#9221: (super!) linear slowdown of parallel builds on 40 core machine -------------------------------------+------------------------------------- Reporter: carter | Owner: Type: bug | Status: new Priority: high | Milestone: 7.12.1 Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #910, #8224 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonmar): @bgamari, correct - ThreadScope won't tell us anything about the origin of blackholes, but it would confirm whether there is a lot of blocking on blackholes. Ideally we should see all the capabilities fully busy when compiling a perfectly parallel workload. Note that dependencies between modules reduce the amount of parallelism available in general, so for a good test it would be best to construct an example with plenty of parallelism. @slyfox, I don't believe perf is telling us anything sensible here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9221#comment:36 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler