Preemptive and Non-Preemptive


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Preemptive and Non-Preemptive


The scheduling which takes place when a process switches from running state to ready state or from waiting state to ready state is called Preemptive Scheduling or Pre-Emption

In Nonpreemptive Scheduling, once the resources (CPU) is allocated to a process, the process holds the CPU till it gets terminated.



Processor Types

• In a single-processor system, therefore, only one program can be running at any one time.



• Processors can have a single core or multiple cores. A processor with two cores is called a dual-core processor, four cores is quad -core..

• Dual core processor is likely to be about one-and-a half times as powerful as a single core processor.

 Multicore processors that enable the computer to execute multiple processes or process threads at the same time in order to increase speed and performance.
• A core is part of a CPU that receives instructions and performs calculations, or actions, based on those instructions.
Multicore



 • it is a type of architecture where a single physical processor contains the core logic of two or more processors. These processors are packaged into a single integrated circuit (IC).



Process termination

There are many reasons for process termination:

Batch job issues halt instruction

User logs off
Process executes a service request to terminate
Error and fault conditions
Normal completion 
Time limit exceeded
Memory unavailable
• Bounds violation; for example: attempted access of (non-existent) 11th element of a 10-element array
• Protection error; for example: attempted write to read-only file
• Arithmetic error; for example: attempted division by zero

• Time overrun; for example: process waited longer than a specified maximum for an event I/O failure
• Invalid instruction; for example: when a process tries to execute data (text)
  
• Data misuse

• Operating system intervention; for example: to resolve a deadlock
• Parent terminates so child processes terminate (cascading termination)
• Parent request

Comments

  1. Gowri ShankarSeptember 10, 2019 at 12:46 AM

    its very useful for my carrer

    ReplyDelete
  2. indhuSeptember 10, 2019 at 1:00 AM

    very easy to understand sir ...thank you sir...

    ReplyDelete
  3. Gnana Surya PSeptember 10, 2019 at 1:05 AM

    Easy to understand the Basics OS concepts sir...Thank you sir

    ReplyDelete
  4. PriyaSeptember 10, 2019 at 1:08 AM

    thank you sir..

    ReplyDelete
  5. NivedhaSeptember 10, 2019 at 1:12 AM

    Thank you for sharing your vision sir.

    ReplyDelete
  6. AnonymousSeptember 10, 2019 at 1:22 AM

    easy to understand switching concept ...

    ReplyDelete
  7. Gnana Surya PSeptember 11, 2019 at 11:49 AM

    Premitive and non-primitive scheduling, processor types are very nice sir... And also easy to understand

    ReplyDelete

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