1.Define entry
section and exit section.
The critical section problem is to
design a protocol that the processes can use to cooperate. Each process must
request permission to enter its critical section. The section of the code
implementing this request is the entry section. The critical section is
followed by an exit section. The remaining code is the remainder section.
2.Give two hardware
instructions and their definitions which can be used for implementing mutual exclusion.
• TestAndSet
boolean
TestAndSet (boolean &target)
{
boolean
rv = target; target = true; return rv;
}
• Swap
void Swap
(boolean &a, boolean &b)
{
boolean
temp = a; a = b;
b = temp;
}
3.What is
semaphores?
A semaphore 'S' is a synchronization
tool which is an integer value that, apart from initialization, is accessed
only through two standard atomic operations; wait and signal.Semaphores can be
used to deal with the n-process critical section problem. It can be also used
to solve various Synchronization problems.
4.Define busy
waiting and spinlock.
When a process is in its critical
section, any other process that tries to enter its critical section must loop
continuously in the entry code. This is called as busy waiting and this type of
semaphore is also called a spinlock,because the process while waiting for the
lock.
5.Define
deadlock.
A process requests resources; if the
resources are not available at that time, the process enters a wait state.
Waiting processes may never again change state, because the resources they have
requested are held by other waiting processes. This situation is called a
deadlock.
