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Date: Thu, 29 Apr 2010 22:12:39 +0300
Message-ID: <x2h320e992a1004291212kb9b5cfd9rf21f38450f981abf@mail.gmail.com>
Subject: Re: [Caml-list] min function, why is it so slow?
From: Eray Ozkural <examachine@gmail.com>
To: Markus Mottl <markus.mottl@gmail.com>
Cc: caml-list@inria.fr
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X-Spam: no; 0.00; eray:01 ozkural:01 markus:01 mottl:01 markus:01 mottl:01 eray:01 ozkural:01 inlining:01 ocamlopt:01 -inline:01 inlined:01 polymorphism:01 ocaml:01 compiler:01 

On Thu, Apr 29, 2010 at 9:47 PM, Markus Mottl <markus.mottl@gmail.com> wrot=
e:
> On Thu, Apr 29, 2010 at 14:34, Eray Ozkural <examachine@gmail.com> wrote:
>> Although I turn on inlining in ocamlopt (-inline 10), I think that the
>> min function is not quite inlined. Indeed, it's faster if I just
>> inline it myself (if a<b a then a else b). It's almost twice as fast
>> this way. Which makes me thinking. I suppose a procedure call cost is
>> incurred. This doesn't change when I define min for two parameters
>> myself in another module. What do you think I am doing wrong?
>
> This is probably a consequence of too much polymorphism. =A0Your min
> function is fully polymorphic, which may prevent the OCaml compiler
> from type specialization, i.e. a generic (=3D slow) comparison function
> will be called. =A0E.g. if your array contains integers or floats, this
> is likely to make a significant difference. =A0Try constraining the type
> of your min function to the one of the array elements. =A0This will
> probably make the problem go away.

Oh, that's a good suggestion, thank you. Let me try it out.

Best,

--=20
Eray Ozkural, PhD candidate.  Comp. Sci. Dept., Bilkent University, Ankara
http://groups.yahoo.com/group/ai-philosophy
http://myspace.com/arizanesil http://myspace.com/malfunct