[GHC] #7561: Unnecessary Heap Allocations - Slow Performance

[GHC]

#7561: Unnecessary Heap Allocations - Slow Performance
-------------------------------+--------------------------------------------
    Reporter:  wurmli          |       Owner:                         
        Type:  bug             |      Status:  new                    
    Priority:  normal          |   Milestone:  7.8.1                  
   Component:  Compiler        |     Version:  7.6.1                  
    Keywords:                  |          Os:  Linux                  
Architecture:  x86_64 (amd64)  |     Failure:  Runtime performance bug
  Difficulty:  Unknown         |    Testcase:                         
   Blockedby:                  |    Blocking:                         
     Related:                  |  
-------------------------------+--------------------------------------------

Comment(by simonpj):

 There seem to be two separate issues here

  1. A profiled program runs a lot faster than a non-profiled one
  2. Two variants of a program that depends on the (complex) vector library
 run with very different speeds.

 Can anyone help boil either (1) or (2) down into a smaller program, or
 otherwise characterise what's going on?  I'm out of bandwidth.  Using
 `-ticky` profiling might help guide you to where the allocation is
 happening.

 Thanks

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7561#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler