Skip to main content

Allocation Of Frames In Operating System

 In this post we will cover the topic :- allocation of frame. As we know an important aspects of operating system is virtual memory, which is implemented by using demand paging technique. Demand paging necessitates the development of a page replacement algorithm and a frame allocation algorithm.

Frame allocation algorithms are used if you have multiple processes. It helps to decide how many frames are allocated to each process. Consider a single user system with 128 KB of memory composed of 1 KB in size. This system has 128 frames. The operating system may take 35 KB leaving 93 frames for the user processes. 

Under pure demand paging all 93 frames would initially be put on free frame list. When a user process started execution, it would generate a sequence of page faults. The first 93 page faults would all get free frames from the free frame list. When the free frame list exhausts, a page replacement algorithm would be used to select one of the 93 in memory pages to be replaced with 94th and so on. When the process is terminated, the 93 frames would once again be placed in free frame list.

There are various constraints to the stratigies for the allocation of frames :-
  One can not allocate more than the total number of available frames.
  At least a minimum number of frames should be allocated to each process. 

This constraints are supported by two reasons :-
 1. As less number of frames are allocated, there is an incresase in the page fault ratio, decreasing the performance of execution of the process.

 2. There should be enough frames to hold all the different pages that any single instruction can reference. 

Share, Follow and please comment if you find anything incorrect or to share more information about the topic discussed above.
 
Labels:

Comments

Post a Comment

Please comment.

Popular posts from this blog

Process Scheduling And Types of Process Schedular :-

        ⇰ PROCESS SCHEDULING Process Scheduling  is a task  of Operating System that schedules processes of different states like new, ready, waiting, terminated  and running.This scheduling helps in allocation of CPU time for each process, and Operating System allocates the CPU time for each procss. And the process scheduling plays important role to keep the CPU busy all the time.  ⏩   Followings are some objectives of Process Scheduling :-  i > To increase the amount of users within acceptable response times.  ii > To maintain the balance between response and utilization of system. iii > To decrease the enforce priorities and  give reference to the processes holding the key resources.      ⇰  PROCESS SCHEDULAR A scheduler carries out the pro cess scheduling work. Schedulers are often implemented so they keep all computer resources busy and  allows multiple users to shar...
8 comments
Read more

Process & Its state And process control block :-

                ⇰  PROCESS :- A process can be thought of as a program in execution. Means when any program is executed it becomes process. A processwill need certain resources such as CPU time , memory, files and I/O devices to complete its task. These resources are allocated to the process either when it is created or at the time of execution.             A process is the unit of work in most systems. A system consistes of a collection of processes. All these processes may execute concurrently. Traditionally a process contained only a single thread. Most modern operating ststems now supports processes that have multiple threads.         The operating system is responsible for several important works of process management as - the creation and deletion of process, the schrduling of process, communication and deadlock handling of process. Process is broudly divided into two ...
Post a Comment
Read more

Tokens and its types in 'C'

   Tokens are the smallest individual unit of a program or in simple words it is a main part of C program.Tokens are the building blocks of any program. The smallest individual and basic unit of a C programming is called c tokens.      *    Normally there are six types of tokens in C:- i> Keywords:-          Keywords are special words that are used to give a special meaning to the program and can't be used as variable and constant.They are basically a sequence of characters that have fixed to mean. For example:-                 auto     double      long     break                 float    short        char     if                while    continue   int       void etc. All...
3 comments
Read more