Bug#738981: Fwd: Bug#738981: Switch to use generic_fpu for ARM
Thomas Orgis
thomas-forum at orgis.org
Thu Feb 20 12:43:45 UTC 2014
> >> > I see. In that case, I'll have to leave the package as it until
> >> > something along those lines is implemented.
So, I got conversion to float implemented now and tested with the
generic_nofpu decoder on x86-64. It _should_ of course work with ARM,
too;-) If you'd like to check the current snapshot of mpg123,
http://mpg123.org/snapshot/mpg123-20140220132548.tar.bz2 ,
you hopefull will find that any normal build of mpg123 (unless
specifying --disable-float explicitly) now offers all usual formats. As
a bonus, I even implemented the 8 Bit A-Law output, which has always
just been a placeholder (nobody missed it, apparently).
I'd be interested on some timings of
mpg123 -t -e s16 test.mp3
mpg123 -t -e f32 test.mp3
with the various builds you'll do for the ARM variants. Best would be running
perl scripts/benchmark-cpu.pl src/mpg123 convergence_-_points_of_view/*.mp3
with
http://mpg123.orgis.org/convergence_-_points_of_view.tar.gz
as reference album, as mentioned on
http://mpg123.orgis.org/benchmarking.shtml
to be able to compare the performance of the code and machine to
others. This yields output like this:
#mpg123 benchmark (user CPU time in seconds for decoding)
#decoder t_s16/s t_f32/s
x86-64 3.39 4.05
generic 6.15 6.01
generic_dither 6.36 5.97
... or this, with --with-cpu=generic_fpu:
#mpg123 benchmark (user CPU time in seconds for decoding)
#decoder t_s16/s t_f32/s
generic 6.14 6.29
(on a Core2Duo machine).
> Yes, you can do that - build several copies of the library and use the
> hwcaps / auxv approach to pick the best one for the hardware at link
> time.
>
> >NEON detection may come... but if we have linker selection, that would
> >be covered right now.
>
> Yup.
Seconding the second part: Linker selection it is. NEON runtime
detection just isn't fun in user code.
The bright side: If the multiple builds are setup and tested, I can
safely release mpg123-1.19.0 with the changes and we finally have this
settled.
Alrighty then,
Thomas
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