Method and system of scheduling out-of-order operations without the requirement to execute compare, ready and pick logic in a single cycle

Abstract

A method and system to schedule out of order operations without the requirement to execute compare, ready and pick logic in a single cycle. A lazy out-of-order scheduler splits each scheduling loop into two consecutive cycles. The scheduling loop includes a compare stage, a ready stage and a pick stage. The compare stage and the ready stage are executed in a first of the two consecutive cycles and the pick stage is executed in a second of the two consecutive cycles. By splitting each scheduling loop into two consecutive cycles, selecting the oldest operation by default and checking the readiness of the oldest operation, it relieves the system of timing requirements and avoids the need for power hungry logic. Every execution of an operation does not appear as one extra cycle longer and the lazy out-of-order scheduler retains most of the performance of a full out-of-order scheduler.