140 lines
3.5 KiB
C
140 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Benchmark find_next_bit and related bit operations.
|
|
*
|
|
* Copyright 2020 Google LLC.
|
|
*/
|
|
#include <stdlib.h>
|
|
#include "bench.h"
|
|
#include "../util/stat.h"
|
|
#include <linux/bitmap.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/time64.h>
|
|
#include <subcmd/parse-options.h>
|
|
|
|
static unsigned int outer_iterations = 5;
|
|
static unsigned int inner_iterations = 100000;
|
|
|
|
static const struct option options[] = {
|
|
OPT_UINTEGER('i', "outer-iterations", &outer_iterations,
|
|
"Number of outer iterations used"),
|
|
OPT_UINTEGER('j', "inner-iterations", &inner_iterations,
|
|
"Number of inner iterations used"),
|
|
OPT_END()
|
|
};
|
|
|
|
static const char *const bench_usage[] = {
|
|
"perf bench mem find_bit <options>",
|
|
NULL
|
|
};
|
|
|
|
static unsigned int accumulator;
|
|
static unsigned int use_of_val;
|
|
|
|
static noinline void workload(int val)
|
|
{
|
|
use_of_val += val;
|
|
accumulator++;
|
|
}
|
|
|
|
#if (defined(__i386__) || defined(__x86_64__)) && defined(__GCC_ASM_FLAG_OUTPUTS__)
|
|
static bool asm_test_bit(long nr, const unsigned long *addr)
|
|
{
|
|
bool oldbit;
|
|
|
|
asm volatile("bt %2,%1"
|
|
: "=@ccc" (oldbit)
|
|
: "m" (*(unsigned long *)addr), "Ir" (nr) : "memory");
|
|
|
|
return oldbit;
|
|
}
|
|
#else
|
|
#define asm_test_bit test_bit
|
|
#endif
|
|
|
|
static int do_for_each_set_bit(unsigned int num_bits)
|
|
{
|
|
unsigned long *to_test = bitmap_zalloc(num_bits);
|
|
struct timeval start, end, diff;
|
|
u64 runtime_us;
|
|
struct stats fb_time_stats, tb_time_stats;
|
|
double time_average, time_stddev;
|
|
unsigned int bit, i, j;
|
|
unsigned int set_bits, skip;
|
|
|
|
init_stats(&fb_time_stats);
|
|
init_stats(&tb_time_stats);
|
|
|
|
for (set_bits = 1; set_bits <= num_bits; set_bits <<= 1) {
|
|
bitmap_zero(to_test, num_bits);
|
|
skip = num_bits / set_bits;
|
|
for (i = 0; i < num_bits; i += skip)
|
|
__set_bit(i, to_test);
|
|
|
|
for (i = 0; i < outer_iterations; i++) {
|
|
#ifndef NDEBUG
|
|
unsigned int old = accumulator;
|
|
#endif
|
|
|
|
gettimeofday(&start, NULL);
|
|
for (j = 0; j < inner_iterations; j++) {
|
|
for_each_set_bit(bit, to_test, num_bits)
|
|
workload(bit);
|
|
}
|
|
gettimeofday(&end, NULL);
|
|
assert(old + (inner_iterations * set_bits) == accumulator);
|
|
timersub(&end, &start, &diff);
|
|
runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
|
|
update_stats(&fb_time_stats, runtime_us);
|
|
|
|
#ifndef NDEBUG
|
|
old = accumulator;
|
|
#endif
|
|
gettimeofday(&start, NULL);
|
|
for (j = 0; j < inner_iterations; j++) {
|
|
for (bit = 0; bit < num_bits; bit++) {
|
|
if (asm_test_bit(bit, to_test))
|
|
workload(bit);
|
|
}
|
|
}
|
|
gettimeofday(&end, NULL);
|
|
assert(old + (inner_iterations * set_bits) == accumulator);
|
|
timersub(&end, &start, &diff);
|
|
runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
|
|
update_stats(&tb_time_stats, runtime_us);
|
|
}
|
|
|
|
printf("%d operations %d bits set of %d bits\n",
|
|
inner_iterations, set_bits, num_bits);
|
|
time_average = avg_stats(&fb_time_stats);
|
|
time_stddev = stddev_stats(&fb_time_stats);
|
|
printf(" Average for_each_set_bit took: %.3f usec (+- %.3f usec)\n",
|
|
time_average, time_stddev);
|
|
time_average = avg_stats(&tb_time_stats);
|
|
time_stddev = stddev_stats(&tb_time_stats);
|
|
printf(" Average test_bit loop took: %.3f usec (+- %.3f usec)\n",
|
|
time_average, time_stddev);
|
|
|
|
if (use_of_val == accumulator) /* Try to avoid compiler tricks. */
|
|
printf("\n");
|
|
}
|
|
bitmap_free(to_test);
|
|
return 0;
|
|
}
|
|
|
|
int bench_mem_find_bit(int argc, const char **argv)
|
|
{
|
|
int err = 0, i;
|
|
|
|
argc = parse_options(argc, argv, options, bench_usage, 0);
|
|
if (argc) {
|
|
usage_with_options(bench_usage, options);
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
for (i = 1; i <= 2048; i <<= 1)
|
|
do_for_each_set_bit(i);
|
|
|
|
return err;
|
|
}
|