Virtual Labs

Reorder Buffer and Out-of-Order Execution

After completing the ROB simulation, what is the main benefit of having a large Reorder Buffer?

a: Faster clock speeds Explanation

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b: More instructions can be in-flight, increasing parallelism Explanation

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c: Reduced power consumption Explanation

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d: Simplified instruction decode Explanation

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Based on your simulation experience, when does an instruction get removed from the ROB?

a: As soon as it finishes execution Explanation

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b: When its result is needed by another instruction Explanation

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c: When it reaches the head of ROB and commits successfully Explanation

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d: After a fixed number of cycles Explanation

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From your simulation observations, what happens to ROB entries when an exception occurs?

a: All entries are immediately cleared Explanation

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b: Only the faulting instruction is removed Explanation

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c: Instructions before the exception commit, younger instructions are flushed Explanation

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d: The processor continues normal operation Explanation

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Based on the simulation timeline you observed, why might an instruction stay in the 'Complete' state for multiple cycles?

a: The functional unit is still busy Explanation

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b: It's waiting for older instructions to commit first Explanation

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c: The instruction is being re-executed Explanation

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d: There's insufficient memory bandwidth Explanation

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In your simulation, how does register renaming interact with the ROB?

a: They operate independently Explanation

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b: ROB entries serve as temporary register names until commit Explanation

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c: Register renaming replaces the need for ROB Explanation

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d: ROB only handles memory operations Explanation

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From analyzing the commit log in your simulation, what can you conclude about instruction commit order?

a: Instructions commit in execution completion order Explanation

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b: Instructions commit based on their execution time Explanation

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c: Instructions always commit in original program order Explanation

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d: Instructions commit randomly to maximize throughput Explanation

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What performance metric from your simulation best indicates ROB effectiveness?

a: Clock frequency Explanation

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b: ROB utilization percentage and average CPI Explanation

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c: Cache hit rate Explanation

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d: Memory bandwidth usage Explanation

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Based on your simulation experience with dependencies, which scenario would benefit most from ROB and out-of-order execution?

a: A sequence of dependent instructions with long latencies Explanation

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b: Independent instructions with varying execution times Explanation

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c: Only memory operations Explanation

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d: Only arithmetic operations Explanation

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From your advanced simulation scenarios, what is the main challenge in implementing large ROBs in real processors?

a: Software compatibility issues Explanation

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b: Hardware complexity, power consumption, and access time Explanation

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c: Operating system limitations Explanation

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d: Compiler optimization difficulties Explanation

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