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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Test for find_*_bit functions.
4 *
5 * Copyright (c) 2017 Cavium.
6 */
7
8/*
9 * find_bit functions are widely used in kernel, so the successful boot
10 * is good enough test for correctness.
11 *
12 * This test is focused on performance of traversing bitmaps. Two typical
13 * scenarios are reproduced:
14 * - randomly filled bitmap with approximately equal number of set and
15 * cleared bits;
16 * - sparse bitmap with few set bits at random positions.
17 */
18
19#include <linux/bitops.h>
20#include <linux/kernel.h>
21#include <linux/list.h>
22#include <linux/module.h>
23#include <linux/printk.h>
24#include <linux/random.h>
25
26#define BITMAP_LEN (4096UL * 8 * 10)
27#define SPARSE 500
28
29static DECLARE_BITMAP(bitmap, BITMAP_LEN) __initdata;
30static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata;
31
32/*
33 * This is Schlemiel the Painter's algorithm. It should be called after
34 * all other tests for the same bitmap because it sets all bits of bitmap to 1.
35 */
36static int __init test_find_first_bit(void *bitmap, unsigned long len)
37{
38 unsigned long i, cnt;
39 ktime_t time;
40
41 time = ktime_get();
42 for (cnt = i = 0; i < len; cnt++) {
43 i = find_first_bit(bitmap, len);
44 __clear_bit(i, bitmap);
45 }
46 time = ktime_get() - time;
47 pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt);
48
49 return 0;
50}
51
52static int __init test_find_next_bit(const void *bitmap, unsigned long len)
53{
54 unsigned long i, cnt;
55 ktime_t time;
56
57 time = ktime_get();
58 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
59 i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;
60 time = ktime_get() - time;
61 pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt);
62
63 return 0;
64}
65
66static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)
67{
68 unsigned long i, cnt;
69 ktime_t time;
70
71 time = ktime_get();
72 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
73 i = find_next_zero_bit(bitmap, len, i) + 1;
74 time = ktime_get() - time;
75 pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
76
77 return 0;
78}
79
80static int __init test_find_last_bit(const void *bitmap, unsigned long len)
81{
82 unsigned long l, cnt = 0;
83 ktime_t time;
84
85 time = ktime_get();
86 do {
87 cnt++;
88 l = find_last_bit(bitmap, len);
89 if (l >= len)
90 break;
91 len = l;
92 } while (len);
93 time = ktime_get() - time;
94 pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt);
95
96 return 0;
97}
98
99static int __init test_find_next_and_bit(const void *bitmap,
100 const void *bitmap2, unsigned long len)
101{
102 unsigned long i, cnt;
103 ktime_t time;
104
105 time = ktime_get();
106 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
107 i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);
108 time = ktime_get() - time;
109 pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt);
110
111 return 0;
112}
113
114static int __init find_bit_test(void)
115{
116 unsigned long nbits = BITMAP_LEN / SPARSE;
117
118 pr_err("\nStart testing find_bit() with random-filled bitmap\n");
119
120 get_random_bytes(bitmap, sizeof(bitmap));
121 get_random_bytes(bitmap2, sizeof(bitmap2));
122
123 test_find_next_bit(bitmap, BITMAP_LEN);
124 test_find_next_zero_bit(bitmap, BITMAP_LEN);
125 test_find_last_bit(bitmap, BITMAP_LEN);
126
127 /*
128 * test_find_first_bit() may take some time, so
129 * traverse only part of bitmap to avoid soft lockup.
130 */
131 test_find_first_bit(bitmap, BITMAP_LEN / 10);
132 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
133
134 pr_err("\nStart testing find_bit() with sparse bitmap\n");
135
136 bitmap_zero(bitmap, BITMAP_LEN);
137 bitmap_zero(bitmap2, BITMAP_LEN);
138
139 while (nbits--) {
140 __set_bit(prandom_u32() % BITMAP_LEN, bitmap);
141 __set_bit(prandom_u32() % BITMAP_LEN, bitmap2);
142 }
143
144 test_find_next_bit(bitmap, BITMAP_LEN);
145 test_find_next_zero_bit(bitmap, BITMAP_LEN);
146 test_find_last_bit(bitmap, BITMAP_LEN);
147 test_find_first_bit(bitmap, BITMAP_LEN);
148 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
149
150 /*
151 * Everything is OK. Return error just to let user run benchmark
152 * again without annoying rmmod.
153 */
154 return -EINVAL;
155}
156module_init(find_bit_test);
157
158MODULE_LICENSE("GPL");
1/*
2 * Test for find_*_bit functions.
3 *
4 * Copyright (c) 2017 Cavium.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of version 2 of the GNU General Public
8 * License as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 */
15
16/*
17 * find_bit functions are widely used in kernel, so the successful boot
18 * is good enough test for correctness.
19 *
20 * This test is focused on performance of traversing bitmaps. Two typical
21 * scenarios are reproduced:
22 * - randomly filled bitmap with approximately equal number of set and
23 * cleared bits;
24 * - sparse bitmap with few set bits at random positions.
25 */
26
27#include <linux/bitops.h>
28#include <linux/kernel.h>
29#include <linux/list.h>
30#include <linux/module.h>
31#include <linux/printk.h>
32#include <linux/random.h>
33
34#define BITMAP_LEN (4096UL * 8 * 10)
35#define SPARSE 500
36
37static DECLARE_BITMAP(bitmap, BITMAP_LEN) __initdata;
38static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata;
39
40/*
41 * This is Schlemiel the Painter's algorithm. It should be called after
42 * all other tests for the same bitmap because it sets all bits of bitmap to 1.
43 */
44static int __init test_find_first_bit(void *bitmap, unsigned long len)
45{
46 unsigned long i, cnt;
47 ktime_t time;
48
49 time = ktime_get();
50 for (cnt = i = 0; i < len; cnt++) {
51 i = find_first_bit(bitmap, len);
52 __clear_bit(i, bitmap);
53 }
54 time = ktime_get() - time;
55 pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt);
56
57 return 0;
58}
59
60static int __init test_find_next_bit(const void *bitmap, unsigned long len)
61{
62 unsigned long i, cnt;
63 ktime_t time;
64
65 time = ktime_get();
66 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
67 i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;
68 time = ktime_get() - time;
69 pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt);
70
71 return 0;
72}
73
74static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)
75{
76 unsigned long i, cnt;
77 ktime_t time;
78
79 time = ktime_get();
80 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
81 i = find_next_zero_bit(bitmap, len, i) + 1;
82 time = ktime_get() - time;
83 pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
84
85 return 0;
86}
87
88static int __init test_find_last_bit(const void *bitmap, unsigned long len)
89{
90 unsigned long l, cnt = 0;
91 ktime_t time;
92
93 time = ktime_get();
94 do {
95 cnt++;
96 l = find_last_bit(bitmap, len);
97 if (l >= len)
98 break;
99 len = l;
100 } while (len);
101 time = ktime_get() - time;
102 pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt);
103
104 return 0;
105}
106
107static int __init test_find_next_and_bit(const void *bitmap,
108 const void *bitmap2, unsigned long len)
109{
110 unsigned long i, cnt;
111 cycles_t cycles;
112
113 cycles = get_cycles();
114 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
115 i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i+1);
116 cycles = get_cycles() - cycles;
117 pr_err("find_next_and_bit:\t\t%llu cycles, %ld iterations\n",
118 (u64)cycles, cnt);
119
120 return 0;
121}
122
123static int __init find_bit_test(void)
124{
125 unsigned long nbits = BITMAP_LEN / SPARSE;
126
127 pr_err("\nStart testing find_bit() with random-filled bitmap\n");
128
129 get_random_bytes(bitmap, sizeof(bitmap));
130 get_random_bytes(bitmap2, sizeof(bitmap2));
131
132 test_find_next_bit(bitmap, BITMAP_LEN);
133 test_find_next_zero_bit(bitmap, BITMAP_LEN);
134 test_find_last_bit(bitmap, BITMAP_LEN);
135
136 /*
137 * test_find_first_bit() may take some time, so
138 * traverse only part of bitmap to avoid soft lockup.
139 */
140 test_find_first_bit(bitmap, BITMAP_LEN / 10);
141 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
142
143 pr_err("\nStart testing find_bit() with sparse bitmap\n");
144
145 bitmap_zero(bitmap, BITMAP_LEN);
146 bitmap_zero(bitmap2, BITMAP_LEN);
147
148 while (nbits--) {
149 __set_bit(prandom_u32() % BITMAP_LEN, bitmap);
150 __set_bit(prandom_u32() % BITMAP_LEN, bitmap2);
151 }
152
153 test_find_next_bit(bitmap, BITMAP_LEN);
154 test_find_next_zero_bit(bitmap, BITMAP_LEN);
155 test_find_last_bit(bitmap, BITMAP_LEN);
156 test_find_first_bit(bitmap, BITMAP_LEN);
157 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
158
159 /*
160 * Everything is OK. Return error just to let user run benchmark
161 * again without annoying rmmod.
162 */
163 return -EINVAL;
164}
165module_init(find_bit_test);
166
167MODULE_LICENSE("GPL");