Typical virtual memory layout, Operating System

Assignment Help:

Using pages makes it easier to manage the whole memory, avoiding excessive fragmentation and waste. As an analogy, think of Tetris, but with only square blocks: it is relatively easy to avoid fragmentation in this case. Both the virtual and the physical memory are divided into pages. As an aside, we often refer to physical memory pages as frames. Every virtual page consists of a range of virtual addresses. Virtual pages are then mapped to physical pages in the physical memory. When an application needs to access a virtual page, the corresponding virtual address is translated into a "real" physical address, and then the actual data might be read and/or written. As a consequence, note that although arrays are contiguous in virtual memory, they may be non-contiguous in physical memory. Note also that some virtual pages do not map to any actual physical memory address, because not all virtual pages are necessarily being used at any given time. The unused virtual pages are called invalid. If a program ever tries to access an invalid page, it pagefaults.

A typical virtual memory layout includes a stack, a mmap region, a heap, and the code of the program (the "text" section). Since mmap and heap grow towards each other, in the worst case they could smash into each other. The same could happen with the stack: if a program recurses for a large number of times, the stack could grow over the mmap region ("stack over?ow") and in this case something bad and usually unpredictable will happen.


Related Discussions:- Typical virtual memory layout

Thread safety, What does it mean for something to be thread-safe? By saying...

What does it mean for something to be thread-safe? By saying that X is thread-safe, we mean that if multiple threads use X at the same time, we don't have to worry about concurrenc

Split the hexadecimal format, The following is a dump of a TCP header in h...

The following is a dump of a TCP header in hexadecimal format: 00CD0018 00000EF1 00000D5D 502200D1 01BF0010 We need to first split the above hex as such 00 CD 00 18 00 00

What is the benefits os co-operating process, What is the benefits OS co-op...

What is the benefits OS co-operating process? Information sharing. Computation speeds up. Modularity. Convenience.

Explain tightly coupled systems and loosely coupled system, Differentiate t...

Differentiate tightly coupled systems and loosely coupled systems? Loosely coupled systems:-  Every processor has its own local memory  Every processor can communicate

Explain the sequence of messages in rpc mechanism, Q. Once more considering...

Q. Once more considering the RPC mechanism consider the exactly once semantic. Does the algorithm for implementing this semantic implement correctly even if the ACK message back to

What is demand paging, What is Demand paging? Virtual memory is commonl...

What is Demand paging? Virtual memory is commonly executed by demand paging. In demand paging, the pager brings only those essential pages into memory instead of swapping in a

Cache replacement policies, The physical memory acts as a cache backed by t...

The physical memory acts as a cache backed by the disk. When the physical memory is full, and we want to read in another page from disk, we have to evict a page from physical memor

What are the two types of fragmentations, Questiion 1 Use Priority Sche...

Questiion 1 Use Priority Scheduling Algorithm to schedule the following processes        Process                 Burst Time             Priority/Time            P1

What is degree of multiprogramming?, What is degree of multiprogramming ? ...

What is degree of multiprogramming ? Degree of multiprogramming signifies the number of processes in memory. If the degree of Multiprogramming is steady after that the average

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