Underwhelming MBP c-ray results...

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bigD
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Underwhelming MBP c-ray results...

Unread postby bigD » Thu Sep 03, 2009 3:40 pm

My primary machine is a 2.4GHz MBP, and because I'm bored I decided to run the c-ray benchmark. Essentially I'm getting a repeatable result of about 876ms. With just one core, I get 1685ms.

Looking at Ian's numbers, a single 2.0GHz G5 does this test in 1073ms. Is the G5 really that much faster than the C2D in FP math? Also strange - my Octane2 completes this test in around 1250ms. That's pretty competitive, given my MBP is about four times faster than my Octane2 in the Blender benchmark. I know we're talking different benchmarks, but the discrepancy seems a little *too* large to me.

Is it possible I'm doing something wrong here? I've tried different combinations of threads from 8 up to 256. My idle time is better than 98%. I used gcc 4.0.1 to do the compile.
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tomvos
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Re: Underwhelming MBP c-ray results...

Unread postby tomvos » Sat Sep 05, 2009 10:47 am

Hi bigD,

which test setup did you actually use? I tried:

Code: Select all

cat scene | ./c-ray-mt -r 1 -t 32 -s 800x600 > foo.ppm


I got an average of ~220 ms on a MBP with a 2,66 GHz Core2Duo (6 MB L2-Cache) using GCC 4.2.1 and Mac OS X 10.6.0.
And an average of ~620 ms on a MBA with a 1,6 GHz Core2Duo (4 MB L2-Cache) using GCC 4.0.1 and Mac OS X 10.5.8.

If you're using the same parameters, then the computation time of your machine should be less than 876 ms.
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bigD
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Re: Underwhelming MBP c-ray results...

Unread postby bigD » Sun Sep 06, 2009 2:57 pm

tomvos wrote:Hi bigD,

which test setup did you actually use? I tried:

Code: Select all

cat scene | ./c-ray-mt -r 1 -t 32 -s 800x600 > foo.ppm


I got an average of ~220 ms on a MBP with a 2,66 GHz Core2Duo (6 MB L2-Cache) using GCC 4.2.1 and Mac OS X 10.6.0.
And an average of ~620 ms on a MBA with a 1,6 GHz Core2Duo (4 MB L2-Cache) using GCC 4.0.1 and Mac OS X 10.5.8.

If you're using the same parameters, then the computation time of your machine should be less than 876 ms.


Thanks for the info! It was very helpful. I was using the same parameters that you were, so I decided to recompile c-ray. After a recompile, my computation time went down to 343ms. I realized that I never actually built c-ray before - I was using the stock binary that came with the archive.

Thanks!
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