16th one , explain please

Will the answer of f1+f2 be 2^3 or 2^4?

A certain computation generates two arrays a and b such that a[i]=f(i) for 0 ≤ i < n and b[i]=g(a[i]) for 0 ≤ i < n. Suppose this computation is decomposed into two concurrent processes X and Y such that X computes the array a and Y computes the array b. The processes employ two binary semaphores R and S, both initialized to zero. The array a is shared by the two processes. The structures of the processes are shown below.
Process X: Process Y:
private i; private i;

for (i=0; i < n; i++) { for (i=0; i < n; i++) {

a[i] = f(i); EntryY(R, S);

ExitX(R, S); b[i]=g(a[i]);

} }
Which one of the following represents the CORRECT implementations of ExitX and EntryY?

(A)
ExitX(R, S) {

P(R);

V(S);

}



EntryY (R, S) {

P(S);

V(R);

}
(B)
ExitX(R, S) {

V(R);

V(S);

}



EntryY(R, S) {

P(R);

P(S);

}
(C)
ExitX(R, S) {

P(S);

V(R);

}

EntryY(R, S) {

V(S);

P(R);

}

(D)
ExitX(R, S) {

V(R);

P(S);

}

EntryY(R, S) {

V(S);

P(R);

}

Somebody please help
#OS

1101

❓ Questions posted on 25/12/2020

GATE2001-20
NAT

Consider a disk with the 100 tracks numbered from 0 to 99 rotating at 3000 rpm. The number of sectors per track is 100 and the time to move the head between two successive tracks is 0.2 millisecond.

B. Consider an initial set of 100 arbitrary disk requests and assume that no new disk requests arrive while servicing these requests. If the head is initially at track 0 and the elevator algorithm is used to schedule disk requests, what is the worse case time to complete all the requests?

Can anyone explain this?

Ans please

a 32-bit machine we subdivide the virtual address into 4 segments as follows:

10-bi

8-bit

6-bit

8 bit

 

We use a 3-level page table, such that the first 10-bit are for the first level and so on. What is the size of a page table for a process that has 256K of memory starting at address 0?