Understanding Computer Processors: Cache, Virtual Memory, and Multi-core, Exams of Computer Science

Download Understanding Computer Processors: Cache, Virtual Memory, and Multi-core and more Exams Computer Science in PDF only on Docsity! EE 457 Computer Systems Organization Review Exam Q & A 2024 1. What is the primary function of Register Transfer Level (RTL) in machine organization? a) To manage the cache hierarchy b) To define the data flow between registers c) To handle the exception handling mechanism d) To optimize the power consumption of the processor Answer: b) To define the data flow between registers Rationale: RTL is a design abstraction which defines the operations, data flows between hardware registers, and the clock cycle timing. 2. How does out-of-order execution enhance CPU performance? a) By reducing the clock speed b) By executing instructions as they are decoded c) By executing instructions based on operand availability rather than their original order d) By increasing the size of the instruction set Answer: c) By executing instructions based on operand availability rather than their original order Rationale: Out-of-order execution allows the CPU to make use of instruction cycles that would otherwise be wasted due to delays. 3. In pipelined processors, what is the purpose of the instruction decode (ID) stage? a) To write the results back to the register file b) To fetch the next set of instructions c) To convert the binary instruction into a signal for the control unit d) To perform the actual arithmetic or logical operation Answer: c) To convert the binary instruction into a signal for the control unit Rationale: The ID stage decodes the fetched instruction into signals that will be used by subsequent stages in the pipeline. 4. What is the role of cache memory in a computer system? a) To provide backup storage in case of system failure b) To store the BIOS settings c) To act as a temporary storage for frequently accessed data to speed up processing 11. How does exception handling in processors contribute to system stability? a) By prioritizing certain processes over others b) By preventing the execution of any new instructions c) By providing a mechanism to handle errors and unusual conditions d) By reducing the need for virtual memory Answer: c) By providing a mechanism to handle errors and unusual conditions Rationale: Exception handling allows the processor to deal with unexpected events without crashing, ensuring continued operation. 12. What is the purpose of multi-threaded processors? a) To increase the physical memory available to the processor b) To allow a single core to execute multiple threads simultaneously c) To reduce the overall power consumption of the system d) To eliminate the need for cache memory Answer: b) To allow a single core to execute multiple threads simultaneously Rationale: Multi-threading increases the efficiency of CPU cores by allowing them to switch between threads, reducing idle time. 13. Why is arithmetic logic unit (ALU) critical in processor design? a) It controls the flow of data within the CPU b) It is responsible for performing all the arithmetic and logical operations c) It manages the communication between the CPU and the I/O devices d) It stores the boot sequence of the computer Answer: b) It is responsible for performing all the arithmetic and logical operations Rationale: The ALU is a fundamental component of the CPU that performs mathematical calculations and logical operations, essential for processing data. 14. What is the impact of increasing the number of pipeline stages in a processor? a) Decreased latency for individual instructions b) Increased complexity of the control logic c) Reduced need for virtual memory d) Lower power consumption Answer: b) Increased complexity of the control logic Rationale: More pipeline stages can lead to higher throughput but also increase the complexity of the control logic required to manage the pipeline. 15. How does speculative execution affect the security of a processor? a) It has no impact on security b) It can potentially expose data through side-channel attacks c) It strengthens the encryption mechanisms d) It reduces the risk of buffer overflow attacks Answer: b) It can potentially expose data through side-channel attacks Rationale: Speculative execution can lead to vulnerabilities like Spectre, where attackers can exploit the speculative execution process to access sensitive data. 1. Which of the following accurately describes Register Transfer Level (RTL) in computer architecture? A) It is a high-level language used for programming the CPU B) It represents the behavior of the digital circuit in terms of the transfer of data between registers C) It is used to design the physical layout of the CPU D) It simulates the behavior of the cache memory Answer: B) It represents the behavior of the digital circuit in terms of the transfer of data between registers. Rationale: RTL focuses on the flow of data within the CPU using registers as the key components. 2. What is the primary function of the Arithmetic Logic Unit (ALU) in a CPU? A) Execute instructions loaded from memory B) Perform arithmetic and logical operations on data C) Manage the cache hierarchy D) Control the flow of data between registers Answer: B) Perform arithmetic and logical operations on data. Rationale: The ALU is responsible for executing arithmetic and logical operations on data within the CPU. 3. In terms of performance, which of the following factors can affect the efficiency of a pipelined processor? A) Clock frequency B) Instruction-level parallelism C) Cache hit rate D) Compiler optimization techniques Answer: C) Cache hit rate. Rationale: A higher cache hit rate can reduce the number of stalls in the pipeline, leading to improved performance. 4. What is the purpose of exceptions in computer architecture? A) Improve the performance of the CPU B) Provide a mechanism for handling errors and abnormal conditions C) Optimize memory access patterns D) Manage the cache coherence protocol Answer: B) Provide a mechanism for handling errors and abnormal conditions. Rationale: Exceptions allow the CPU to handle unexpected events such as division by zero or invalid memory access. 5. Which of the following best describes out-of-order execution in a CPU? A) Instructions are executed in the order they are fetched from memory B) Instructions are executed based on their dependency on preceding instructions C) Instructions are executed concurrently in multiple pipelines D) Instructions are executed using speculative execution techniques Answer: B) Instructions are executed based on their dependency on preceding instructions. Rationale: Out-of-order execution allows the CPU to execute instructions independently of their original sequential order, improving performance. 6. How does speculative execution help improve the performance of a Answer: C) By allowing multiple threads to execute concurrently on a single core. Rationale: Multi-threading allows a single core to execute multiple threads concurrently, effectively increasing the core's utilization and improving overall performance. 13. Which of the following best describes the purpose of branch prediction in processor design? A) To predict the outcome of conditional branches and optimize instruction execution B) To prioritize certain instructions over others based on their criticality C) To manage the cache coherence protocol for multi-core processors D) To optimize memory access patterns and cache usage Answer: A) To predict the outcome of conditional branches and optimize instruction execution. Rationale: Branch prediction helps the CPU anticipate the outcome of branching instructions and minimize stalls by speculatively executing instructions. 14. How does the size of the cache memory impact the performance of a processor? A) A larger cache size improves performance by reducing the number of cache misses B) A smaller cache size improves performance by minimizing cache access times C) Cache size has no effect on processor performance D) Cache size influences the clock frequency of the CPU Answer: A) A larger cache size improves performance by reducing the number of cache misses. Rationale: A larger cache size increases the likelihood of having data available in the cache, reducing the time it takes to access data from main memory. 15. Which of the following factors can affect the efficiency of a pipelined processor? A) Clock frequency B) Cache hit rate C) Memory bandwidth D) Branch prediction accuracy Answer: D) Branch prediction accuracy. Rationale: Branch prediction accuracy can impact the efficiency of a pipelined processor by reducing stalls caused by incorrect branch predictions. 16. What role does the instruction decoder play in the execution of instructions in a processor? A) Translate machine instructions into microinstructions for execution B) Manage the cache hierarchy for instruction access C) Decode and interpret instructions fetched from memory for execution D) Coordinate the scheduling of instructions in a pipelined processor Answer: C) Decode and interpret instructions fetched from memory for execution. Rationale: The instruction decoder extracts the opcode and operands from fetched instructions, preparing them for execution within the CPU. 17. How does the use of cache memory improve the performance of a computer system? A) By reducing the clock frequency of the CPU B) By increasing the size of the addressable memory space for applications C) By storing frequently accessed data closer to the CPU for faster access D) By eliminating the need for virtual memory management Answer: C) By storing frequently accessed data closer to the CPU for faster access. Rationale: Cache memory reduces the time it takes to access frequently used data by storing it in a smaller, faster memory space closer to the CPU. 18. Which of the following statements is true about virtual memory management in a computer system? A) Virtual memory eliminates the need for physical memory B) Virtual memory allows applications to address a larger memory space than physical memory C) Virtual memory is used for managing the cache hierarchy D) Virtual memory is unrelated to memory access patterns Answer: B) Virtual memory allows applications to address a larger memory space than physical memory. Rationale: Virtual memory extends the addressable memory space for applications by using disk storage as an extension of physical memory. 19. How does the use of multi-core processors impact the memory bandwidth of a computer system? A) Multi-core processors reduce memory bandwidth through cache sharing B) Multi-core processors increase memory bandwidth by splitting data access across multiple cores C) Multi-core processors have no impact on memory bandwidth D) Multi-core processors prioritize memory access for critical data Answer: B) Multi-core processors increase memory bandwidth by splitting data access across multiple cores. Rationale: Multi-core processors can access memory in parallel, increasing overall memory bandwidth for improved performance. 20. Which of the following best describes cache coherence in a multi-core processor system? A) Ensuring that each core has its own private cache memory B) Ensuring that all cores have a consistent view of shared memory C) Optimizing memory access patterns for each core independently D) Synchronizing the clock frequencies of all cores for consistent performance Answer: B) Ensuring that all cores have a consistent view of shared memory. Rationale: Cache coherence protocols maintain data consistency across shared memory locations accessed by multiple cores in a multi-core processor system. 21. In a multi-threaded processor, how does the Memory Management Unit (MMU) facilitate memory access for each thread? A) By coordinating thread execution on multiple cores B) By translating virtual addresses to physical addresses for each thread C) By optimizing memory access patterns for improved performance such as addition, subtraction, AND, OR, and NOT operations, on input data. What is the main advantage of pipelined processors in comparison to non- pipelined processors? Answer: Pipelined processors can achieve higher instruction throughput by allowing the processor to work on multiple instructions simultaneously, thereby reducing the overall execution time. When does an exception occur in the context of computer architecture and design? Answer: An exception occurs when the processor encounters an unexpected condition during the execution of an instruction, such as division by zero or invalid memory access. How does out-of-order execution contribute to enhancing processor performance? Answer: Out-of-order execution allows the processor to rearrange the order of instruction execution to maximize the utilization of execution units, thereby reducing idle time and improving overall performance. What is the purpose of speculative execution in modern processor design? Answer: Speculative execution is employed to predict the outcome of conditional branches in the program, enabling the processor to execute instructions ahead of time, thereby potentially reducing the impact of branch mispredictions on performance. What role does the cache memory play in a computer system? Answer: The cache memory serves as a high-speed storage buffer between the processor and main memory, aiming to reduce the average time to access data and instructions. How does virtual memory contribute to the efficient utilization of physical memory in a computer system? Answer: Virtual memory allows the system to use disk space as an extension of physical memory, enabling efficient management of memory resources and facilitating the execution of larger programs. What distinguishes multi-core processors from single-core processors? Answer: Multi-core processors integrate multiple processing cores on a single chip, allowing for parallel execution of tasks and improved overall system performance. In the context of multi-threaded processors, what is the significance of thread-level parallelism? Answer: Thread-level parallelism enables multiple threads within a program to execute concurrently, thereby leveraging the capabilities of multi-core processors and enhancing overall performance. Why is cache coherence essential in the context of multi-core processor systems? Answer: Cache coherence ensures that the data stored in the caches of multiple cores remains consistent, thereby preventing inconsistencies and maintaining the integrity of shared data in a multi-core environment. What is the primary purpose of the RTL in computer architecture? Answer: The Register Transfer Level (RTL) serves as an abstraction level that specifies the data paths and control signals between registers and the associated functions. Which factor primarily determines the performance of a processor in a computer system? Answer: The performance of a processor is primarily determined by its clock speed, also known as clock frequency, which dictates the number of instructions executed per unit time. In the context of arithmetic operations, what is the purpose of the Arithmetic Logic Unit (ALU) in a processor? Answer: The ALU is responsible for performing arithmetic and logic operations, such as addition, subtraction, AND, OR, and NOT operations, on input data. What is the main advantage of pipelined processors in comparison to non- pipelined processors? Answer: Pipelined processors can achieve higher instruction throughput by allowing the processor to work on multiple instructions simultaneously, thereby reducing the overall execution time. When does an exception occur in the context of computer architecture and design? Answer: An exception occurs when the processor encounters an unexpected condition during the execution of an instruction, such as division by zero or invalid memory access. How does out-of-order execution contribute to enhancing processor performance? Answer: Out-of-order execution allows the processor to rearrange the order of instruction execution to maximize the utilization of execution units, thereby reducing idle time and improving overall performance. What is the purpose of speculative execution in modern processor design? Answer: Speculative execution is employed to predict the outcome of conditional branches in the program, enabling the processor to execute instructions ahead of time, thereby potentially reducing the impact of branch mispredictions on performance. What role does the cache memory play in a computer system? Answer: