RUNAHEAD EXECUTION: AN EFFECTIVE ALTERNATIVE TO LARGE INSTRUCTION WINDOWS

摘要

AN INSTRUCTION WINDOW THAT CAN TOLERATE LATENCIES TO DRAM MEMORY IS PROHIBITIVELY COMPLEX AND POWER HUNGRY TO AVOID HAVING TO BUILD SUCH LARGE WINDOWS, RUNAHEAD EXECUTION USES OTHERWISE-IDLE CLOCK CYCLES TO ACHIEVE AN AVERAGE 22 PERCENT PERFORMANCE IMPROVEMENT FOR PROCESSORS WITH INSTRUCTION WINDOWS OF CONTEMPORARY SIZES. THIS TECHNIQUE INCURS ONLY A SMALL HARDWARE COST AND DOES NOT SIGNIFICANTLY INCREASE THE PROCESSOR'S COMPLEXITY.