SDP10_Final_Exam_Part2

Good Guy Beket
Quiz by Good Guy Beket, updated more than 1 year ago
Good Guy Beket
Created by Good Guy Beket about 3 years ago
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Description

final_part2_sdp10

Resource summary

Question 1

Question
Consider the following code. Assume the compiler is performing no optimization. Which of the following strategies would improve the speed of this code the most in the case where it returns true?
Answer
  • Unroll the loop
  • Pull the (x % i)==0 into a function isDivisibleBy
  • Declare int sx = (int)sqrt(x) and change i < sqrt(x) to i < s
  • Move the check for (x % 2) != 0 to before the loop

Question 2

Question
By default, OpenMp _____ assigns loop iterations to threads. When the parallel for block is entered, it assigns each thread the set of loop iterations it is to execute?
Answer
  • static
  • runtime
  • dynamic
  • auto

Question 3

Question
OpenMP assigns one iteration to each thread. When the thread finishes, it will be assigned the next iteration that hasn’t been executed yet.
Answer
  • runtime
  • dynamic
  • static
  • auto

Question 4

Question
This is an example of? (IMAGE) /*set elements of array to 0*/ void clear_array (int *desc, int n){ int i; for (i = 0; i<n; i++) dest[i] = 0; } /*set elements of array to 0, Unrolled X4*/ ... ...
Answer
  • Loop Unrolling
  • Loop fission
  • none
  • Loop fusion

Question 5

Question
This is an example of? (IMAGE) /*convert string to lowercase: slow*/ void lower1 (char *s) { int i; for (i = 0; i < strlen(s); i++) if (s{i} >= 'A' && s[i] <= 'Z') s[i] -= ('A' - 'a'); } /*Convert string to lowercase: faster*/ void lower2(char *s) { ... ... }
Answer
  • Loop fission
  • Code motion
  • Loop unrolling
  • Loop blocking

Question 6

Question
In given two C modules which rule will Unix linker use to resolve multiple symbol definition?
Answer
  • Given a strong symbol and multiple weak symbols, choose the strong symbol.
  • Given multiple weak symbols, chose any of the weak symbols
  • Multiple strong symbols are not allowed.
  • None of these

Question 7

Question
In C, on a 34-bit x86 machine, the expression (1<<31) results in a negative integer
Answer
  • True
  • False

Question 8

Question
Which of the following move operations is the following instruction an example of: movl (%edx), %eax ?
Answer
  • memory to immediate
  • register to memory
  • memory to register
  • error, can't move memory to memory

Question 9

Question
What is the value of the following C expression? x = 0xBC and y = 0x35 (x & !y)
Answer
  • 0x1200
  • 0xFFFF
  • 0x0001
  • 0x0000

Question 10

Question
In general, which of the following is slowest?
Answer
  • moving from one register to another
  • comparing two numbers to decide where to jump
  • doing division
  • accessing memory

Question 11

Question
Good software design includes writing procedures for code you might otherwise repeat in-line. Pulling code into procedures can help some branch predictors; how else can it improve your program’s performance and/or your compiler’s ability to optimize your code?
Answer
  • more opportunities for loop unrolling
  • less chance of compiler having to worry about aliasing and side effects
  • more opportunities for pipeline-level parallelism
  • better instruction cache hit rate

Question 12

Question
This is an example of?
Answer
  • Parrallel processing
  • Serial processing
  • none of the above
  • Linear processing

Question 13

Question
This is an example of?
Answer
  • Parallel processing
  • Serial processing
  • none of the above
  • Linear processing

Question 14

Question
The code ( a && b ) || (!a && !b) implements —
Answer
  • Equality
  • MUX
  • Adder
  • Set membership

Question 15

Question
Consider the following code fragment (IMAGE) int a; int b; int main(int argc, char * argv[]){ int x; int y; … /* some code*/ }
Answer
  • The value of &y is closer to the value of &x than to the value &
  • The values of &a and &b are closer to each other then the values &x and &y
  • The values of *a and *b are closer to each other than the values of *x and *y
  • The value of *y is closer to the value of *x than to the value of *a

Question 16

Question
Compare the size of int and int*
Answer
  • each one of the above depends on the computer
  • int has fewer bits
  • int* has fewer bits
  • they have the same number of bits

Question 17

Question
In C, if x is an integer variable, the expression “x << 3” computes x * 8 but does not change the value of x.
Answer
  • true
  • false

Question 18

Question
Using a base address [Eb]%edx=0x1000, and index register [ei]%ecx=0x02, compute the effective address for (IMAGE) : movl 8(%edx,%ecx, 4), %eax)
Answer
  • 0x1032
  • 0x1016
  • 0x1064
  • 0x1010

Question 19

Question
Using a base address [Eb]%edx=0x1000, and index register [ei]%ecx=0x03, compute the effective address for (IMAGE): movl 8(%edx, %ecx, 4), %eax
Answer
  • 0x1032
  • 0x1016
  • 0x1064
  • 0x1014

Question 20

Question
What value ends up in EAX after the following code is executed?
Answer
  • 48 (decimal) or 00110000 (binary) or 0x30 (hex)
  • 50 (decimal) or 00110010 (binary) or 0x32 (hex)
  • 46 (decimal) or 00101110 (binary) or 0x2E (hex)
  • 52 (decimal) or 00110100 (binary) or 0x34 (hex)

Question 21

Question
Two computers A and B with a cache in the CPU chip differ only in that A has an L2 cache and B does not. Which of the following are possible?
Answer
  • 1 and 2 only
  • 1 only
  • 2 only
  • 2 and 3 only

Question 22

Question
Which of the following code snippets is fastest ? Assume n is very large(more than ten thousand)
Answer
  • for(k=0; k<n; k+=16) for(l=0; l<n; l+=16) for(j=0;j<16;j+=1) for(i=0;i<16;i+=1) a[i+l][j+k] = b[j+k][i+l];
  • two or more of the above are equivalently the fastest
  • for(j=0;j<n;j+=1) for(i=0;i<n;i+=1) a[i][j] = b[j][i];
  • for(i=0;i<n;i+=1) for(j=0;j<n;j+=1) a[i][j] = b[j][i];

Question 23

Question
Which of the following code snippets is fastest? Assume n is very large (more than ten thousand).
Answer
  • for(i=0;i<n;i+=1) for(j=0;j<n;j+=1) a[i][j] = b[j][i];
  • for(j=0;j<n;j+=1) for(i=0;i<n;i+=1) a[i][j] = b[j][i
  • for(k=0; k<n; k+=16) for(l=0; l<n; l+=16) for(j=0;j<16;j+=1) for(i=0;i<16;i+=1) a[i+l][j+k] = b[i+l][j+k];
  • two or more of the above are equivalently the fastest

Question 24

Question
Good software design includes writing procedures for code you might otherwise repeat in-line. Pulling code into procedures involves call/return overhead; how else can it HURT your program's performance and/or your compiler's ability to optimize your code?
Answer
  • more chance of compiler having to worry about aliasing and side effects
  • fewer opportunities for pipeline-level parallelism
  • worse instruction cache hit rate
  • fewer opportunities for loop unrolling

Question 25

Question
Good software design includes writing procedures for code you might otherwise repeat in-line. Pulling code into procedures can help some branch predictors; how else can it IMPROVE your program’s performance and/or your compiler’s ability to optimize your code?
Answer
  • more opportunities for loop unrollin
  • less chance of compiler having to worry about aliasing and side effects
  • more opportunities for pipeline-level parallelism
  • better instruction cache hit rate

Question 26

Question
Consider a direct-mapped cache with 256 sets and 16 byte blocks. In this cache the address 0x12345 maps to the same set as which of the following addresses?
Answer
  • 0x02345
  • 0x22244
  • 0x12354
  • 0x12040

Question 27

Question
Parallel processing mechanisms to achieve parallelism in uniprocessor system are:
Answer
  • All of the above
  • Multiple function units
  • Parallelism and pipelining within CPU
  • Multiprogramming and time sharing

Question 28

Question
This is an example of?
Answer
  • Hybrid system
  • shared memory UMA
  • Distributed memory architecture
  • Shared memory NUMA

Question 29

Question
This is an example of? (IMAGE)
Answer
  • None
  • Loop unrolling
  • Loop fusion
  • Loop fission

Question 30

Question
This is an example of?
Answer
  • Loop fission
  • Loop fusion
  • None
  • Loop unrolling

Question 31

Question
Program take as input a collection of relocatable object files and command-line arguments and generate as output a fully linked executable object file that can be loaded and run:
Answer
  • Static linker
  • Dynamic linker
  • Both
  • None

Question 32

Question
... involve identifying a computation that is performed multiple times (e.g., within a loop), but such that the result of the computation will not change.
Answer
  • Side effect
  • Code motion
  • Loop unrollin
  • Memory aliasing

Question 33

Question
... construct encloses code, forming a parallel region.
Answer
  • Parallel
  • Serial

Question 34

Question
... is the default schedule type. Upon entering the loop, each thread independently decides which chunk of the loop they will process.
Answer
  • static
  • dynamic
  • runtime
  • guided

Question 35

Question
By default, OpenMP _____ assigns loop iterations to threads. When the parallel for block is entered, it assigns each thread the set of loop iterations it is to execute?
Answer
  • static
  • dynamic
  • runtime
  • auto

Question 36

Question
The _______ directive causes threads encountering the barrier to wait until all the other threads in the same team have encountered the barrier.
Answer
  • single
  • barrier
  • nowait
  • private
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