NVIDIA Reveals Kal-El's Fifth "Companion" CPU Core

by Marco Chiappetta — Tuesday, September 20, 2011, 07:17 PM EDT

Over the past seven months or so, NVIDIA has revealed a number of details regarding its upcoming mobile wonder-chip, codenamed Kal-El. According to information provided by NVIDIA dating all the way back to February, Kal-El was to be the world’s first mobile quad-core SoC, sporting an integrated 12-core GeForce GPU, with support for resolutions up to 2560x1600, and performance that’s roughly 5x that of the current Tegra 2.

News out of NVIDIA today, however, reveals that Kal-El actually has 5 CPU cores, four high-performance cores for general processing duties a low-power “companion” core that’ll only be used for background tasks, active standby, and for some music and video playback. NVIDIA is calling this approach Variable Symmetric Multiprocessing, or vSMP.

Kal-El's Low-Power Companion Core

“Our next-generation Tegra processor, codenamed “Project Kal-El,” is widely known as the world’s first quad-core mobile chip. Today, we’re unveiling Kal-El’s little-known fifth core in two new whitepapers that detail its “Variable SMP” architecture.” said NVIDIA’s Matt Wuebbling on a blog post on the company’s website. “This extra core – which we call the “companion core” – runs at a lower frequency and operates at exceptionally low power. During less power-hungry tasks like web reading, music playback and video playback, Kal-El completely powers down its four performance-tuned cores and instead uses its fifth companion core. For higher performance tasks, Kal-El disables its companion core and turns on its four performance cores, one at a time, as the work load increases.”

Core Management, Based On Workload

According to the white papers, the “Companion” core is completely OS transparent, which means the OS and applications are not aware of the core, but they are able to take advantage of it, automatically. Being able to transparently switch between the high-performance cores and low-power Companion core should result in significant power savings. The Companion core uses specialized, low-power transistors that operate at lower frequencies than the high-performance standard cores. However, all five of the cores employ the same ARM Cortex A9 CPU cores. The Companion core is said to operate between 0Mhz (gated, off) and 500MHz, while the performance optimized cores can operate between 0MHz (gated, off) and the SoC’s maximum GHz rating.

NVIDIA’s vSMP technology manages the workload distribution between the Companion and main cores based on the OS and application requirements. The actual management is handled by Kal-El’s Dynamic Voltage and Frequency Scaling (DVFS) feature and CPU Hot-Plug management software and does not require any modifications to the operating system.

(source: NVIDIA)

According to numbers released by NVIDIA, Kal-El’s unique CPU core configuration and transistor mix give it some marked advantages over competing offerings, both in terms of power and performance. The chart above (provided by NVIDIA) illustrates what we’re referring to—Kal-El is not only the lowest power solution when clocks don’t surpass 1GHz, but its performance is almost double that of current dual-core SoCs, even though Kal-El has twice of the number of CPU cores.

Tags: Nvidia, GeForce, Mobile, ARM, Cortex, cores, A-9, SoC, Kal-El

Marco Chiappetta

Marco's interest in computing and technology dates all the way back to his early childhood. Even before being exposed to the Commodore P.E.T. and later the Commodore 64 in the early ‘80s, he was interested in electricity and electronics, and he still has the modded AFX cars and shop-worn soldering irons to prove it. Once he got his hands on his own Commodore 64, however, computing became Marco's passion. Throughout his academic and professional lives, Marco has worked with virtually every major platform from the TRS-80 and Amiga, to today's high end, multi-core servers. Over the years, he has worked in many fields related to technology and computing, including system design, assembly and sales, professional quality assurance testing, and technical writing. In addition to being the Managing Editor here at HotHardware for close to 15 years, Marco is also a freelance writer whose work has been published in a number of PC and technology related print publications and he is a regular fixture on HotHardware’s own Two and a Half Geeks webcast. - Contact: marco(at)hothardware(dot)com