a policy used to ensure that jobs that have been in the system for a long time in the lower-level queues will eventually complete their execution.
Aging
the acts of saving a job’s processing information in its PCB so the job can be swapped out of memory and of loading the processing information from the PCB of another job into the appropriate registers so the CPU can process it.
Context switching occurs in all preemptive policies.
context switching
a job that will perform a great deal of nonstop processing before issuing an interrupt.
CPU-bound
a nonpreemptive process scheduling policy (or algorithm) that handles jobs according to their arrival time.
first-come, first-served (FCFS)
a synonym for the Job Scheduler
high-level scheduler
a job that requires a large number of input/output operations, resulting in too much free time for the CPU.
I/O-bound
signifies that a job’s execution is delayed indefinitely because it is repeatedly preempted so other jobs can be processed
indefinite postponement
a hardware signal that suspends execution of a program and activates the execution of a special program known as the interrupt handler.
interrupt
the program that controls what action should be taken by the operating system when a sequence of events is interrupted.
interrupt handler
the high-level scheduler of the Processor Manager that selects jobs from a queue of incoming jobs based on each job’s characteristics.
Job Scheduler
the condition of a job as it moves through the system from the beginning to the end of its execution.
Job status
a synonym for the Process Scheduler
low-level scheduler
a scheduler used by the Processor Manager when the system to remove active processes from memory becomes overloaded. The middle-level scheduler swaps these processes back into memory when the system overload has cleared.
middle-level scheduler
a process scheduling scheme (used with other scheduling algorithms) that groups jobs according to a common characteristic.
multiple-level queues
a technique that allows a single processor to process several programs residing simultaneously in main memory and interleaving their execution by overlapping I/O requests with CPU requests.
Multiprogramming
a common term used to identify an I/O request from a program in a multiprogramming environment that would cause a process to wait “naturally” before resuming execution.
Natural wait
a job scheduling strategy that functions without external interrupts so that once a job captures the processor and begins execution, it remains in the running state uninterrupted until it issues an I/O request or it’s finished
nonpreemptive scheduling policy
any process scheduling strategy that, based on predetermined policies, interrupts the processing of a job and transfers the CPU to another job. It is widely used in time-sharing environments
preemptive scheduling policy
a nonpreemptive process scheduling policy (or algorithm) that allows for the execution of high-priority jobs before low-priority jobs.
Priority scheduling
an instance of execution of a program that is identifiable and controllable by the operating system.
Process
a data structure that contains information about the current status and characteristics of a process.
Process Control Block (PCB)
the low-level scheduler of the Processor Manager that establishes the order in which processes in the READY queue will be served by the CPU.
Process Scheduler
an algorithm used by the Job Scheduler to allocate the CPU and move jobs through the system.
process scheduling algorithm
any policy used by the Processor Manager to select the order in which incoming jobs will be executed.
process scheduling policy
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Chapter 1103
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Chapter 25
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Review Questions13
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Chapter 361
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Chapter 441
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Key Terms79
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Chapter 527
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Chapter 5 key terms19
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Chapter 3 Key Terms32
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Chapter 4 Key Terms37
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Chapter 2 Key Terms18
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Chapter 1 Key Terms32
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Chapter 645
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Chapter 6 Key Terms25
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Chapter 756
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Chapter 7 Key Terms42
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Chapter 8 Key Terms33
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Chapter 847
