionIn situ compression is a compromise between traditional post hoc and emerging in situ visualization and analysis. While the merits and limitations of various compressor options have been well studied, their performance impacts on scientific simulations are less clear, especially on large scale supercomputer systems. This study fills in this gap by performing in situ compression experiments on a leading supercomputer system. More specifically, we measured the computational and I/O impacts of a lossy wavelet compressor and analyzed the results with respect to various in situ processing concerns. We believe this study provides a better understanding of in situ compression as well as new evidence supporting its viability, in particular for wavelets.