#8224: Excessive system time -- new IO manager problem? -------------------------------------+------------------------------------- Reporter: rrnewton | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Runtime System | Version: 7.7 Resolution: | Keywords: IO Manager, | System Time Operating System: Linux | Architecture: x86_64 Type of failure: Runtime | (amd64) performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #9221 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): I tried reproducing this with cf5eec3eaa638719fd9768c20271f8aa2b2eac1f on a 2-socket, 24-core machine I have access to. I was unable to see anything like the system time numbers like reported in comment:17, {{{#!bash $ cat >T8224.hs <<EOF main = return () EOF $ inplace/bin/ghc-stage2 -threaded -rtsopts T8224.hs $ time ./T8224 +RTS -N32 real 0m0.016s user 0m0.008s sys 0m0.012s }}} and {{{#!bash $ cat >T8224a.hs <<EOF import Control.Monad import Control.Concurrent main = do n <- getNumCapabilities forM_ [1..n] $ \_ -> forkIO $ return () threadDelay (4 * 1000 * 1000) EOF $ inplace/bin/ghc-stage2 -threaded -rtsopts T8224a.hs $ time ./T8224a +RTS -N32 real 0m4.018s user 0m0.160s sys 0m0.028s }}} All-in-all this doesn't seem terribly unreasonable to me. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8224#comment:29> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler