[Radiance-general] OS X G5 performace [was: No more Mr. Nice Guy]

[Greg Ward]

Hi Thomas,

Thanks for the hint as to what options to set on the G5!  I had  
played around with these some time ago -- using gcc 3.3, I think --  
and never found a combination that both sped up the process and  
avoided problems.  I'm sure I tried removing one at a time, but not  
with the latest compiler.  Indeed, this combo seems to be a winner,  
at least for the G5 -- about 20% faster than -O3 by itself.

Running Mark Stock's bench4 on the HEAD release on my 2.5GHz G5, I  
get a user time total of 4956.56 seconds, which is maybe a few  
percent better than what one might expect just from the clock speed  
difference.

I also ran the new smp test, and got about 95% linearity (a 3.8  
times) speedup using all four processors.  This was good news to me,  
as I had some concern that the dual core processors would have a  
bottleneck with memory access.  Apparently, the enlarged caches deal  
with this pretty gracefully, and the fact that rpiece shares memory  
can't hurt.  It's too bad Apple is going with Intel instead of AMD --  
I might have waiting if that had been the case.  As it is, I don't  
think they'll better the G5 quad for some time.

-Greg

> From: Thomas Bleicher <tbleicher at arcor.de>
> Date: December 18, 2005 7:39:15 AM PST
> ...
> I've recompiled my binaries with the new source code and heavy  
> optimizing
> of compiler options. With processor performace at "Highest" I get the
> following result for Mark's benchmark test (details for Mark and other
> compiler switch freaks out there):
>
> rpict time:	6403.98 user
> processor:	G5
> num procs:	1
> clock speed:	2 GHz
> cache:		512 kB
> OS:		OS X Tiger 10.4.3
> Radiance vers:	3.8a Patch 2 (?)
> compiler:	GCC 4.0.0 20041026 (build 4061)
> rays:		693777405
> options:	-O3 -fgcse-sm -funroll-loops -fstrict-aliasing
>                 -fsched-interblock
>                 -falign-loops=16 -falign-jumps=16 -falign-functions=16
>                 -falign-jumps-max-skip=15 -falign-loops-max-skip=15
>                 -ffast-math -freorder-blocks -freorder-blocks-and- 
> partition
>                 -finline-floor -mdynamic-no-pic -mpowerpc-gpopt
>                 -force_cpusubtype_ALL -mtune=G5 -mcpu=G5 -mpowerpc64
>
> Note: These options are equal to the "-fast" optimization switch of  
> the gcc
>       for G5 except for one missing "-malign-natural" option which  
> breaks
>       rpict and probably a lot of other programs.
>
> Finally this iMac is up to the Athlon XP on Mark's page and acceptable
> for a real "desktop" machine where fan noise is much more important  
> than
> render speed.
>
> Happy holiday season and i hope everyone gets a PowerMac G5 Quad under
> their christmas tree,
>
> Thomas