We are running into the same issue:
everything runs fine under high load for 45s (very deterministically)
All threads get bumped from Performance Cores to Efficient Cores for 5-10s
All threads come back to Performance Cores.
We have a few C++ threads (which we manually mark as .userInteractive using pthread_set_qos_class_self_np) and Swift queues (which when created are marked as qos: .userInteractive).
We only seem to get this issue when running on A12 Bionic devices (iPad Min 5th Generation, iPad 8th generation).
Looks like the OP also is using an A12 Bionic device (iPhone XR).
We don't experience on older chips (A10X) or newer (A14).
Any ideas?
Topic:
App & System Services
SubTopic:
Core OS
Tags: