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?

Application of consumer behaviour, Q. Explain application of consumer behav...

Q. Explain application of consumer behaviour? Consumer behaviour is described as the dynamic interaction of affect and cognition and behaviour and the environment by human bein

Explain drawbacks of fixed partitioning, The drawbacks of fixed partitionin...

The drawbacks of fixed partitioning are: The number of partitions are précised at system generation time limits the number of active processes in the system. For the re

Explain hierarchical paging method, Hierarchical paging method Most mo...

Hierarchical paging method Most modern computer systems maintain a large logical-address space. In this situation the page table itself turns into excessively large. To remedy

Conservative garbage collection, Conservative GC can be used for languages ...

Conservative GC can be used for languages such as C and C++, which were not explicitly designed for garbage collection. This is a non-copying technique. A conservative garbage coll

Lru implementation details, Now, let us discuss two related algorithms for ...

Now, let us discuss two related algorithms for deciding which pages to evict. The clock algorithm is one of the most popular choices. It works by keeping frames in a circular struc

Explain the thread local storage (tls), Explain the Thread Local Storage (T...

Explain the Thread Local Storage (TLS)    Windows NT provides unique functions for per-thread data management. Thread local storage (TLS) is a concept defined in NT so develope

Operating System, my Operating System is windows trust but when the windows...

my Operating System is windows trust but when the windows start say its windows xp. help pleaes

Explain external fragmentation?, Explain external fragmentation? Extern...

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 ma

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