Check out the scheduler documentation that Apple has in the xnu repo. https://github.com/apple-oss-distributions/xnu/blob/main/doc...
replyThis is exactly what I was looking for. Thanks. Lots of technical details here for those interested.
replyreply
Excellent, thanks!
replyThe baseline is static: low QoS tasks are dispatched to the E cores, while high QoS tasks are dispatched to P cores. IIRC high QoS cores can migrate to the E cores if all P cores are loaded, but my understanding is that the lowest QoS tasks (background) never get promoted to P cores.
replyHow is the QoS communicated to the scheduler? Is there a mark on the binary or does the code do it at thread startup?
replyThe Apple software stack makes heavy use of thread pools via libdispatch. Individual work items are tagged with QoS, which influences which thread picks up the work item from the queue.
replyIt’s done in code.
replydeleted
replyThe article mentions P or E is generally decided by if it's a "background" process (whatever than means). Possible some (undocumented) designation in code or directive to the compiler of the binary decides this at compile time.
reply> whatever than means
replyIt’s a QoS level: https://developer.apple.com/documentation/dispatch/dispatchq...