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

Demand paging, Demand paging gives that pages could only be brought into ...

Demand paging gives that pages could only be brought into memory if the running process acts them. This is usually referred to as lazy evaluation as only those pages operated by

Explain the statements present in assembly language, Explain the Statements...

Explain the Statements Present in Assembly Language An assembly program consists of subsequent three types of statements: a. Imperative statements: this point out an action

What is multiprogramming, Q. What is Multiprogramming? Multiprogrammin...

Q. What is Multiprogramming? Multiprogramming When two or more programs are in memory at the same instance, sharing the processor is referred to multiprogramming opera

Error detection, about error detection in operating system and how does it ...

about error detection in operating system and how does it take place?

Advanced synchronization in operating system, Recall that condition variabl...

Recall that condition variables are synchronization primitives that enable threads to wait until a particular condition occurs. Generalizing, the combination of locks and condit

Explain lru additional reference bits algorithm, Additional Reference bits...

Additional Reference bits algorithm Here we keep an 8-bit byte for every page in memory. At standard intervals the reference bit is shifted by the OS. If a shift register conta

Benefits of virtual memory, Q.  When virtual memory is executed in a comput...

Q.  When virtual memory is executed in a computing system there are convinced costs associated with the technique and certain benefits. List the costs as well as the benefits. Is i

Is it essential to bind a real-time thread to an lwp, Q. Presume an operati...

Q. Presume an operating system maps user-level threads to the kernel using the many-to-many model and the mapping is done through LWPs. Additionally the system allows developers to

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