What type of fragmentation is there in case of paging and why

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Share On Telegram. Share On Reddit. Share On WhatsApp. Stay up to date. In other words, this denotes the case of internal fragmentation in the page frame F1. Again, external fragmentation may occur if some space of the main memory could not be included in a page frame. But this case is very rare as usually the size of a main memory, the size of a page frame as well as the total no.

Because a page has fixed size, but processes may request more or less space. Say a page is 32 units, and a process requests 20 units. Then when a page is given to the requesting process, that page is no longer useable despite having 12 units of free "internal" space.

Because in paging, a process is allowed to be allocated spaces that are non-contiguous in the physical memory. Meanwhile, the logical representation of those blocks will be contiguous in the virtual memory. This is what I mean:. A process requires units of space. This is 4 pages as in the previous example. Unregardless of the actual page numbers formally frame numbers in the physical memory, you give those pages the numbers 0, 1, 2, and 3. This is the virtual representation that is the defining characteristic of paging itself.

Those pages may be 21, , 23, in the actual physical memory. But they can really be anything, contiguous or non-contiguous. Therefore, even if paging leaves small free spaces in between used spaces, those small free spaces can still be used together as if they were one contiguous block of space. That's why external fragmentation won't happen. Frames are allocated as units. If the memory requirements of a process do not happen to coincide with page boundaries, the last frame allocated may not be completely full.

For example, if the page size is 2, bytes, a process of 72, bytes will need 35 pages plus 1, bytes. In the worst case, a process would need 11 pages plus 1 byte.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. How is there internal fragmentation in paging and no external fragmentation? Ask Question. Asked 6 years, 1 month ago. Computer Graphics. Software Engineering. Web Technology. Cyber Security. C Programming. Control System. Data Mining. Data Warehouse. Javatpoint Services JavaTpoint offers too many high quality services. In this article, you will learn about fragmentation and its types.

What is Fragmentation? Causes of Fragmentation User processes are loaded and unloaded from the main memory, and processes are kept in memory blocks in the main memory. Types of Fragmentation There are mainly two types of fragmentation in the operating system.

These are as follows: Internal Fragmentation External Fragmentation Internal Fragmentation When a process is allocated to a memory block, and if the process is smaller than the amount of memory requested, a free space is created in the given memory block.

How to avoid internal fragmentation? External Fragmentation External fragmentation happens when a dynamic memory allocation method allocates some memory but leaves a small amount of memory unusable.

For Example: Let's take the example of external fragmentation. How to remove external fragmentation? Advantages and disadvantages of fragmentation There are various advantages and disadvantages of fragmentation.

Some of them are as follows: Advantages There are various advantages of fragmentation. Some of them are as follows: Fast Data Writes Data write in a system that supports data fragmentation may be faster than reorganizing data storage to enable contiguous data writes. Fewer Failures If there is insufficient sequential space in a system that does not support fragmentation, the write will fail. Storage Optimization A fragmented system might potentially make better use of a storage device by utilizing every available storage block.

Disadvantages There are various disadvantages of fragmentation. Due to this space is left and memory remains unused hence, cause external fragmentation. So to tackle this problem the concept of paging was introduced where we divide the process into small pages and these pages are allocated memory non-contiguously into the RAM. In the non-contiguous memory allocation technique, different parts of the same process are stored in different places of the main memory.

Paging is a non-contiguous memory allocation technique in which secondary memory and the main memory is divided into equal size partitions. The partitions of the secondary memory are called pages while the partitions of the main memory are called frames. They are divided into equal size partitions to have maximum utilization of the main memory and avoid external fragmentation.

Example: We have a process P having process size as 4B, page size as 1B. Also, when this process goes into the main memory for execution then depending upon the availability, it may be stored in non-contiguous fashion in the main memory frame as shown below:. As a CPU always generates a logical address and we need a physical address for accessing the main memory.

This mapping is done by the MMU memory management Unit with the help of the page table. Lets first understand some of the basic terms then we will see how this translation is done.