Makespan Scheduling

Makespan scheduling optimizes GPU utilization across multi-step workloads that require endpoint transitions (eviction, loading, inference, restoration).

What is a Makespan?

A makespan is the total time from start to finish of a complex workload that may require:

1. GPU eviction: Stopping a low-priority endpoint to free GPUs
2. Endpoint startup: Loading a different model
3. Workload execution: Running the actual inference
4. Baseline restoration: Reloading the original endpoint

Example: Render Pipeline

makespan.execute
├── allocate_gpus              # OR-Tools resource assignment
├── evict_if_needed            # Preemption decisions
├── start_endpoints            # vLLM process spawning
│   └── endpoint.start: rendering
│       ├── process_spawn
│       ├── model_load         # ~240s for large models
│       └── health_check
├── execute_workload           # Actual inference/rendering
└── restore_baseline           # Return to set points

AgendaTracker

The AgendaTracker records scheduled endpoint transitions so the Health Observer can distinguish intentional state changes from failures:

tracker.register_operation(
    operation_id=op_id,
    workload_id=wl_id,
    control_mode=ControlMode.POSITIVE,
    target_endpoints=["reasoning", "fast"],
)

Control Modes

Tracing

Each makespan is traced as a parent span with child spans for each operation phase. This enables end-to-end visibility into complex multi-step operations, including time spent in external API calls (treated as black-box stages).