First hit on google for "MEMORYCLERK_SQLBUFFERPOOL single page allocator"
And the BoL page for the DMV you're using
http://msdn.microsoft.com/en-us/library/ms175019%28v=sql.105%29.aspx
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability