Lint

          WT_LSM_MERGE_THROTTLE_THRESHOLD)
lsm/lsm_tree.c  608  Warning 647: Suspicious truncation
                                                                           _
                  WT_LSM_MERGE_THROTTLE_FACTOR * lsm_tree->merge_throttle);
lsm/lsm_tree.c  610  Warning 524: Loss of precision (assignment) (double to
    long)
                          _
          gen0_chunks < WT_LSM_MERGE_THROTTLE_THRESHOLD) {
lsm/lsm_tree.c  612  Warning 647: Suspicious truncation
                                               _
                  lsm_tree->merge_throttle / WT_LSM_MERGE_THROTTLE_FACTOR;
lsm/lsm_tree.c  614  Warning 524: Loss of precision (assignment) (double to
    long)
Be more careful to merge within levels unless we get aggressive.

In some workloads, we would merge ~7 L0 chunks into L1, then merge that L1 chunk with 6 L0 chunks into L2, making merge ~33% less efficient than it should be.