The number of merged cards in the statistics are skewed by the merged cards cache: for code simplicity reasons g1 pushes a set number of dummy cards into the merge cards queue.

These dummy cards also wrongly show up in statistics. E.g.

[0.991s][debug][gc,phases ] GC(11) Remembered Sets (ms): Min: 0.03, Avg: 0.03, Max: 0.03, Diff: 0.01, Sum: 0.11, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Eager Reclaim (ms): skipped
[0.991s][debug][gc,phases ] GC(11) Merged Inline: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged ArrayOfCards: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged Howl: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged Full: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged Howl Inline: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged Howl ArrayOfCards: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged Howl BitMap: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged Howl Full: Min: 0, Avg: 0.0, Max: 0, Diff: 0, Sum: 0, Workers: 4
[0.991s][debug][gc,phases ] GC(11) Merged Cards: Min: 8, Avg: 8.0, Max: 8, Diff: 0, Sum: 32, Workers: 4

I.e. "Merged Cards" contains 32 (= 4 * 8 dummy cards).

This skews statistics/predictions a bit. Fix.