The garbage collection advantage: improving program locality

As improvements in processor speed continue to outpace improvements in cache and memory speed, poor locality increasingly degrades performance. Because copying garbage collectors move objects, they have an opportunity to improve locality. However, no static copying order is guaranteed to match program traversal orders. This paper introduces online object reordering (OOR) which includes a new dynamic, online class analysis for Java that detects program traversal patterns and exploits them in a copying collector. OOR uses runtime method sampling that drives just-in-time (JIT) compilation. For each hot (frequently executed) method, OOR analysis identifies the hot field accesses. At garbage collection time, the OOR collector then copies referents of hot fields together with their parent. Enhancements include static analysis to exclude accesses in cold basic blocks, heuristics that decay heat to respond to phase changes, and a separate space for hot objects. The overhead of OOR is on av...

• Type: Conference
• Year: 2004
• Where: OOPSLA
• Authors: Xianglong Huang, Stephen M. Blackburn, Kathryn S. McKinley, J. Eliot B. Moss, Zhenlin Wang, Perry Cheng
• Keywords: Copying, Copying Orders, OOPSLA 2004, Program Traversal