Technical mental model

Round-robin scheduling appears simple, but fairness and latency depend on queue integrity, time-slice size, and blocking behavior handling.

Ready-queue rotation should be deterministic and bounded-cost.

Time quantum selection balances responsiveness against switch overhead.

Blocked tasks must leave rotation immediately and re-enter safely.

Equations and constraints that drive decisions

Approximate waiting time in equal-quantum round-robin:

Where:

• $n$: runnable tasks
• $q$: quantum

Implementation walkthrough

Implementation sequence:

1. Build queue operations with invariant checks in debug builds.
2. Start with measurable quantum and tune using observed latency metrics.
3. Track context-switch overhead to prevent excessive churn.
4. Stress with mixed CPU-bound and blocked tasks to verify fairness.

Validation and debugging checklist

• Overshort quantum burns CPU in context switching.
• Overlong quantum harms responsiveness.
• Queue corruption can masquerade as random task hangs.
• Fairness claims should be backed by runtime traces.

A production-ready round-robin scheduler is defined by predictable queue behavior, not by simple code shape alone.