Problem

• Do not use sleep() to pace frames!

Best Practice

• Target explicit frame rate
• Use the following APIs (iOS 10.3 +)
  - MTLDrawable addPresentedHandler
  - MTLCommandBuffer presentDrawable afterMinimumDuration
  - MTLCommandBuffer presentDrawable atTime

Thread Stalling

Render thread gets preempted due to low priority

• Priority decay
• Priority inversion

Best Practice

Configure the render thread

• Priority 45
• Opt out of Quality of Service

Thermal Throttling

Impact on system performace

• High device temperature
• Low power mode enabled

Best Practice

• Adjust the workload to the system state
• Use the following APIs
  - iOS 11.0+ : NSProcessInfo thermalState
  - iOS 10.3+ : MTLCommandBuffer GPUStartTime/ GPUEndTime
  - iOS 9.0+ : NSProcessInfo lowPowerModeEnabled

Adjust the Workload

• Target sustainable framerate
• Reduce the resolution
• Simplify the shadow maps
• Use smaller textures
• Decrease the level of detail (LOD) for geometry
• Simplify post-processing and effects

Wasted GPU Time

Waste of power and GPU budget

• Large resources
• Unused GPU work