Why Quad-Core?

We are entering into a new era, ladies and gentlemen. Well, “era” may not be the right word considering how quickly things change in these here mobile parts, but the fact remains the same: Quad-core mobile processors are here. And the ones that aren’t quite here yet are coming.

While many of our brilliantly geeky readers need no tutorial on the advantages of four processing cores, some of you may be thinking “Uh… OK, why do I care?” So I took it upon myself to place a few calls and get some of the big guns — Qualcomm, Nvidia, and TI — to explain why exactly you should care (or shouldn’t), and what kind of differences technology like this can make in the average user’s daily phone usage.

Right off the bat, there are a few myths we need to squash, the most prominent being the misguided belief that doubling cores automatically doubles processing performance. That’s not so true. Upgrading from a single-core CPU to a dual-core processor yields 50 percent better performance, while upgrading from dual-core to quad-core increases performance by just 25 percent. The second commonly held but utterly untrue belief is that all mobile processors are created equally. These companies actually work extra hard to differentiate themselves, which is difficult when the end-user has little say over which processors get stuck in which devices.

Generally speaking (as in, with no particular brand or model in mind), a quad-core CPU should most noticeably do two things. The first is to improve performance during multi-tasking or use of multi-threaded applications. Web browsing, for example, is a multi-threaded process, as are many advanced gaming applications. Android is also natively multi-threaded. The second noticeable improvement quad-core should yield is an increase in battery life. Now, your average CPU usually only consumes about 15 percent of your battery life during regularly daily usage, so the improvements won’t usually be that staggering. Still, battery life is a big problem right now in mobile and any improvement is a worthwhile one.

Nvidia has been the first to bring quad-core processing to mobile, in the form of its Tegra 3 Kal-El SoC. Aside from the general benefits afforded by four cores, Nvidia specifically differentiates itself with what it calls a Companion core. The Companion core is a patented fifth core that maxes out at speeds of 500MHz. It uses patented technology known as variable symmetry multiprocessing (vSMP), which allows the processor to power cores on and off based on the device’s workload.

The Companion core handles just about everything during low performance tasks and in stand-by mode, like email and monitoring the network for incoming calls. When you start on something more performance-intensive, like web browsing, facial recognition or photo stitching, other cores are powered on to handle the task. This is Nvidia’s way of improving performance while saving battery life, while others have found different ways to make quad-core stand out.

Qualcomm, for example, is about to release its APQ8064 SoC, which has a special trick. Most multicore processors clock up and down at the same time. Qualcomm’s processor, on the other hand, is able to clock one core at the max while clocking the second needed core only to the speed it needs to complete the task.

In other words, since Qualcomm’s processor cores can be clocked individually, a task that overflows on the first core may only need the second core spinning at 60 percent of its max speed. So just like Nvidia’s Companion core hooks you up on the battery life front, so will Qualcomm’s individual clocking technology.

Texas Instruments, however, has yet to outline plans for their quad-core offerings and seems to be sticking with dual-core OMAP SoCs for the time being. That said, TI maintains that its OMAP 5 SoCequipped with a dual-core Cortex A15 processor (and two Cortex M4 cores) is a mature system that is more efficient at handling instructions. Some even refer to it as a quad-core system, though TI itself still calls this a dual-core SoC. And they believe it’ll compete. The company went so far as to say that its smart multi-core architecture actually takes 30 percent more instructions than the Cortex-A9 MPCore’s four processing cores as seen in Nvidia’s Tegra 3.

The truth is this is just the beginning when it comes to the migration toward four cores, and there’ll be plenty more to learn in the coming months.