+The growning number in the second column shows how many RRD have been
+updated ... If everything is in cache, the number will Jump to $Chunk almost
+immediately. Then the system will seem to hang as 'sync' runs, to make sure
+all data has been written to disk prior to the next perftest run. This may
+not be 100% real-life, so you may want to remove the sync just for fun
+(then it is even less real-life, but different)