ARM big.LITTLE processing is a power-optimization technology from ARM, where high-performance CPUs and efficiency-tuned CPUs are combined in a cache coherent compute cluster, and software dynamically transitions to the appropriate CPU. The software control mechanisms have been evolving toward a fully heterogeneous scheduling model, Global Task Scheduling, which is now ready for deployment. This software model runs on the same big.LITTLE technology, but it brings new capabilities. This paper will discuss the fundamental operation of big.LITTLE technology and the current results, in performance and power, on mobile use cases as measured on silicon platforms from ARM partners.