[vector] #32: Performance of concatMap and O2/Odph

vector vector at projects.haskell.org
Wed Oct 27 11:08:29 EDT 2010

#32: Performance of concatMap and O2/Odph
Reporter:  choener   |        Owner:       
    Type:  defect    |       Status:  new  
Priority:  critical  |    Milestone:  0.7.1
 Version:  0.6       |   Resolution:       
Keywords:            |  
Comment (by rl):

 Alas, the two bugs I found so far have been fixed but that didn't help. I
 have a suspicion about what's going on here but I need to produce a small
 testcase which demonstrates the problem to Simon PJ and that's tricky.
 I'll keep working on it, though, it's on the top of my list.

 That said, `concatMap` is never going to be really fast. You would
 probably benefit from having segmented operations in the style of the dph-
 prim-seq package. I'm going to move those into a separate, nice package
 eventually but that won't happen in the next couple of weeks. I'll see if
 I can rewrite your code to use segmentation on the weekend. Are these
 really the loops you use in your code? If not, where can I find this
 particular bit? In !RNAFold? Are there benchmarks I could run?

Ticket URL: <http://trac.haskell.org/vector/ticket/32#comment:8>
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