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S?awomir Szczyrba <cre### [at] ofthenight> wrote:
> 8: -O3 -march=pentium4 -msse2 -mfpmath=sse -malign-double \
> -minline-all-stringops -ffast-math -fomit-frame-pointer \
> -funroll-loops -fexpensive-optimizations -foptimize-sibling-calls
According to my own tests some of those options actually slow down
POV-Ray instead of speeding it up. Adding a new optimization option does
not always mean that the binary will be faster.
My own experiments show that this combination gives the fastest binary,
at least in a pentium4:
-O3 -march=pentium4 -ffast-math -mfpmath=sse -msse2 -funroll-loops
-ftsp-ordering
--
- Warp
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Houston, we got a Warp...
> My own experiments show that this combination gives the fastest binary,
> at least in a pentium4:
>
> -O3 -march=pentium4 -ffast-math -mfpmath=sse -msse2 -funroll-loops
> -ftsp-ordering
>
Well, my compiler doesn't know this option :)
[steev]/tmp# gcc -ftsp-ordering hello.c
cc1: error: unrecognized command line option "-ftsp-ordering"
[steev]/tmp# icc -ftsp-ordering hello.c
icc: Command line warning: ignoring unknown option '-ftsp-ordering'
--
________
\__ \__ \_______________________________________________________________
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> Well, my compiler doesn't know this option :)
>
> [steev]/tmp# gcc -ftsp-ordering hello.c
> cc1: error: unrecognized command line option "-ftsp-ordering"
That's because it's been removed in the latest gcc series (IIRC 3.4.x inclusive).
- NC
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Nicolas Calimet <pov### [at] freefr> wrote:
> > Well, my compiler doesn't know this option :)
> >
> > [steev]/tmp# gcc -ftsp-ordering hello.c
> > cc1: error: unrecognized command line option "-ftsp-ordering"
> That's because it's been removed in the latest gcc series (IIRC 3.4.x
inclusive).
It doesn't matter anyways. It only gave a very minimal speedup.
--
- Warp
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Speed... kills... ;)
Well, '-unroll-loops' kills. Images. :)
'Benchmark' results + images + differences between images...
< http://shodan.selfip.net/~steev/pov/ >
--
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\__ \__ \_______________________________________________________________
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If I understand your results correctly, the left image is that produced
by the binary compiled with the specified options, the middle image is the
difference-image with a reference (presumably calculated with the official
binary for Linux?) and the right image is the inverted difference. Correct?
> Well, '-unroll-loops' kills. Images. :)
From you results it seems that it's actually -ffast-math that changes the
result of the top-left corner (your last test shows that -funroll-loops does
produce a correct image). But what is really strange is your second result:
a distorted image is also produced with -march=i686 ??? Hard to believe...
In any case, on an Intel Pentium 4 or higher processor, it is clear again
that one should use ICC to compile POV from sources.
- NC
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S?awomir Szczyrba wrote:
> BOFH excuse 72: S?awomir Szczyrba did it
>
> Speed... kills... ;)
> Well, '-unroll-loops' kills. Images. :)
>
> 'Benchmark' results + images + differences between images...
It is perfectly expected that there are slight difference. The huge
difference is precision bug in your math library though. It should not occur
with a standard(s) conforming library.
Thorsten
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S?awomir Szczyrba <cre### [at] ofthenight> wrote:
> 'Benchmark' results + images + differences between images...
> < http://shodan.selfip.net/~steev/pov/ >
I think the base image is wrong.
I just tried benchmark.pov in my system, with povray compiled with
-O3 -march=pentium4 -ffast-math -mfpmath=sse -msse2 -funroll-loops
and it rendered correctly.
There must be something odd with either your version of gcc or your
system libraries or something.
--
- Warp
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Welcome to the real world, eh Nicolas Calimet ?
> If I understand your results correctly, the left image is that produced
> by the binary compiled with the specified options, the middle image is the
> difference-image with a reference (presumably calculated with the official
> binary for Linux?) and the right image is the inverted difference. Correct?
>
Calculated with binary created from source tarball.
No extra options, just autoconf guess...
> - NC
Slawek
--
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> I just tried benchmark.pov in my system, with povray compiled with
> -O3 -march=pentium4 -ffast-math -mfpmath=sse -msse2 -funroll-loops
> and it rendered correctly.
>
I'll check it again, then.
> There must be something odd with either your version of gcc or your
> system libraries or something.
>
Everything's OOTB, except kernel.
Hm, why not. Next test:
Fedora's kernel vs. my own one... :)
Slawek
--
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_/ __/ __/
\__ \__ \_______________________________________________________________
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