linux/lib/find_bit_benchmark.c
Thomas Gleixner 5b497af42f treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of version 2 of the gnu general public license as
  published by the free software foundation this program 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 general public license
  for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 64 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.894819585@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:36:38 +02:00

159 lines
3.9 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Test for find_*_bit functions.
*
* Copyright (c) 2017 Cavium.
*/
/*
* find_bit functions are widely used in kernel, so the successful boot
* is good enough test for correctness.
*
* This test is focused on performance of traversing bitmaps. Two typical
* scenarios are reproduced:
* - randomly filled bitmap with approximately equal number of set and
* cleared bits;
* - sparse bitmap with few set bits at random positions.
*/
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/random.h>
#define BITMAP_LEN (4096UL * 8 * 10)
#define SPARSE 500
static DECLARE_BITMAP(bitmap, BITMAP_LEN) __initdata;
static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata;
/*
* This is Schlemiel the Painter's algorithm. It should be called after
* all other tests for the same bitmap because it sets all bits of bitmap to 1.
*/
static int __init test_find_first_bit(void *bitmap, unsigned long len)
{
unsigned long i, cnt;
ktime_t time;
time = ktime_get();
for (cnt = i = 0; i < len; cnt++) {
i = find_first_bit(bitmap, len);
__clear_bit(i, bitmap);
}
time = ktime_get() - time;
pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt);
return 0;
}
static int __init test_find_next_bit(const void *bitmap, unsigned long len)
{
unsigned long i, cnt;
ktime_t time;
time = ktime_get();
for (cnt = i = 0; i < BITMAP_LEN; cnt++)
i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;
time = ktime_get() - time;
pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt);
return 0;
}
static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)
{
unsigned long i, cnt;
ktime_t time;
time = ktime_get();
for (cnt = i = 0; i < BITMAP_LEN; cnt++)
i = find_next_zero_bit(bitmap, len, i) + 1;
time = ktime_get() - time;
pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
return 0;
}
static int __init test_find_last_bit(const void *bitmap, unsigned long len)
{
unsigned long l, cnt = 0;
ktime_t time;
time = ktime_get();
do {
cnt++;
l = find_last_bit(bitmap, len);
if (l >= len)
break;
len = l;
} while (len);
time = ktime_get() - time;
pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt);
return 0;
}
static int __init test_find_next_and_bit(const void *bitmap,
const void *bitmap2, unsigned long len)
{
unsigned long i, cnt;
ktime_t time;
time = ktime_get();
for (cnt = i = 0; i < BITMAP_LEN; cnt++)
i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);
time = ktime_get() - time;
pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt);
return 0;
}
static int __init find_bit_test(void)
{
unsigned long nbits = BITMAP_LEN / SPARSE;
pr_err("\nStart testing find_bit() with random-filled bitmap\n");
get_random_bytes(bitmap, sizeof(bitmap));
get_random_bytes(bitmap2, sizeof(bitmap2));
test_find_next_bit(bitmap, BITMAP_LEN);
test_find_next_zero_bit(bitmap, BITMAP_LEN);
test_find_last_bit(bitmap, BITMAP_LEN);
/*
* test_find_first_bit() may take some time, so
* traverse only part of bitmap to avoid soft lockup.
*/
test_find_first_bit(bitmap, BITMAP_LEN / 10);
test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
pr_err("\nStart testing find_bit() with sparse bitmap\n");
bitmap_zero(bitmap, BITMAP_LEN);
bitmap_zero(bitmap2, BITMAP_LEN);
while (nbits--) {
__set_bit(prandom_u32() % BITMAP_LEN, bitmap);
__set_bit(prandom_u32() % BITMAP_LEN, bitmap2);
}
test_find_next_bit(bitmap, BITMAP_LEN);
test_find_next_zero_bit(bitmap, BITMAP_LEN);
test_find_last_bit(bitmap, BITMAP_LEN);
test_find_first_bit(bitmap, BITMAP_LEN);
test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
/*
* Everything is OK. Return error just to let user run benchmark
* again without annoying rmmod.
*/
return -EINVAL;
}
module_init(find_bit_test);
MODULE_LICENSE("GPL");