How do Alder lake CPUs work?

[MasteredDelta]

How do the performance and efficiency core work in Alder Lake CPUs work? Like do the performance cores only work for games and efficiency cores only work for working?

[Bobbysixjp]

The P cores are mainly used during gaming whilst the E cores take care of background tasks. When not gaming I’ve noticed that all cores are being used to some extent. Disabling the E cores does not have a detrimental effect on gaming performance as far as I can tell. 

[Chris Pratt]

First, do you have Windows 11 or are you still on 10? Windows 11 has a new core scheduler designed to work with big.LITTLE architectures like Alder Lake's.

 

In that respect, it's up to the core scheduler to make decisions about what cores to use when. It will prioritize the P cores for active foreground application tasks, and prioritize the E cores for background apps and tasks. The keyword is prioritize, because it depends on what else is going on. A P core might be used for a background task is all the E cores are occupied. Likewise, E cores may be used for foreground app tasks if all the P cores are already in use.

 

Again, this only applies to Windows 11. Windows 10 doesn't have an optimized core scheduler, so core utilization will be virtually random there.

[YoungBlade]

In theory, high demand tasks, like gaming, video editing, code compilation, etc, will prioritize the P cores, using them until the P cores aren't enough and then using the E cores as a backup to add extra CPU performance. In these situations, the E cores will be assigned system tasks and other low priority tasks like music playback and virus scans until called upon.

 

In practice, it's a bit hit and miss right now. Some games and applications run better with E cores disabled because they get used on accident. Some applications straight up refuse to work unless E cores are disabled. Windows 11 helps, but ultimately, I don't expect the big-LITTLE thing to work until applications are coded specifically to take advantage of the design.

 

This is nothing to be alarmed about. New tech will have growing pains. Just like back in the early 00s when dual-core CPUs became a thing - it took time for most applications to properly utilize two cores.

[MasteredDelta]

On 1/1/2022 at 11:28 PM, Chris Pratt said:

First, do you have Windows 11 or are you still on 10? Windows 11 has a new core scheduler designed to work with big.LITTLE architectures like Alder Lake's.

 

In that respect, it's up to the core scheduler to make decisions about what cores to use when. It will prioritize the P cores for active foreground application tasks, and prioritize the E cores for background apps and tasks. The keyword is prioritize, because it depends on what else is going on. A P core might be used for a background task is all the E cores are occupied. Likewise, E cores may be used for foreground app tasks if all the P cores are already in use.

 

Again, this only applies to Windows 11. Windows 10 doesn't have an optimized core scheduler, so core utilization will be virtually random there.

I'll be on W10, is that an issue though?

[Chris Pratt]

1 hour ago, MasteredDelta said:

I'll be on W10, is that an issue though?

Yes and no. It will work, but you won't get any of the benefits of the big.LITTLE architecture. Tasks will be scheduled on cores pretty much randomly, so you might sometimes have performance cores working on background tasks and efficiency cores chewing through the actual productivity or gaming workloads.