GATE CS 2008

Question 31

Which of the following must be true for the RFE (Return from Exception) instruction on a general purpose processor?

I.   It must be a trap instruction
II.  It must be a privileged instruction
III. An exception cannot be allowed to occur during 
     execution of an RFE instruction 

• I only
• II only
• I and II only
• I, II and III only

Question 32

For inclusion to hold between two cache levels L1 and L2 in a multi-level cache hierarchy, which of the following are necessary?

I. L1 must be a write-through cache
II. L2 must be a write-through cache
III. The associativity of L2 must be greater than that of L1
IV. The L2 cache must be at least as large as the L1 cache 

• IV only
• I and IV only
• I, III and IV only
• I, II, III and IV

Question 33

Which of the following are NOT true in a pipelined processor?

I.  Bypassing can handle all RAW hazards.
II. Register renaming can eliminate all register 
    carried WAR hazards.
III. Control hazard penalties can be eliminated by 
     dynamic branch prediction.

• I and II only
• I and III only
• II and III only
• I, II and III

Question 34

The use of multiple register windows with overlap causes a reduction in the number of memory accesses for

I. Function locals and parameters
II. Register saves and restores
III. Instruction fetches   

• I only

• II only

• III only

• I, II and III

Question 35

In an instruction execution pipeline, the earliest that the data TLB (Translation Lookaside Buffer) can be accessed is

• before effective address calculation has started

• during effective address calculation

• after effective address calculation has completed

• after data cache lookup has completed

Question 36

Consider the following functions:

f(n) = 2n
g(n) = n!
h(n) = nlogn

Which of the following statements about the asymptotic behaviour of f(n), g(n), and h(n) is true?

(A) f(n) = O(g(n)); g(n) = O(h(n))
(B) f(n) = [Tex]\\Omega[/Tex](g(n)); g(n) = O(h(n))
(C) g(n) = O(f(n)); h(n) = O(f(n))
(D) h(n) = O(f(n)); g(n) = [Tex]\\Omega[/Tex](f(n)) 

• A
• B
• C
• D

Question 37

The minimum number of comparisons required to determine if an integer appears more than n/2 times in a sorted array of n integers is

• Θ(n)

• Θ(logn)

• Θ(n*logn)

• Θ(1)

Question 38

A B-tree of order 4 is built from scratch by 10 successive insertions. What is the maximum number of node splitting operations that may take place?

• 3

• 4

• 5

• 6

Question 39

G is a graph on n vertices and 2n - 2 edges. The edges of G can be partitioned into two edge-disjoint spanning trees. Which of the following is NOT true for G?

• There are two edge-disjoint paths between every pair to vertices
  

• The minimum cut in G has at least two edges
  

• For every subset of k vertices, the induced subgraph has at most 2k-2 edges
  

• There are two vertex-disjoint paths between every pair of vertices
  

Question 40

Consider the Quicksort algorithm. Suppose there is a procedure for finding a pivot element which splits the list into two sub-lists each of which contains at least one-fifth of the elements. Let T(n) be the number of comparisons required to sort n elements. Then

• T(n) <= 2T(n/5) + n

• T(n) <= T(n/5) + T(4n/5) + n

• T(n) <= 2T(4n/5) + n

• T(n) <= 2T(n/2) + n