[GHC] #12964: Runtime regression to RTS change

[GHC]

#12964: Runtime regression to RTS change
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        Reporter:  nomeata           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Runtime System    |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonmar):

 The fact that some of these tests seem to wobble around in response to
 unrelated changes suggests that it's something like an alignment or
 locality issue.  These can be a pain to track down, especially when the
 difference is only 5%.  The best plan of attack is to use perf to identify
 where the extra cycles are going (hopefully the extra 5% is localised in
 one place) and then go from there.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12964#comment:1>
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