SDL3 CPU Subsystem wishlist

[icculus]

SDL_GetCPUCount() could probably stand to be more useful:

• Is a given core physical or logical (is this a hyperthread? Maybe I don't want to assign heavy-lifting to that).
• Is a given core low-power (which you see in newer Apple hardware, and I assume eventually other major platforms, too).

Also, a way to set thread affinity would be nice.

Take all these things together, and you can build a job system where you have threads waiting for jobs on specific physical cores, so they work at full efficiency and don't compete, and can optionally assign less critical jobs to queues on low-powered cores.

Originally posted by @icculus in https://github.com/libsdl-org/SDL/issues/3519#issuecomment-1233114454

[icculus]

Remove 3dnow! support. If not, at least disable it in the default config to save some build time.

Originally posted by @eloj in https://github.com/libsdl-org/SDL/issues/3519#issuecomment-1138705035

[icculus]

I think we're happy with where this currently stands, so I'm closing this.