[lispm]

See also ftp://publications.ai.mit.edu/ai-publications/pdf/AITR-1417.pdf. for an early perspective on generational GC.

Ephemeral GC btw. means something slightly different. An ephemeral GC is mostly concerned with the detection and collection of short lifetime objects in main memory.

The main problem is that architectures, implementations, actual computers, programs were so different, that you could find all kinds of numbers. Even a generational GC can get extremely busy and may not prevent from having full GCs over large virtual memory from time to time. It's also a huge difference if the GC was incremental (the work was spread over the whole compuation) or if the system stopped for much of the GC work.