Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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);
Define ‘LRU’ page replacement policy LRU is Least Recently Used page replacement policy.
Modern networks are not implemented as a single piece of software; that would render the task of dealing with multiple technologies and manufacturers virtually impossible. The solu
about error detection in operating system and how does it take place?
Binary number based systems Binary is a ' base 2' number system, only two numbers exist namely '0' and '1'. Conversion from binary to base 10 is easy if the number column techn
Q. Capability lists are typically kept within the address space of the user. How does the system make sure that the user cannot modify the contents of the list? Answer: An ap
What are the use of job queues, ready queues and device queues? As a process enters a system they are put in to a job queue. These queues having of all jobs in the system. The
acyclic graph directories
Virtual file systems The file-system execution having of three major layers. The first layer is the file-system interface, based on the open, read, write and close calls and fi
What is a file path name? A list of the subdirectories, directories, and files we must traverse to reach a file from the root directory.
Interrupts The hardware mechanism that enables a device to inform the CPU is called an interrupt. The basic interrupt mechanism works as follows. The CPU hardware has a wire kn
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd