This paper presents a fast and simple contention-aware scheduling policy for CMP systems that relies on information collected at runtime with no additional hardware support. Our approach is based on a classification scheme that detects activity and possible interference across the entire memory hierarchy, including both shared caches and memory links. We schedule multithreaded applications taking into account their class, targeting both total system throughput and application fairness in terms of fair distribution of co-execution penalties. We have implemented a user level scheduler and evaluated our policy in several scenarios with different contention levels and a variety of multiprogrammed multithreaded workloads. Our results demonstrate that the proposed scheduling policy outperforms the established Linux and Gang schedulers, as well as a number of research contention-aware schedulers, both in system throughput and application fairness.