EM18 · Sem 7 · Real-time systems
RTOS: earliest deadline first
Aim: Show that EDF can schedule any task set with U ≤ 1.
🧪 Live simulation🧊 Real-time 3D bench⚠ Simulated values, not physical measurements
🔬 Virtual lab
Starting the lab…
📘 Theory
EDF always runs the job with the nearest deadline. It is optimal on one processor: any set with utilisation up to 100 % meets all deadlines, while RM may fail above about 69–83 %.
EDF schedulable ⇔ U ≤ 1 (implicit deadlines)
🧰 Apparatus (virtual)
- RTOS scheduler simulator
📝 Procedure
🎤 Viva questions
Why do many RTOSes still use fixed priorities
Simpler, predictable under overload, and easier to certify.
What happens to EDF under overload
Misses can cascade unpredictably.
🛡️ Safety
Virtual board. On real hardware, check supply voltages and pin current limits, and power motors and servos from a separate supply.