glibc/benchtests/bench-memset-walk.c
Siddhesh Poyarekar 36bb8edf51 benchtests: Memory walking benchmark for memset
This benchmark is an attempt to eliminate cache effects from string
benchmarks.  The benchmark walks backward through a large memory area
and sets different sizes of memory and alignments one at a time
instead of looping around in the same memory area.  This is a good
metric to have alongside the simple memset benchmark (which is only
really useful for smaller sizes) especially for larger sizes where the
likelihood of the call being done only once is pretty high.

	* benchtests/bench-memset-walk.c: New file.
	* benchtests/Makefile (string-benchset): Add it.
2017-10-05 22:20:23 +05:30

139 lines
3.5 KiB
C

/* Measure memset function throughput with large data sizes.
Copyright (C) 2017 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
#ifndef WIDE
# define TEST_NAME "memset"
#else
# define TEST_NAME "wmemset"
#endif /* WIDE */
#define START_SIZE (1)
#define MIN_PAGE_SIZE (getpagesize () + 32 * 1024 * 1024)
#define TIMEOUT (20 * 60)
#include "bench-string.h"
#ifndef WIDE
# define MEMSET memset
# define CHAR char
# define SIMPLE_MEMSET simple_memset
# define MEMCMP memcmp
#else
# include <wchar.h>
# define MEMSET wmemset
# define CHAR wchar_t
# define SIMPLE_MEMSET simple_wmemset
# define MEMCMP wmemcmp
#endif /* WIDE */
#include <assert.h>
#include "json-lib.h"
typedef CHAR *(*proto_t) (CHAR *, int, size_t);
CHAR *
inhibit_loop_to_libcall
SIMPLE_MEMSET (CHAR *s, int c, size_t n)
{
CHAR *r = s, *end = s + n;
while (r < end)
*r++ = c;
return s;
}
IMPL (SIMPLE_MEMSET, 1)
static void
do_one_test (json_ctx_t *json_ctx, impl_t *impl, CHAR *s, CHAR *s_end,
int c __attribute ((unused)), size_t n)
{
size_t i, iters = MIN_PAGE_SIZE / n;
timing_t start, stop, cur;
TIMING_NOW (start);
for (i = 0; i < iters && s <= s_end; s++, i++)
CALL (impl, s, c, n);
TIMING_NOW (stop);
TIMING_DIFF (cur, start, stop);
/* Get time taken per function call. */
json_element_double (json_ctx, (double) cur * n / i);
}
static void
do_test (json_ctx_t *json_ctx, int c, size_t len)
{
json_element_object_begin (json_ctx);
json_attr_uint (json_ctx, "length", len);
json_attr_uint (json_ctx, "char", c);
json_array_begin (json_ctx, "timings");
FOR_EACH_IMPL (impl, 0)
{
do_one_test (json_ctx, impl, (CHAR *) buf1,
(CHAR *) buf1 + MIN_PAGE_SIZE - len, c, len);
realloc_bufs ();
}
json_array_end (json_ctx);
json_element_object_end (json_ctx);
}
int
test_main (void)
{
json_ctx_t json_ctx;
size_t i;
test_init ();
json_init (&json_ctx, 0, stdout);
json_document_begin (&json_ctx);
json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
json_attr_object_begin (&json_ctx, "functions");
json_attr_object_begin (&json_ctx, TEST_NAME);
json_attr_string (&json_ctx, "bench-variant", "walk");
json_array_begin (&json_ctx, "ifuncs");
FOR_EACH_IMPL (impl, 0)
json_element_string (&json_ctx, impl->name);
json_array_end (&json_ctx);
json_array_begin (&json_ctx, "results");
for (i = START_SIZE; i <= MIN_PAGE_SIZE; i <<= 1)
/* Test length alignments from 0-16 bytes. */
for (int j = 0; j < i && j < 16; j++)
do_test (&json_ctx, 65, i + j);
for (i = START_SIZE; i <= MIN_PAGE_SIZE; i <<= 1)
for (int j = 0; j < i && j < 16; j++)
do_test (&json_ctx, 0, i + j);
json_array_end (&json_ctx);
json_attr_object_end (&json_ctx);
json_attr_object_end (&json_ctx);
json_document_end (&json_ctx);
return ret;
}
#include <support/test-driver.c>