Immigration Site

I had filed my EB2 I 140 in March 2010 and is still pending with Texas service center. I had written to the local congressman about the situation and they came back and said that my I 140 is under background check.

I am trying to understand the options. Should I be waiting or file a Mandamus if so is there a set number of days after which I can file Mandamus. Can someone let me know if you are anyone who knew was in a similar situation?