Skip to content
Related Articles
Get the best out of our app
GeeksforGeeks App
Open App

Related Articles

Thread Models in Operating System

Improve Article
Save Article
Like Article
Improve Article
Save Article
Like Article

A thread is a light weight process which is similar to a process where every process can have one or more threads. Each thread contains a Stack and a Thread Control Block. There are four basic thread models : 

1. User Level Single Thread Model : 

  • Each process contains a single thread.
  • Single process is itself a single thread.
  • process table contains an entry for every process by maintaining its PCB.


2. User Level Multi Thread Model : 

  • Each process contains multiple threads.
  • All threads of the process are scheduled by a thread library at user level.
  • Thread switching can be done faster than process switching.
  • Thread switching is independent of operating system which can be done within a process.
  • Blocking one thread makes blocking of entire process.
  • Thread table maintains Thread Control Block of each thread of a process.
  • Thread scheduling happens within a process and not known to Kernel.


3. Kernel Level Single Thread Model : 

  • Each process contains a single thread.
  • Thread used here is kernel level thread.
  • Process table works as thread table.


4. Kernel Level Multi Thread Model : 

  • Thread scheduling is done at kernel level.
  • Fine grain scheduling is done on a thread basis.
  • If a thread blocks, another thread can be scheduled without blocking the whole process.
  • Thread scheduling at Kernel process is slower compared to user level thread scheduling.
  • Thread switching involves switch.



My Personal Notes arrow_drop_up
Last Updated : 10 Feb, 2022
Like Article
Save Article
Similar Reads