On Sun, 03 Nov 2002 16:28:23 -0800, Roz <Rzl### [at] netscapenet> wrote:
> Safari wrote:
>> On Sun, 03 Nov 2002 14:34:11 -0800, Roz <Rzl### [at] netscapenet> wrote:
>>>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
>> 
>> 
>> that tiny bit turns out to be 15-45% back here in Finland.
>> ICC 6.0.1 on Linux[1] versus Official POV-Ray 3.50c:
                                ^^^^^^^^^^^^^^^^^^^^^^
> 
> Well now you've done it. After reading earlier posts I figured I could
> skip the huge download of ICC (if it's still available for download). Now
> you've tempted me into clobbering my poor modem connection ;)

work, library, school + CD-RW,... ;)
it contains also IA-64 -versions, take that into account if you
can extract the tarball on some *NIX shell etc. and download only IA-32
stuff with your modem...
 
> Was this the official GCC compile of POV-Ray 3.50c for Linux you were

it was Official POV-Ray 3.50c as stated a couple of lines above.

> comparing speeds on or a more optimized one you compiled yourself?
> The GCC compile I did is still a good bit faster than the official one.
> Mark Gordon can't put too many special optimizations in the official

he can put any optimizations as long as with the same input the
binary produces the same output ;)

> binary or he'd sacrifice compatibility.
> 
> My main thinking is that if I can make a compile using GCC that will
> be very close in speed to whatever ICC can produce, then it's not

not with GCC v3.2 I fear, but you can try.

> worth the hassle of downloading ICC and making a compile with it.
> 
>> was profiling (-prof_genx & -prof_use) used in the Windows version?
>> it can speed up by 25%.
>> option -pc80 seemed to speed up at least some scenes by 8%.
>> also, remember to use -limf instead of -lm.
>> -wp_ipo and -rcd seemed to break the compile at least with ICC 6.0.0,
>> haven't tried with 6.0.1.
> 
> I've never tried the Intel compiler. Do you have a list of all the options
> you recommend to use? I'll have to do some studying in between large
> work related projects. *sigh*

-O3 -tpp6 -xi -restrict -align -ipo -ipo_obj -unroll -pc80
(re-experiments for options -wp_ipo and -rcd scheduled for far future, 
IIRC, -rcd did not make any difference, YMMV).
remember to use also -prof_dir /tmp/some/dir.
and don't bother with -xM -xK -xW ...

for me -tpp6 is faster because I have Celeron, P4 users might want
to try also -tpp7...  but sometimes -tpp7 produces faster binaries
for me (but not with POV-Ray).
I don't know which option is better for Athlon.

>>>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.
>> 
>> 
>> like what scene files were used when generating profiling data
>> with binary generated by icc -prof_genx ... ;)
>>  
> 
> Exactly! Well I don't know the details of the option you're describing but

it makes ICC generate statistics about branches etc done while rendering,
with the profiling data it can generate faster code.  I didn't find info
what is taken into account when profiling, surely also other things are
done besides branches...

for example, if the scene files do not make use of radiosity feature,
profiling data for radiosity code in POV-Ray can't be generated and
radiosity-code's speed in the final executable generated by ICC with
-prof_use will be sub-optimal...  so render many different scene files
with the binary compiled with -prof_genx.
I hope you understood something from that.

> there was much left out of that 10% slower comment and I couldn't
> just let it sit there without a response.
> 
> -Roz

-- 
Safari - y7p### [at] sneakemailcom
"Talk is cheap. Show me the code." - Linus Torvalds

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