Issue about Cortex-A9 Dhrystone performance

Hi,

We found the following document on Cortex-A9 performance.

List of ARM microarchitectures - Wikipedia, the free encyclopedia

Which claims 2.5 DMIPS/MHz per core for Cortex-A9 2GHz@2 core. However, our Dhrystone result on Cortex-A9 1.2GHz@2 core only showed roughly 1 DMIPS/MHz per core.

We downloaded the Dhrystone benchmark from the following link and cross-compiled it with gcc version 4.5.2.

dhrystone 2.1 - Download, Browsing & More | Fossies Archive

We realize that Dhrystone measurements will vary due to differences in compilers and OS. And I would like to know whether our result is reasonable or not?

Best,

Ying

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  • No I don't think that result is reasonable

    I think the test should fit in the cache so the memory speed shouldn't matter.

    I'm sorry  this is the is it plugged in question but just to be certain.

    What flags did you supply to gcc, did you specify gcc -O3 -Ofast -mcpu=cortex-a9 -mfpu=neon-f16 –DNDEBUG   (the fpu option shouldn't really matter but just to have  a standard set, only the -O3 should have a large effect)


    How are you certain it was running at 1.2GHz rather than thermally throttled like many smartphones do after they done some hard work for a while?

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  • No I don't think that result is reasonable

    I think the test should fit in the cache so the memory speed shouldn't matter.

    I'm sorry  this is the is it plugged in question but just to be certain.

    What flags did you supply to gcc, did you specify gcc -O3 -Ofast -mcpu=cortex-a9 -mfpu=neon-f16 –DNDEBUG   (the fpu option shouldn't really matter but just to have  a standard set, only the -O3 should have a large effect)


    How are you certain it was running at 1.2GHz rather than thermally throttled like many smartphones do after they done some hard work for a while?

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