public boolean isEncodingFasterThanIo() {
    return isEncodingFasterThanIo;
  }
Order all working memtables in system by memory cost of actual data points in memtable. Mark
the top K TSPs as to be flushed, so that after flushing the K TSPs, the memory cost should be
less than FLUSH_THRESHOLD
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/rescon/memory/SystemInfo.java