[FFmpeg-devel] [PATCH 1/2] swresample: Refactor resample asm and port it to yasm

Michael Niedermayer michaelni at gmx.at
Wed Mar 19 18:34:39 CET 2014


On Wed, Mar 19, 2014 at 02:24:05PM -0300, James Almer wrote:
> On 19/03/14 9:18 AM, Michael Niedermayer wrote:
> > On Wed, Mar 19, 2014 at 02:49:33AM -0300, James Almer wrote:
> >> This reduces code duplication and makes it easier to implement new asm 
> >> functions in the future
> >>
> >> Signed-off-by: James Almer <jamrial at gmail.com>
> >> ---
> >>  libswresample/resample.c            | 96 ++++++++++---------------------------
> >>  libswresample/resample_template.c   | 49 +++++++------------
> >>  libswresample/swresample_internal.h | 24 ++++++++++
> >>  libswresample/x86/Makefile          |  1 +
> >>  libswresample/x86/resample.asm      | 64 +++++++++++++++++++++++++
> >>  libswresample/x86/resample_mmx.h    | 74 ----------------------------
> >>  libswresample/x86/swresample_x86.c  | 16 +++++++
> >>  7 files changed, 148 insertions(+), 176 deletions(-)
> >>  create mode 100644 libswresample/x86/resample.asm
> >>  delete mode 100644 libswresample/x86/resample_mmx.h
> > 
> > what effect does this has on speed?
> > you are adding a function call in a in inner loop
> 
> At least on my end it seems to be a couple cycles faster (Measured with 
> timer.h macros surrounding the c->scalarproduct() function call, and the 
> COMMON_CORE inline asm in the pre-patch version).

IMO to meassure the call overhead the timer macros should be
farther out, that is outside that loop
we want to know how the extra function call interacts with the
code before and after
the timer code will affect this interaction if its between


> 
> If you can, measure it yourself as well to be sure.
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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notwithstanding go out to meet it. -- Thucydides
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