Re: [GHC] #8611: nofib’s cacheprof’s allocations nondeterminisitic

[GHC]

#8611: nofib’s cacheprof’s allocations nondeterminisitic
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  NoFib benchmark   |              Version:  8.5
  suite                              |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by sgraf):

 Some notes from my Windows machine:

 - In the default build configuration with `-O2`, allocations are
 completely stable. Maximum residency is unstable, though.
 - The instability in max residency goes away if I do similar surgically
 `seq`s as above.
 - In `-O0`, I even get unstable allocations on Windows, with the samples
 spread wider than on Linux the other day.
 - In `-O0 -prof -fprof-auto` there's still a seldom, minimal instability
 of 40 bytes delta
 - Judging from `+RTS -S` output, the culprit seems to be an errorneous
 life set. Comparing two reports from different runs, there was always a
 point at which the live bytes differed and only much later total bytes
 allocated would differ. I had a sample where the difference was 1488 bytes
 in (minor) collection no. 11. These allocations seem to be kept live until
 the end of the program, and more live data is added during the run of the
 program.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8611#comment:9>
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