macOS: Audio Workgroup threads not running on P-Cores

Question

Created Mar ’23

Replies 1

Boosts 0

Participants 2

We have noticed that in our application that creates worker threads for audio processing, these threads (time-constrained priority) in some cases do not run on the P-Cores (on Apple Silicon Macs).

It was my understanding that once we use audio workgroups, the scheduler will always schedule our threads on the P-Cores.

This works okay as long as the CoreAudio buffer size used is 256 samples or less (@ 48K). But if the buffer size is 512 or above, the threads are run on E-Cores (checked using System Trace).

Is this expected behavior?

Can I find any documentation for this (short of analyzing the scheduler source in kernel)?

Thanks. Devendra.

Boost

Answer 1

KonradGlAudio OP

Mar ’24

From my experience this seems to be expected. The scheduler will only let your threads run on p-cores if the load is high enough. So as long as you don't have any audible drop-outs you should be fine.

0