October 24, 2011 -- This article presents the rationale and design behind the first big.LITTLE system from ARM based on the high-performance Cortex-A15 processor, the energy efficient Cortex-A7 processor, the coherent CCI-400 interconnect and supporting IP.

The range of performance being demanded from modern, high-performance, mobile platforms is unprecedented. Users require platforms to be accomplished at high processing intensity tasks such as gaming and web browsing while providing long battery life for low processing intensity tasks such as texting, e-mail and audio.

In the first big.LITTLE system from ARM a "big" ARM Cortex-A15 processor is paired with a "LITTLE" Cortex-A7 processor to create a system that can accomplish both high intensity and low intensity tasks in the most energy efficient manner. By coherently connecting the Cortex-A15 and Cortex-A7 processors via the CCI-400 coherent interconnect the system is flexible enough to support a variety of big.LITTLE use models, which can be tailored to the processing requirements of the tasks.

By Peter Greenhalgh. (Greenhalgh is a Consultant Engineer at ARM and the technical lead for microprocessor hardware development.)