From: Jon Harrop <jon@ffconsultancy.com>
To: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Re: Mini ray tracer
Date: Tue, 3 May 2005 23:47:15 +0100 [thread overview]
Message-ID: <200505032347.15897.jon@ffconsultancy.com> (raw)
In-Reply-To: <slrnd7d1d1.dg5.brown@panic.cs.bris.ac.uk>
On Monday 02 May 2005 20:48, Julian Brown wrote:
> Interesting results, but it's kind of unfair to leave optimisation turned
> off for g++! What kind of results do you get with, say, -O3 -ffast-math?
Sorry, I just misquoted the compile line, which really did have optimisations
on:
g++ -O2 -march=athlon-tbird ray.cpp -o ray
-O3 and -ffast-math make little difference (OCaml is still substantially
faster).
From my AMD64 results, it appears that g++ is having the floating point
problem that ocamlopt usually has. Specifically, it is producing very poor FP
performance on x86 but much better on AMD64.
Even more curiously, using single precision in the C++ version (which is
difficult to do in the OCaml version), the performance is vastly better on
x86 but vastly worse on AMD64?!? My uneducated guess is a float-align problem
but I haven't really looked into it.
--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
Objective CAML for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists
next prev parent reply other threads:[~2005-05-03 22:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-28 9:37 Jon Harrop
2005-05-02 19:48 ` Julian Brown
2005-05-03 22:47 ` Jon Harrop [this message]
2005-05-04 6:24 ` [Caml-list] " Florian Hars
2005-05-04 7:27 ` Jon Harrop
2005-05-04 11:22 ` Jon Harrop
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