Simulating MPI applications: the SMPI approach

International audienceThis article summarizes our recent work and developments on SMPI, a flexible simulator of MPI applications. In this tool,we took a particular care to ensure our simulator could be used to produce fast and accurate predictions in a wide variety of situations.Although we did build SMPI on SimGrid whose speed and accuracy had already been assessed in other contexts, moving suchtechniques to a HPC workload required significant additional effort. Obviously, an accurate modeling of communications and networktopology was one of the key to such achievements. Another less obvious key was the choice to combine in a single tool the possibilityto do both offline and online simulation