A non-transitory computer readable medium for a real time analysis of a computer system performs a method of describing an occurrence pattern, for which a set of tasks is provided. The tasks are partially repeatedly requested by the system and processed or repeatedly generate events by requests to partial components of the system. An occurrence pattern of the events requesting the tasks or events generated by the task during the real-time analysis is represented by a description of event densities. The description includes a set of elements describing a portion of the occurrence pattern of the events. At least two elements for the description of the part of the occurrence pattern include a further set of elements providing a plurality of hierarchical levels. The further sets and thus the part of the occurrence pattern described by the further sets differ from each other.