Multi threading operating system

Multi threading

operating system

· Multi threading is a technique in which a process, executing an application is divided into threads that can run concurrently

· A thread is a dispatch able unit of work. It includes a processor context and its own data area for sack .

· A thread execute sequentially and is interruptible so that the processor can turn to another thread.

· Thus, a thread represents a light weight process and is the smallest unit of CPU utilization it is like a mini process.

· A process, on other hand is a collection of one or more threads and associated system resources

· A thread is not a process by itself. Cannot run on its own. It always run within a process.

· Thus, a multithreaded process may have multiple execution flows, different once belonging to difficult threads.

Multi Threading Operating

System

A thread is not a process by itself .it cannot run on its own. It always run within a process

The various States exhibited by windows thread are:

1. Ready. A ready thread may be scheduling for execution. The kernel dispatcher keeps track of all ready threads and schedules them in priority order.

2. Standby. A thread that has been selected to run next on a particular processor is said to be in standby state. The thread waits in this state until the processor is made available.

3. Running the thread that is currently CPU is in running state.it keeps the processor until it is preempted by a higher priority thread or it gets blocked or its time slice expires.

4. Waiting. A thread enters waiting state when:

(a) It is blocked on event .

(b) It voluntarily waits for synchronization purpose.

When waiting condition is satisfied, the thread moves back to ready state if all the resource are available.

5. Transition. A thread enters this state after waiting if it is ready to run but resources are not available.

6. Terminated. A thread can be terminated by itself, by another thread or when its parent process terminates.

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Thread

Thread What is Thread? A thread is a flow of execution through the process code, with its own program counter that keeps track of which instruction to execute next, system registers which hold its current working variables, and a stack which contains the execution history. A thread shares with its peer threads few information like code segment, data segment and open files. When one thread alters a code segment memory item, all other threads see that. A thread is also called a lightweight process . Threads provide a way to improve application performance through parallelism. Threads represent a software approach to improving performance of operating system by reducing the overhead thread is equivalent to a classical process. Each thread belongs to exactly one process and no thread can exist outside a process. Each thread represents a separate flow of control. Threads have been successfully used in implementing network servers and web server. They also provide a suitable foundation ...

Multi Level Queue Scheduling (MLQ)

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Multitasking System

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Virtual Machine Architecture

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Distributed system

Distributed system · A distributed system is a collection of processor located in geographical dispersal physical location. · In this system, the workhold is distributed or divided between two or more computers that are linked together by communication network . that is the different processors communicate using communication links, such as telephone lines and buses3 · The various processors do not share memory, clock ,or peripheral devices instead each processors has its local memory. · The purpose of distributed system is to provide an efficient and convenient environment for sharing of resources. · Some example of distributed operating system are amoeba, angle, chorus, much, alpha kernel. · ...

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