Staged Tuning: A Hybrid (Compile/Install-time) Technique for Improving Utilization of Performance-asymmetric Multicores

Emerging trends towards performance-asymmetric multicore processors (AMPs) are posing new challenges, because for effective utilization of AMPs, code sections of a program must be assigned to cores such that the resource needs of the code sections closely match the resources available at the assigned core. Computing this assignment can be difficult especially in the presence of unknown or many target AMPs. We observe that finding a mapping between the code segment characteristics and the core characteristics is inexpensive enough, compared to finding a mapping between the code segments and the cores, that it can be deferred until installation-time for more precise decision. We present staged tuning which combines extensive compile time analysis with intelligent binary customization at install-time. Staged tuning is like staged compilation, just for core assignment. Our evaluation shows that staged tuning is effective in improving the utilization of AMPs. We see a 23% speedup over untuned workloads.