Re: [fluid-dev] problems with fluidsynth 1.1.6 on a raspberry pi

[S. Christian Collins]

How much better is the performance when using linear interpolation
instead of fourth order?
-~Chris

On 11/18/2012 11:42 PM, David Henningsson wrote:
> On 11/18/2012 07:56 PM, Pedro Lopez-Cabanillas wrote:
>> El Domingo, 18 de noviembre de 2012 12:51:58 David Henningsson escribió:
>>> I'll do some experiments with it when I have some more time.
>>
>> My bet is floating point exceptions.
>
> I tried to verify this theory on my Nexus 7 device. I've tried to
> compile with -ffast-math, with according to documentation should
> activate flush-to-zero mode, as well as activating it explicitly with
> this code:
>
>   asm(
>     "vmrs r10, FPSCR \n"
>     "orr r10, r10, #0x01000000 \n"
>     "vmsr FPSCR, r10 \n"
>   );
>
> ...but this did not give a notable performance difference.
>
> I also compared double vs single precision floats, and singles were
> somewhat faster.
>
> My test scenario was this command line:
>
> time fluidsynth -F /tmp/result.wav -z 4096
> /usr/share/sounds/sf2/FluidR3_GM.sf2 ~/Downloads/NIGHTSIN.KAR
>
> Doubles: 81 seconds
> Singles: 65 seconds
> ...so about 20% faster.
>
> I also ran it with perf. Here are the top five results:
>
> Doubles:
>     31.86%      24682     fluid_rvoice_dsp_interpolate_4th_order
>     29.41%      22568     fluid_rvoice_buffers_mix
>     14.81%      11418     fluid_iir_filter_apply
>      9.01%       6952     fluid_revmodel_processmix
>      3.31%       2568     fluid_rvoice_write
>
> Singles:
>     34.70%      21826     fluid_rvoice_dsp_interpolate_4th_order
>     24.55%      15519     fluid_rvoice_buffers_mix
>     15.00%       9506     fluid_iir_filter_apply
>      9.21%       5837     fluid_revmodel_processmix
>      3.76%       2297     fluid_rvoice_write
>
> // David
>
>
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