http://www.greenbot.com/article/287...-to-know-about-nvidias-new-tegra-x1-chip.html
The Tegra X1 is packing four Cortex-A57 cores (the big cores) and four Cortex-A53 cores (the little cores). The big cores are fast and use more power, but the little cores are great for background processing and are much more power-efficient. Most chips that use this eight-core configuration are tied together using a system from ARM called big.LITTLE. The newest version of this technology moves data between the two CPU islands with so-called global task scheduling. With the latest version of global task scheduling (sometimes called heterogeneous multi-processing), you can get any mix of the eight big and little cores.
Rather than using ARMs method for controlling all eight cores, Nvidia is using cluster migration with a custom cache coherence system to shuffle data between the two islands. Under this model, the OS scheduler only sees one cluster (either big or little) at a time.
So what does all that mean?
The Tegra X1 only runs processes on one set of cores at a time, but the data can be moved back and forth between the big power-hungry cores and the small power-efficient cores. Cluster migration is typically be less efficient than global task scheduling, but Nvidia says its custom interconnect has vastly improved the power efficiency of cluster management.