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 a program that is in execution is known as, Define a program in exec...

Define a program in execution is known as A program in execution is known as a process

Explain formal language grammar, Explain Formal Language Grammar A form...

Explain Formal Language Grammar A formal language grammar is a set of formation rules which explain which strings formed from the alphabet of a formal language are syntacticall

Inter-process Communication !, My code it didn''t run properly ,i tried to ...

My code it didn''t run properly ,i tried to pass 2 parameter example : ./a.out ls -ll ,but it execute only the ls instead of the ls -ll ! plz help amd thank you ! #include #inclu

Dual Mode Operation, I am not getting what you have tried to describe here....

I am not getting what you have tried to describe here. Can you elaborate more about this, i will be thankful to you. Vinay

What is external fragmentation?, What is external fragmentation? As pro...

What is external fragmentation? As process are removed from and loaded to the memory free memory space is bracken into pieces .external fragmentation take place when enough mem

What is process control block, What is process control block? Every pro...

What is process control block? Every process is represented in the OS by a process control block. It has many pieces of information associated with an exact process.

Operating system as user interface, Q. Operating System as User Interface? ...

Q. Operating System as User Interface? • Every general purpose computer comprises the operating system, hardware, system programs and application programs. The hardware compris

Memory hierarchy, Difference between cache and associate memory

Difference between cache and associate memory

Can page tables be set up to replicate base registers, Q. We have an OS (o...

Q. We have an OS (operating system) for a machine that uses base and limit registers however we have modified the machine to provide a page table. Can the page tables be set up 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