Darwin PMDA Phase 2: Expand macOS metrics for Apple Silicon

[tallpsmith]

Overview

Expand Darwin PMDA with ~100 additional metrics targeting Apple Silicon Macs (graceful degradation for Intel).

Metric Categories

• Thermal & Temperature: CPU/GPU temps, fan speeds, thermal pressure (~15 metrics)
• GPU & Graphics: Utilization, VRAM usage, hardware inventory (~7 metrics)
• Power & Battery: Battery health, charge cycles, power consumption (~15 metrics)
• Process I/O: Per-process disk I/O, QoS CPU time, memory footprint (~15 metrics)
• Enhanced Network: IPv6 statistics, advanced TCP metrics (~15 metrics)
• Disk & Storage: Queue depth, APFS-specific metrics (~10 metrics)
• System Limits: Resource limits, IPC pools (~10 metrics)
• Additional: Scheduler stats, device enumeration, memory compression deep-dive (~23 metrics)

API Accessibility

• No special privileges: GPU, battery (IOPowerSources), sysctl metrics, process APIs
• May require root/entitlements: SMC temperature sensors, IOReport power metrics
• Community-documented: SMC interface (reverse-engineered, not Apple-supported)

Implementation Strategy

Phased approach in 4 waves: quick wins (sysctl), medium effort (GPU/battery/IPv6), higher effort (thermal/SMC), optional specialized features.

Detailed research and implementation plan: darwin-pmda-phase2-research.md

Related: Phase 1 (PR #2442) added 60+ metrics covering memory compression, TCP/UDP/ICMP stats, VFS, and process counts.

[tallpsmith]

Completed as par of PR #2466