[GHC] #7606: Stride scheduling for Haskell threads with priorities

[GHC]

#7606: Stride scheduling for Haskell threads with priorities
---------------------------------+------------------------------------------
    Reporter:  ezyang            |       Owner:  ezyang          
        Type:  feature request   |      Status:  new             
    Priority:  normal            |   Milestone:  7.8.1           
   Component:  Runtime System    |     Version:  7.7             
    Keywords:                    |          Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown    
  Difficulty:  Unknown           |    Testcase:                  
   Blockedby:                    |    Blocking:                  
     Related:                    |  
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Comment(by ezyang):

 When I attempt to replicate the conditions of #3838 (by removing the
 thread bump), I do not see any appreciable increase in runtime. This
 occurs even if I explicitly yield while inside the atomicModifyIORef
 (using unsafePerformIO), or I increase the number of threads being run. My
 conclusion is that a small pileup does occur, but since there's no longer
 a global list we keep traversing it's not expensive. But I can't rule out
 (1) the test-case having enough incidental other changes that have made it
 stop tickling the bug, or (2) some other RTS change masking over this
 particular problem. A conundrum!

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7606#comment:37>
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