[Haskell-cafe] FPS lib

[Krasimir Angelov]

2005/10/19, Donald Bruce Stewart <dons at cse.unsw.edu.au>:
> kr.angelov:
> > Hello Guys,
> >
> > I tried my own version of PackedStrings and the results are very nice.
> > It is entirely based on ByteArray# and Int#. I have made two tests:
> >
> > Elapsed time
> > |     | FastPackedString | PackedString |
> > +-----+------------------+--------------+
> > |test1|           99.26s |        3.81s |
> > |test2|          175.88s |        5.28s |
> >
> > Maximum Memory Residency
> > |     | FastPackedString | PackedString |
> > +-----+------------------+--------------+
> > |test1|          40.60Mb |      36.25Mb |
> > |test2|          91.58Mb |      33.94Mb |
>
> Wow. Now this is really surprising.
>
> Firstly, I would point out that only testing pack and concat may be
> slightly unrepresentative :)

Of course the representative benchmark needs more test cases.

> However, on my machine:
>
>    OpenBSD/Pentium-M 1.6G/ghc-6.5 -O
>    Elapsed time:        FPS          Simon's PackedString   Krasimir's
>    test1                1.966s (40M)      2.151s (36M)      2.235s (36M)
>    test2                6.048s (24M)      3.160s (73M)      2.318s (39M)
>
> Which is basically what I expected. Though perhaps I need to improve
> concat (we currently do things a little strangely in concat, due to the
> darcs legacy), but pack itself is nice and fast.
>
>    Linux/Pentium 4 3.6G/ghc-6.4.1 -O
>    test1               35.37s            30.97s             2.180s
>    test2               90.93s            60.55s             1.916s
>
> Ah!! So what's going on on Linux, I wonder. Could it be something about
> 6.4.1? Are we seeing the difference between ForeignPtrs from 6.4 to 6.5?
> I will investigate.

I wonder why the test results are so different. I made my benchmark on
WinXP on Celeron 3GHz with GHC from CVS HEAD.

Cheers,
  Krasimir