Problem: Whenever a process is constantly checking value while waiting (see while(s==0)) and wasting CPU cycles, we can take the following train of thought to avoid this situation:

P(Semaphore s)

{

s=s-1;

if(s<0){

block();

}

}

V(Semaphore s)

{

s=s+1;

if(s >=0){

wakeup(p);

}

}