[Radiance-general] Re: Radiance - Mac Performance

Thu, 29 May 2003 22:19:57 -0700

Hi Marcus,

Of course, I'm a big fan of Apple computers.  They offer a great 
combination of quality (i.e., sturdiness, reliability, and aesthetics) 
over Wintel computers.  However, I'm forced to agree with Rob that in 
terms of peformance vis a vis Radiance, your best value is a probably a 
home-built, dual-processor Linux box.  I very nearly got one myself, 
but decided instead to pay roughly twice as much to get a dual 1.4 GHz 
PowerMac G4 with 1 GByte of RAM and a DVD writer for about $3K.  Its 
performance and features are comparable to PCs I could have bought 
prebuilt for around $1.5K.  The advantage is that I don't have to 
administer a Linux system, which I've found in the past to be a pain in 
the butt.  Mac OS X, built on FreeBSD, is a snap by comparison, and 
what's better is I can run Word and Excel and all those other Microsoft 
nasties without having to reboot into another system.  Better still, I 
get to run Photosphere, which I've spent two years developing and don't 
have time to port to other systems right now.

The hype about the G4 being superior for scientific applications is a 
PR effort by Apple to save face for a processor that despite many 
design superiorities, just hasn't kept pace with Intel and AMD's 
aggressive speed increases.  To be fair, you can use the Altvec 
processor (a short vector SIMD on the G4) to get substantial speed 
boosts if you go to the extra work to use it.  I haven't done any 
custom hardware coding in Radiance, and I'm unlikely to in the future.  
Others are welcome, of course.

In your case, a dual-processor Wintel machine with dual-boot into Linux 
or (my recommendation) FreeBSD may be the best option with your 
existing software investment.

I don't know what a 64-bit processor will buy in terms of Radiance 
performance.  Other than getting past the 2 GByte memory addressing 
limit, there might be some improvement in floating point speed since 
you can load double's into registers, but 64-bit integers are not 
really useful as far as I'm concerned.

-Greg

> From: "Marcus Jacobs" <[email protected]>
> Date: Thu May 29, 2003  7:40:25  PM US/Pacific
> To: [email protected]
> Subject: [Radiance-general] Radiance - Mac Performance
> Reply-To: [email protected]
>
> Dear Group
>
> I am in the evaluation phase in my quest to purchase a new computer. 
> From what I have been told, the Motorola G4 processor is far superior 
> in scientific calculations as compared to x-86 based processors (i.e. 
> Intel/AMD). If it weren't for the existing investment that I have in 
> PC based software (particularly software that utilizes a dongle which 
> will not work on a Mac even with virtual PC), I would probably 
> purchase one. But because of the existing investment that I do have in 
> PC based software, I am trying to do a cost versus benifit analysis 
> for purchasing a Mac. Has anyone here been able to do a rough estimate 
> as to the decrease in rendering time when using a Mac as compared to 
> x-86 based processors. I was considering in lieu of purchasing a Mac, 
> I would purchase a dual Pentium 4 Zeon and compile it on Linux. If I 
> am correct, the GNU C compiler has a SSE2 optimization option. Also I 
> have l have looked at puchasing a AMDs 64 bit Opteron based 
> workstation. I do believe there can be some performance gains achieved 
> if it can be used in conjunction with a 64 bit Operating System. 
> Anyway, you all can see that i am very confused as to which direction 
> I should take so any advice is very much appreciated.
>
> Thanks
>
> Marcus D. Jacobs