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

Virtual memory, In modern operating systems, applications do not directly a...

In modern operating systems, applications do not directly access the physical memory. Instead, they use so-called virtual memory, where each virtual address is translated to a phys

Important system components, Organizational, Structural, Logical and Execut...

Organizational, Structural, Logical and Execution Relationships Between Important System Components in Linux Kernel Subsystems A. Description of the Project You are require

Explain fifo page replacement in detail, FIFO page replacement This is...

FIFO page replacement This is the easiest page replacement algorithm. Here the 1 st page toward the inside is the 1 st to leave that is the oldest page leaves. To execute th

Operational management, explain the link between operations management and ...

explain the link between operations management and strategic planning of daily goods shop

Briefly discuss on page replacement, Briefly discuss on page replacement? ...

Briefly discuss on page replacement? Page replacement approach is fixed as follows. If no frame is free, we search one that is not presently being used and free it. We can fre

Explain page traffic, The term ‘page traffic’ explains   Page traffic’...

The term ‘page traffic’ explains   Page traffic’ explains the movement of pages in and out of memory.

Software for business management integrated into network, Software for busi...

Software for business management integrated into a social network Project Description: We are seeking top professionals to build software with us that manages the business.

Lock revenue variable, Demonstrate that your program (include the program o...

Demonstrate that your program (include the program output as part of the final report) can produce the correct output with the following parameters. For each case comment if the ou

Explain the sleep (ms) function, Explain the Sleep (ms) Function  This ...

Explain the Sleep (ms) Function  This call places the current thread in a suspended state for the number of milliseconds passed as the parameter (ms). After that Windows NT wil

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