Garbage collection software integrated with the system swapper in a virtual memory system

The authors have designed and implemented a modular Lisp interpreter for garbage collector evaluation. Data structures such as the list store, the hash table, the symbol table and the stacks were kept in separate modules with only the routines needed to handle them. Routines in other modules may only read and manipulate these data structures through the specified routines. Using this approach, when a garbage collector strategy or method of storing list cells is changed only the store module need be modified. Test programs and measurement strategies were designed for evaluating garbage collector performance in a virtual memory environment. Three garbage collectors have been coded and tested. They are a conventional link reversal marking garbage collector, a conventional recopying garbage collector, and a garbage collector integrated with the system swapper. The implementations are described and their performances are compared.