Monitor number of records returned in a long-running SELECT statement during SSAS processing
If you connect SQL Server Profiler to SSAS and watch the Progress Report Current events with an EventSubclass=ReadData the IntegerData column will show the cumulative rows read so far for that SSAS partition.  


  Integerdata:   Contains the integer data associated with the reported
  event, such as the current count of the number of rows processed for a
  processing event.