使用功率密度緩和的方式應用於熱感知擺放的優化

Abstract

在此篇論文中，熱感知擺放的問題被重新審視。在先前的研究中，主要著重 於全域擺放(global placement)階段，且效能通常是和擺置器(placer)相關。在 此篇研究中溫度緩和的技術在後擺放(post-placement)階段被實現且與全域擺 放是完全獨立的。我們提出的架構首先確定傳遞的方向藉由避開路徑上的障礙物， 接著將功率密度從高溫區傳遞開來在每步驟中去平衡局部的功率密度。平衡局部 功率密度的問題被模組化成供給-需求(supply-demand)的問題且其解可以得到 最小量總區塊位移。一個解析式溫度分佈演算法緊密地整合在整體架構中且不斷 地根據改變的擺放區塊去更新溫度分佈圖。實驗結果展示出我們提出的技術可以 有效地使溫度分佈變得平緩，和我們類似simPL 方法的擺放器相比可以達到最大 溫差9.3%的改善及最高晶片溫度7.8%的降幅。

In this thesis, the problem of temperature aware placement is revisited. Previous works on temperature oriented techniques primarily focus their attention on global placement stage, and performance is generally placer dependent. The temperature mitigation technique in this work is implemented at post-placement stage which is entirely independent of global placers. Our proposed framework first determines direction of propagation by avoiding obstacles on the path, then propagates power density away from high temperature regions by balancing regional power density in each incremental step. The problem of balancing regional power density is modeled as a supply-demand problem and solution is obtained with minimal total displace- ment of cells. An analytical temperature profiling algorithm is tightly integrated within the framework to constantly update temperature profile in response to in- cremental change in placement. Empirical result demonstrates that our proposed technique can effectively smooth out temperature profile by reducing maximum tem- perature difference by 9.3%, maximum on chip temperature by 7.8%, compared with our placer which is similar to simPL.