Nvidia Claims Tegra 3 “Kal El” Has Fifth "Companion" Core

Nvidia: Tegra 3 “Kal-El” Has Five Cores

by Anton Shilov
09/20/2011 | 08:27 PM

Nvidia Corp. on Tuesday revealed that its upcoming Tegra 3 “Kal-El” system-on-chip for tablets, smartbooks and smartphones will integrate an additional fifth “companion” core that will ensure maximum power efficiency of devices powered by Kal El, but will make it slightly harder to produce the chip.


Nvidia has always claimed that its Tegra Kal-El is the industry’s first SoC for tablets and advanced smartphones with for general purpose ARM Cortex-A9 cores. However, it now appears that Nvidia utilized its own variable symmetric multiprocessing (vSMP) technology for Kal-El and integrated yet another low-power ARM Cortex-A9 “companion” core that performs various background tasks while devices are in active standby mode. Generally speaking, Tegra 3 appears to be a five-core SoC.

The companion core will be architecturally similar to other general-purpose cores – it will retain the Cortex-A9 micro-architecture. However, it is made using 28LP (low-power) process technology (and thus can operate at significantly lowered voltages) and operates at clock-speeds in the range between 0MHz and 500MHz, whereas other cores are capable of working at over 1GHz frequencies.

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.

Patented hardware and software CPU management logic continuously monitors the SoC workload to automatically and dynamically enable and disable the companion core and the main general-purpose performance-optimized ARM cores. The decision to turn on and off the companion and main cores is purely based on current SoC workload levels and the resulting CPU operating frequency recommendations made by the CPU frequency control subsystem embedded in the operating system kernel.

“The Variable SMP architecture is also completely OS transparent, which means that operating systems and applications don’t need to be redesigned to take advantage of the fifth core,” explained Matt Wuebbling, director of Tegra product marketing at Nvidia.

Since vSMP technology does not allow both the companion core and the main cores to be enabled at the same time, there are no penalties involved in synchronizing caches between cores running at different frequencies.

Nvidia Kal El system-on-chip (SoC) is based on four high-performance Cortex-A9 general-purpose cores and one power-optimized Cortex-A9 core, features a GeForce graphics processor with twelve stream processors and will have a new display and video engines capable of supporting Blu-ray disc video playback and stereo-3D graphics output. Other capabilities and clock-speeds of the novelty are not known previously. The chip developer claims that the new chip outperforms Nvidia Tegra 2 by up to five times and will consume lower amount of energy.