Nvidia's Tegra 3 marks start of 'different cores for different chores'

Tegra 3 is the first quad-core for tablets and smartphones, but the real story is the fifth core--the start of a trend toward combining different cores on a chip to boost performance and at the same time extend battery life.

The headline on the Tegra 3 processor, which Nvidia made official yesterday, is that it is the first quad-core processor for tablets and smartphones. But it is Tegra's fifth "companion core," only recently disclosed, which is the real story and the start of a trend in which more chipmakers will combine different processing cores on a single chip to boost performance and at the same time squeeze more battery life out of mobile devices.

The Tegra 3 processor is based on four ARM Cortex-A9 cores running at speed up to 1.4GHz and a 12-core GeForce graphics processor. That's a lot of horsepower for a tablet or smartphone, and Nvidia is promising "PC-class performance levels" and three times the graphics performance of the Tegra 2. In particular, it is emphasizing mobile gaming with advanced features such as realistic physics effects, dynamic lighting and stereoscopic 3D. Nvidia says more than 40 games will be available by the end of the year with more in development.

The problem with all this performance is that it comes at the cost of battery life, and that's where the extra companion core comes in. The fifth core is also based on the Cortex-A9 architecture, but it is designed to run at only 500MHz. That's sufficient to handle lightweight tasks-checking e-mail and Twitter feeds in the background, browsing basic Web sites, listening to music and watching videos-without using as much power as the four main cores. Tegra 3 automatically switches between the main cores and the companion core depending on the workload. The result, according to Nvidia, is 60 percent lower power consumption than Tegra 2 and up to 12 hours of battery life during HD video playback.

In a previous post, I noted that this idea-known as heterogeneous multiprocessing-isn't new. But it is about to become more mainstream as chip designers look for new ways to scale performance and cut power. Texas Instruments' OMAP 5 platform, which will start shipping next year, combines dual Cortex-A15 cores with two Cortex-M4 processors and Imagination Technologies' PowerVR SGX544 graphics. And ARM will be making heterogeneous multiprocessing available "off-the-shelf" to all chip makers with its Big.Little architecture that combines two or four "big" A15 cores with two or four "little" A7 cores. Broadcom, Freescale, Samsung, ST-Ericsson and TI, among others, have licensed both the A7 and A15 and could offer Big.Little processors starting in 2013.

In comparison to Tegra 3, these are more heterogeneous designs in the sense that they mix and match very different cores and should therefore be able to stretch across a broader range of performance and power levels. They will also be manufactured on a more advanced 28nm process, which helps with performance, power and cost.

But Nvidia deserves credit for being first to push the envelope here. The first device to offer Tegra 3 is likely to be the Asus Eee Pad Transformer Prime, a 10-inch tablet that will start at $499 with 32GB of storage and Android 3.2 (the keyboard dock is an extra $149). It should be shipping by the end of the year. The first Tegra 3 smartphones, perhaps including the rumored HTC Edge, should follow later in 2012.