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?

How is it different from the unbounded buffer algori, How is it different f...

How is it different from the unbounded buffer algorithm ? Explain.

Case studies, Did Abhinav agree to the initial timeline requested by Rebecc...

Did Abhinav agree to the initial timeline requested by Rebecca

Research proposal, what topic i choose for os research proposal

what topic i choose for os research proposal

Define the os/2 threads code, Define the OS/2 threads code The sample p...

Define the OS/2 threads code The sample program in Listing is very similar to the NetWare example. OS/2 commands are substituted for the pseudocode commands controlling thread

Define properties of time sharing operating system, Define properties of Ti...

Define properties of Time sharing operating system Time sharing:- T his systems uses CPU scheduling and multiprogramming to provide economical interactive use of a system. The

Demand paging, Demand paging With demand paging, a page is called into...

Demand paging With demand paging, a page is called into memory only when a location on that page is actually indexed during run time. With pre-paging, pages other than the one

Define paging , Paging: Only the needed memory pages are moved to main me...

Paging: Only the needed memory pages are moved to main memory from the swap machine for execution. Process size does not matter. Produce the concept of the virtual memory. It

BC0056, Write a C program that illustrates the creation of child process us...

Write a C program that illustrates the creation of child process using fork system call. One process finds sum of even series and other process finds sum of odd series.

Explai basic concepts of demand paging, Basic concepts When a process i...

Basic concepts When a process is to be changed in, the pager guesses which pages will be used before the process is changed out again. Instead of swapping in a entire process,

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