1
GATE CSE 2021 Set 2
MCQ (More than One Correct Answer)
+2
-0

Consider a computer system with multiple shared resource types, with one instance per resource type. Each instance can be owned by only one process at a time. Owning and freeing of resources are done by holding a global lock (L). The following scheme is used to own a resource instance:

function OWNRESOURCES(Resource R)

Acquire lock L / / a global lock

if R is available then

Acquire R

Release lock L

else

if R is owned by another process P then

Terminate P, after releasing all resources owned by P

Acquire R

Restart P

Release lock L

end if

end if

end function

Which of the following choice(s) about the above scheme is/are correct?

A
The scheme may lead to starvation.
B
The scheme may lead to live-lock.
C
The scheme ensures that deadlocks will not occur.
D
The scheme violates the mutual exclusion property.
2
GATE CSE 2021 Set 2
MCQ (More than One Correct Answer)
+1
-0
Which of the following statement(s) is/are correct in the context of CPU scheduling?
A
Implementing preemptive scheduling needs hardware support.
B
Turnaround time includes waiting time.
C
Round-robin policy can be used even when the CPU time required by each of the processes is not known apriori.
D
The goal is to only maximize CPU utilization and minimize throughput.
3
GATE CSE 2021 Set 2
MCQ (More than One Correct Answer)
+2
-0

Consider the following multi-threaded code segment (in a mix of C and pseudocode), invoked by two processes P1 and P2, and each of the processes spawns two threads T1 and T2:

int x = 0; // global

Lock L1; // global

main() {

create a thread to execute foo(); // Thread T1

create a thread to execute foo(); // Thread T2

wait for the two threads to finish execution;

print (x);}

foo() {

int y = 0;

Acquire L1;

x = x + 1;

y = y + 1;

Release L1;

print (y); }

Which of the following statement(s) is/are correct ?

A
Both T1 and T2, in both the processes, will print the value of y as 1.
B
At least one of P1 and P2 will print the value of x as 4
C
Both P1 and P2 will print the value of x as 2.
D
At least one of the threads will print the value of y as 2.
4
GATE CSE 2021 Set 2
Numerical
+2
-0

Consider a three-level page table to translate a 39-bit virtual address to a physical address as shown below.

GATE CSE 2021 Set 2 Operating Systems - Memory Management Question 9 English

The page size is 4 KB (1 KB = 210 bytes) and page table entry size at every level is 8 bytes. A process P is currently using 2 GB (1 GB = 230 bytes) virtual memory which is mapped to 2 GB of physical memory. The minimum amount of memory required for the page table of P across all levels is _______ KB.

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