[FFmpeg-devel] [PATCH 1/2] avcodec/x86: move simple_idct to external assembly

[Ronald S. Bultje]

Hi,

On Mon, May 29, 2017 at 5:26 PM, Michael Niedermayer <michael at niedermayer.cc
> wrote:

> On Mon, May 29, 2017 at 09:40:49PM +0200, James Darnley wrote:
> > On 2017-05-29 16:51, James Darnley wrote:
> > > ---
> > > Changes:
> > >  - Changed type of d40000 constant to dwords because it gets used as
> dwords.
> > >  - Changed or removed HAVE_MMX_INLINE preprocessor guards.
> > >  - Added note about conversion from inline.
> > >  - New file no longer has "2" suffix.
> > >  - Whitespace (indentation and alignment).
> > >
> > >  libavcodec/tests/x86/dct.c     |   2 +-
> > >  libavcodec/x86/Makefile        |   4 +-
> > >  libavcodec/x86/idctdsp_init.c  |   4 -
> > >  libavcodec/x86/simple_idct.asm | 889 ++++++++++++++++++++++++++++++
> +++++++++
> > >  libavcodec/x86/simple_idct.c   | 929 ------------------------------
> -----------
> > >  5 files changed, 892 insertions(+), 936 deletions(-)
> > >  create mode 100644 libavcodec/x86/simple_idct.asm
> > >  delete mode 100644 libavcodec/x86/simple_idct.c
> >
> > Ronald queried on IRC about the performance.  The libavcodec/tests/dct
> > utility reports these numbers
> >
> > Yorkfield:
> >  - inline:   IDCT SIMPLE-MMX: 15715.9 kdct/s
> >  - external: IDCT SIMPLE-MMX: 15699.9 kdct/s
> >
> > Skylake-U:
> >  - inline:   IDCT SIMPLE-MMX: 11193.3 kdct/s
> >  - external: IDCT SIMPLE-MMX: 11189.7 kdct/s
>
> Its better to benchmark by decoding some videos as the sparsness of
> the coeffs affects speed


The vp9 checkasm idct test already tests this (for performance as well as
coverage purposes), maybe dct-test should include a test for "sub-idcts"
(including, but not limited to, dc-only) also?

Ronald