#8224: Excessive system time -- new IO manager problem? -------------------------------------+------------------------------------- Reporter: rrnewton | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: Runtime System | Version: 7.7 Resolution: | Keywords: IO Manager, Operating System: Linux | System Time Type of failure: Runtime | Architecture: x86_64 (amd64) performance bug | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Comment (by simonmar): One reason for extra user/system time that could account for your results in #910 is that if there isn't enough parallelism during GC then you'll have 30 threads spinning looking for work, and doing the occasional sched_yield(). Spinning accounts for the user time, the sched_yield() accounts for the system time. Still, it does look like a lot, so it would be good to look at some !ThreadScope traces. That doesn't account for the 200ms in the empty program though, so there could be something else going on here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8224#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler