GPU Support (NVIDIA + AMD)

Joulie supports node-level GPU power-cap intents for NVIDIA and AMD.

Validation status

GPU support has been validated in simulator mode only (no bare-metal GPU access yet). The host code paths are designed to work on bare metal (NVIDIA + AMD) when GPU nodes are available.

Contract model

NodePowerProfile.spec.gpu.powerCap defines a per-GPU cap intent:

  • scope: perGpu
  • capWattsPerGpu (absolute, optional)
  • capPctOfMax (percentage, optional)

Precedence:

  1. capWattsPerGpu if present
  2. otherwise capPctOfMax

The same cap is applied uniformly to all GPUs on the node.

Heterogeneous nodes

Joulie supports heterogeneous GPU fleets by profile percentages:

  • performance profile: capPctOfMax=100
  • eco profile: capPctOfMax lower than 100 (for example 60)

Optional deterministic mode (simulator-oriented): operator can resolve percentages to absolute watts using model mapping (GPU_MODEL_CAPS_JSON) and write capWattsPerGpu.

Agent host backends

  • NVIDIA: host backend uses NVIDIA tooling (power-limit set per device).
  • AMD: host backend uses ROCm SMI tooling (rocm-smi) where supported.

When capabilities are unavailable/unsupported, status is reported as blocked rather than failing the whole reconcile loop.

Simulator mode

Simulator control endpoint accepts gpu.set_power_cap_watts with capWattsPerGpu.

Simulator telemetry includes:

  • gpu.present
  • gpu.vendor
  • gpu.count
  • gpu.powerWattsTotal
  • gpu.avgPowerWattsTotal
  • gpu.capWattsPerGpuApplied
  • gpu.utilization

Per-device entries also expose:

  • temperatureC
  • thermalThrottle
  • avgPowerWatts

This makes it easier to compare:

  • internal power-cap dynamics,
  • exported averaged telemetry,
  • and sustained thermal behavior during long runs.

Scheduling guidance

Keep workload intent guidance unchanged:

  • performance-sensitive pods: prefer NotIn ["eco"]
  • eco-only (advanced): In ["eco"] and optionally joulie.io/draining NotIn ["true"]

GPU resource requests (nvidia.com/gpu, amd.com/gpu) are orthogonal to Joulie power-profile labels. Joulie GPU capping is node-level and not a GPU slicing API.

Example

See: