Abstract. The upcoming profiling API standard OMPT can describe almost all profiling events required to construct grain graphs, a recent visualization that simplifies OpenMP performance analysis. We propose OMPT extensions that provide the missing descriptions of task creation and parallel for-loop chunk scheduling events, making OMPT a sufficient, standard source for grain graphs. Our extensions adhere to OMPT design objectives and incur a low overhead for BOTS (up to 2% overhead) and SPEC OMP2012 (1%) programs. Although motivated by grain graphs, the events described by the extensions are general and can enable cost-effective, precise measurements in other profiling tools as well.