New server.dpm_force_performance_level_overrides (engine name → level,
e.g. {"radeon":"high"}). At engine startup the engine writes the level
to every amdgpu card's power_dpm_force_performance_level — locking a
Polaris/GCN card to fixed top clocks avoids the DPM power-state
transitions that hang these cards under sustained Vulkan compute
(current default is 'auto', the hang-prone mode). Card is matched by PCI
vendor id (0x1002), robust to DRM card renumbering across resets.
Best-effort: an unprivileged container logs the exact host command on
PermissionError.

Pairs with two config-only stability levers applied for the radeon:
n_ctx reduction (qwen3 1024→512, gme 1536→1024) to keep all three
embedders in real VRAM with headroom (no GTT-over-PCIe spill during
compute — another Polaris hang trigger), and max_parallel_requests
override {"radeon":1} to serialize Vulkan submissions.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014S8VtAvG499SsCbeESRK7V