Hi there, I mailed to this list in May (http://www.haskell.org/pipermail/haskell-cafe/2009-May/062126.html) with no answer at all. So I wrote a smaller program to demonstrate my problem/question. Maybe now someone can help me now. I wrote a small program that does nothing but listening on a TCP port. After connection is done it simply terminates. #> cat Test.hs module Main where import Network main :: IO () main = (do servSock <- {-# SCC "cc1" #-}listenOn . PortNumber $ 10000 (handle, host, port) <- {-# SCC "cc2" #-}accept servSock return () )`catch` (putStrLn . show) #> I compile, run (connection from elsewhere, so program terminates) and watch the .prof output #> ghc --make -threaded -O2 -prof -caf-all -auto-all Test.hs Linking Test ... #> ./Test +RTS -p #> cat Test.prof Thu Jun 18 12:24 2009 Time and Allocation Profiling Report (Final) Test +RTS -p -RTS total time = 0.32 secs (16 ticks @ 20 ms) total alloc = 32,384 bytes (excludes profiling overheads) COST CENTRE MODULE %time %alloc MAIN MAIN 100.0 7.8 CAF GHC.Conc 0.0 4.0 CAF GHC.Handle 0.0 26.8 cc1 Main 0.0 3.8 cc2 Main 0.0 55.8 ... snip ... #> My actual question is, where does the 100% individual time from MAIN come from, how can I debug that in other programs and where does this MAIN cost centre come from? thanks for your help Sebastian ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.