DescriptionClock synchronization is a key prerequisite for accurate performance analysis. This is particularly true for most HPC systems, due to the lack of a system-wide timer. The effects of different clock properties lead to false measurements and wrong conclusions. Often these errors remain undetected by the user. Different environmental effects cause continuous changes to clock properties over time. This behavior is ignored by the usual post-mortem approach for clock synchronization. In order to improve time measurement accuracy we implemented a method for continuous clock synchronization. In this work, we share our experiences and draw conclusions for tool development.