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 about deadlock prevention, Explain about deadlock prevention? I...

Explain about deadlock prevention? In order for the occurrence of deadlock, the four conditions like mutual exclusion, hold and wait, no pre-emption and  circular wait must hap

Write a note on multithreading, Write a note on multithreading. Multith...

Write a note on multithreading. Multithreading is the capability of an operating system to execute different parts of a program called as threads, at the same time. The program

Page fault handling , Page Fault Handling conditions like, where the copy...

Page Fault Handling conditions like, where the copy on write bit of a page is set and that page is send by more than one process, the Kernel assign new page and copies the conten

How is process management done in multiprocessing systems, How is process m...

How is process management done in multiprocessing systems ? There are two accost for the process management in multiprocessor systems. Master-slave configuration Sy

Requirements to satisfied by the critical section problem, What are the req...

What are the requirements to be satisfied by the critical section problem? Following are the necessities to be satisfied by the critical section problem: a)      Mutual exc

Write about critical regions and monitors, Write about critical regions and...

Write about critical regions and monitors. Critical region definition Monitor definition Implementation of the conditional-region construct Syntax of monitor Monito

Define criterion for classification of data structures, Define what can be ...

Define what can be used as a criterion for classification of data structures utilized in language processing              Answer: nature of a data structure, lifetime of a dat

DOS, Ask question #Minimum 500 words accepted#

Ask question #Minimum 500 words accepted#

What is banker''s algorithm, What is banker's algorithm? Banker's algor...

What is banker's algorithm? Banker's algorithm is a deadlock avoidance algorithm that is applicable to a resource-allocation system with multiple examples of each resource type

Why is it complicated to protect a system, Q. Why is it complicated to prot...

Q. Why is it complicated to protect a system in which users are allowed to do their own I/O? Answer: In earlier chapters we identified a distinction among kernel and user mod

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