This probably isn't crystal clear from this post alone, but for PageRank the 42GB working set has a good mix of read and write. Specifically, about 14GB of targ

This probably isn't crystal clear from this post alone, but for PageRank the 42GB working set has a good mix of read and write. Specifically, about 14GB of target rank vector gets +='d all over the place. If they got hammered randomly, then lots of paging and writing would happen.