[GHC] #15999: Stabilise nofib runtime measurements

[GHC]

#15999: Stabilise nofib runtime measurements
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        Reporter:  sgraf             |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  ⊥
       Component:  NoFib benchmark   |              Version:  8.6.2
  suite                              |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #5793 #9476       |  Differential Rev(s):  Phab:D5438
  #15333 #15357                      |
       Wiki Page:                    |
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Comment (by simonmar):

 So as I understand it, the GC "wibbles" you're talking about are caused by
 the number of GCs we run? Making a small change to the nursery size can
 make the difference between N and N+1 GC runs, which could be a large
 difference in runtime.

 You're only looking at `-G1`, right? Generational GC often has weird
 effects based on the timing of when a GC runs. I think there will still be
 issues when there's an old-gen collection right around the end of the
 program run - making a small change may mean the difference between
 running or not running the expensive GC.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15999#comment:6>
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