If you want to check, you can run
KILL <session_id> WITH STATUSONLY
Run that on a session that's not rolling back and you get an error. Run it on one that is rolling back and you get an estimate of rollback completion.
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