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CPU Optimization. Out-of-Order Execution (OoOE). Stalling a Checkout Line Ever forgot to get a barcode?. CPU with separate instruction and data caches. FLASH. RAM. Instruction Cache. Data Cache. ALU. An Ideal Pipeline. Pipeline with instruction & data cache. Instruction NOT in cache.
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CPU Optimization Out-of-Order Execution (OoOE)
CPU with separate instruction and data caches FLASH RAM Instruction Cache Data Cache ALU
An Ideal Pipeline Pipeline with instruction & data cache Instruction NOT in cache Operand NOT in cache
Example: How long would this program take to execute? R1 = R2 R2 = R1 + R3 R4 = R3 + R5 *R3, R4, R5 Already in data cache
Sequential Execution Time = 12 Units Re-ordered Execution Time = 12 Units
The CDC 6600. The first computer to use OoOE (1964) Source: wikipedia