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?

What is the purpose of the virtual memory in windows xp, Question: a) T...

Question: a) The following refers to optimization under Windows XP: i) Give five steps which could undertake to enhance overall system performance in a default Windows XP in

Describe demand-paged environment, Q. Which of the subsequent programming ...

Q. Which of the subsequent programming techniques and structures are good for a demand-paged environment? Which aren't good? Describe your answers. a. Stack b. Hashed symbol

Define buffering, Define buffering. A buffer is a memory area that keep...

Define buffering. A buffer is a memory area that keeps data whereas they are transferred among two devices or among a device and an application. Buffering is done for three rea

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

Define the properties of batch operating systems, Define the properties ope...

Define the properties operating systems: Batch :- Jobs with similar needs are batched together and  run through the computer as a group by an operator or automatic job sequenc

Explain the resource ownership by platform, Explain the Resource Ownership ...

Explain the Resource Ownership by Platform Ownership of data items may further be complicated by concepts defined in certain operating systems. Each operating system defines "p

Define multithreading, Define multithreading The proficiency of an oper...

Define multithreading The proficiency of an operating system to execute different parts of a program called threads simultaneously is called as multithreading. A thread is a fl

Explain linked allocation, Linked allocation With linked allocation, ev...

Linked allocation With linked allocation, every file is a linked list of disk blocks; the disk blocks might be scattered anywhere on the disk. The directory has a pointer to th

What is low-level formatting, What is low-level formatting? Before a di...

What is low-level formatting? Before a disk can kept data, it must be required into sectors that the disk controller can read and write. This procedure is called low-level form

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