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SDP10 Final - Part I

Beschreibung

SDP10 Quiz am SDP10 Final - Part I, erstellt von Csse 1502 am 12/05/2018.
Csse 1502
Quiz von Csse 1502, aktualisiert more than 1 year ago
Csse 1502
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Zusammenfassung der Ressource

Frage 1

Frage
In given two C modules which rule will Unix linker use to resolve multiple symbol definition?
Image:
1 (binary/octet-stream)
Antworten
  • Multiple strong symbols are not allowed
  • None of these
  • Given multiple weak symbols, chose any of the weak symbols
  • Given a strong symbol and multiple weak symbols, choose the strong symbol.

Frage 2

Frage
Suppose we attempt to compile and link the following two C modules. Linker will generate an error?
Image:
2 (binary/octet-stream)
Antworten
  • true
  • false

Frage 3

Frage
Suppose we attempt to compile and link the following two C modules. Linker will generate an error?
Image:
3 (binary/octet-stream)
Antworten
  • true
  • false

Frage 4

Frage
A branch instruction
Antworten
  • Sets the program counter to one of two possible values
  • Increases the program counter by a fixed amount
  • Sets the program counter to one of many possible values
  • Unconditionally sets the program counter to its operand

Frage 5

Frage
In binary, the number 1/3 is 0.01010101 . . .. In the following, assume that x is an int and y is a short. (short)((0x5555 * (int)y)>>16) and y/3 could differ even when neither computation overflows
Antworten
  • True
  • False

Frage 6

Frage
A callee-saved register should be saved before it is written to in a procedure
Antworten
  • True
  • False

Frage 7

Frage
In binary, the number 1/3 is 0.01010101 . . .. In the following, assume that x is an int and y is a short. For each x there exists some integer w (which may be different for different xs) such that abs(x/3 - q) < 10, where q = (((0x55555555>>w)*x)>>(32-w)).
Antworten
  • false
  • true

Frage 8

Frage
In the FDEMW five-stage pipeline we analyzed in class, if we want to stall memory how many pipeline registers should be given the "stall" signal?
Antworten
  • 4
  • 0
  • 5
  • 3

Frage 9

Frage
A CPU register file is a small storage device that
Antworten
  • Consists of a collection of word size registers
  • Houses a critical variable for the duration of the execution of a program
  • Records the results of periodic CPU diagnostics
  • Is automatically loaded when CPU instruction refers to a word of normal memory

Frage 10

Frage
In the FDEMW five-stage pipeline we analyzed in class, if we want to stall decode how many pipeline registers should be given the “normal operation” signal?
Antworten
  • 3
  • 0
  • 4
  • 5
  • 2
  • 1

Frage 11

Frage
Using a base address [Eb] %edx= 0x1000, and index register [Ei] %ecx=0x02, compute the effective address for:
Image:
1 (binary/octet-stream)
Antworten
  • 0x1064
  • 0x1032
  • 0x1016
  • 0x1010

Frage 12

Frage
A memory leak is caused by a
Antworten
  • Failure to free allocated memory
  • Function that allocates a large amount of memory from the heap
  • None of these
  • Bug in the memory allocator that fails to free memory

Frage 13

Frage
In the two's complement number representation, a negative number with more leading ones is larger (i.e. less negative) than a negative number with fewer leading ones.
Antworten
  • true
  • false

Frage 14

Frage
When shifting a two’s complement number to the left, an overflow can only occur if the number is negative, since positive numbers have a zero in the leftmost bit
Antworten
  • false
  • true

Frage 15

Frage
A program cannot accidentally use another program's memory space and "crash" a computer that uses (see the img) 1- virtual memory address 2- program relocation 3- separate instruction and data caches
Antworten
  • 1 only
  • 1 and 2
  • 2
  • 1,2,3

Frage 16

Frage
In x86 assembly, the eax register can be used to hold integers but not addresses.
Antworten
  • false
  • true

Frage 17

Frage
A program written directly in machine language (binary) would run faster than the same program written in assembly code and then assembled.
Antworten
  • False
  • True

Frage 18

Frage
Initially byte i of memory is i + 0x20 (mod 256), %eax contains the number 3, and %ebx contains the number 5. What is in %ebx after running x86 movl (%eax), %ebx?
Antworten
  • none of the above
  • 3
  • 0x25
  • 0x23

Frage 19

Frage
Adding local variables is usually used to reduce what source of inefficiency?
Antworten
  • unnecessary memory references
  • condition checking overhead
  • data dependencies
  • poor branch prediction

Frage 20

Frage
Asserting a word line and asserting (to "high" voltage) a bit line writes a 1 to a DRAM cell)
Antworten
  • False
  • True

Frage 21

Frage
Inline substitution (also called inlining) is usually used to reduce what source of inefficiency?
Antworten
  • procedure call overhead
  • poor branch prediction
  • poor cache locality
  • unnecessary memory references

Frage 22

Frage
Using a base address [Eb] %edx=0x1000, and index register [Ei] %ecx=0x03, compute the effective address for:
Image:
1 (binary/octet-stream)
Antworten
  • 0x1032
  • 0x1014
  • 0x1064
  • 0x1016

Frage 23

Frage
Jump in the following Y86-64 program. How many times does the addq instruction execute?
Image:
Image (binary/octet-stream)
Antworten
  • 4
  • 3
  • 5
  • 10

Frage 24

Frage
Jump tables, such as are used for switch statements, require that the new PC be determined by a memory read. Suppose we added an assembly instruction memjump accepting a single memory address as its parameter, like memjump (%eax). In the five-stage example pipeline (F D E M W), for how many cycles will we need to bubble and/or stall stage F after executing a memjump?
Antworten
  • 3
  • 4
  • 5
  • 6

Frage 25

Frage
Let f32 be the number of distinct numbers that can be represented in 4-byte IEEE-style floating point and u32 be the number of distinct numbers that can be represented as unsigned 4-byte integers. Which of the following is true?
Antworten
  • f32 < u32−1
  • f32 > u32 +1
  • f32 = u32
  • f32 = u32+1

Frage 26

Frage
Let s8 be the number of distinct numbers that can be represented as signed (two's complement) 1-byte integers and u8 be the number of distinct numbers that can be represented as unsigned 1-byte integers. Which of the following is true?
Antworten
  • s8 = u8
  • s8 > u8+1
  • s8 = u8 - 1
  • s8 < u8-1

Frage 27

Frage
Assume a set-associative and a direct-mapped cache both have the same address size, same data capacity, and same number of index bits. This means
Image:
в (binary/octet-stream)
Antworten
  • II and III
  • .

Frage 28

Frage
Assume x is the most positive signed integer. What is x + 1?
Antworten
  • none of the above
  • +∞
  • -1
  • -x

Frage 29

Frage
Logical address is calculated by: segment.base + eff_addr
Antworten
  • Selector: eff_addr
  • Segment base + lin_addr
  • Selector: offset
  • Segment base + eff_addr

Frage 30

Frage
Assuming the standard IEEE-style bias, what is the smallest number of bits a float point number could have and represent the number −29/4 exactly?
Antworten
  • 8
  • 4
  • 6
  • 12

Frage 31

Frage
Buses are typically designed to transfer fixed-sized chunks of bytes known as
Antworten
  • words
  • frames
  • records
  • pages

Frage 32

Frage
Capacity misses are typically discussed in connection with?
Antworten
  • fully-associative cache
  • direct-mapped caches
  • set-associative caches
  • all of the above

Frage 33

Frage
Check the following (listed in alphabetical order) in order of importance when optimizing code that operates on very large arrays: B = Body of loop optimization (function inlining, efficient math), C = Cache locality, O = big-O of algorithm used
Antworten
  • BCO
  • OBC
  • BOC
  • COB

Frage 34

Frage
Compare the size of int and int*
Antworten
  • each one of the above depends on the compute
  • int has fewer bits
  • int* has fewer bits
  • they have the same number of bit

Frage 35

Frage
Loop blocking is usually used to reduce what source of inefficiency?
Antworten
  • poor cache locality
  • data dependencies
  • poor branch prediction
  • procedure call overhead

Frage 36

Frage
Loop unrolling is usually used to remove what source of inefficiency?
Antworten
  • poor cache locality
  • data dependencies
  • poor branch prediction
  • procedure call overhead

Frage 37

Frage
Programs with good ______ ______, tend to access a referenced memory location multiple times in the near future.
Antworten
  • Temporal locality
  • Spatial locality
  • Repetitive locality
  • Associative locality

Frage 38

Frage
Putting \#include "foo.h" in your C file is the equivalent of typing the contents of foo.h into your file
Antworten
  • true
  • false

Frage 39

Frage
Consider the following code fragment
Image:
Q (binary/octet-stream)
Antworten
  • The value of &y is closer to the value of &x than to the value &a
  • The value of *y is closer to the value of *x than to the value *a
  • The value of *a and *b are closer to each other than the values of *x and *y
  • The value of &a and &b are closer to each other than the values of &x and &y

Frage 40

Frage
Compared to dynamic RAM (SRAM), dynamic RAM (DRAM) is
Antworten
  • a) DRAM is cheaper than SRAM
  • b) DRAM is faster than SRAM
  • c) DRAM is more likely to be used for main memory than for on-chip caches
  • d) SRAM is more likely to be used for main memory than for on-chip cache
  • a) DRAM uses more transistors per bit than SRAM
  • b) DRAM uses a capacitor to store a value
  • c) Typically a computer has more DRAM than SRA

Frage 41

Frage
Compiling C into x86 assembly comprises translating each C statement into a single assembly instruction.
Antworten
  • False
  • True

Frage 42

Frage
Conflict misses are typically discussed in connection with?
Antworten
  • direct-mapped caches
  • set-associative caches
  • fully-associative caches
  • all of the above

Frage 43

Frage
Rank the following in order of significance when writing code that deals with large arrays: - Algorithmic efficiency (i.e., big-O), - Computational efficiency (e.g., loop unrolling, inlining, etc), - L cache Locality.
Antworten
  • ACL
  • ALC
  • LCA
  • CAL

Frage 44

Frage
CPE (cycles per element, also called cycles per execution or cycles per instruction in other sources). If we have code with 20 CPE and run it on a problem where my algorithm executes on 100 elements; I should expect the runtime to be
Antworten
  • 50-220 cycles
  • 0-50 cycles
  • 220-1100 cycles
  • 1100-2200 cycles

Frage 45

Frage
Reassociation of operators is usually used to reduce what source of inefficiency?
Antworten
  • data dependencies
  • condition checking overhead
  • poor branch prediction
  • poor cache locality

Frage 46

Frage
Register %edx is one of the "callee-save" registers. This means that if procedure baz calls procedure xyxxy
Antworten
  • baz may assume xyxxy did not change %edx
  • xyxxy may communicate with baz through register %edx
  • baz must assume xyxxy could have changed %edx
  • baz may communicate with xyxxy through register %edx

Frage 47

Frage
Register %esi is one of the "caller-save" registers. This means that if procedure baz calls procedure xyxxy
Antworten
  • baz must assume xyxxy could have changed %esi
  • xyxxy may communicate with baz through register %esi
  • baz may assume xyxxy did not change %esi
  • baz may communicate with xyxxy through register %esi

Frage 48

Frage
Dirty bits are associated with (pick the best answer)
Antworten
  • write-back caches
  • write-through caches
  • set-associative caches
  • direct-mapped caches

Frage 49

Frage
Edsger Dijkstra wrote "Go To Statement Considered Harmful" in 1968 in which he argued (translated into current language) that code that uses goto becomes needlessly hard to read and maintain compared to only using if and while. In assembly, we use the goto-like jump instructions extensively; the main reason for this is?
Antworten
  • goto is only bad when mixed with higher-level constructs
  • Dijkstra was wrong
  • no one is reading assembly anyway
  • there is no other alternative in assembly

Frage 50

Frage
Every procedure in an x86 assembly program must be declared using .globl
Antworten
  • False
  • True

Frage 51

Frage
Which of the following is a good reason (are good reasons) to equip the CPU with small amounts of fast memory? I. To make the design of the compiler simpler II. To make some CPU instructions smaller III. To make some CPU instructions faster
Antworten
  • III only
  • II and III only
  • I, II, and III
  • II only

Frage 52

Frage
Given 6-bit numbers where 010001 + 001010 = 010110, which of the following describes the number representation used?
Antworten
  • floating-point with 2 exponent bits
  • floating-point with 3 exponent bits
  • integer
  • floating-point with 4 exponent bits

Frage 53

Frage
Given 6-bit numbers where 010101 + 000001 = 010110, which of the following describes the number representation used?
Antworten
  • integer
  • floating-point with 3 exponent bits
  • floating-point with 1 exponent bits
  • floating-point with 2 exponent bits

Frage 54

Frage
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?
Antworten
  • 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

Frage 55

Frage
Return from function issues a bubble in pipeline.
Antworten
  • true
  • false

Frage 56

Frage
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?
Antworten
  • 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

Frage 57

Frage
SRAM is "static" in the sense that if the power is turned off, SRAM will continue to store data (e.g. as in flash memory in MP3 players or USB thumb drives).
Antworten
  • false
  • true

Frage 58

Frage
Suppose addresses A and B have different tags but the same index (for those caches that have tags and indexes, that is). Assume the cache is empty prior to the accesses listed in the questions. In the access pattern "read A, then read B, then read A, then read B" the second read of A will be a miss for?
Antworten
  • a direct-mapped cache
  • a set-associative cache
  • a fully-associative cache
  • all of the above

Frage 59

Frage
How does knowing you have a pipelined processor change the code you write?
Antworten
  • it suggests optimizations like multiple accumulators
  • it suggests optimizations like adding local variables
  • it suggests optimizations like loop unrolling
  • it suggests optimizations like loop reordering

Frage 60

Frage
Suppose addresses A and B have different tags but the same index (for those caches that have tags and indexes, that is). Assume the cache is empty prior to the accesses listed in the questions. In the access pattern "read A, then read B" the read of B will be a miss for
Antworten
  • all of the above
  • a fully-associative cache
  • a direct-mapped cache
  • a set-associative cache

Frage 61

Frage
How is "-1" (decimal) represented in an 8-bit 2's complement binary format?
Antworten
  • 11111111
  • .

Frage 62

Frage
Suppose page table entries are 8 bytes long and virtual addresses are 32 bytes long. If each page table is to fit on a single page, what is the smallest pages can be if we have a 2-level page table hierarchy?
Antworten
  • bigger than any of the above options
  • 2 KB
  • 512 B
  • smaller than any of the above options

Frage 63

Frage
How is 46 (decimal) represented in an 8-bit 2's complement binary format?
Antworten
  • 00101100
  • 00101110
  • 00011110
  • 01000110

Frage 64

Frage
How is -10 (decimal) represented in an 8-bit 2's complement binary format?
Antworten
  • 11110110
  • 10001010
  • 11110101
  • 11111010

Frage 65

Frage
Which of the following move operations is the following instruction an example of movl (%edx), (%eax)?
Antworten
  • error, can’t move memory to memory
  • memory to immediate
  • register to memory
  • memory to register

Frage 66

Frage
In the access pattern “write A, then write B, then write A”, to minimize writes to the higher-level cache we should pick which of the following?
Antworten
  • a write-through fully-associative cache
  • a write-back fully-associative cache
  • a write-through direct-mapped cache
  • a write-back direct-mapped cache
  • two or more of the above are equivalently the best option

Frage 67

Frage
How many hex digits are needed to represent the decimal number 67?
Antworten
  • 2
  • 6
  • 4
  • 7

Frage 68

Frage
How many ints fit inside x if x is declared as int *x = malloc(8); ? Word size is 4.
Antworten
  • 2
  • 1
  • 8
  • 0

Frage 69

Frage
Which of the following move operations is the following instruction an example of movl (%edx), %eax?
Antworten
  • error, can’t move memory to memory
  • memory to register
  • register to memory
  • memory to immediate

Frage 70

Frage
How many rules do Unix linkers use for dealing with multiply defined symbol
Antworten
  • 3
  • 4
  • 5
  • 2

Frage 71

Frage
Suppose an array of char (8-bit values) {0x12, 0x34, 0x56, 0x78} is stored at address 0x24 of a little-endian computer. What byte is stored at address 0x26?
Antworten
  • 0x56
  • 0x00
  • 0x65
  • A known value not listed here

Frage 72

Frage
If a computer has 8GB memory, a single 1MB cache, and 4KB of registers, the total amount of data it can store is?
Antworten
  • more than 8GB but less than 8GB + 1MB
  • more than 8GB + 1MB but less than 8GB + 1MB + 1KB
  • more than 8GB + 1MB + 4KB
  • 8GB + 1MB + 4KB

Frage 73

Frage
Suppose the 32-bit value 0x12345678 is stored at address 0x24 of a big-endian computer. What byte is stored at address 0x23?
Antworten
  • 0x65
  • 0x34
  • 0x43
  • A known value not listed here
  • An unknown value because the number does not overlap address 0x25

Frage 74

Frage
When the following code fragment is executed on a computer with 32-bit integers and a fully-associative cache with 16-byte cache lines, how many bytes of the array A[] will be fetched into the cache from main memory
Image:
Q (binary/octet-stream)
Antworten
  • At most 96
  • Exactly 17
  • Exactly 32
  • At most 80

Frage 75

Frage
If a wire carries a logical value of 0, its voltage level will be 0 Volts.
Antworten
  • False
  • True

Frage 76

Frage
If we fail to find data in a cache because we have never accessed the data before, we call that a
Antworten
  • cold miss
  • capacity miss
  • conflict miss
  • forced miss

Frage 77

Frage
If we fail to find data in a cache because we've read too much data since we last accessed that same data, we call that a
Antworten
  • capacity miss
  • cold miss
  • conflict miss
  • forced miss

Frage 78

Frage
Suppose the 32-bit value 0x12345678 is stored at address 0x24 of a big-endian computer. What byte is stored at address 0x25?
Antworten
  • 0x56
  • A known value not listed here
  • 0x65
  • 0x43
  • An unknown value because the number does not overlap address 0x25
  • F 0x34

Frage 79

Frage
If we were running a non-pipelined processor (like SEQ) with a real memory system, which of the following optimization strategies would no longer provide a speed benefit?
Antworten
  • using multiple accumulators
  • adding local variables
  • function call inlining
  • none of the above would provide a speed benefit

Frage 80

Frage
The .data section of an x86 assembly program is used to specify the parameters for each procedure.
Antworten
  • false
  • true

Frage 81

Frage
In C, a pointer variable is used for storing an address
Antworten
  • True
  • False

Frage 82

Frage
If x is the most negative signed integer, what is -x?
Antworten
  • the most negative signed number
  • one
  • the most positive signed number
  • negative one

Frage 83

Frage
In a DRAM, all cells have to be periodically refreshed, not just the ones that have been read.
Antworten
  • True
  • False

Frage 84

Frage
In a program with good ____________, if a memory location is referenced once, then the program is likely to access nearby memory locations in the near future
Antworten
  • Spatial locality
  • Temporal locality
  • Repetitive locality
  • Associative locality

Frage 85

Frage
The ASCII code for the character 'B' is 0x42. What is the ASCII hex code for the character 'D'?
Antworten
  • 0x4B
  • 0x5A
  • 0x48
  • 0x44

Frage 86

Frage
If we were running a non-pipelined processor (like SEQ) with a real memory system, which of the following optimization strategies would not longer provide a speed benefit?
Antworten
  • none of the above would provide a speed benefit
  • adding local variables
  • using multiple accumulators
  • function call inlining

Frage 87

Frage
In C, local variables allocated inside functions are allocated:
Antworten
  • On the stack
  • In static storage
  • In virtual memory
  • In the heap

Frage 88

Frage
In C, using default floating point settings, a special value of "infinity" is computed when
Antworten
  • A floating-point computation results in an overflow
  • Program execution is halted
  • An erroneous value is computed and execution continues
  • An exception is raised

Frage 89

Frage
The ASCII code for the character 'B' is 0x42. What is the ASCII hex code for the character ‘E’?
Antworten
  • 0x45
  • 0x48
  • 0x56

Frage 90

Frage
In given two C modules which rule will Unix linker use to resolve multiple symbol definition?
Image:
вв (binary/octet-stream)
Antworten
  • 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

Frage 91

Frage
The assembly instruction int x used to make system calls only accepts a 1-byte (256-value) argument x, but Linux uses it to support over 300 system calls. How does it do that?
Antworten
  • SRAM would lose its data, DRAM would keep its data
  • SRAM would keep its data, DRAM would keep its data
  • SRAM would keep its data, DRAM would lose its data
  • SRAM would lose its data, DRAM would lose its data

Frage 92

Frage
The contents of how many program registers are modified by an assembly push operation?
Antworten
  • 1
  • 2
  • 3 or more
  • it depends on that argument of the push

Frage 93

Frage
The difference between the SAR (arithmetic shift right) and SHR (logical shift right) operations is that SAR puts a one into the leftmost bit after a shift and SHR puts a zero.
Antworten
  • false
  • true

Frage 94

Frage
The EBP is a callee-saved register.
Antworten
  • true
  • false

Frage 95

Frage
The EFLAGS register contains the zero flag and the sign flag?
Antworten
  • true
  • false

Frage 96

Frage
What is the value of the following C expression? x=0x1234 and y=0x3 ((x >> y) << y)
Antworten
  • 0x1230
  • 0x1234
  • 0x0246
  • 0x1200

Frage 97

Frage
The hardware is aware of the program stack
Antworten
  • true
  • false

Frage 98

Frage
The instruction addq %rax, %rbx changes what?
Antworten
  • The contents of the rbx register
  • The contents of memory at an address found in the rax register
  • The contents of memory at an address found in the rbx register
  • The contents of the rax register

Frage 99

Frage
What is the value of the following C expression? x=0x00 and y=0xA5 x && ~y
Antworten
  • 0xFF50
  • 0x0000
  • 0x0001
  • 0x11A5

Frage 100

Frage
The instruction cmp eax,ebx (or cmp %ebx,%eax in AT&T syntax) computes the value of EAX - EBX.
Antworten
  • true
  • false

Frage 101

Frage
_______ - program transformation that reduces the number of iterations for a loop by increasing the number of elements computed on each iteration
Antworten
  • Loop unrolling
  • Memory aliasing
  • Side effect
  • Code motion

Frage 102

Frage
The valid bit is associated with
Antworten
  • fully-associative caches
  • write-through caches
  • set-associative caches
  • direct-mapped caches

Frage 103

Frage
It is possible to explicitly specify the number of threads to be created in the team, using the _____ attribute:
Antworten
  • pragma omp
  • parallel
  • private
  • Num_threads

Frage 104

Frage
CPU optimized for throughput
Antworten
  • True
  • False

Frage 105

Frage
The working set of a program is formed by
Antworten
  • The pages that the program is actively using
  • The libraries required by the program
  • The memory of the program that is currently in physical memory
  • All the files the program needs to execute

Frage 106

Frage
This problem occurs when a larger type is converted into a smaller type or with the signed-unsigned operations?
Antworten
  • truncation
  • overflow

Frage 107

Frage
Using multiple accumulators is usually used to reduce what source of inefficiency?
Antworten
  • unnecessary memory references
  • condition checking overhead
  • data dependencies
  • poor branch prediction

Frage 108

Frage
169. In C a single statement that performs the equivalent of y=x*100; but without using the multiply operator (*);
Antworten
  • y = (x>>6)+(x<<5)+(x<<2)
  • y = (x<<6)+(x<<3)+(x>>2)
  • y = (x<<5)+(x<<5)+(x<<7)
  • y = (x<<6)+(x<<5)+(x<<2)

Frage 109

Frage
We can encode the C command a ? b : c, where all three variables are of type int,
Antworten
  • ((-!!a) & b) | ((-!a) & c)
  • ((!!a) &amp; b) | ((!a) &amp; c)
  • Any of the above
  • (a &amp; b) | ((!a) &amp; c)

Frage 110

Frage
We say that pipelining generally increases latency. That statement means (select all that are part of the definition of "increases latency")
Antworten
  • each instruction takes more time to complete
  • each instruction takes less time to complete
  • entire programs take more time to complete
  • entire programs take less time to complete

Frage 111

Frage
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?
Image:
Q (binary/octet-stream)
Antworten
  • 1 & 2 only
  • 2 & 3 only
  • 1 only
  • 2

Frage 112

Frage
At which of the following times is a stack frame created?
Image:
Q (binary/octet-stream)
Antworten
  • II and III only
  • II only
  • III only
  • I and II only

Frage 113

Frage
The bitwise and operation (& in C) can be used to flip the bits of a word
Antworten
  • true
  • false

Frage 114

Frage
Linking can be performed at
Antworten
  • run time
  • compile time
  • all of the above
  • load time

Frage 115

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

Frage 116

Frage
This is an example of?
Image:
Q (binary/octet-stream)
Antworten
  • Hybrid system
  • shared memory UMA
  • Distributed memory architecture
  • Shared memory NUMA

Frage 117

Frage
This is an example of?
Image:
Q (binary/octet-stream)
Antworten
  • None
  • Loop unrolling
  • Loop fusion
  • Loop fission

Frage 118

Frage
This is an example of?
Image:
Q (binary/octet-stream)
Antworten
  • MIMD
  • MISD
  • SIMD
  • SISD

Frage 119

Frage
This is an example of?
Image:
й (binary/octet-stream)
Antworten
  • MIMD
  • MISD
  • SIMD
  • SISD

Frage 120

Frage
This is an example of?
Image:
ц (binary/octet-stream)
Antworten
  • MIMD
  • MISD
  • SIMD
  • SISD

Frage 121

Frage
This is an example of?
Image:
у (binary/octet-stream)
Antworten
  • MIMD
  • MISD
  • SIMD
  • SISD

Frage 122

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

Frage 123

Frage
How is 148 (decimal) represented in a 16-bit 2’s complement binary format?
Antworten
  • 0000 0000 1101 0111
  • 0000 0000 0010 1001
  • 1111 1111 0010 1000
  • 1111 1111 0110 1100

Frage 124

Frage
In a Compare the runtime of y = x * 5 and y = (x<<2) + x, measured by the time it takes for the resulting value of y to be available somewhere in the pipeline.
Antworten
  • y = x * 5 is faster
  • y = (x<<2) + 5 is faster
  • not given
  • they take the same number of cycles

Frage 125

Frage
What is the difference between 15 and $15?
Antworten
  • 15 is an address, $15 is a value
  • 15 is a value, $15 is an address
  • 15 is legal in assembly, $15 is not
  • $15 is legal in assembly, 15 is not

Frage 126

Frage
What is the result of the following assembly code instruction?
Image:
Image (binary/octet-stream)
Antworten
  • Fetch the data from register %ecx and store in register %eax
  • Fetch the data from the register %ecx and store in the memory address indicated by (%eax)
  • Fetch the data from the register %eax and store in register %ecx
  • Fetch the data from the memory address indicated by (%eax) and store in the register %ecx

Frage 127

Frage
What is the value of the following C expression? x=0xA0 and y=0x0F ~x||~y
Antworten
  • 0х0001
  • 0х6000
  • 0xFF50
  • 0xFFFF

Frage 128

Frage
What value ends up in EAX afer the following code is executed?
Image:
Image (binary/octet-stream)
Antworten
  • 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)

Frage 129

Frage
When shifting a two's complement number to the left, an overflow can only occur if the number is negative, since positive numbers have a zero in the leftmost bit.
Antworten
  • True
  • False

Frage 130

Frage
Which of the five phases determines how many bytes long an instruction is?
Antworten
  • Fetch
  • Decode
  • Writeback
  • Execute

Frage 131

Frage
Which of the five phases determines what the next PC is?
Antworten
  • Fetch
  • Memory
  • Execute
  • Decode

Frage 132

Frage
Which of the five phases determines the destination register for instructions that write to registers?
Antworten
  • Decode
  • Writeback
  • Fetch
  • Execute

Frage 133

Frage
Which of the following computations may be performed by exactly one CPU instruction? (img) a = 5; a = b + c * 5; for (i = 0; i < 10; i += a[i++]);
Antworten
  • I, II, and III
  • II only
  • I and II only
  • I only

Frage 134

Frage
Which of the following is true?
Antworten
  • A direct-mapped cache is a set-associative cache with set size 1
  • A direct-mapped cache is a fully-associative cache with only one set
  • A direct-mapped cache is a fully-associative cache with set size 1
  • A direct-mapped cache is a set-associative cache with only one set

Frage 135

Frage
Which of the following manages the transfer of data between the cache and main memory
Antworten
  • Operating system
  • Compiler
  • Hardware
  • Registry

Frage 136

Frage
Which of the following manages the transfer of data between the CPU registers and the cache
Antworten
  • Operating system
  • Compiler
  • Hardware
  • Registry

Frage 137

Frage
Which of the following registers is the lower order 16 bit register of register %ecx?
Antworten
  • %cx
  • %cl
  • %ch
  • %cy

Frage 138

Frage
Which of the following statements about alignment within C struct's is true?
Antworten
  • A constant offset associated with the member is added to the address
  • The struct consists of an array of pointers to the elements of the struct
  • The element name is looked up in a symbol table
  • A linear search is made from the base address of the struct

Frage 139

Frage
Which of the following statements about floating-point numbers in C is true?
Image:
Image (binary/octet-stream)
Antworten
  • II only
  • III only
  • I
  • I and II

Frage 140

Frage
Which one of the following IA32 registers is typically used for stack management?
Antworten
  • %esp
  • %eax
  • %ebx
  • %edi

Frage 141

Frage
Which one of the following optimizations does not provide any speed benefit for a non-pipelined processor, such as SEQ?
Antworten
  • Storing reused computed values in variables instead of recomputing them
  • Invocation inlining
  • Using more efficient algorithms
  • Reassociation

Frage 142

Frage
Which of the following levels of a typical memory hierarchy transfers data in chunks of smallest size?
Antworten
  • Main memory < ---> disk
  • Cache < ---> main memory
  • They all transfer one byte at a time
  • CPU registers < ---> cache

Frage 143

Frage
In C, a pointer variable is used for storing an address
Antworten
  • True
  • False

Frage 144

Frage
If we cut power for one millisecond, which of the following is true?
Antworten
  • SRAM would keep its data, DRAM would lose its data
  • SRAM would lose its data, DRAM would keep its data
  • SRAM would lose its data, DRAM would lose its data
  • SRAM would keep its data, DRAM would keep its data

Frage 145

Frage
If we cut power for one minute, which of the following is true?
Antworten
  • SRAM would lose its data, DRAM would lose its data
  • SRAM would lose its data, DRAM would keep its data
  • SRAM would keep its data, DRAM would keep its data
  • SRAM would keep its data, DRAM would lose its data

Frage 146

Frage
Select the most correct statement from the following as applied over the last two decades:
Antworten
  • Processors get faster but memory does not
  • Processors and memory both get faster, but memory gets faster faster that processors do
  • Processors and memory both get faster, but processors get faster than memory does
  • Memory gets faster but processor does not

Frage 147

Frage
Which one of the following optimizations does not provide any speed benefit for a non-pipelined processor, such as SEQ?
Antworten
  • Using more efficient algorithms
  • Invocation inlining
  • Reassociation
  • Storing reused, computed values in variables instead of recomputing them

Frage 148

Frage
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?
Image:
Image (binary/octet-stream)
Antworten
  • 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 < sx
  • Move the check for (x % 2) != 0 to before the loop

Frage 149

Frage
Consider the following code. This code would most likely benefit from which of the following optimization strategies
Image:
Image (binary/octet-stream)
Antworten
  • Using multiple accumulators
  • Improving cache locality
  • Loop unrolling
  • Adding local variables

Frage 150

Frage
What does the following C code print?
Image:
Image (binary/octet-stream)
Antworten
  • P = 103, c = 101
  • P = 104, c = 101
  • P = 105, c = 103
  • P = 104, c = 102

Frage 151

Frage
The bitwise and operation (& in C) can be used to flip the bits of a word
Antworten
  • True
  • False

Frage 152

Frage
The bitwise xor operation (^ in C) can be used to flip the bits of a word
Antworten
  • True
  • False

Frage 153

Frage
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?
Antworten
  • 0x02345
  • 0x22244
  • 0x12040
  • 0x12354

Frage 154

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

Frage 155

Frage
Consider the following code. Which of the following changes would make the largest positive impact on its cache locality?
Image:
Image (binary/octet-stream)
Antworten
  • Put the for-i loop inside of the for-j loop instead of the other way around
  • Store the result of (i*101)%n outside the inner loop
  • Block the accesses by nesting three or four for loops instead of just two
  • Change int** to int*

Frage 156

Frage
Consider the following code. Assume the compiler is performing no optimizations and that isPrime is the exact code presented in another question on this exam. Which of the following strategies would improve the speed of this code the most?
Image:
Image (binary/octet-stream)
Antworten
  • Inline the isPrime call
  • Add a second ans accumulator
  • Swap the order of the if statements
  • Change the nested if statements to a single if with a &&

Frage 157

Frage
Consider the following two versions of a C function: (Assume len is larger than 10)
Image:
Image (binary/octet-stream)
Antworten
  • sum1
  • None of them
  • sum2
  • Both of them

Frage 158

Frage
Which of the following is necessary true regarding the following code fragment?
Image:
Image (binary/octet-stream)
Antworten
  • It exhibits locality of reference but only when a == b
  • It exhibits locality of reference because the variables are allocated near each other
  • It exhibit no locality of reference
  • It exhibits locality of reference no matter where the variables are allocated

Frage 159

Frage
A & B is the bitwise version of A && B; A | B is the bitwise version of A || B; which of the following is the bitwise version of A == B?
Antworten
  • ~(a = b)
  • a = b
  • ~ (a ^ b)
  • a ^ b

Frage 160

Frage
The unary & operator returns (in C language)
Antworten
  • The logical “and” of two integer operands
  • The logical “or” of two integer operands
  • The value of a data object
  • The address of a data object

Frage 161

Frage
In C a single statement that performs the equivalent of y = x *100, but without using the multiply operator (*)
Antworten
  • y = (x<<6) + (x<<5) + (x<<2)
  • y = (x>>6) + (x<<5) + (x<<2)
  • y = (x<<6) + (x<<3) + (x>>2)
  • y = (x<<5) + (x<<5) + (x<<7)

Frage 162

Frage
Adding local variable is usually used to reduce what source inefficiency?
Antworten
  • Condition checking overhead
  • Poor branch prediction
  • Unnecessary memory references
  • Data dependencies

Frage 163

Frage
If, in C, an array is declared by “int a[10];”, then accessing a[11] during execution will generate an error message.
Antworten
  • True
  • False

Frage 164

Frage
In C, if x is an integer variable, the expression “x << 3” computes x * 8 but does not change the value of x.
Antworten
  • True
  • False

Frage 165

Frage
Which of the following code snippets is fastest? Assume n is very large (more than ten thousand).
Antworten
  • 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];
  • Image:
    Image (binary/octet-stream)
  • two or more of the above are equivalently the fastest

Frage 166

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

Frage 167

Frage
In binary, the number 1/3 is 0.01010101 . . .. In the following, assume that x is an int and y is a short. (short)((0x5555 * (int)y)>>16) and y/3 could differ because of overflow
Antworten
  • True
  • False

Frage 168

Frage
How is 148 (decimal) represented in a 16-bit 2’s complement binary format?
Antworten
  • 0000 0000 1101 0111
  • 0000 0000 0010 1001
  • 1111 1111 0010 1000
  • 1111 1111 0110 1100

Frage 169

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

Frage 170

Frage
In a Compare the runtime of y = x * 5 and y = (x<<2) + x, measured by the time it takes for the resulting value of y to be available somewhere in the pipeline.
Antworten
  • y = x * 5 is faster
  • they take the same number of cycles
  • not given
  • y = (x<<2) + 5 is faster

Frage 171

Frage
The program counter contains:
Antworten
  • The address of the CPU instruction that is about to be executed
  • The number of programs currently running
  • The number of CPU instructions a program has executed so far
  • The number of processes currently running

Frage 172

Frage
A memory leak is caused by a:
Antworten
  • Bug in the memory allocator that fails to free memory
  • Failure to free allocated memory
  • None of these
  • Function that allocates a large amount of memory from the heap

Frage 173

Frage
Registers and cache memory are the same thing
Antworten
  • False
  • True

Frage 174

Frage
In a computer in which both addresses and integers are 32 bits wide, how many bytes of memory will the compiler allocate for the following code fragment?
Image:
2018 05 13 131017 (binary/octet-stream)
Antworten
  • 32
  • 8
  • 16
  • 4

Frage 175

Frage
In C, local variables allocated inside functions are allocated:
Antworten
  • On the stack
  • In the heap
  • In virtual memory
  • In static storage

Frage 176

Frage
What is the value of the following C expression? x=0xA0 and y=0x0F ~x || ~y
Antworten
  • 0x0000
  • 0xFF50
  • 0xFFFF
  • 0x0001

Frage 177

Frage
What is an example of?
Image:
2018 05 13 131348 (binary/octet-stream)
Antworten
  • Loop unrolling
  • Loop fission
  • none
  • Loop fusion

Frage 178

Frage
How is 215 (decimal) represented in a 16-bit 2's complement binary format?
Antworten
  • 1111 1111 0010 1001
  • 0000 0000 1101 0111
  • 0000 0000 0010 1001
  • 1111 1111 0010 1000

Frage 179

Frage
This code indicates that Work2 and Work3 must be run in _______ :
Image:
2018 05 13 131712 (binary/octet-stream)
Antworten
  • none
  • parallel
  • sequence
  • both

Frage 180

Frage
____ 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.
Antworten
  • Code motion
  • Side effect
  • Loop unrolling
  • Memory aliasing

Frage 181

Frage
In C, for the expression (x | THE_MASK), where THE_MASK has at least one bit that is not zero, the result will be zero if all the bits of x are zero.
Antworten
  • True
  • False

Frage 182

Frage
What is the value of the following C expression? x = 0x128 and y = 0x2 ~x << y (in hex)
Antworten
  • 0x000004A0
  • 0x000FFB5C
  • 0xFFFFFB5C
  • 0x00FF04A0

Frage 183

Frage
In C, using default floating point settings, a special value of "infinity" is computed when:
Antworten
  • A floating-point computation results in an overflow
  • Program execution is halted
  • An exception is raised
  • An erroneous value is computed and execution continues

Frage 184

Frage
GPU optimized for latency.
Antworten
  • true
  • false

Frage 185

Frage
If you don’t explicitly specify the number of threads (OpenMP) how many thread will be executed?
Antworten
  • 1
  • Depends on the number of cores on computer
  • 2
  • 4

Frage 186

Frage
CPU optimized for latency
Antworten
  • true
  • false

Frage 187

Frage
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:
Antworten
  • Static linker
  • Dynamic linker
  • Both
  • none

Frage 188

Frage
If we find the data we want in a cache, we call that a
Antworten
  • Cache find
  • Cache hit
  • Cache miss
  • Cache success

Frage 189

Frage
The___construct forms a region that contains one or more structured blocks. Each block of a_____ directive executed once by one of the threads (any one) in the team?
Antworten
  • parallel
  • master
  • section
  • schedule

Frage 190

Frage
Pick a value for A and for B which will cause the two procedures below to return different results.
Image:
2018 05 13 132528 (binary/octet-stream)
Antworten
  • a=7; b=1;
  • a=1; b=2;
  • a=1; b=5;
  • a=1; b=1;

Frage 191

Frage
Pick a value for A and for B which will cause the two procedures below to return the same results.
Image:
2018 05 13 132636 (binary/octet-stream)
Antworten
  • ОДИНАКОВЫЕ ВОЗВРАЩАЮТ: (7,1) (1,5) (1,1)
  • нет других вариантов

Frage 192

Frage
A is the 4-bit value 0011 and B is the 4-bit value 0110. What is A^B?
Antworten
  • 0011
  • 1110
  • 0111
  • 0101

Frage 193

Frage
Consider the following code. This code would most likely benefit from which of the following optimization strategies.
Image:
2018 05 13 133034 (binary/octet-stream)
Antworten
  • improving locality
  • loop unrolling
  • using multiple
  • adding local variables

Frage 194

Frage
Conflict misses are typically discussed in connection with?
Antworten
  • all of the above
  • fully-associative caches
  • set-associative caches
  • direct-mapped caches

Frage 195

Frage
What is -5 as a six bit two’s complement number? Answer in binary
Antworten
  • 101111
  • 111011
  • 000001
  • 011011

Frage 196

Frage
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?
Antworten
  • static
  • runtime
  • dynamic
  • auto

Frage 197

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

Frage 198

Frage
How is 28 (decimal) represented in an 8-bit 2’s complement binary format?
Antworten
  • 0001 1100
  • 1110 0100
  • 1100 1011
  • 1110 0011

Frage 199

Frage
The ASCII code for the character ‘b’ is 98. How can the character ‘b’ be represented in binary using ASCII codes?
Antworten
  • 1011 1111
  • 1010 1111
  • 0110 0010
  • 1000 0001

Frage 200

Frage
This code indicates that any of the tasks Work1, Work2 + Work3 and Work4 may run in _____________:
Image:
2018 05 13 133639 (binary/octet-stream)
Antworten
  • parallel
  • sequence
  • both
  • none
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