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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 | // 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_first_and_bit(void *bitmap, const void *bitmap2, unsigned long len) { static DECLARE_BITMAP(cp, BITMAP_LEN) __initdata; unsigned long i, cnt; ktime_t time; bitmap_copy(cp, bitmap, BITMAP_LEN); time = ktime_get(); for (cnt = i = 0; i < len; cnt++) { i = find_first_and_bit(cp, bitmap2, len); __clear_bit(i, cp); } time = ktime_get() - time; pr_err("find_first_and_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_nth_bit(const unsigned long *bitmap, unsigned long len) { unsigned long l, n, w = bitmap_weight(bitmap, len); ktime_t time; time = ktime_get(); for (n = 0; n < w; n++) { l = find_nth_bit(bitmap, len, n); WARN_ON(l >= len); } time = ktime_get() - time; pr_err("find_nth_bit: %18llu ns, %6ld iterations\n", time, w); 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_nth_bit(bitmap, BITMAP_LEN / 10); /* * 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_first_and_bit(bitmap, bitmap2, BITMAP_LEN / 2); 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(get_random_u32_below(BITMAP_LEN), bitmap); __set_bit(get_random_u32_below(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_nth_bit(bitmap, BITMAP_LEN); test_find_first_bit(bitmap, BITMAP_LEN); test_find_first_and_bit(bitmap, bitmap2, 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_DESCRIPTION("Test for find_*_bit functions"); MODULE_LICENSE("GPL"); |