GHC-6.4.1 much slower than GHC-6.4

[Mirko Rahn]

Hello,

I was surprised about really big differences in running times between 
6.4 and 6.4.1, whereby 6.4.1 is *much* slower:

*** 6.4: cpu-time interesting (3,3): 00:01:38.08
*** 6.4.1: cpu-time interesting (3,3): 00:05:58.91

Here we have a factor of about 3.6!! Are there others that have noticed 
such behavior? What could be the reason for that?

Sorry, my example is a small monster, but at the moment there is neither 
time left to search for the reason for this behavior nor to break it 
down to some smaller pieces of code. I just noticed it...

However, you can find the source tree in

http://liinwww.ira.uka.de/~rahn/src/

The file

http://liinwww.ira.uka.de/~rahn/src/prog.tar.gz

contains the tree as well. For the output above: Extract, cd proj/prog 
and run

rahn at i90pc18:~/local/proj/prog$ for version in 6.4 6.4.1; do find . 
-name '*.hi' | rm -f ; ghc-$version --make -Wall -cpp 
-D__POS__='__FILE__ ++ "[" ++ show(__LINE__::Int) ++ "]: " ++ ' 
-fglasgow-exts -fallow-overlapping-instances 
-fallow-undecidable-instances -O Prog/Interesting.hs -o 
Prog/Interesting.$version.bin 2>/dev/null >/dev/null; echo -n "*** 
$version: " ; ./Prog/Interesting.$version.bin 2>&1 | grep time ; done

Regards, Mirko

P.S.: I run a debian-box with i686 GNU/Linux 2.6.11.11 and a dualcore P4 
3.2 GHz.

-- 
-- Mirko Rahn -- Tel +49-721 608 7504 --
--- http://liinwww.ira.uka.de/~rahn/ ---