The use of cache memories challenges the design and verification of high-integrity systems by making WCET analysis and measurement, the central input to schedulability analysis, considerably more laborious and less robust. In this paper we identify the sources of instruction cacherelated variability and gage them with ad-hoc experiments. In that light, we perform a critical review of state-of-the-art approaches to coping with and reducing the unpredictability of cache behavior. Finally we single out practices and recommendations that we deem best fit to attack the sources of unpredictability and discuss their applicability to a real processor for use in European space industry.