[Haskell-cafe] Haskell performance question

[Xiao-Yong Jin]

Don Stewart <dons at galois.com> writes:

> Can you start by retrying with flags from the spectral-norm benchmark:
>
>     http://shootout.alioth.debian.org/gp4/benchmark.php?test=spectralnorm&lang=ghc&id=0
>
> The interaction with gcc here is quite important, so forcing -fvia-C
> will matter.

Clearly things has been changed, since the release of ghc-6.8.1.  I tried them
with my laptop, and here are the results of N=3000.


C++ g++
=======

real    0m4.553s
user    0m4.551s
sys     0m0.002s

changed one option: -march=nocona


Haskell GHC
===========

real 0m34.392s
user 0m34.316s
sys 0m0.074s

I used `unsafePerformIO' with `INLINE', because I don't know
where `inlinePerformIO' is now.  And also the `-optc-march'
is changed to `nocona'.


Haskell GHC #2
==============

real    0m20.069s
user    0m20.052s
sys     0m0.017s

The same label `Haskell GHC #2' on that web page.  This is
the one without any optimisation.  And it out performs the
previous heavily optimised one.  Is it because I used
`unsafePerformIO' instead of the original `inlinePerformIO'?
`-optc-march' is also changed to `nocona'.


Is it only my laptop, or ghc-6.8.1 is indeed much faster
than 6.6.1 and the internal has changed so much that the old
optimisation no longer works?

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.8.1
$ gcc --version
gcc (GCC) 4.1.2 (Gentoo 4.1.2 p1.0.2)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Intel(R) Core(TM)2 Duo CPU     T7700  @ 2.40GHz


Xiao-Yong
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