Re: [Discuss-gnuradio] Performance on ARM Cortex-A8

[Thomas Tsou]

On Fri, Jul 15, 2011 at 1:24 PM, Marcus D. Leech <address@hidden> wrote:
> On 07/13/2011 04:40 AM, Riadh Elloumi wrote:
>> I used all the optimized code for Cortex-A8 like dotprod_ccf_armv7_a.c.
>> My compilation flags are: -mcpu=cortex-a8 -mfloat-abi=softfp -mfpu=neon
>> -O2. I used fftw-3.2.2.
>
> What does -mfloat-abi=softfp do?  Does that cause software floating-point to
> be used?
>  If it does, then your floating-point performance is going to be completely
> awful.

No, it's one way of specifying hardware instructions.

http://gcc.gnu.org/onlinedocs/gcc-4.4.6/gcc/ARM-Options.html

"`softfp' allows the generation of code using hardware floating-point
instructions, but still uses the soft-float calling conventions."

"Use -mfloat-abi=softfp with the appropriate -mfpu option to allow the
compiler to generate code that makes use of the hardware
floating-point capabilities for these CPUs."

  Thomas