Oversubscription of computational resources on multicore desktop systems

The increasing pervasiveness of multicore processors in today's computing systems will increase the demand for techniques to adapt application level parallelism. In this paper we demonstrate the impact of oversubscription in the context of a desktop scenario and show that using too many threads in one application can lead to significant performance loss for other applications within the system environment (in our example more than 30%). We examine how common parallelization tools are trying to exploit parallelism while not causing oversubscription and find that common tools do not offer a mechanism which sufficiently takes into account the computational load of the system. Oversubscription is not easy to detect from an application perspective due to the fair scheduling of common operating systems. Nonetheless, we do present an approach for detecting oversubscription by exploiting a scheduling artifact in the average execution time of a parallel code section.