#9105: Profiling binary consumes CPU even when idle on Linux. ----------------------------+--------------------------------- Reporter: robinp | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------+--------------------------------- The program is main = forever $ threadDelay 1000000 >> return () . Compiled with 32bit GHC 7.6.3 or 7.8.2 on Debian (inside a VM), GHC 7.4.1 on Ubuntu (not VM). The non-profiling binary doesn't consume CPU, the profiling does ~10% (of a 2Ghz machine). Running with +RTS -I0, so this is not the idle gc. When strace-ing, the profiling one seems to receive a constant flow of SIGVTALRM, while the normal receives one burst each second. I see I can switch off "master tick interval" with -V0, and then CPU is not used, but the consequences of this are not very well documented (apart from context switching becoming deterministic). Interestingly, if I compile using profiling on Windows (latest haskell- platform, 64bit), it doesn't use more CPU than the non-profiling. So, the question is, why does this happen on Linux, and if it can be avoided somehow. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9105 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler