The TempDB Spotlight usage increases over time on the monitored server.




http://sqlity.net/en/671/deferred-deallocations-of-pages-in-tempdb/
https://social.msdn.microsoft.com/Forums/sqlserver/en-US/af168419-5ad9-44eb-b377-fb5560c76a1b/tempdb-deallocation-dmdbsessionspaceusage?forum=sqldatabaseengine