I thought based on the title it would a be a simple GC that worked similarly to a real treadmill. The GC would move used objects to the front (as if they were

I thought based on the title it would a be a simple GC that worked similarly to a real treadmill. The GC would move used objects to the front (as if they were running forward). The unused objects would either be moved (or left in place) to the back (as if they stopped running). All memory in the back would be considered free space when alloc-ing. But the article quickly says thats not going to happen since its "in-place" and I have no idea what my idea would be already called.