Add an API to allow getting the number of "performance" cores-only

Feature or enhancement

Proposal:

Currently Python provides os.cpu_count() which returns the total number of physical CPU cores.

On macOS M-class machines (and probably other ARM hardware), there are actually two types of CPU cores: performance cores, and efficiency cores.

For many tasks where a user wants to do "1 task per core", it really only makes sense to do 1 task per performance core.

Therefore it'd be sensible to expose this number. On macOS it can be found with the hw.perflevel0.logicalcpu sysctl.

This could be done in one of two ways, a new function, e.g. os.performance_cpu_count(), or as a keyword-argument to os.cpu_count(performance_cores_only=True).

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

先閱讀現有的 os.cpu_count() API 及其平台特定實作，然後調查提案中描述的 macOS hw.perflevel0.logicalcpu sysctl。比較在支援平台上採用新函式和關鍵字引數的方案，並找出相關測試。當選定的 API 能可靠地提供效能核心數量，且對支援的系統具備文件化的行為與測試涵蓋率時，即表示完成。