Problem 38 - Consider a real-time OS that has a built-in preemptive scheduler. Each task has a unique priority and the lower the priority id, the higher the priority of the task. The time required to process interrupts is ignored and the time is in terms of OS ticks. Consider the following task dependency graph Mailbox D Task D Mailbox B Task B Mailbox E Task E Task A Mailbox F Task F Mailbox C Task C Mallbox G Task G For this particular problem we have the following assumptions: * periodic tasks are characterized as (e, fj), where e is the execution time and i is the idle time after the task has completed its execution * a task with an input mailbox is suspended until a message is posted in its mailbox Consider seven tasks with the following characteristics: task A with priority 1 and (2, 20); task B with priority 2 and (4, 0); task C with priority 3 and (3, 0); task D with priority 4 and (3, 0); task E with priority 5 and (2, 0); task F with priority 6 and (4, 0); task G with priority 7 and (2, 0). All of the above tasks are created at time 0 and their priorities are assigned statically For each of the following questions, show the schedule for a single-processor system for the first 20 OS ticks. For each OS tick write which task is running (if the processor is idle, write X) (a) a message is posted in a mailbox after the source task has completed its executiorn (b) a message is posted in a mailbox after the source task has executed for 1 OS tick (c) a message is posted in a mailbox after the source task has executed for 2 OS ticks Problem 38 - Consider a real-time OS that has a built-in preemptive scheduler. Each task has a unique priority and the lower the priority id, the higher the priority of the task. The time required to process interrupts is ignored and the time is in terms of OS ticks. Consider the following task dependency graph Mailbox D Task D Mailbox B Task B Mailbox E Task E Task A Mailbox F Task F Mailbox C Task C Mallbox G Task G For this particular problem we have the following assumptions: * periodic tasks are characterized as (e, fj), where e is the execution time and i is the idle time after the task has completed its execution * a task with an input mailbox is suspended until a message is posted in its mailbox Consider seven tasks with the following characteristics: task A with priority 1 and (2, 20); task B with priority 2 and (4, 0); task C with priority 3 and (3, 0); task D with priority 4 and (3, 0); task E with priority 5 and (2, 0); task F with priority 6 and (4, 0); task G with priority 7 and (2, 0). All of the above tasks are created at time 0 and their priorities are assigned statically For each of the following questions, show the schedule for a single-processor system for the first 20 OS ticks. For each OS tick write which task is running (if the processor is idle, write X) (a) a message is posted in a mailbox after the source task has completed its executiorn (b) a message is posted in a mailbox after the source task has executed for 1 OS tick (c) a message is posted in a mailbox after the source task has executed for 2 OS ticks