protected String throughputDesc(double speed) {
    if (speed >= 1E15) { // large enough to say it is unlimited
      return "unlimited";
    } else {
      return String.format("%.2f MB/second", speed / 1024 / 1024);
    }
  }
Stores the information of one controlled compaction.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/throttle/PressureAwareThroughputController.java