Real-time Operating System Labs

Lab 1 : Periodic Task Emulation

Objectives

• To implement periodic tasks
• To observe the scheduling behaviors
  • Fixed priority scheduling

Task Sets

Two sets of periodic tasks

• Task set 1 = { t1(1, 3), t2(3, 6) }
• Task set 2 = { t1(1, 3), t2(3, 6), t3(4, 9) }
• Tasks all arrive at the same time
• Show context switch behaviors
• Show deadline violations if there is any

Notes

• Add message at 3 place

  • OSStart : preempt (from idle to task1)
  • OSInitExit : preempt
  • OS_Sched : complete

• The deadline violation message should show its deadline rather than the time we know it

  • For example, in the set1, the task3 should violate at 9 tick, but we can only know it at 2x tick. In this case, we need to print 9 rather than 2x

Lab 2 : EDF Scheduler

Objectives

• To implement an EDF scheduler in uC/OS-II

Task Sets

Two sets of periodic tasks

• Task set 1 = { t1(1, 3), t2(3, 5) }
• Task set 2 = { t1(1, 4), t2(2, 5), t3(2, 10) }

Notes

• Use EDF scheduling at OSStart, OSInitExit, OS_Sched
• The following loop can iterate through the TCB list

  OS_TCB *ptcb;
  for (ptcb = OSTCBList; ptcb != (OS_TCB*)0; ptcb = ptcb->OSTCBNext) {
      // do something
  }

Lab 3 : Ceiling Priority Protocol

Objectives

• To implement Ceiling Priority Protocol (CPP) for ucOS’s mutex locks

Task Sets

Two scenario

• Scenario 1 : removing multiple blockings

  

• Scenario 2 : avoiding deadlocks

  

Notes

• For the pointers pointing to error message, the memory should be allocated before passing it as parameter (OSMutexCreate, OSMutexPend)

  INT8U R1_error;
  R1 = OSMutexCreate(1, &R1_error);
  ...
  INT8U error;
  OSMutexPend(R1, 5, &error);