Question

Which of the following statements are True? There might be multiple answers.

1. By adding caches between main memory and the CPU, the time it takes on average to retrieve blocks of data from main memory is longer than it would be if the cache did not exist.
2. Little's Law governs the overall speedup of a program when using special hardware architectures like GPUs or multiple cores when they are operating on shared memory.
3. Processor Pipelining is bound to always improve latency of execution of the overall program.
4. Future software engineers don't need any knowledge of computer archtiecture. Just grinding away on leet code is enough.
5. Iron's Law of performance can be stated as "Execution Time = Instruction Count * Cycles per Instruction * Clock rate"

Answer 1

None of the given statements are completely true. Caches reduce retrieval time, Little's Law does not govern hardware speedup, Pipeline can improve throughput but not always latency, knowledge of computer architecture is crucial for software engineers, and Iron's Law was confused with Amdahl's Law.

Step-by-step explanation:

Out of the statements given, none are completely true:

1. Caches are actually designed to decrease the average time to retrieve data by storing frequently accessed data closer to the CPU. Therefore, caches reduce the time it takes on average to retrieve blocks of data from main memory.
2. Little's Law refers to the queuing theory in operations research, and it does not specifically govern the speedup of programs using hardware architectures like GPUs or multicore systems operating on shared memory.
3. Processor Pipelining can improve the throughput of a CPU by executing different stages of instructions simultaneously. However, it does not always improve the latency for a single instruction or the overall program execution, especially in the case of pipeline hazards or branch mispredictions.
4. Knowledge of computer architecture is important for software engineers as it can affect code optimization and performance, and understanding architecture can lead to more effective programming beyond algorithm challenges.
5. Iron's Law of performance is incorrectly stated. The correct formulation is known as Amdahl's Law, which can be represented as Execution Time = (Instruction Count * Cycles per Instruction) / Clock rate.