Faster than light

In the last post, I discussed the fastest possible execution time of a test program, the "speed of light," as it were. There was an important assumption in this calculation: that the CPU issued one instruction per cycle. A common technique to improve performance in modern processors is issuing multiple instructions in the same cycle, also known as superscalar. I hadn't put much thought into a superscalar design given the focus on utilizing the wide vector unit. However, some helpful comments in a previous post have led me to reconsider this decision.