[GHC] #7258: Compiling DynFlags is jolly slow

[GHC]

#7258: Compiling DynFlags is jolly slow
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        Reporter:  simonpj           |                Owner:  simonpj
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.6.1
      Resolution:                    |             Keywords:  deriving-perf
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Very curious.  I see in comment:79

 {{{
 Before
         total time  =       26.00 secs   (25996 ticks @ 1000 us, 1
 processor)
         total alloc = 14,921,627,912 bytes  (excludes profiling overheads)

 After
         total time  =       13.31 secs   (13307 ticks @ 1000 us, 1
 processor)
         total alloc = 15,772,184,488 bytes  (excludes profiling overheads)
 }}}
 I don't think I have ever before seen a program that actually allocates
 more (15G instead of 14G) and yet runs in half the time.  Usually
 allocation and runtime are more or less correlated.  But apparently not in
 this case.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7258#comment:81>
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