在JAVA虛擬機器上利用物件重用緩衝區加速物件存取

Abstract

Java為物件導向之語言，因此在Java程式中，會有許多物件存取的動作。然而這些動作需要很多的執行時間以及多次的記憶體存取。在本篇論文中，我們提出一個軟體緩衝區，我們稱作物件重用緩衝區，並且利用許多程式物件存取都有集中於一些少數的類別以及物件變數之特性，將這些經常使用的物件變數放入我們所設計之物件重用緩衝區。接下來物件存取都經由此物件重用緩衝區，以加速物件之存取動作。藉由Trace-driven的方式對Embedded CaffeineMark標竿程式進行模擬，結果顯示在JIT compiler中，若每次記憶體存取為兩個週期時，預估整體效能將增進1.12倍，並且於記憶體存取大於十個週期之平台之上，預估整體效能可以增進1.5倍之上。

One of Java program characteristic is object-oriented; there are lots of object access operation and these operation need lots of time and memory access. In this thesis, we proposed a method of software buffer and using characteristic of object field access are gathering to some classes and instance variables in lots of Java program. We buffer these instance variables in our object-field reusing buffer and access these instance variables from the buffer to accelerate object-field access. By Trace-driven simulation of the proposed method on Embedded CaffeineMark benchmark show that our proposed method can achieve 1.12 speedup over JIT compiler where memory access cycle counts is two cycles. And we predicted that our proposed method could achieve 1.5 above speedup over JIT compiler where memory access cycle counts is over ten cycles.