[Haskell-cafe] Re: Efficient signal processing

[Donald Bruce Stewart]

lemming:
> 
> On Sun, 17 Jun 2007, Donald Bruce Stewart wrote:
> 
> > simonmarhaskell:
> > > Henning Thielemann wrote:
> > >
> > > >The program is compiled with GHC-6.4 and option -O2, CPU clock 1.7 GHz.
> > >
> > > ByteString is much faster with GHC 6.6, IIRC.  We optimised the
> > > representation of ForeignPtr, and ByteString takes advantage of that.  I
> > > recommend upgrading.
> >
> > Yes, a 2x speedup isn't uncommon.
> 
> Indeed, in my simple example the speedup factor was 2. However this is
> still far from being enough for real-time signal processing. I found
> another problem: The rounding functions from RealFrac are much slower than
> GHC.Float.double2Int. I've set up a bug ticket in GHC trac.

if there's floating point math involved, carefully check the Core
output. -ddump-simpl -O2

> 
> > ByteString is even faster with the GHC head, branch, given the cranked
> > up rules and constructor specialisation.
> 
> Can I test them without compiling GHC myself? I.e. can I still install the
> FPS package separately?

oh, i was just suggesting trying the GHC HEAD branch for its improved
optimisations, not the `unstable' branch of fps.

-- Don