The GPU is one of the most important parts of our phone or Android tablet, whether you're rocking a Moto G, a Galaxy Note 4 or a Nexus 7 (2013), but for many it is still a great unknown. As in every Android for Beginners article, we aim to shed some light on a fundamental but often overlooked aspect of Android. This time, we'll shed some light on a dark part of our phone's hardware: what is a GPU and how does it work?
What is a GPU?
GPU stands for Graphics Processing Unit, so that probably already gives you an indication of what it does. It is a processor dedicated solely to graphics processing operations or “floating point” calculations.
One of the main functions of the GPU is to lighten the load on the CPU (Central Processing Unit), especially when running graphics intensive applications like hi-res games or 3D graphics apps.
For example, consider a game like a first-person shooter. The GPU, in this case, would be responsible for creating graphics, textures and colors within the game, while the CPU, not having to work the graphics, can use its resources for artificial intelligence or calculations of the game's mechanics.
A GPU's architecture does not differ too much from a CPU, however, its construction is much more optimized towards the efficient calculation of graphical information. Therefore, if you were to ask your GPU to perform anything other than graphical tasks, it would suddenly become an ineffective and slow component rather than the fine-tuned tool it is.
Types of GPU
Dedicated graphics cards provide higher power. They are specifically designed for this work, and are integrated with the motherboard through a separate port. These kinds of GPU also have separate RAM to the CPU that can only be used by the GPU. You don't find these kinds of graphics cards in Android devices, but rather in desktop PCs and laptops.
Integrated graphics are more familiar to Android users because they are included on what we call a System-on-a-Chip (SoC) like the Snapdragon 810 which includes an integrated Adreno 430 GPU. This time, the memory used is the system memory and the GPU is integrated into the processor itself.
There are also hybrid GPUs which are a mixtures of both types. That is, they have a small amount of dedicated RAM, but also use system memory.
How does a GPU work?
Unlike central processors, with a few cores running at high speed, GPUs have many processing cores running at low speeds. These cores are basically aimed at two different functions: the processing of vertices and pixels.
Vertex processing essentially revolves around the idea of coordinate systems. The GPU handles geometric calculations to reproduce dimensional space on your screen. This results in things like depth and spatial data in games and the possibility of rotation in three-dimensional space.
The pixel processing of GPUs, or to put it more simply, the graphics we see, is very complex and requires even more processing power than is required by vertices. Pixel processing renders the various layers and applies the effects needed to create complex textures to get the most realistic graphics possible.
After both of these processes have been handled, the result is transported to a digital readout, in this case, the screen of your smartphone or tablet. The processes I have described here occur continuously, millions of times a second, as we play a game. (Now you know why your phone sometimes heats up.)
Of course, it's all a lot more complicated than this, but you should now be able to fake your way through a conversation on GPUs without looking too clueless. Or perhaps you are inspired to go out and read more on the topic?
If you have any questions about GPUs just ask below. What part of your smartphone would you like explained next?