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?

Describe internal layout of the file system in windows 2000, Describe the i...

Describe the internal layout of the file system in windows 2000. The basic entity in NTFS is a volume and a volume is created by the Windows 2000 disk administrator utility and

#title. operation research, What are the features of Operation Research app...

What are the features of Operation Research approach?

Main advantage of the layered approach to system design, What is the main a...

What is the main advantage of the layered approach to system design? As in all cases of modular design, designing an operating system in a modular way has several benefits. Th

What are race conditions?, What are race conditions? Race conditions ar...

What are race conditions? Race conditions are problems that take place due to the sharing of the same file by several processes. In such a case none of the processes is able to

Explain the architecting for processes, Explain the Architecting For Proces...

Explain the Architecting For Processes Processes are very important to the server application developer, as they may be used to increase responsiveness, deduction time, and tur

Explain memory management using buddy sustem, MEMORY MANAGEMENT USING BUDDY...

MEMORY MANAGEMENT USING BUDDY SUSTEM Here we are dividing the memory as powers of two as well as we are selecting the space which is smallest but large enough to hold a process

Define properties of distributed operating system, Define properties of Dis...

Define properties of Distributed operating system Distributed:- This system distributes computation among several physical processors. The processors do not share memory or a

Explain variable partitioning technique, VARIABLE PARTITIONING We can d...

VARIABLE PARTITIONING We can differ the partitions and change the location according to the size of the process. Here if a 10k process enters we are able to make a space of

What are the various page replacement algorithms, What are the various page...

What are the various page replacement algorithms used for page replacement? FIFO page replacement Optimal page replacement LRU page replacement LRU approximat

Memory management, 4. Describe priority scheduling algorithm. Consider the ...

4. Describe priority scheduling algorithm. Consider the following set of processes. Show the order in which the algorithm will schedule these processes. Assume preemptive and non-p

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