Write a note on semaphores, Operating System

Assignment Help:

Write a note on semaphores

A semaphore is a tool meant for synchronizing multiple processes trying to access a shared variable. That is a semaphore is used to deal with the critical section problem or in other words to evade the race condition. A semaphore S is in fact an integer variable that apart from initialization is accessed only through two standard atomic operations:

*Wait and signal.

 

The traditional definition of wait in pseudo code is:

    wait (S) {

             while (S<=0)

                ; // no-op

             S--;

    }

The traditional definition of signal in pseudo code is:

    signal (S) {

               S++;

    }

 

For each process P,

    do {

WAIT

           Critical Section

SIGNALS

 

          } while (1);

 

A semaphore is able to be defined as:

typedef struct {

             int value;

             struct process *L;

} semphore;

 

Once more, the wait semaphore operation can be defined as:

void wait (semaphore S) {

                S.value--;

                if (S.value < 0) {

                    add this process to S.L;

                    block();

                }

}

 

As well, the signal semaphore operation is able to be defined as:

void signal( semaphore S) {

                   S.value++;

                   if (S.value <= 0) {

                       remove a process P from S.L;

                       wakeup(P);

                   }

}


Related Discussions:- Write a note on semaphores

Explain about operating system services, Q. Explain about Operating System ...

Q. Explain about Operating System Services? An operating system offers services to programs and to users of those programs. It provided by one environment for execution of

Define coding in an independent service architecture, Define Coding in an i...

Define Coding in an independent service architecture Coding in an independent service architecture alleviates many of the traditional dependencies of monolithic applications.

Write a note on threads, Question 1 Explain (a) tightly coupled systems   ...

Question 1 Explain (a) tightly coupled systems                               (b) Loosely coupled system Question 2 Describe the RPC model Question 3 Write a note o

Nachos oprating system assignment, i am just wondering if you have expert i...

i am just wondering if you have expert in nachos operating system thank you

Analysis of Pseudocode Sempahore Solution, Gopher Gallery consists of a sho...

Gopher Gallery consists of a shopping mall and a cart ride that covers the 150 acre habitat. There are m visitors and n single-person vehicles. Visitors stroll around the mall at

Define maintaining data on a per client basis, Define Maintaining Data on a...

Define Maintaining Data on a Per Client Basis Perhaps the most dramatic syntactical programming change for the application developer of client – server applications is maintain

Memory management, example of first fit best fit and worst fit

example of first fit best fit and worst fit

Roles of operating systems, Describe Three major roles of operating systems...

Describe Three major roles of operating systems in business computer systems

Explain the real time operating system, Explain the Real Time Operating Sys...

Explain the Real Time Operating System A real-time operating system comprises definite, fixed time constraints. Processing should be done in the defined constraints, or the sys

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd