Hybrid CPUs and games development

[vgilsoler]

For those could be interested in how the hybrid CPU architecture has changed for gaming and an explanation why intel 12th gen CPU and later can be less performant than older CPUs.

https://www.intel.com/content/www/us/en/developer/articles/guide/12th-gen-intel-core-processor-gamedev-guide.html

It can be moved to other forum by the moderators if they consider it.

 

[blkspade]

The situation doesn't even need a massive explainer. The E cores have lower clocks and lower IPC, so if game render gets pushed to them it increases latency to the GPU. They are disproportionately slower at turning in work. Game devs need to just be sure to disregard them as eligible cores to not hamper game performance. IF/when games start demanding more than 16 threads, they'll be useless. E-cores are practically just productivity accelerators, for tasks that aren't latency sensitive, and basically exist because Intel can't keep P-core parity with AMD inside a sensible power envelope.

[Dragon1-1]

They can still be useful for either low demand stuff like audio processing and offloading all non-game related stuff that the OS does in the background. Still, I'm sticking with AMD for the foreseeable future, possibly the mid-end X3D series, to avoid scheduling issues with assigning appropriate threads to the 3D cache cores. Having a ridiculous number of cores isn't optimum, anyway, single core performance and L3 cache matter more for gaming.

[vgilsoler]

Before the hybrid cpus the devs just need to send the treads to windows cpu scheduler and let the OS do their magic, but after gen12 this method is no it’s no longer working well. So the devs needs to check if the next  available core is performant or efficient, and if the thread can run in both types of core or only in one of them. Obviously this increases the complexity of the code and the workload of developers to produce an optimized software. 

[blkspade]

On 12/22/2023 at 5:54 PM, Dragon1-1 said:

They can still be useful for either low demand stuff like audio processing and offloading all non-game related stuff that the OS does in the background. Still, I'm sticking with AMD for the foreseeable future, possibly the mid-end X3D series, to avoid scheduling issues with assigning appropriate threads to the 3D cache cores. Having a ridiculous number of cores isn't optimum, anyway, single core performance and L3 cache matter more for gaming.

That's kind of the rub there, that if they are working to do those in background in conjunction with P core doing anything else, you are sucking down even more power to do that than AMD own equally high core count CPUs. It's not even the same situation with the 7950X3D because it's largely only ever going to happen if game isn't auto-whitelisted by the game bar, which is solved in 2 clicks. Even more is that if its happening its practically transparent to your experience that you'd only know by feeling the need to confirm. Render threads hitting the E-cores actually turn into a nightmare.