Real-Time Operating Systems

More documents

Recommendations

Info

¿ Inheritance Priority inheritance and priority ceiling ¿ Ceiling 23 Achieving predictability: architecture ¿ Obvious source for unpredictability: ¿ Memory accesses not deterministic ¿ Example: • hit ratio = 90 %, T cache = 10ns, T mem = 50ns • => 10 % of accesses have access time 18% larger than cacheless case ¿ Solutions: ¿ systems without cache (or disabled) ¿ precise estimation of caching behaviour • <strong>Systems</strong> with application-specific buffers 24 12
Achieving predictability: memory management ¿ Avoid non-deterministic delays ¿ No conventional demand paging (page fault handling!) • May use selecitve page locking to increase determinism ¿ Typically used: ¿ Memory segmentation ¿ Static partitioning ¿ Problems: ¿ flexibility reduced ¿ careful balancing required 25 Achieving predictability: Applications ¿ Current programming languages not expressive enough to prescribe precise timing ¿ Need of specific RT languages ¿ Desirable features: ¿ no dynamic data structures ¿ no recursion ¿ only time-bound loops 26 13
Page 1 and 2: Real-Time Operating Systems 1 Summa
Page 3 and 4: ¿ Real-time Introduction (3) ¿ Ti
Page 5 and 6: RTOS 9 Real-time Operating Systems
Page 7 and 8: Real-time Operating Systems (3) ¿
Page 9 and 10: Achieving predictability: interrupt
Page 11: Priority inversion (2) ¿ Basic pri
Page 15 and 16: Processes ¿ Called tasks in the RT
Page 17 and 18: Scheduling constraints ¿ The follo
Page 19 and 20: Periodic and aperiodic tasks ¿ Per
Page 21 and 22: Real-time scheduling 41 ¿ Given: S
Page 23 and 24: Scheduling metrics ¿ n tasks ¿ Av
Page 25 and 26: Jackson’s algorithm [1955] ¿ 1 |
Page 27 and 28: Horn’s algorithm ¿ Example: 53 S
Page 29 and 30: Introduction ¿ Periodic activities
Page 31 and 32: Processor utilization factor (2) ¿
Page 33 and 34: Cyclic executive approach ¿ Schedu
Page 35 and 36: Process-based scheduling ¿ Fixed-p
Page 37 and 38: RM schedulability test (2) ¿ For l
Page 39 and 40: EDF algorithm ¿ Dynamic scheduling
Page 41 and 42: Deadline monotonic (DM) scheduling
Page 43 and 44: EDF for D
Page 45 and 46: Periodic task scheduling: summary D

Real-Time Operating Systems

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?