JDK-8351011 proposes using a single VirtualSpace for the young and tenured generations to simplify sizing the heap when using automatic heap sizing. The typical case is that after a full collection, the young generation is empty. With a single VirtualSpace serving both young and tenured generations, it is easier to resize the heap regions without needing to move data around when the young generation is placed after the tenured generation. Expansion and contraction of the committed heap memory is straightforward in this case e.g. reducing the size of the young generation can be done by uncommitting from the end of the single VirtualSpace holding the entire heap. This issue proposes swapping the order of the young and tenured generations in memory via an experimental product flag: -XX:+SwapSerialGCGenerations