Explain external fragmentation?, Operating System

Assignment Help:

Explain external fragmentation?

External fragmentation is the process where the free space and the space still available for use, in a piece of storage become separated into many small pieces. It is caused over time by de-allocating ("freeing") and allocating pieces of the storage space of many different sizes. The result is that, although one may perhaps have plenty of free space, it mayn't be able to all used, or at least used as effectively as one would like to.

For instance in a dynamic memory allocation a block of 1000 bytes might be requested but the largest contiguous block of free space or memory hole has only 300. Still if there are ten blocks of 300 bytes of free space separated by allocated regions one still cannot allocate the requested block of 1000 bytes.

External fragmentation also takes place in file systems as many files of different sizes are change size, created, and are deleted. The effect is even worse if a file which is separated into many small pieces is deleted, for the reason that this leaves similarly small regions of free space.

External fragmentation is able to be eliminated through a process called compaction, where existing objects are all moved in to one large adjacent block, keep left all of the remaining free space in one large block. Moving garbage collectors use compaction to enhance dynamic memory allocation performance and tools that defragment disk drives as well perform a compaction step. It is frequently possible to do a partial but still useful form of compaction more efficiently or to continually compact in an incremental fashion therefore that external fragmentation is always kept low.

 


Related Discussions:- Explain external fragmentation?

Explain chaining to handle collision, Explain Chaining to Handle Collision ...

Explain Chaining to Handle Collision Chaining:  One easy scheme is to chain all collisions in lists attached to the suitable slot. This permits an unlimited number of collision

Linux, Discuss the risks of having a single root user

Discuss the risks of having a single root user

Locks - mutexes, Locks (also known as mutexes, short for mutual exclusion l...

Locks (also known as mutexes, short for mutual exclusion locks) provide mutual exclusion to shared data inside a critical session. They are implemented by means of two atomic routi

Write a short note on pcb, Write a short note on PCB? Every process is ...

Write a short note on PCB? Every process is represented in the operating system by a process control block also called a task control block. It contains more information regard

Activities of operating system - memory management, Q. What are the three m...

Q. What are the three main activities of an operating system in regard to memory management? Answer: a. Keep follows of which parts of memory are currently being used and

How is memory management done using linked lists?, How is memory management...

How is memory management done using linked lists?   Each one node of the l list will have 4 fields as follows 1-this tells whether it s a hole or a process 2-starting ad

Correct the code for visitor and vehicle portion, Gopher Gallery consists o...

Gopher Gallery consists of a shopping mall and a cart ride that covers the 150 acre habitat. There are m visitors and n single-person vehicles. Visitors stroll around the mall at t

Explain gui based operating system, GUI - Short for Graphical User Interfa...

GUI - Short for Graphical User Interface a GUI Operating System contains icons and graphics and is commonly navigated by using a computer mouse. Below are some instances of GUI Op

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd