The world of CPUs is undergoing a shift. Not only do we now have many CPU cores in our laptop and desktop PCs, but there’s also now a mix of different core types: the P- and E-cores are here.
Symmetrical vs. Asymmetrical CPU Design
In a traditional multi-core CPU, every CPU core is identical. They all have the same performance rating and use the same amount of power. The problem with this is that when your CPU is idling or doing simple tasks, there’s a minimum level of power usage you cannot drop below without switching the CPU off entirely. This isn’t the end of the world when it comes to devices that draw their power from the wall, but if you’re running on battery power, every watt counts!
Smartphones quickly adopted a solution where you’d have some power-hungry cores that provided high-end performance and a number of efficient cores that sip power but perform well enough to run background system tasks or run basic applications such as email, social media, or web browsing.
The high-performance cores automatically kick in when you fire up a video game or in short bursts when a more basic app needs better performance to do a specific task, before falling back on the power-efficient cores.
Asymmetrical Design on PC
While the idea of having mixed CPU core types in a single package isn’t new, it’s not something that’s found in mainstream PCs. At least, that was true up to the release of Intel’s 12th-generation Alder Lake CPUs. These are Intel’s first mainstream CPUs to feature a mixture of different cores.
Within each model of 12th-generation Intel CPU, you’ll find E-cores (Efficiency) and P-cores (Performance) in the CPU package. The relative numbers between these two types of core can vary, but the full Alder Lake CPU die has eight P- and eight E- cores, which is found in the i9 CPU models. The i7 and i5 models have an 8/4 and 6/4 design for P- and E- cores respectively.
The Benefits of E- and P- Cores
There are many benefits to having this hybrid architecture approach in a CPU. Laptop users are going to benefit the most since the majority of daily tasks are not performance intensive. If all you need is the power of your E-cores, you’ll enjoy a cooler and quieter computer with longer battery life.
When you’ve got your laptop plugged into the wall or if you’re using a desktop computer, those E-cores are still important. Let’s say you’re playing a video game that needs all the CPU power you can throw at it. The game can have full access to all performance cores, while your E-cores take care of background processes and applications such as Slack, Skype, downloads, etc.
In the future, intensive applications that are written with hybrid CPUs in mind may even spawn threads that are assigned to both kinds of cores depending on their demands. E-cores are simpler and less expensive to produce, so using them to augment and free up cutting-edge performance cores is a smart idea.
In the case of Alder Lake CPUs at least, the P- and E- cores have been designed in such a way that they don’t interfere with each other so each can do their jobs independently.
Unfortunately, this radical shift in x86 CPU architecture isn’t happening without some teething troubles.