Skip to main content

Thrashing In Operating System

 Thrashing is a condition or a situation when the system is spending a major period of time on servicing the page faults, but the actaul processing done is very negligible.
   "A process is said to be thrashing if it is spending more tim in servicing page fault than executing."

The basic concept involved is that if a process is allocated too few frames, then there will be too many and too few frequent page faults. As a result, no useful work would be done by the CPU and CPU utilization would fall drastically. The long term schedular would then try to improve the CPU utilization by loading some more processes into the memory thereby increasing degree of multiprogramming.

This would further decrease in the CPU utilization trigerring a chain reaction of higher page faults followed by an increase in the degree of multiprogramming called thrashing.
In the above diagram, initially degree of multiprogramming upto some extent of point ( sau lamda), the CPU utilization is very high and the system resource are utilized 100%. But if we further increase the degree of multiprogramming CPU utilization will drastically fall down and the system will spent more time only in the page replacement and time taken to complete execution of process will increase. This is the situation in system is called thrashing.

CAUSE OF THRASHING :-
1. High degree of multiprogramming :-
     It the number of processes keeps on increasing in the memory then number of frames alloted to each process will be decreased. So, less number frames will be available to each process. Due to this, page fault will occur more frequently and more CPU time will be wasted in just swapping in ans out of pages and the utilization will keep on decreasing.

2. Lack of frames :-
    If a process has less number of frames then less pages of that process willbe able to reside in memory and hence more frequent swapping in and out will be required. Hence sufficient amount of frames must be allocated to each process in order to prevent thrashing.

RECOVERY FROM THRASHING :-
  Do not allow system to go int thrashing by instructing long term schedular not to bring the processes into memory after the threshold.

If the system is already in thrashing then instruct the mid term schedular to suspend some of the processes so that we can recover the system from thrashing.


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 share system resources  to achieve  multiprogramming .  There are  mainy three types of pro
8 comments
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 keywords must be written in lower case.It is 32 in number. ii> Identifiers:-         The identifiers are basically a token. It can be a variable's name or a label's name. So identifiers are actually a user defined data. But there are certain rules to frame an identifier. They are as follo
3 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 types:-  i> System  Process. ii> User Process. Early computers allowed only one program be ex
Post a Comment
Read more