[GHC] #14980: Runtime performance regression with binary operations on vectors

[GHC]

#14980: Runtime performance regression with binary operations on vectors
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        Reporter:  ttylec            |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  vector
                                     |  bitwise operations
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 ttylec):

 Indeed, sorry I didn't write earlier. But enabling profiling kills the
 performance boost.

 I suspect that the order-of-magnitude speedup is due to some really low
 level optimization. When the analogous code is run as a part of bigger
 code, the `unboxed vector` version scales across cores linearly up to 20
 sth cores, while the `binary packed` does not scale linearly even with 2
 cores.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14980#comment:16>
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