The Value of Thumb-2
mans.rullgard at linaro.org
Thu Oct 20 22:27:47 UTC 2011
On 20 October 2011 23:22, Michael Hope <michael.hope at linaro.org> wrote:
> On Fri, Oct 21, 2011 at 11:16 AM, Mans Rullgard
> <mans.rullgard at linaro.org> wrote:
>> On 20 October 2011 23:07, Michael Hope <michael.hope at linaro.org> wrote:
>>> On Fri, Oct 21, 2011 at 7:48 AM, James Tunnicliffe
>>> <james.tunnicliffe at linaro.org> wrote:
>>>> This isn't exactly overflowing with up to date numbers, but...
>>>> Slides 14 and 15 say that across EEMBC Thumb-2 gives 98% of the
>>>> performance of ARM 32 bit instructions (assume performance optimised)
>>>> and binaries are 26% smaller (didn't catch what binary/binaries that
>>>> was). These are numbers from 2007 and benchmarked on an ARM 11. I
>>>> assume using ARMCC.
>>> I just ran EEMBC with gcc-linaro-4.6-2011.10 with -mfpu=neon -O3
>>> -mtune=cortex-a9 and got similar numbers. Five of the 32 tests ran
>>> faster with Thumb-2 which is nice. I'll send the results privately as
>>> I'm not sure we can share.
>> How much faster? What about the ones that didn't run faster?
> More than 10 %. I can't share raw numbers in public as our EEMBC
> license doesn't allow it. I've sent the raw numbers to the
> linaro-toolchain-benchmarks list.
Yes, I saw it.
>> I also don't think EEMBC is representative of real-world apps.
> Agreed. It's an embedded benchmark. SPEC would be interesting.
I don't think it's representative of anything, embedded or
>>> EEMBC embeds the test data in the executable so it it's hard to tell
>>> the change in text size.
>> The 'size' command?
> It turns the images and such into C arrays so they appear in the text
> segment. Hmm, I wonder if they get split into .rodata?
Arrays end up in .data or .rodata, never .text.
Mans Rullgard / mru
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