big.LITTLE

Support in Arm DS-5 Development Studio

The next generation of Arm®-based SoC devices benefit from a power-saving combination of state-of-the-art technologies, including big.LITTLE. To make the most of the underlying architecture, we know that software needs to be equally well designed. Arm DS-5 Development Studio gives you a market-proven suite of tools to make your software as energy-efficient as possible, from basic drivers all the way up to complex Linux and Android applications.


 

big.LITTLE SoC Bring-up

A complex, power saving technology like big.LITTLE relies on hardware managed cache coherency in its most efficient operating mode. DS-5 gives you the debug and trace tools necessary to make sure that your hardware is behaving as expected, along with a simple means of configuring the CoreSight elements of your SoC design.

By default, the DS-5 Debugger perspective is arranged into multicore and multicluster groups, allowing you to see at a glance how big and LITTLE cores are performing. Software execution is synchronized across each view to give a comprehensive insight from source code to instruction. Each view can be linked to a specific core and is fully customizable.

DS-5 comes with the unique debug and trace services layer (DTSL) to abstract away the complexity associated with low-level CoreSight access. Turning on trace sources, managing funnels and replicators is greatly simplified through use of pre-written Java classes that can be customized and called as required. This saves you significant time when bringing up multicluster big.LITTLE SoCs, allowing you to concentrate on improving system performance.


Making Power Management the Unsung Hero

Everybody wants a mobile device to last as long as possible between charges. Everybody also wants console-quality gaming and high-definition videos, GPS, a host of sensors, a camera with a flash and of course, a super dense, bright screen. For this, power management has to be truly clever, taking full advantage of technologies like big.LITTLE, though often going as far as powering down the debug domain to save watts.

Implementing this power management requires a debug probe and debugger which are robust enough to gather complex information sets during power-cycling. DSTREAM was designed with this in mind and is able to cope with aggressive power management techniques, providing you debug and trace information that will help to vastly improve the end user experience for your customers.


Streamline for big.LITTLE

Streamline performance analyzer was designed with multicore processors in mind. Starting at cluster level, you can drill down to individual cores, applications, threads and lines of source code to quickly spot bottlenecks that might be slowing your system down. This top-down approach is ideally suited to big.LITTLE, with core map mode allowing you insight into which cluster your applications are executing on at any one time, as well as the speed at which they switch between big and LITTLE clusters.

A wide range of hardware and software counters are available, supporting everything from system IP through to application level. By creating your own expressions, you can customize Streamline charts depending on your analysis needs.

The screen capture on the right illustrates the different core and cluster views available in Streamline. This capture was made using a Cortex®-A15 cluster and Cortex-A7 cluster in big.LITTLE configuration. As you can see, executing the Xaos example program requires only the LITTLE cores in this case.


big.LITTLE Support in DS-5 Ultimate Edition

In the Armv8 architecture, a low power, energy efficient (LITTLE) cluster of Cortex-A53 processors handles the lightweight tasks that mobile devices typically carry out, such as messaging, audio, scrolling the screen and browsing the web. This cluster is complemented by a (big) cluster of Cortex-A57 processors, designed to meet the requirements of high-end applications.

DS-5 Ultimate Edition makes handling this setup straightforward, giving you the flexibility to monitor execution across each cluster of 64-bit processors. DS-5 Ultimate Edition Debugger provides comprehensive support for big.LITTLE, allowing a coordinated view across software execution, or alternatively, individual views of a particular processor.

To the OS, the big.LITTLE configuration appears as a standard SMP processor, with the only requirement being a kernel space patch.