[GHC] #5367: Program in (-N1) runs 10 times slower than it with two threads (-N2)

[GHC]

#5367: Program in (-N1) runs 10 times slower than it with two threads (-N2)
--------------------------------------+-------------------------------------
  Reporter:  wuxb                     |          Owner:  simonmar      
      Type:  bug                      |         Status:  closed        
  Priority:  high                     |      Milestone:  7.4.1         
 Component:  Runtime System           |        Version:  7.0.4         
Resolution:  wontfix                  |       Keywords:  thread ffi    
  Testcase:                           |      Blockedby:                
Difficulty:                           |             Os:  Linux         
  Blocking:                           |   Architecture:  x86_64 (amd64)
   Failure:  Runtime performance bug  |  
--------------------------------------+-------------------------------------

Comment(by marlowsd@…):

 commit 78e6b615329dd8ea4527b499107048693c87f895
 {{{
 Author: Simon Marlow <marlowsd at gmail.com>
 Date:   Wed Aug 3 13:41:33 2011 +0100

     small optimisation for the program in #5367: if the worker thread
     being woken already has its wakeup flag set, don't bother signalling
     its condition variable again.

  rts/Capability.c |   12 +++++++-----
  1 files changed, 7 insertions(+), 5 deletions(-)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5367#comment:4>
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