[GHC] #9221: (super!) linear slowdown of parallel builds on 40 core machine

[GHC]

#9221: (super!) linear slowdown of parallel builds on 40 core machine
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        Reporter:  carter                        |            Owner:
            Type:  bug                           |           Status:  new
        Priority:  high                          |        Milestone:
       Component:  Compiler                      |          Version:  7.8.2
      Resolution:                                |         Keywords:
Operating System:  Unknown/Multiple              |     Architecture:
 Type of failure:  Compile-time performance bug  |  Unknown/Multiple
       Test Case:                                |       Difficulty:
        Blocking:                                |  Unknown
                                                 |       Blocked By:
                                                 |  Related Tickets:
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Comment (by carter):

 so my understanding is that the parUpsweep function in
 compiler/main/GhcMake.hs is the main culprit / object to focus on for this
 performance issue, right? (literally the only thing thats tripped the the
 -jN ghc invocation )

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9221#comment:1>
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