On Wed, 30 Oct 2002 21:07:23 +0100, Felix Wiemann wrote:
> Steve wrote:
> 
>> The new binary seems to be a great improvement on the original 3.5
>> verison, but it's still quite a bit slower than Micha Riser's
>> custom compile for PIII (running here on a PII).
>> 
>> However I've come accross a major problem with Micha's version today,
>> there are many scenes it won't render.
> 
> You are running a compile for PIII on a PII? Why are you surprised that it 
> doesn't work?
> 

With computers nothing surprises me, and it does work, just not for all scenes. 

You'll no bout be very surprised to find that the Athlon optimized binary works
perfectly on the PII. 

-- 
#local i=.1;#local I=(i/i)/i;#local l=(i+i)/i;#local ll=(I/i)/l;box{<-ll,
-((I/I)+l),-ll><ll,-l,ll>pigment{checker scale l}finish{ambient((I/l)/I)+
(l/I)}}sphere{<i-i,l-l,(I/l)>l/l pigment{rgb((I/l)/I)}finish{reflection((
I/l)/I)-(l/I)specular(I/l)/I}}light_source{<I-l,I+I,(I-l)/l>l/l} // Steve

Post a reply to this message

In article <chr### [at] netplexaussieorg> , 
Christopher James Huff <chr### [at] maccom>  wrote:

>> You are running a compile for PIII on a PII? Why are you surprised that it
>> doesn't work?
>
> Read it again...the PIII optimized compile is the faster one on his
> machine.

Yes, but as the Pentium II does not support the SSE instructions it is
surprising that it works at all!  Apparently the compiler used doesn't add a
lot of SSE instructions...

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

In article <slr### [at] zeroppsorguk> , Steve 
<ste### [at] zeroppsuklinuxnet>  wrote:

> You'll no bout be very surprised to find that the Athlon optimized binary
> works perfectly on the PII.

No wonder assuming the Athlon specific compile does not use 3dnow
instruction set extensions ... because without them, the instruction set is
basically identical.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

Thorsten Froehlich wrote:

> In article <chr### [at] netplexaussieorg> ,
> Christopher James Huff <chr### [at] maccom>  wrote:
> 
>>> You are running a compile for PIII on a PII? Why are you surprised that
>>> it doesn't work?
>>
>> Read it again...the PIII optimized compile is the faster one on his
>> machine.
> 
> Yes, but as the Pentium II does not support the SSE instructions it is
> surprising that it works at all!  Apparently the compiler used doesn't add
> a lot of SSE instructions...

gcc 3.1 does not use the SSE instruction by itself, you would have to use 
inline assembler to make it use them. So there is porbably only a few 
PIII-specific instructions left that it uses at all. This explains why it 
sometimes works on a PII as well. I had even turned off the SSE 
optimization when I compiled with the Intel compiler (only some of the 
5-components colour calculations could have been vectorized anyways) 
because it did not result in a speed-up, but rather a slow-down.

- Micha

-- 
objects.povworld.org - The POV-Ray Objects Collection
book.povworld.org    - The POV-Ray Book Project

Post a reply to this message

Steve wrote:

> On Wed, 30 Oct 2002 21:07:23 +0100, Felix Wiemann wrote:
>> Steve wrote:
> 
> You'll no bout be very surprised to find that the Athlon optimized binary
> works perfectly on the PII.
> 

I have explicitly written on the download page that the athlon binary - 
while being optimized for athlons - is compiled to work an all 
pentium-compatible machines.

- Micha

-- 
objects.povworld.org - The POV-Ray Objects Collection
book.povworld.org    - The POV-Ray Book Project

Post a reply to this message

In article <3dc0f069$1@news.povray.org>,
 "Thorsten Froehlich" <tho### [at] trfde> wrote:

> Yes, but as the Pentium II does not support the SSE instructions it is
> surprising that it works at all!  Apparently the compiler used doesn't add a
> lot of SSE instructions...

Right, but it does work, Steve was saying it worked faster than the 
original 3.5. The post I replied to only made sense if it didn't work. 
"Why are you surprised that it doesn't work?"

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

Post a reply to this message

about the sse comment
gcc3.2 (and 3.1) work with sse/sse2, but there are still a ton of x87 calls
based on the way the code is laid out.
unfortunately based on my testing the windows binary is still at least 10%
faster than the best binary I was able to make with gcc 3.2.
I think the code needs to be restructured to get a big speed boost.


"Micha Riser" <mri### [at] gmxnet> wrote in message
news:3dc0ffc1@news.povray.org...
Thorsten Froehlich wrote:

> In article <chr### [at] netplexaussieorg> ,
> Christopher James Huff <chr### [at] maccom>  wrote:
>
>>> You are running a compile for PIII on a PII? Why are you surprised that
>>> it doesn't work?
>>
>> Read it again...the PIII optimized compile is the faster one on his
>> machine.
>
> Yes, but as the Pentium II does not support the SSE instructions it is
> surprising that it works at all!  Apparently the compiler used doesn't add
> a lot of SSE instructions...

gcc 3.1 does not use the SSE instruction by itself, you would have to use
inline assembler to make it use them. So there is porbably only a few
PIII-specific instructions left that it uses at all. This explains why it
sometimes works on a PII as well. I had even turned off the SSE
optimization when I compiled with the Intel compiler (only some of the
5-components colour calculations could have been vectorized anyways)
because it did not result in a speed-up, but rather a slow-down.

- Micha

--
objects.povworld.org - The POV-Ray Objects Collection
book.povworld.org    - The POV-Ray Book Project

Post a reply to this message

bstone wrote:
> about the sse comment
> gcc3.2 (and 3.1) work with sse/sse2, but there are still a ton of x87 calls
> based on the way the code is laid out.
> unfortunately based on my testing the windows binary is still at least 10%
> faster than the best binary I was able to make with gcc 3.2.
> I think the code needs to be restructured to get a big speed boost.

There must be some stuff in the Windows official binary that takes advantage
of the Pentium specifically. Either that or gcc 3.1 likes Athlons better :P

On my Athlon XP 1900+ I get consistently faster renders with my custom 
Athlon
build of POV-Ray 3.5 vs the Windows official binary. The difference is very
small and nothing to get excited about but it certainly isn't 10% slower.
Here's a couple of render times from some tests I did this morning:

benchmark.pov
-------------
Windows official binary   = 26m 24s (1584s)
Athlon targeted gcc build = 25m  7s (1507s)

balcony.pov
-----------
Windows official binary   = 8m 14s (494s)
Athlon targeted gcc build = 7m  3s (423s)

The compiler flags used to make the Athlon targeted build using gcc 3.1 
were:

-O3 -s -mcpu=athlon -march=athlon -finline-functions -ffast-math \
-fomit-frame-pointer -Wall -funroll-loops -fexpensive-optimizations \
-malign-double -foptimize-sibling-calls -minline-all-stringops 
$(NOMULTICHAR)

I don't know if this sheds any light on anything and I'm certainly no
expert! I just found it kind of interesting.

-Roz

Post a reply to this message

Roz <Rzl### [at] netscapenet> wrote:
> There must be some stuff in the Windows official binary that takes advantage
> of the Pentium specifically.

  I think that it's simply that Intel's compiler can compile better for
Intel processors than gcc.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

Post a reply to this message

Warp wrote:
> Roz <Rzl### [at] netscapenet> wrote:
> 
>>There must be some stuff in the Windows official binary that takes advantage
>>of the Pentium specifically.
> 
> 
>   I think that it's simply that Intel's compiler can compile better for
> Intel processors than gcc.
> 

Yes, that makes sense because they (Intel) should know all the ins and 
outs of
their own processor ;)  Looking back through old posts to this newsgroup 
there's
some indication that icc custom builds are just a tiny bit faster than gcc
builds. They're all so close to each other now that I'm not worried 
about it.
I just didn't want people to get the impression that the 10% slower thing
bstone mentioned was universal. There's many factors involved beyond the
compiler used including type of processor.

-Roz

Post a reply to this message