While ARM's big.LITTLE has evolved from its initial simplistic CPU migration and cluster migration iterations to simultaneous multi-processing (global task scheduling) to energy aware scheduling, the strict segmentation between big and LITTLE clusters has remained non-ideal. For example, the efficiency of shared memory access among CPUs and the speed of task migration have been significant downsides. Yesterday ARM announced the future of multi-core CPU design for its IP ecosystem, a series of technologies collectively branded DynamIQ which has major implications for SoC design.
I believe the reason DynamIQ took so long to announce, and was probably a ton of work to bring about, was how many interconnected systems were required to be redesigned in concert. And it was probably harder still to get them all working together well and efficiently. New interconnect designs and features are necessary to make the newly possible cluster designs work, and there is a new memory subsystem design for which no details are yet being provided. IP blocks such as accelerators can also now be plugged into these fabrics through a new dedicated low-latency port.
One of the biggest takeaways is that it will finally be possible to combine different core designs together within a cluster. If all of the enabling cache design and scheduling are well-implemented, such CPU designs could theoretically realize significant performance and efficiency improvements. Hopefully a DynamIQ system will not be too much harder to implement for silicon vendors, but I wouldn't assume it will be easy. ARM will really have to make it workable with its stock IP at the very least.
It's hard to say much more about DynamIQ, as ARM is still holding back most of the important details, which I would not really be qualified talk about anyway. There are other announcements such as new CPU instructions for deep learning, which I personally care less about but are still very important for many designs, such as IoT systems without a DSP or GPU. Since Cortex-A53's successor is likely coming at some point, depending on ARM's design goals, I wonder if the first DynamIQ systems will be based entirely on that new core.