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 partitions and mounting, Partitions and mounting A disk can be ...

Partitions and mounting A disk can be sliced into many partitions, or a partition can span multiple disks. Every partition can be either "raw", having no file system, or "cooke

What are the issues in designing a network-fault tolerance, Fault tolerance...

Fault tolerance : Machine failures, Communication faults, storage device crashes, and decays of storage media must be tolerated by the system to some extent. A fault tolerant sy

Explain about time sharing systems, Q. Explain about Time Sharing Systems? ...

Q. Explain about Time Sharing Systems? Time Sharing Systems Multi-programmed batched systems provide an environment where various system resources (for illustration CP

Bounded and unbounded buffer, Ask question #Minimum 100 difference between ...

Ask question #Minimum 100 difference between bounded and unbounded buffer words accepted#

Lexical substitution during macro expansion, Lexical substitution during ma...

Lexical substitution during macro expansion Lexical substitution is employed to produce an assembly statement from a model statement. A model statement contains 3 types of stri

Describe internal layout of the file system in windows 2000, Describe the i...

Describe the internal layout of the file system in windows 2000. The basic entity in NTFS is a volume and a volume is created by the Windows 2000 disk administrator utility and

Malloc, I need help implementing malloc

I need help implementing malloc

Can we call trap as an interrupt??, is there any difference between the tra...

is there any difference between the trap and interrupt??

Explain the concept of process, Q. Explain the Concept of Process? A pr...

Q. Explain the Concept of Process? A process is sequential program in execution. A process states the basic unit of computation for the computer. Components of process are:

Write an equation for this seek time, Q. The accelerating search for descr...

Q. The accelerating search for described in subsequent exercise is typical of hard-disk drives. By contrast floppy disks and several hard disks manufactured before the mid-1980s t

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