[Haskell-cafe] FPS lib

[Donald Bruce Stewart]

dons:
> john:
> > On Wed, Oct 19, 2005 at 10:07:37AM +1000, Donald Bruce Stewart wrote:
> > > 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 :)
> > > 
> > > 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'd be very wary of switching entirely to non-portable ghc primop-based
> > > code, as FPS already run ons hugs and I think nhc.
> > 
> > can we add Data.PackedString and my PackedString (in the jhc repo) to
> > the testing lineup?
> > 
> > actually, is the test code available somewhere?
> 
> Ok, so we have:
>     FPS is at                           http://www.cse.unsw.edu.au/~dons/fps.html
>     SimonM's code I've posted at:       http://www.cse.unsw.edu.au/~dons/packedstring.tar.gz
>     Data.PackedString in the base hier libs
>     Krasimir's primop code posted online.
>     John's code in the jhc repo (where?)
> 
> And also, potentially, is the FastString.hs code in ghc's utils/ dir.
> 
> I'm not sure if just testing pack and concat are very useful though.
> Pack, at least, is rarely used in the way we're testing it -- generally
> you avoid having Strings in the first place. 
> 
> There's some other tests in Simon's code, and a full regress suite in
> FPS, using some large data sets.
> 
> What are we trying to establish here? 

(As I'd be willing to set up a nice benchmark script for all this code)

-- Don