Skip to main content

Preemptive and non preemptive in operating system-computer world

 Preemptive and non preemptive 

Preemptive 

In preemptive Scheduling algorithm, the the running process is interested by the higher priority process. When a currently running  process finish execution, the priority of the ready state process is checked against that of the running process. If the priority of the ready process is higher, it is allocated to the CPU.

  1. A Scheduling discipline is primitive, if the CPU is taken away from the process after being allocated. 
  2. Cost of the preemptive scheduling is higher then non preemptive scheduling.
  3. Higher priority jobs are processed before the lower priority jobs. 

Non preemptive

In non preemptive Scheduling, the CPU has been allocated to a process, the process keeps the CPU until it release the CPU either by switching to the waiting state. This scheduling method is used by Microsoft Windows 3.x, window 95 introduced preemptive scheduling.

  1. A scheduling discipline is non preemptive, if the process has been given the CPU, the CPU cannot taken away from that process.
  2. It is not costly as compared to preemptive scheduling.
  3. Short jobs are made to wait by longer jobs. 

CPU scheduling decisions may take place under the following circumstances 

  1. When a process switches from the running state to the waiting state. 
  2. When a process switch from the running state to the ready state. 
  3. When a process which from the waiting state to the ready estate. 
  4. When a process terminates.  
  5. When scheduling takes place only under circumstance 1 and 4, we can say that the scheduling scheme is non preemptive or Co-operative, otherwise it is preemptive. 

Comments

Post a Comment

Popular posts from this blog

Single partition allocation, Multiple-partition allocation and Fixed Equal-size partitions in operating system-computer world

  Single partition allocation, Multiple-partition allocation and Fixed Equal-size partitions in operating system Single partition allocation In this scheme operating system is residing in law memory and user process are executing in higher memory. Advantages It is simple  It is easy to understand and use Disadvantages User job is limited to the size of available memory. It leads to poor Utilization of processor and memory. Multiple-partition allocation  It is the simplest method for allocating  memory is divided memory into several fixed size partitions. Fixed Equal-size partitions It divides the main memory Into equal number of fixed sized partitions, operating system occupies some fixed portion and remaining portion of main memory is available for user processes. Advantages It supports multi programming. A process whose size is less then or equal to the partitions size can be loaded into any available partition. Disadvantages If a program is big to fit in...
Post a Comment
Read more

Difference between HTML and DHTML-computer world

     Difference between HTML and DHTML  HTML is a markup language, while DHTML is a collection of Technology.  DHTML creates dynamic web page, whereas HTML create static web page.  DHTML allow including small animations and dynamic menus in web pages but HTML is not able to do so.   HTML used events, methods, properties to insulate dynamism in HTML pages.   HTML is used to describe the web page but DHTML is a collection of JavaScript and style sheet in an HTML page. HTML sites will be show upon client side Technologies, while  DHTML site will be fast enough upon client side Technologies as most of entries are checked on browser itself and not waste time rendering to server for mistake.  HTML creates a plain web page without any style and scripts called as HTML. Whereas,  DHTML creates a page with HTML, CSS,DOM And scripts called as DHTML.  HTML cannot any server side code but XHTML may contain server side code.  ...
Post a Comment
Read more

Distributed transaction model-oocomputerworld

  Distributed transaction model Distributed transaction model:- To access the various data items in a distributed system is usually e accomplished through transaction there are two type of transaction that we need to consider The local transaction The Global transaction    The local transaction:- The local transaction are those that access and update data is only one local database.  The global transaction:- global transaction are those that access and update data in several local database in the case of global transaction the task is more complicated since several nodes may be participating in execution the failure of a communication link connecting these nodes may result in erroneous computation.  System structure :- Each node has its oven local transaction manager whose function is to ensure those transaction that execute at that site. The various transaction manager corporate to execute global transaction. To understand how such a manager can be impl...
Post a Comment
Read more