CrazyEngineers Archive
Old, but evergreen and popular discussions on CrazyEngineers, presented to you in read-only mode.
@Sahithi Pallavi • 16 Nov, 2009
Today my sir asked this question in the class..! No one gave the correct answer for this question..!

What is the need to use Virtual Memory ?

Why dont we take the data directly from the physical Memory?

Why We need this extra work of using logical addresses for Virtual Memory ?

Can anyone give me the clear answer..!

Sorry guys if its a simple question?
@Mahesh Dahale • 16 Nov, 2009 Windows XP Professional uses a process called demand paging to exchange data between random access memory (RAM) and paging files on the hard disk. When you install Windows XP Professional, Setup creates a virtual-memory paging file, PAGEFILE.SYS, on the partition in which you installed
Windows XP Professional. The default or recommended paging file size for Windows XP Professional is equal to 1.5 times the total amount of RAM. For best results, never set the value of the paging file size to less than the recommended amount. Typically, you can leave the size of the paging file set to the default value and let Windows XP Professional manage the file size. In some circumstances, such as when you run a large number of applications simultaneously, you might find it advantageous to use a larger paging file or multiple paging files.

by this you will get an idea
@Sahithi Pallavi • 16 Nov, 2009 Thanks for your information mahesh...!
@faizaan • 17 Nov, 2009 virtual memory is one of the most important concept which must be properly understood in order to know how actually operating system allows those large programs (programs larger than size of main memory) to run without any problem.

As you know that program is divided into number of pages of some fixed size .In olden days to run a program all pages of that program need to be present in main memory but as time passed and multi programming came into picture & program sizes increased drastically so it was not possible to keep all pages of all programs in main memory but yes each program can have all its pages on secondary storage (disk).So virtual memory allows us to keep only those pages currently needed by our program & keep all other pages on secondary storage so when ever there is need of page it can be brought from disk.

Thus we can say that virtual memory allows to keep copy of whole address space of process in secondary storage.

We need to do extra work of using logical address & mapping from pages in disk to pages in main memory in order to run program that is much larger than our actual physical main memory.

Please correct me if i am wrong as i am also student studying o.s in current semister.
@Sahithi Pallavi • 18 Nov, 2009 Thank you fiazaan...!
4.5k views

Related Posts

@Ankita Katdare · Jun 14, 2012

Here is a list of project ideas for projects of Electronics & Communication (Telecommunication) Engineers. Students belonging to third year or final year can use these projects as mini-projects as...
20.3k views

@Ankita Katdare · Jul 22, 2014

Micromax has launched a brand new 32 inch LED TV in India as an addition to its portfolio which has two more LED TVs to offer. The Micromax 32T42ECHD is...
8.9k views

@Morningdot Hablu · Nov 16, 2010

hello friend's, I think during exam time we all need the collection of the questions that cover all the topics of the programming language. Not only during exam time it...
4k views

@Manish Goyal · Nov 21, 2009

Today there was my internal viva of dbms in which i was asked 3 questions that i would like to share with you 1 what is partial key? 2 what...
7.1k views

@Sarathkumar Chandrasekaran · Apr 18, 2014

We know that ABS- Anti lock braking system has been a good safety system which helps to stop the locking of wheel during braking which predominantly takes place in cold...
20k views