After 7097048, the jmap -heap output looks similar to that of the other GCs (see below). It might be helpful to extend it a bit with some G1-specific information, like region size / number of regions / etc. Additionally, given that for G1 the "To" survivor space will always be empty, maybe we want to remove that section and rename the "From Space" section as simply "Survivor Space". (Thanks to Bengt for these suggestions.)