[FFmpeg-devel] [PATCH v2 3/4] checkasm: improve print format

[Ramiro Polla]

On Sun, Aug 25, 2024 at 7:52 PM J. Dekker <jdek at itanimul.li> wrote:
> On Thu, Aug 22, 2024, at 16:57, Ramiro Polla wrote:
> > On Wed, Aug 21, 2024 at 1:26 PM J. Dekker <jdek at itanimul.li> wrote:
> >>
> >> Port dav1d's checkasm output format to FFmpeg's checkasm, includes
> >> relative speedups and aligns results.
> >>
> >> Signed-off-by: J. Dekker <jdek at itanimul.li>
> >> ---
> >>  tests/checkasm/checkasm.c | 53 +++++++++++++++++++++++++++++++++++----
> >>  1 file changed, 48 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
> >> index c5c1eeb07a..f43c1c50f0 100644
> >> --- a/tests/checkasm/checkasm.c
> >> +++ b/tests/checkasm/checkasm.c
> >> @@ -18,6 +18,31 @@
> >>   * You should have received a copy of the GNU General Public License along
> >>   * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
> >>   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> >> + *
> >> + * Copyright © 2018, VideoLAN and dav1d authors
> >> + * Copyright © 2018, Two Orioles, LLC
> >> + * All rights reserved.
> >> + *
> >> + * Redistribution and use in source and binary forms, with or without
> >> + * modification, are permitted provided that the following conditions are met:
> >> + *
> >> + * 1. Redistributions of source code must retain the above copyright notice, this
> >> + *    list of conditions and the following disclaimer.
> >> + *
> >> + * 2. Redistributions in binary form must reproduce the above copyright notice,
> >> + *    this list of conditions and the following disclaimer in the documentation
> >> + *    and/or other materials provided with the distribution.
> >> + *
> >> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
> >> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
> >> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> >> + * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
> >> + * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
> >> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
> >> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
> >> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> >> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
> >> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> >>   */
> >
> > Do we need this double licensing?
> >
> >>
> >>  #include "config.h"
> >> @@ -575,6 +600,16 @@ static int measure_nop_time(void)
> >>      return nop_sum / 500;
> >>  }
> >>
> >> +static inline double avg_cycles_per_call(const CheckasmPerf *const p)
> >> +{
> >> +    if (p->iterations) {
> >> +        const double cycles = (double)(10 * p->cycles) / p->iterations - state.nop_time;
> >> +        if (cycles > 0.0)
> >> +            return cycles / 4.0; /* 4 calls per iteration */
> >> +    }
> >> +    return 0.0;
> >> +}
> >> +
> >>  /* Print benchmark results */
> >>  static void print_benchs(CheckasmFunc *f)
> >>  {
> >> @@ -584,17 +619,25 @@ static void print_benchs(CheckasmFunc *f)
> >>          /* Only print functions with at least one assembly version */
> >>          if (f->versions.cpu || f->versions.next) {
> >>              CheckasmFuncVersion *v = &f->versions;
> >> +            const CheckasmPerf *p = &v->perf;
> >> +            const double baseline = avg_cycles_per_call(p);
> >> +            double decicycles;
> >>              do {
> >> -                CheckasmPerf *p = &v->perf;
> >>                  if (p->iterations) {
> >> -                    int decicycles = (10*p->cycles/p->iterations - state.nop_time) / 4;
> >> +                    p = &v->perf;
> >> +                    decicycles = avg_cycles_per_call(p);
> >>                      if (state.csv || state.tsv) {
> >>                          const char sep = state.csv ? ',' : '\t';
> >> -                        printf("%s%c%s%c%d.%d\n", f->name, sep,
> >> +                        printf("%s%c%s%c%.1f\n", f->name, sep,
> >>                                 cpu_suffix(v->cpu), sep,
> >> -                               decicycles / 10, decicycles % 10);
> >> +                               decicycles / 10.0);
> >>                      } else {
> >> -                        printf("%s_%s: %d.%d\n", f->name, cpu_suffix(v->cpu), decicycles/10, decicycles%10);
> >> +                        const int pad_length = 10 + 50 -
> >> +                            printf("%s_%s:", f->name, cpu_suffix(v->cpu));
> >> +                        const double ratio = decicycles ?
> >> +                            baseline / decicycles : 0.0;
> >> +                        printf("%*.1f (%5.2fx)\n", FFMAX(pad_length, 0),
> >> +                            decicycles / 10.0, ratio);
> >
> > It looks a bit noisy to always print "( 1.00x)" for the C versions.
> > Perhaps it could be left empty or print "ref".
> >
> > Also do you plan on improving it even further? For example printing a
> > table like this:
> >                        c     sse           avx
> > blockdsp.clear_block:  34.0  3.5 ( 9.59x)  1.8 (18.92x)
>
> I would like to leave it as is initially. It can always be changed later though the intention here is to sync it up with dav1d's checkasm.

Should we aim to first improve dav1d's checkasm and then merge the
changes back in FFmpeg?