size are reported in table 1 of fig9 the minimum heap sizes are in general quite reasonable u2014 from just under 1 1 to 1 7 times the maximum live data set this is considerably less than is typically required by software real time collectors or even non real time collectors when tuned for throughput maximum collection times u201c max gc u201d u2014 in cycles generally go down considerably as the number of heaps increases this indicates that the multiple heaps are achieving significant useful parallelism in their mark engines the effects of parallelism are even more surprising given that the percentage of non null pointers that are foreign u201c foreign ptrs u201d varies from roughly 25 to 75 apparently each foreign pointer generates sufficient local work that there is some benefit on the other hand the marking engines are stalled have no pointers in their mark queues to process a considerable fraction of the time u201c mark stalled u201d this is due to two factors cross heap pointers and the multi stage pipeline of our design however this does not seem to harm the overall performance when foreign pointers cannot be sent to the remote heap the object containing them must be re enqueued in the local mark queue as described above leading to additional work the most significant effect is seen when the number of pointers.