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Re: [PATCH] benchtests: Add strtod benchmark


On 4 November 2013 10:30, Adhemerval Zanella
<azanella@linux.vnet.ibm.com> wrote:
> Hi all,
>
> This patch add a benchtest for 'strtod'. I used as possible input the testing
> values from both 'stdlib/tst-strtod.c' and 'stdlib/tst-atof2.c'. I'm aware it
> might not be the best inputs that might cover all the strtod cases or even the
> user realcases, however adjustment can me made in the future.
>
> ---
>
> 2013-11-04  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
>
>         * benchtests/Makefile: Add bench-strtod.
>         * benchtests/bench-strtod.c: New file: strtod benchtest.
>
> --
>
> diff --git a/benchtests/Makefile b/benchtests/Makefile
> index aec395a..5eb65e5 100644
> --- a/benchtests/Makefile
> +++ b/benchtests/Makefile
> @@ -32,7 +32,9 @@ string-bench := bcopy bzero memccpy memchr memcmp memcpy memmem memmove \
>  string-bench-ifunc := $(addsuffix -ifunc, $(string-bench))
>  string-bench-all := $(string-bench) $(string-bench-ifunc)
>
> -benchset := $(string-bench-all)
> +stdlib-bench := strtod
> +
> +benchset := $(string-bench-all) $(stdlib-bench)
>
>  LDLIBS-bench-acos = -lm
>  LDLIBS-bench-acosh = -lm
> diff --git a/benchtests/bench-strtod.c b/benchtests/bench-strtod.c
> new file mode 100644
> index 0000000..72151f9
> --- /dev/null
> +++ b/benchtests/bench-strtod.c
> @@ -0,0 +1,119 @@
> +/* Measure strtod implementation.
> +   Copyright (C) 2013 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#define TEST_MAIN
> +#define TEST_NAME "strtod"
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include "bench-timing.h"
> +
> +#define INNER_LOOP_ITERS 65536
> +
> +struct ltest
> +  {
> +    const char *str;
> +  };

Is there a reason why this struct is needed rather than using a const
char * directly?

> +static const struct ltest inputs[] =
> +  {
> +    { "1e308" },
> +    { "100000000e300" },
> +    { "0x1p1023" },
> +    { "0x1000p1011" },
> +    { "0x1p1020" },
> +    { "0x0.00001p1040" },
> +    { "1e-307" },
> +    { "0.000001e-301" },
> +    { "0.0000001e-300" },
> +    { "0.00000001e-299" },
> +    { "1000000e-313" },
> +    { "10000000e-314" },
> +    { "100000000e-315" },
> +    { "0x1p-1021" },
> +    { "0x1000p-1033" },
> +    { "0x10000p-1037" },
> +    { "0x0.001p-1009" },
> +    { "0x0.0001p-1005" },
> +    { "12.345" },
> +    { "12.345e19" },
> +    { "-.1e+9" },
> +    { ".125" },
> +    { "1e20" },
> +    { "0e-19" },
> +    { "4\00012" },
> +    { "5.9e-76" },
> +    { "0x1.4p+3" },
> +    { "0xAp0" },
> +    { "0x0Ap0" },
> +    { "0x0A" },
> +    { "0xA0" },
> +    { "0x0.A0p8" },
> +    { "0x0.50p9" },
> +    { "0x0.28p10" },
> +    { "0x0.14p11" },
> +    { "0x0.0A0p12" },
> +    { "0x0.050p13" },
> +    { "0x0.028p14" },
> +    { "0x0.014p15" },
> +    { "0x00.00A0p16" },
> +    { "0x00.0050p17" },
> +    { "0x00.0028p18" },
> +    { "0x00.0014p19" },
> +    { "0x1p-1023" },
> +    { "0x0.8p-1022" },
> +    { "Inf" },
> +    { "-Inf" },
> +    { "+InFiNiTy" },
> +    { "0x80000Ap-23" },
> +    { "1e-324" },
> +    { "0x100000000000008p0" },
> +    { "0x100000000000008.p0" },
> +    { "0x100000000000008.00p0" },
> +    { "0x10000000000000800p0" },
> +    { "0x10000000000000801p0" },
> +    { NULL }
> +};
> +
> +int
> +do_bench (void)
> +{
> +  const size_t iters = INNER_LOOP_ITERS;
> +  const struct ltest *lt;
> +

I guess there should be a call to TIMING_INIT here. Not sure it is
essential but it would be consistent at least.

> +  for (lt = inputs; lt->str != NULL; ++lt)
> +    {
> +      char *ep;
> +      timing_t start, stop, cur;
> +
> +      printf ("Input %-24s:", lt->str);
> +      TIMING_NOW (start);
> +      for (size_t i = 0; i < iters; ++i)
> +       strtod(lt->str, &ep);
> +      TIMING_NOW (stop);
> +
> +      TIMING_DIFF (cur, start, stop);
> +      TIMING_PRINT_MEAN ((double) cur, (double) iters);
> +      putchar ('\n');
> +    }
> +
> +  return 0;
> +}
> +
> +#define TEST_FUNCTION do_bench ()
> +
> +#include "../test-skeleton.c"

Otherwise looks good to me.

-- 
Will Newton
Toolchain Working Group, Linaro


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