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?

Define the term system software, Question: (a) Define the term system ...

Question: (a) Define the term system software and application software, giving an example for each. (b) Draw a diagram to represent the abstract view of a computer system i

Why interrupt can be used, Why interrupt can be used? The majority of t...

Why interrupt can be used? The majority of the different parts of the PC need to send information to and from the processor and they expect to be able to get the processor's at

Explain deadlock prevention, Deadlock Prevention Prevention is the name...

Deadlock Prevention Prevention is the name given to method that guarantee that deadlocks can never happen for the reason that the way the system is structured. Since 4 conditio

Explain demand paging in virtual memory system, Question 1 Explain with di...

Question 1 Explain with diagram all possible states a process visits during the course of its execution Question 2 Discuss Inter-process Communication. What is critical-secti

Show the services which provided by operating system, Q. Show the services ...

Q. Show the services which provided by operating system? A) Resource Allocation: If there are more than one user or jobs running at the same instance then resource

Synchronization, As we already know, threadsmust ensure consistency; otherw...

As we already know, threadsmust ensure consistency; otherwise, race conditions (non-deterministic results) might happen. Now consider the "too much milk problem": two people share

What do you mean by reference counts, Q. If each the access rights to an o...

Q. If each the access rights to an object are deleted the object can no longer be accessed. At this stage the object should also be deleted and the space it occupies should be ret

What is multiprogramming, What is Multiprogramming? Multiprogramming is...

What is Multiprogramming? Multiprogramming is the capability of am operating system to support multiple applications running concurrently. Multiprogramming simply means that an

Bag of tasks, The producer-consumermodel above has a standard human analogy...

The producer-consumermodel above has a standard human analogy of an assembly line. Humans have specialized skills, however, whereas threads running the same program do not need to

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