Future embedded systems are expected to use chip-multiprocessors to provide the execution power for increasingly demanding applications. Multiprocessors increase the pressure on the memory bandwidth and processor local caching is mandatory. However, data caches are known to be very hard to integrate into the worst-case execution time (WCET) analysis. We tackle this issue from the computer architecture side: provide a data cache organization that enables tight WCET analysis. Similar to the cache splitting between instruction and data, we argue to split the data cache for different data areas. In this paper we show cache simulation results for the split-cache organization, propose the modularization of the data cache analysis for the different data areas, and evaluate the implementation costs in a prototype chip-multiprocessor system.