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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.
34 */
35static int __init test_find_first_bit(const void *bitmap, unsigned long len)
36{
37 static DECLARE_BITMAP(cp, BITMAP_LEN) __initdata;
38 unsigned long i, cnt;
39 ktime_t time;
40
41 bitmap_copy(cp, bitmap, BITMAP_LEN);
42
43 time = ktime_get();
44 for (cnt = i = 0; i < len; cnt++) {
45 i = find_first_bit(cp, len);
46 __clear_bit(i, cp);
47 }
48 time = ktime_get() - time;
49 pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt);
50
51 return 0;
52}
53
54static int __init test_find_first_and_bit(const void *bitmap, const void *bitmap2,
55 unsigned long len)
56{
57 static DECLARE_BITMAP(cp, BITMAP_LEN) __initdata;
58 unsigned long i, cnt;
59 ktime_t time;
60
61 bitmap_copy(cp, bitmap, BITMAP_LEN);
62
63 time = ktime_get();
64 for (cnt = i = 0; i < len; cnt++) {
65 i = find_first_and_bit(cp, bitmap2, len);
66 __clear_bit(i, cp);
67 }
68 time = ktime_get() - time;
69 pr_err("find_first_and_bit: %18llu ns, %6ld iterations\n", time, cnt);
70
71 return 0;
72}
73
74static int __init test_find_next_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_bit(bitmap, BITMAP_LEN, i) + 1;
82 time = ktime_get() - time;
83 pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt);
84
85 return 0;
86}
87
88static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)
89{
90 unsigned long i, cnt;
91 ktime_t time;
92
93 time = ktime_get();
94 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
95 i = find_next_zero_bit(bitmap, len, i) + 1;
96 time = ktime_get() - time;
97 pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
98
99 return 0;
100}
101
102static int __init test_find_last_bit(const void *bitmap, unsigned long len)
103{
104 unsigned long l, cnt = 0;
105 ktime_t time;
106
107 time = ktime_get();
108 do {
109 cnt++;
110 l = find_last_bit(bitmap, len);
111 if (l >= len)
112 break;
113 len = l;
114 } while (len);
115 time = ktime_get() - time;
116 pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt);
117
118 return 0;
119}
120
121static int __init test_find_nth_bit(const unsigned long *bitmap, unsigned long len)
122{
123 unsigned long l, n, w = bitmap_weight(bitmap, len);
124 ktime_t time;
125
126 time = ktime_get();
127 for (n = 0; n < w; n++) {
128 l = find_nth_bit(bitmap, len, n);
129 WARN_ON(l >= len);
130 }
131 time = ktime_get() - time;
132 pr_err("find_nth_bit: %18llu ns, %6ld iterations\n", time, w);
133
134 return 0;
135}
136
137static int __init test_find_next_and_bit(const void *bitmap,
138 const void *bitmap2, unsigned long len)
139{
140 unsigned long i, cnt;
141 ktime_t time;
142
143 time = ktime_get();
144 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
145 i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);
146 time = ktime_get() - time;
147 pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt);
148
149 return 0;
150}
151
152static int __init
153test_bitmap_find_next_zero_area_off(unsigned long *bitmap, unsigned long len)
154{
155 unsigned long i, cnt;
156 ktime_t time;
157
158 time = ktime_get();
159 for (cnt = i = 0; i < BITMAP_LEN; cnt++)
160 i = bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN, i, 8, 0, 0) + 1;
161 time = ktime_get() - time;
162 pr_err("bitmap_find_next_zero_area_off:%7llu ns, %6ld iterations\n", time, cnt);
163
164 return 0;
165}
166
167static int __init find_bit_test(void)
168{
169 unsigned long nbits = BITMAP_LEN / SPARSE;
170
171 pr_err("\nStart testing find_bit() with random-filled bitmap\n");
172
173 get_random_bytes(bitmap, sizeof(bitmap));
174 get_random_bytes(bitmap2, sizeof(bitmap2));
175
176 test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
177 test_find_next_bit(bitmap, BITMAP_LEN);
178 test_find_next_zero_bit(bitmap, BITMAP_LEN);
179 test_find_last_bit(bitmap, BITMAP_LEN);
180 test_find_nth_bit(bitmap, BITMAP_LEN / 10);
181
182 /*
183 * test_find_first_bit() may take some time, so
184 * traverse only part of bitmap to avoid soft lockup.
185 */
186 test_find_first_bit(bitmap, BITMAP_LEN / 10);
187 test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN / 2);
188 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
189
190 pr_err("\nStart testing find_bit() with sparse bitmap\n");
191
192 bitmap_zero(bitmap, BITMAP_LEN);
193 bitmap_zero(bitmap2, BITMAP_LEN);
194
195 while (nbits--) {
196 __set_bit(get_random_u32_below(BITMAP_LEN), bitmap);
197 __set_bit(get_random_u32_below(BITMAP_LEN), bitmap2);
198 }
199
200 test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
201 test_find_next_bit(bitmap, BITMAP_LEN);
202 test_find_next_zero_bit(bitmap, BITMAP_LEN);
203 test_find_last_bit(bitmap, BITMAP_LEN);
204 test_find_nth_bit(bitmap, BITMAP_LEN);
205 test_find_first_bit(bitmap, BITMAP_LEN);
206 test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN);
207 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
208
209 /*
210 * Everything is OK. Return error just to let user run benchmark
211 * again without annoying rmmod.
212 */
213 return -EINVAL;
214}
215module_init(find_bit_test);
216
217MODULE_DESCRIPTION("Test for find_*_bit functions");
218MODULE_LICENSE("GPL");