We’ve been trained to think that more cores equals more performance, but in mobile we’re noticing a trend that dual core processors sometime out perform their quad core brothers. Why? There isn’t really a simple answer to that question since every processor is different in terms of pipeline depth, clock-speed, cache, optimization and especially, customized features. Sometimes more cores can mean more power savings, but worse performance, or vice versa. And it all depends on the combination of cores and features used in the processor.
In some cases, customization of a dual core can out-do a quad core. For example, when a chip has out-of-order instruction processing, things can move a lot faster. Many of Qualcomm’s chips have this feature, which allows the chip to process simple, small instructions faster while the big complex orders wait in the wings. Marketing folks aren’t the techiest of people and it’s really quite a lot easier to boast about the number of cores and clock speed than customized features that will cause the eyes of the average consumer to glaze over.
ARM just announced that the Cortex A15 quad core processor will be ready in mass quantities for this year’s new cell phones. In all likelihood we’ll probably see the A15 in our devices a lot more next year. The quad core update could be great in terms of battery life and it will be interesting to see how it does in meeting performance standards.