[GHC] #8948: Profiling report resolution too low

[GHC]

#8948: Profiling report resolution too low
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       Reporter:  tibbe             |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Profiling         |           Version:  7.6.3
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 When running criterion benchmarks under profiling, the criterion internals
 usually dominate the report. That means that the code you actually care
 about ends up with very low percentages:

 {{{
                                                             individual
 inherited
 COST CENTRE              MODULE             no.  entries  %time %alloc
 %time %alloc
 ...
  Full                    Data.HashMap.Base  360   725180    0.2    0.5
 0.4    0.9
   Leaf/neq               Data.HashMap.Base  364     5151    0.0    0.0
 0.0    0.0
   BitmapIndexed/update   Data.HashMap.Base  362   227250    0.1    0.2
 0.2    0.3
    BitmapIndexed/insert  Data.HashMap.Base  365    78376    0.0    0.0
 0.0    0.0
    Leaf/neq              Data.HashMap.Base  363   132411    0.0    0.1
 0.0    0.1
   BitmapIndexed/insert   Data.HashMap.Base  361   191597    0.0    0.1
 0.0    0.1
  BitmapIndexed/update    Data.HashMap.Base  357     4545    0.0    0.0
 0.0    0.0
   BitmapIndexed/insert   Data.HashMap.Base  359     3030    0.0    0.0
 0.0    0.0
   Leaf/neq               Data.HashMap.Base  358     1515    0.0    0.0
 0.0    0.0
  BitmapIndexed/insert    Data.HashMap.Base  356     1414    0.0    0.0
 0.0    0.0
  Leaf/neq                Data.HashMap.Base  355      101    0.0    0.0
 0.0    0.0
  Empty                   Data.HashMap.Base  354      101    0.0    0.0
 0.0    0.0
 }}}

 If you're interested in comparing the relative time spent in these
 functions, that's not really possible as these numbers have too low
 accuracy.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8948>
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