GHC-6.4.1 much slower than GHC-6.4

[Christian Maeder]

(Moved to glasgow-haskell-bugs)

Below is my profiling data (on Linux turing 2.6.11.4-21.9-default)
Any ideas?

Cheers Christian


	   interesting-ghc-6.4 +RTS -p -RTS

	total time  =      253.76 secs   (12688 ticks @ 20 ms)
	total alloc = 15,991,765,312 bytes  (excludes profiling overheads)

COST CENTRE                    MODULE               %time %alloc

transF                         NFA.Type              13.9    1.1
trans_manyF                    NFA.Type               6.4   10.3
steps                          Util.Graph.BFS         6.4    2.1
build                          PCP.Rules.Excl.Type    5.5    9.4
dfs_collect                    Util.Graph.DFS         5.0    3.9
step                           Util.Graph.BFS         4.4    0.6
isPartOf                       Util.Words             2.9    5.8
lang_ok                        PCP.Rules.Type         2.9    5.0
dfs_abort                      Util.Graph.DFS         2.2    2.3
meet                           PCP.Search             2.2    0.5
transF                         NFA.DFA.Type           1.9    1.4
genericCross                   Util.Cross             1.8    4.3
complement                     NFA.Det                1.7    1.1
det_tqf                        NFA.Det                1.7    3.2
det_dfa                        NFA.Det                1.6    1.0
productive                     NFA.Intersect          1.5    3.6
subset                         NFA.Subset             1.5    2.3
map_fun                        Util.Map               1.5    1.2
build                          NFA.DFA.Hopcroft       1.4    2.9
apply                          PCP.Rules.Rule         1.3    2.6
apply                          PCP.Rules.Type         1.2    1.5
hop                            NFA.DFA.Hopcroft       1.1    1.0
ok                             PCP.Util.OK            1.0    0.8
select                         PCP.Rules.Type         0.9    1.3
is_final                       NFA.Type               0.6    1.0
final_conf                     PCP.Rules.Rule         0.6    1.1
sublistsN                      Util.Words             0.5    1.2


	   interesting-ghc-6.4.1 +RTS -p -RTS

	total time  =     1020.74 secs   (51037 ticks @ 20 ms)
	total alloc = 70,086,586,572 bytes  (excludes profiling overheads)

COST CENTRE                    MODULE               %time %alloc

transF                         NFA.Type              17.3    1.6
dfs_abort                      Util.Graph.DFS         7.4    7.4
trans_manyF                    NFA.Type               7.3   11.5
build                          PCP.Rules.Excl.Type    5.7    6.8
dfs_collect                    Util.Graph.DFS         5.3    3.6
intersect                      NFA.Intersect          4.6    9.8
satisfies_conditions           PCP.Rules.Excl.Excl    4.2    5.0
subset                         NFA.Subset             4.1    7.1
genericCross                   Util.Cross             2.3    5.3
isPartOf                       Util.Words             2.2    3.5
steps                          Util.Graph.BFS         2.1    0.5
candidates                     PCP.Rules.Excl.Excl    2.0    2.4
det_tqf                        NFA.Det                1.7    2.9
det_dfa                        NFA.Det                1.6    1.0
transF                         NFA.DFA.Type           1.5    1.0
build                          NFA.DFA.Hopcroft       1.4    2.6
power_splitL                   Util.Words             1.3    1.3
map_fun                        Util.Map               1.2    1.0
step                           Util.Graph.BFS         1.1    0.1
productive                     NFA.Intersect          1.1    2.6
complement                     NFA.Det                1.1    0.6
candidates                     PCP.Rules.Excl.Div     1.0    1.0
lang_ok                        PCP.Rules.Type         0.7    1.1
splits                         Util.Words             0.6    1.0

Mirko Rahn wrote:
> 
> 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.
>