Much has been said about ARM‘s big.LITTLE processor architecture, which greatly improves the efficiency of smartphones, tablets and even some low-power notebooks. But do you know how it works and why it has been a revolution? In this article we are going to explain it to you and we are going to go one step further, wondering why it is not used in desktop PC processors .
In October 2011, the manufacturer ARM announced the new big.LITTLE architecture along with its Cortex-A7 processor, which was designed to be architecturally compatible with the Cortex-A15. Since then, many processors have followed in their footsteps, seeing the good results, but what exactly does this processor architecture consist of?
What is big.LITTLE architecture
big.LITTLE is an architecture called heterogeneous because it combines relatively small and energy-saving cores (LITTLE) with others much larger and more powerful but with higher consumption (big), all in the same processor. The idea is to create a multi-core processor that can better meet modern dynamic computing needs and use less power.
Usually only one core group will be active at the same time. In other words, when the device is idle or performing light tasks, it will be using the LITTLE cores while the big ones will be deactivated, but when any application that demands more power is running, then the big cores will be activated, deactivating the LITTLE ones. For this reason, these types of processors have a large number of cores, because in essence what they have are two processors in the same die .
In this way, the device has the expected performance for each type of application that is run, but always trying to reduce consumption. For example, when you are simply browsing the Internet or using the camera, the LITTLE cores will be used, which provide enough performance for it and save battery power, but when we run a game, the big core pack will start to work, to give us the best performance although consume more.
Why can’t we find this architecture on PC?
Although the intention of this heterogeneous architecture is to save battery -something that could be used in laptops-, it is also a concept that could be used in PCs, especially now that manufacturers are investing more efforts in improving efficiency than in improving performance. So why don’t we see big.LITTLE processors on PC?
The answer is simple but complicated at the same time. To start with, logically ARM has the patent for the technology and can only be implemented with ARM processors, which can be very good for smartphones or low-power devices but are clearly insufficient for modern desktop PCs . This is undoubtedly the first and most important reason why it is not implemented on PC.
The second reason is because of the sets of instructions used on a PC, quite different from those that can be used on smartphones. ARM has its own sets of instructions, while Intel and AMD use those of the x86-64 architectures. And since PC software is programmed precisely for these architectures, there would be huge ARM compatibility issues.
