Notice that in this method job to job transition was

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Unformatted text preview: me is usually not a suitable measure for interactive systems, because in an interactive system a process can produce some output fairly early during its execution and can continue executing while previous results are being output to the user. Thus another measure used in case of interactive systems is response time, which is the interval from the time of submission of a job to the system for processing to the time the first response for the job is produced by the system. In any computer system, it is desirable to maximize throughput and to minimize turnaround time and response time. PROCESS MANAGEMENT A process (also called job) is a program in execution. The main objective of the process management module of an operating system is to manage the processes submitted to the system in such a manner so as to minimize the idle time of the various processors (CPU, I/O processors, etc.) of the computer system. In this section, we will learn about some of the mechanisms commonly used in modern operating systems to achieve this objective. We will also see how these mechanisms have gradually evolved from the early days of computers. Process Management in Early Systems In early computer systems, a job was typically executed in the following manner: 1. A programmer would first write the program on paper. 2. It was then punched on cards or paper tape along with its data. 3. The deck.of cards or the paper tape containing the program and data was then submitted at tin reception counter of the computer centre. 4. An operator would then take the card deck or paper tape and manually load it into the system from card reader or paper tape reader. The operator was also responsible for loading any other software resource (such as a language compiler) or setting hardware devices required for the execution of the job. Before loading of the job, the operator had to use the front panel switches of the compute system to clear the main memory to remove any data remaining from the previous job. 5. The operator would then set the appropriate switches in the front panel to run the job. 6....
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