Re: [PATCH v1 1/5] benchtests: Improve bench-strrchr

["H.J. Lu" <hjl.tools@gmail.com>]

On Thu, Apr 21, 2022 at 3:08 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Thu, Apr 21, 2022 at 3:13 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Wed, Apr 20, 2022 at 8:14 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > >
> > > 1. Use json-lib for printing results.
> > > 2. Expose all parameters (before pos, seek_char, and max_char where
> > >    not printed).
> > > 3. Add benchmarks that test multiple occurence of seek_char in the
> > >    string.
> > > ---
> > >  benchtests/bench-strrchr.c | 126 ++++++++++++++++++++++++-------------
> > >  1 file changed, 82 insertions(+), 44 deletions(-)
> > >
> > > diff --git a/benchtests/bench-strrchr.c b/benchtests/bench-strrchr.c
> > > index abdae60c51..cceea77e1b 100644
> > > --- a/benchtests/bench-strrchr.c
> > > +++ b/benchtests/bench-strrchr.c
> > > @@ -23,6 +23,7 @@
> > >  # define TEST_NAME "strrchr"
> > >  #endif
> > >  #include "bench-string.h"
> > > +#include "json-lib.h"
> > >
> > >  #define BIG_CHAR MAX_CHAR
> > >
> > > @@ -53,7 +54,8 @@ SIMPLE_STRRCHR (const CHAR *s, int c)
> > >  }
> > >
> > >  static void
> > > -do_one_test (impl_t *impl, const CHAR *s, int c, CHAR *exp_res)
> > > +do_one_test (json_ctx_t *json_ctx, impl_t *impl, const CHAR *s, int c,
> > > +            CHAR *exp_res)
> > >  {
> > >    CHAR *res = CALL (impl, s, c);
> > >    size_t i, iters = INNER_LOOP_ITERS8;
> > > @@ -61,8 +63,8 @@ do_one_test (impl_t *impl, const CHAR *s, int c, CHAR *exp_res)
> > >
> > >    if (res != exp_res)
> > >      {
> > > -      error (0, 0, "Wrong result in function %s %p %p", impl->name,
> > > -            res, exp_res);
> > > +      error (0, 0, "Wrong result in function %s %p %p", impl->name, res,
> > > +            exp_res);
> >
> > These changes aren't needed.
> >
> > >        ret = 1;
> > >        return;
> > >      }
> > > @@ -72,24 +74,28 @@ do_one_test (impl_t *impl, const CHAR *s, int c, CHAR *exp_res)
> > >      {
> > >        CALL (impl, s, c);
> > >      }
> > > -  TIMING_NOW (stop);
> > >
> > > +  TIMING_NOW (stop);
> >
> > Not needed.
>
> Will fix in V2
> >
> > >    TIMING_DIFF (cur, start, stop);
> > >
> > > -  TIMING_PRINT_MEAN ((double) cur, (double) iters);
> > > +  json_element_double (json_ctx, (double) cur / (double) iters);
> > > +  return;
> >
> > Return isn't needed.
>
> Will fix in V2.
> >
> > >  }
> > >
> > >  static void
> > > -do_test (size_t align, size_t pos, size_t len, int seek_char, int max_char)
> > > +do_test (json_ctx_t *json_ctx, size_t align, size_t pos, size_t len,
> > > +        int seek_char, int max_char, size_t freq)
> > >  /* For wcsrchr: align here means align not in bytes,
> > >     but in wchar_ts, in bytes it will equal to align * (sizeof (wchar_t))
> > >     len for wcschr here isn't in bytes but it's number of wchar_t symbols.  */
> > >  {
> > >    size_t i;
> > > +  size_t pos_chunk_sz = freq ? (pos / freq) : pos;
> > > +  size_t last_pos = len;
> > >    CHAR *result;
> > >    CHAR *buf = (CHAR *) buf1;
> > >
> > > -  align &= 7;
> > > +  align &= (getpagesize () - 1);
> >
> > If we have such large alignments, the tests may be skipped.
> > Should we change it to 127 instead?
>
> There is logic around page cross cases in x86_64 versions so think
> makes sense to support benchmarking it.
>
> Also i think that would tend to give the previous version a bit of
> an unfair disadvantage as the slow aligning case will never be
> tested in the new version.

If "align" is close to the page size, will it trigger

 if ((align + len) * sizeof (CHAR) >= page_size)
    return;

and skip page cross cases?

> >
> > >    if ((align + len) * sizeof (CHAR) >= page_size)
> > >      return;
> > >
> > > @@ -103,6 +109,16 @@ do_test (size_t align, size_t pos, size_t len, int seek_char, int max_char)
> > >        if ((i > pos || pos >= len) && buf[align + i] == seek_char)
> > >         buf[align + i] = seek_char + 10 + (random () & 15);
> > >      }
> > > +
> > > +  if (pos_chunk_sz == 0 && pos)
> > > +    pos_chunk_sz = 1;
> > > +
> > > +  for (i = pos_chunk_sz; i < pos && i < len; i += pos_chunk_sz)
> > > +    {
> > > +      buf[align + i] = seek_char;
> > > +      last_pos = i;
> > > +    }
> > > +
> > >    buf[align + len] = 0;
> > >
> > >    if (pos < len)
> > > @@ -110,66 +126,88 @@ do_test (size_t align, size_t pos, size_t len, int seek_char, int max_char)
> > >        buf[align + pos] = seek_char;
> > >        result = (CHAR *) (buf + align + pos);
> > >      }
> > > +  else if (last_pos < len)
> > > +    result = (CHAR *) (buf + align + last_pos);
> > >    else if (seek_char == 0)
> > >      result = (CHAR *) (buf + align + len);
> > >    else
> > >      result = NULL;
> > >
> > > -  printf ("Length %4zd, alignment in bytes %2zd:", len, align * sizeof (CHAR));
> > > +  json_element_object_begin (json_ctx);
> > > +  json_attr_uint (json_ctx, "len", len);
> > > +  json_attr_uint (json_ctx, "pos", pos);
> > > +  json_attr_uint (json_ctx, "align", align);
> > > +  json_attr_uint (json_ctx, "freq", freq);
> > > +  json_attr_uint (json_ctx, "seek", seek_char);
> > > +  json_attr_uint (json_ctx, "max_char", max_char);
> > > +  json_array_begin (json_ctx, "timings");
> > >
> > >    FOR_EACH_IMPL (impl, 0)
> > > -    do_one_test (impl, (CHAR *) (buf + align), seek_char, result);
> > > +    do_one_test (json_ctx, impl, (CHAR *) (buf + align), seek_char, result);
> > >
> > > -  putchar ('\n');
> > > +  json_array_end (json_ctx);
> > > +  json_element_object_end (json_ctx);
> > >  }
> > >
> > >  int
> > >  test_main (void)
> > >  {
> > > -  size_t i;
> > > +  json_ctx_t json_ctx;
> > > +  size_t i, j;
> > > +  int seek;
> > >
> > >    test_init ();
> > > +  json_init (&json_ctx, 0, stdout);
> > >
> > > -  printf ("%20s", "");
> > > -  FOR_EACH_IMPL (impl, 0)
> > > -    printf ("\t%s", impl->name);
> > > -  putchar ('\n');
> > > +  json_document_begin (&json_ctx);
> > > +  json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
> > >
> > > -  for (i = 1; i < 8; ++i)
> > > -    {
> > > -      do_test (0, 16 << i, 2048, 23, SMALL_CHAR);
> > > -      do_test (i, 16 << i, 2048, 23, SMALL_CHAR);
> > > -    }
> > > +  json_attr_object_begin (&json_ctx, "functions");
> > > +  json_attr_object_begin (&json_ctx, TEST_NAME);
> > > +  json_attr_string (&json_ctx, "bench-variant", "");
> > >
> > > -  for (i = 1; i < 8; ++i)
> > > -    {
> > > -      do_test (i, 64, 256, 23, SMALL_CHAR);
> > > -      do_test (i, 64, 256, 23, BIG_CHAR);
> > > -    }
> > > -
> > > -  for (i = 0; i < 32; ++i)
> > > -    {
> > > -      do_test (0, i, i + 1, 23, SMALL_CHAR);
> > > -      do_test (0, i, i + 1, 23, BIG_CHAR);
> > > -    }
> > > +  json_array_begin (&json_ctx, "ifuncs");
> > > +  FOR_EACH_IMPL (impl, 0)
> > > +    json_element_string (&json_ctx, impl->name);
> > > +  json_array_end (&json_ctx);
> > >
> > > -  for (i = 1; i < 8; ++i)
> > > -    {
> > > -      do_test (0, 16 << i, 2048, 0, SMALL_CHAR);
> > > -      do_test (i, 16 << i, 2048, 0, SMALL_CHAR);
> > > -    }
> > > +  json_array_begin (&json_ctx, "results");
> > >
> > > -  for (i = 1; i < 8; ++i)
> > > +  for (seek = 0; seek <= 23; seek += 23)
> > >      {
> > > -      do_test (i, 64, 256, 0, SMALL_CHAR);
> > > -      do_test (i, 64, 256, 0, BIG_CHAR);
> > > +      for (j = 1; j < 32; j += j)
> > > +       {
> > > +         for (i = 1; i < 9; ++i)
> > > +           {
> > > +             do_test (&json_ctx, 0, 16 << i, 2048, seek, SMALL_CHAR, j);
> > > +             do_test (&json_ctx, i, 16 << i, 2048, seek, SMALL_CHAR, j);
> > > +           }
> > > +
> > > +         for (i = 1; i < 8; ++i)
> > > +           {
> > > +             do_test (&json_ctx, i, 64, 256, seek, SMALL_CHAR, j);
> > > +             do_test (&json_ctx, i, 64, 256, seek, BIG_CHAR, j);
> > > +
> > > +             do_test (&json_ctx, i * 15, 64, 256, seek, SMALL_CHAR, j);
> > > +             do_test (&json_ctx, i * 15, 64, 256, seek, BIG_CHAR, j);
> > > +           }
> > > +
> > > +         for (i = 0; i < 32; ++i)
> > > +           {
> > > +             do_test (&json_ctx, 0, i, i + 1, seek, SMALL_CHAR, j);
> > > +             do_test (&json_ctx, 0, i, i + 1, seek, BIG_CHAR, j);
> > > +           }
> > > +         if (seek == 0)
> > > +           {
> > > +             break;
> > > +           }
> > > +       }
> > >      }
> > >
> > > -  for (i = 0; i < 32; ++i)
> > > -    {
> > > -      do_test (0, i, i + 1, 0, SMALL_CHAR);
> > > -      do_test (0, i, i + 1, 0, BIG_CHAR);
> > > -    }
> > > +  json_array_end (&json_ctx);
> > > +  json_attr_object_end (&json_ctx);
> > > +  json_attr_object_end (&json_ctx);
> > > +  json_document_end (&json_ctx);
> > >
> > >    return ret;
> > >  }
> > > --
> > > 2.25.1
> > >
> >
> >
> > --
> > H.J.



-- 
H.J.