Optimise my ray tracer - comp.lang.java.programmer

Message from discussion Optimise my ray tracer

Jon Harrop

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More options 11 Jun 2005, 17:40

Newsgroups: comp.lang.java.programmer

From: Jon Harrop <use...@jdh30.plus.com>

Date: Sat, 11 Jun 2005 17:40:42 +0100

Local: Sat 11 Jun 2005 17:40

Subject: Re: Optimise my ray tracer

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Lasse Reichstein Nielsen wrote:
> Jon Harrop <use...@jdh30.plus.com> writes:
>> I have taken startup time into consideration. Java is still consistently
>> many times slower than most other languages.

> Is this using the original code that was posted here? Because it can
> be written significantly better.

Great, tell me how (provided it doesn't get too much longer).

> Just making the Vector class static will reduce its number of fields
> by 25%, which should make a significant cut in the initialization time
> for each Vector.

One my machine, the original took 31s for:

$ javac ray.java
$ java ray 256>image.pgm

With the vector class declared static (what exactly does this do?) it takes
29s, which is not significantly faster.

In contrast, Mlton-compiled SML is much shorter (79 vs 110 LOC) and runs
about 5x as fast, taking only 6s to ray trace exactly the same image.

So we really need much better optimisations if Java is going to perform
anything like as well as the other languages. Am I missing something
simple, like JIT or optimisation flags?

--
Dr Jon D Harrop, Flying Frog Consultancy
http://www.ffconsultancy.com

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