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Date: | 2005-05-03 (22:47) |
From: | Jon Harrop <jon@f...> |
Subject: | Re: [Caml-list] Re: Mini ray tracer |
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