1. Problem 11: Complex Hierarchical Scheduling Full Processor FP T3T2 T4T1 EDF T6T5 RM T10T9T8T7 EDFSPS DPS 10 Tasks - with jitter - with bursts - deadline = period - deadline < period - deadline > period - preemptive & independent 3 Scheduling Policies - Rate Monotonic - Earliest Deadline First - Fixed Priority Hierarchical Scheduling Static & Dynamic Polling Servers Total Utilization: 98.5% Schedulable? Min. req. processor speed? Priority 1 Priority 4 Priority 3 Priority 2

2. Real-Time Load Specification pSPS = 4(period)pDPS = 3(period) eSPS = 1(execution share) eDPS =1(execution share) dSPS = 4(deadline)dDPS = 3(deadline)

3. Periodic Server A polling server can be thought of as a periodic task T (p, e). When the server-task T is selected to run by the scheduler, the server-task checks whether workload is waiting to be processed by the server. If yes, the server will provide e resources to process the waiting workload. If no work is available for the server, the task will immediately be finished, i.e. the server will not check for arriving work anymore until the next period starts. While the server is processing, it is preemptable. When it is preempted, it is put back into the ready-queue. If the server could not provide e resources during a time interval T, even though there was always enough work available, then this is treated the same as a deadline-miss. I.e. the system is considered to be not schedulable.