On Fri, 2007-10-12 at 20:25 -0700, Stefan O'Rear wrote:
> On Sat, Oct 13, 2007 at 12:09:57AM +0200, ntupel wrote:
> > setup :: (Ord a, IArray a2 a, IArray a1 e, Num a) => [e] -> [a] -> (a1 Int
> > e, a1 Int e, a2 Int a)
> > calcAlias :: (Ord e, Num e, IArray a e, Ix i, IArray a2 e1, IArray a1 e1)
> > => a2 i e1 -> a1 i e1 -> a i e -> [i] -> [i] -> (a1 i e1, a i e)
> > next :: (IArray a2 e1, IArray a e1, Ord e, IArray a1 e, RandomGen t, Random
> > e) => (a Int e1, a2 Int e1, a1 Int e) -> t -> (e1, t)
> > randomList :: (Random e, RandomGen t1, IArray a2 e, Ord e, IArray a t,
> > IArray a1 t) => (a Int t, a1 Int t, a2 Int e) -> t1 -> [t]
>
...
> I would try specializing to StdGen, UArray, and Int, for RandomGen,
> IArray, and Random respectively.
Thanks for your reply Stefan. Unfortunately I could measure only a
relatively small improvement by changing to concrete types, e.g. using
setup :: [a] -> [Double] -> (Array Int a, Array Int a, UArray Int
Double)
calcAlias :: Array Int a -> Array Int a -> UArray Int Double -> [Int] ->
[Int] -> (Array Int a, UArray Int Double)
next :: (Array Int a, Array Int a, UArray Int Double) -> StdGen -> (a,
StdGen)
randomList :: (Array Int a, Array Int a, UArray Int Double) -> StdGen ->
[a]
the sample code was about one second faster when compiled with -O2.
Profiling again indicated that most time was spend in random and randomR
(I manually added cost centers into "next"):
main +RTS -p -RTS
total time = 8.00 secs (160 ticks @ 50 ms)
total alloc = 2,430,585,728 bytes (excludes profiling overheads)
COST CENTRE MODULE %time %alloc
random Random 60.0 54.5
randomR Random 20.0 23.3
next Random 17.5 17.0
main Main 1.9 2.5
randomList Random 0.6 2.8
previously (i.e. with long class contexts) it looked like this:
main +RTS -p -RTS
total time = 7.85 secs (157 ticks @ 50 ms)
total alloc = 2,442,579,716 bytes (excludes profiling overheads)
COST CENTRE MODULE %time %alloc
random Random 58.6 54.5
randomR Random 22.9 23.3
next Random 14.6 16.5
main Main 2.5 2.5
randomList Random 1.3 3.1
Many thanks again,
Thoralf
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