All four cases 123 and 4 preemptive scheduling

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All four cases, 1,2,3 and 4 Preemptive Scheduling Preemptive Scheduling New Exit Admit Release Running Ready Dispatch Time-out Blocked Event occurs Event wait 1. Wait for I/O/ waitpid()/ P()/ Acquire() etc 4. A Process terminates 2. Interrupt occurs, move from Running to Ready 3. Event I/O Completion/ exit(0) / V() / Release()
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8 All four cases, 1,2,3 and 4 Preemptive Scheduling Preemptive Scheduling New Exit Admit Release Running Ready Dispatch Time-out Blocked Event occurs Event wait 2. Interrupt occurs, move from Running to Ready 3. Event I/O Completion/ exit(0) / V() / Release() In case of 2 and 3, there is a choice Whether to continue, with the same process or select a new one from the ready queue
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9 Scheduling Issues Scheduling Issues Fairness Don’t starve process Priorities Most important first Deadlines Task X must be done by time t Optimization Throughput, response time Reality - No universal scheduling policy Many models
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10 Optimization Criteria Optimization Criteria CPU Utilization Keep the CPU as busy as is possible May range from 0% to 100% Throughput Number of processes completed per unit time E.g. long processes 1 process / hr Short processes 10 processes / hr
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11 Turnaround Time How long it take to execute a Process Turnaround = Completion_Time Submission_Time Turnaround = Wait_Time GetIntoMemory + Wait_Time ReadyQueue + Wait_Time BlockQueue + CPU_Execution_Time Optimization Criteria Optimization Criteria
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12 Optimization Criteria Optimization Criteria Scheduling Algorithm does not effect the waiting time in Block Queue It only effect the Waiting Time in the Ready Queue Waiting Time Sum of the periods spent waiting in the Ready Queue
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13 Optimization Criteria
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