Reducing Garbage Collector Cache Misses

Boehm, Hans

HP Development Company

关键词: garbage collection;    memory management;    cache;    prefetch;   

RP-ID  :  HPL-2000-99

学科分类：计算机科学（综合）

美国|英语

来源: HP Labs

【 摘 要 】

Cache misses are currently a major factor in the cost of garbage collection, and we expect them to dominate in the future. Traditional garbage collection algorithms exhibit relatively little temporal locality; each live object in the heap is likely to be touched exactly once during each garbage collection. We measure two techniques for dealing with this issue: prefetch-on-grey, and lazy sweeping. The first of these is new in this context. Lazy sweeping has been in common use for a decade. It was introduced as a mechanism for reducing paging and pause times; we argue that it is also crucial for eliminating cache misses during the sweep phase. Our measurements are obtained in the context of a non-moving garbage collector. Fully copying garbage collection inherently requires more traffic through the cache, and thus probably also stands to benefit substantially from something like the prefetch-on-grey technique. Generational garbage collection may reduce the benefit of these techniques for some applications, but experiments with a non-moving generational collector suggest that they remain quite useful. 7 Pages