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Difference between Virtual Memory and Job Pool
Introduction
Virtual memory − Virtual memory is a mechanism used to manage memory using hardware and software. It is a part of the secondary storage that gives the user an illusion that it is a part of main memory. It helps in running multiple applications with low main memory and increases the degree of multiprogramming in systems.
Job pool −Job pool is a type of data structure in a batch processing system where various jobs are queued to be implemented when all the resources are made available. When a job is executed, it is fully present in memory. Job pools are used to store processes in a hard disk for some time and then later load them into the main memory.
Difference between virtual memory and job pool
S.No |
Virtual memory |
Job pool |
|---|---|---|
1. |
Virtual memory is a management technique that gives users an illusion of a large memory storage. |
Job pool is a program of the operating system that is located in the operating system and stores newly created processes while they are waiting for their respective resources |
2. |
It represents the addresses generated by the CPU virtually. |
Job pool represents the pool from which the long term scheduler chooses which job will be executed first. |
3. |
While loading processes from the hard disk to the main memory, virtual memory is not required if there is no need for infinite memory. |
While loading processes from the hard disk to the main memory, a job pool is always required to store a newly created process. |
4. |
A part of the process needs to be in memory for execution. |
A newly created process is stored here, waiting for the required resources. |
5. |
The concept behind virtual memory is that it creates an illusion that we are working with very large memory when actually we are using only a part of the memory. |
The concept of the job pool states that a newly created process is stored in a pool called a job pool where these processes wait for the resources to get allocated in order to get executed. |
Virtual memory advantages
In virtual memory automatic data movement is possible.
Greater speed of executing a portion of a programme whenever required.
It has greater capacity for addresses as does the main memory.
Eliminates the need to manage shared memory by the applications and when RAM space is full users are spared from installing memory modules.
Limitations of using virtual memory
Applications run slower if they are running from virtual memory.
Data must be mapped between virtual and physical memory, which requires extra hardware support for address translations, slowing down a computer further.
It lessens the amount of available hard drive space.
Thrashing can occur if there is not enough RAM, which will make the computer perform slower.
Advantages of job pool
When a job is successfully run, the operating system releases its memory.
When a process is finished, the next job from the job pool is run without any user interaction.
Processing takes place in order in which they are received, i.e., first come,first serve, or according to the priority.
Conclusion
Virtual memory is a memory management technique that gives the users an illusion of infinite memory.
Job pool is a program of the operating system that is located in the operating system and stores newly created processes while they are waiting for their resources.
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