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?

Determine the scheduling technique, The scheduling technique in which CPU i...

The scheduling technique in which CPU is allocated to the process with least CPU-burst time is known as  Shortest job first Scheduling is a scheduling technique in which CPU i

Which algorithm makes the most efficient use of memory, Question : (a) ...

Question : (a) The dynamic allocation problem is how to satisfy a request of size n from a list of free holes into memory. The best-fit, first-fit and worst-fit strategies are

Typical virtual memory layout, Using pages makes it easier to manage the wh...

Using pages makes it easier to manage the whole memory, avoiding excessive fragmentation and waste. As an analogy, think of Tetris, but with only square blocks: it is relatively ea

Microsoft, Discuss the high barriers to entry in the market for PL operatin...

Discuss the high barriers to entry in the market for PL operating systems

Multiprogramming, how response times are reduced by allowing time sharing o...

how response times are reduced by allowing time sharing on top of multiprogramming

Catalogue the design goals of windows xp, Q. Catalogue the design goals of ...

Q. Catalogue the design goals of Windows XP. Answer: Design goals comprise security and reliability and Windows and POSIX application compatibility with high performance and ex

Operation managmant, what is the function of operation management?

what is the function of operation management?

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

Multiprogramming, ? FREE ASSOCIATION ASSIGNMENTS of multiprograming

? FREE ASSOCIATION ASSIGNMENTS of multiprograming

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