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

[GHC]

#9221: (super!) linear slowdown of parallel builds on 40 core machine
-------------------------------------------------+-------------------------
        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:
-------------------------------------------------+-------------------------

Comment (by hvr):

 Replying to [comment:2 slyfox]:
 > Notice how sys time creeps up taking over performance gain on N>4.

 It's also quite visible in the quick R plot I made:

 [[Image(graph1.png)]]

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9221#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler