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Posted By Admin @ Mar 04, 2022

Tittle: What kinds of problems paging was designed to solve

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The main problem which is solved by making use of the paging is the elimination of the need for the contiguous allocation of the physical memory. It be said that the use of this memory management scheme provides a process with the non-contiguous physical address space. Paging helps to divide the memory into pages of the fixed sizes. In order to make possible the faster access of data, paging was designed. The phenomenon that lies behind is about the provision of the pages from the main memory which are already copied by the OS from the storage device to the main memory. For a process, paging makes its physical address space to be non-contiguous. In this way, the physical memory is better allocated to the processes. The problem of external fragmentation is also dealt by the paging.

Describe the problems created by paging itself

For the paging system, the major problems which are created by paging include as given:

• There is an immense need that the virtual address to physical address mapping required to be fast.

• For the large virtual address space and size, there is a need for the large page table.

Just one memory reference is required in order to fetch an instruction. It is the case when the paging is absent. For the paging phenomenon there is the need for just one memory reference in order to have the access to the page table. The execution speed is entirely dependent on the concept and the rate of getting the instructions as well as the data by the CP. In case, per instruction two memory references are required, it ultimately reduces the performance to half. Mostly the programs have the access to the limited number of pages (Vetter, Cruickshank, (Victor), & Armin Röll, 2019).

Explain why the disadvantages of paging do not outweigh the benefits

For a process, paging makes its physical address space to be non-contiguous. The advantages which are provided by the paging are more than its disadvantages. This is the main reason that the disadvantages of paging do not outweigh the benefits. The benefits which are provide the paging includes as given:

• It provides with the easy as well as cheap allocation of the memory.

• It makes a free page to be extracted out from the memory by the operating system.

• The concept of external fragmentation is better dealt by the paging. It is basically eliminated by the paging.

• It makes possible the scattering of the page frames all over the PM.

• The mapping of the pages is possible through the paging.

• Pre-paging as well as the demand paging is possible through the paging.

• Swapping becomes more efficient.

• There is no need for taking into consideration the fragmentation.

As far as the disadvantages for paging are concerned, these are as given:

• Guarded page tables

• Inversion of the page tables

• Requirements for the memory. It includes the requirement for one entry for each VM page.

• The improvements are possible by making use of TLB.

• The time required to access the memory is longer. It can be said that the longer times are required for page table look up.

• The virtual memory size is limited by using PTLR (Page Table Length Register).

• Internal fragmentation

• Provision of the facility to use variable page sizes as well as the multilevel page tables.

The advantages and the disadvantages of paging reveal that the benefits associated with paging make it more significant than its disadvantages (McHoes & Flynn, 2017).

References of Hardware and Operating System

McHoes, A., & Flynn, I. M. (2017). Understanding Operating Systems. Cengage Learning.

Vetter, S., Cruickshank, J., (Victor), Y. L., & Armin Röll, I. R. (2019). IBM Power System E980: Technical Overview and Introduction. IBM Redbooks.