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 ageing, Define Ageing Ageing is a method of enhancing the priori...

Define Ageing Ageing is a method of enhancing the priority of process waiting in Queue for CPU allocation

Explain rehashing to handle collision, Explain Rehashing to Handle Collisio...

Explain Rehashing to Handle Collision Rehashing:  Re-hashing schemes make use of a second hashing operation while there is a collision. If there is an additional collision, we

Software for business management integrated into network, Software for busi...

Software for business management integrated into a social network Project Description: We are seeking top professionals to build software with us that manages the business.

How is process management done in multiprocessing systems, How is process m...

How is process management done in multiprocessing systems ? There are two accost for the process management in multiprocessor systems. Master-slave configuration Sy

Least-recently used, LRU evicts the page which was last accessed the farthe...

LRU evicts the page which was last accessed the farthest into the past of any page resident in physical memory, i.e. the least-recently used page. LRU approximates OPT when the rec

Sector sparing, What is sector sparing is proper definition

What is sector sparing is proper definition

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

Define the throughput of a system, Define the “Throughput” of a system  ...

Define the “Throughput” of a system  Throughput is Number of programs processed by it per unit time

Linux os, Introduction of linux

Introduction of linux

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