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tests: drop misleading fixed-benchmark

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Because this benchmark performed wl_fixed_to_double conversions
on a long sequence of consecutive integers, the compiler could
optimize away the addition performed in wl_fixed_to_double, merging
it with the loop iteration code. This made tests/fixed-benchmark.c
significantly underestimate the actual cost of the current
wl_fixed_to_double implementation.

Signed-off-by: Manuel Stoeckl <code@mstoeckl.com>
This commit is contained in:
Manuel Stoeckl 2023-02-25 15:57:47 -05:00 • committed by Simon Ser
parent d40052e083
commit b1b97e8d34
2 changed files with 0 additions and 116 deletions
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107
tests/fixed-benchmark.c
View file

@ -1,107 +0,0 @@
/*
* Copyright © 2012 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial
* portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <assert.h>
#include "wayland-private.h"
volatile double global_d;
static void
noop_conversion(void)
{
wl_fixed_t f;
union {
int64_t i;
double d;
} u;
for (f = 0; f < INT32_MAX; f++) {
u.i = f;
global_d = u.d;
}
}
static void
magic_conversion(void)
{
wl_fixed_t f;
for (f = 0; f < INT32_MAX; f++)
global_d = wl_fixed_to_double(f);
}
static void
mul_conversion(void)
{
wl_fixed_t f;
/* This will get optimized into multiplication by 1/256 */
for (f = 0; f < INT32_MAX; f++)
global_d = f / 256.0;
}
double factor = 256.0;
static void
div_conversion(void)
{
wl_fixed_t f;
for (f = 0; f < INT32_MAX; f++)
global_d = f / factor;
}
static void
benchmark(const char *s, void (*f)(void))
{
struct timespec start, stop, elapsed;
clock_gettime(CLOCK_MONOTONIC, &start);
f();
clock_gettime(CLOCK_MONOTONIC, &stop);
elapsed.tv_sec = stop.tv_sec - start.tv_sec;
elapsed.tv_nsec = stop.tv_nsec - start.tv_nsec;
if (elapsed.tv_nsec < 0) {
elapsed.tv_nsec += 1000000000;
elapsed.tv_sec--;
}
printf("benchmarked %s:\t%ld.%09lds\n",
s, elapsed.tv_sec, elapsed.tv_nsec);
}
int main(void)
{
benchmark("noop", noop_conversion);
benchmark("magic", magic_conversion);
benchmark("div", div_conversion);
benchmark("mul", mul_conversion);
return 0;
}

9
tests/meson.build
View file

@ -54,15 +54,6 @@ tests_protocol_c = custom_target(
output: 'tests-protocol.c'
)
benchmark(
'fixed-benchmark',
executable(
'fixed-benchmark',
'fixed-benchmark.c',
dependencies: [ test_runner_dep, rt_dep ]
)
)
executable(
'exec-fd-leak-checker',
'exec-fd-leak-checker.c',