An Oldest - First Selection Logic Implementation forNon - Compacting

An Oldest-First Selection Logic Implementation for Non-Compacting Issue Queues Alper Buyuktosunoglu, Ali El-Moursy, David H. Albonesi Department of Electrical and Computer Engineering University of Rochester Abstract|Microprocessor power dissipation is a growing concern, so much so that it threatens to limit future performance improvements. A major consumer of microprocessor power is the issue queue. Many microprocessors, such as the Compaq Alpha 21264 and IBM POWER4TM , use a compacting latch-based issue queue design which has the advantage of simplicity of design and veri cation. The disadvantage of this structure, however, is its high power dissipation. In this paper, we propose a new selection logic implementation in conjunction with a non-compacting issue queue. This scheme achieves comparable delays to the existing position-based selection approach used for compacting issue queues, yet results in far less power with a small performance loss.