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1// SPDX-License-Identifier: GPL-2.0-only2/*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 boot10 * is good enough test for correctness.11 *12 * This test is focused on performance of traversing bitmaps. Two typical13 * scenarios are reproduced:14 * - randomly filled bitmap with approximately equal number of set and15 * 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 50028 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 after34 * 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_first_and_bit(void *bitmap, const void *bitmap2, unsigned long len)53{54 static DECLARE_BITMAP(cp, BITMAP_LEN) __initdata;55 unsigned long i, cnt;56 ktime_t time;57 58 bitmap_copy(cp, bitmap, BITMAP_LEN);59 60 time = ktime_get();61 for (cnt = i = 0; i < len; cnt++) {62 i = find_first_and_bit(cp, bitmap2, len);63 __clear_bit(i, cp);64 }65 time = ktime_get() - time;66 pr_err("find_first_and_bit: %18llu ns, %6ld iterations\n", time, cnt);67 68 return 0;69}70 71static int __init test_find_next_bit(const void *bitmap, unsigned long len)72{73 unsigned long i, cnt;74 ktime_t time;75 76 time = ktime_get();77 for (cnt = i = 0; i < BITMAP_LEN; cnt++)78 i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;79 time = ktime_get() - time;80 pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt);81 82 return 0;83}84 85static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)86{87 unsigned long i, cnt;88 ktime_t time;89 90 time = ktime_get();91 for (cnt = i = 0; i < BITMAP_LEN; cnt++)92 i = find_next_zero_bit(bitmap, len, i) + 1;93 time = ktime_get() - time;94 pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);95 96 return 0;97}98 99static int __init test_find_last_bit(const void *bitmap, unsigned long len)100{101 unsigned long l, cnt = 0;102 ktime_t time;103 104 time = ktime_get();105 do {106 cnt++;107 l = find_last_bit(bitmap, len);108 if (l >= len)109 break;110 len = l;111 } while (len);112 time = ktime_get() - time;113 pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt);114 115 return 0;116}117 118static int __init test_find_nth_bit(const unsigned long *bitmap, unsigned long len)119{120 unsigned long l, n, w = bitmap_weight(bitmap, len);121 ktime_t time;122 123 time = ktime_get();124 for (n = 0; n < w; n++) {125 l = find_nth_bit(bitmap, len, n);126 WARN_ON(l >= len);127 }128 time = ktime_get() - time;129 pr_err("find_nth_bit: %18llu ns, %6ld iterations\n", time, w);130 131 return 0;132}133 134static int __init test_find_next_and_bit(const void *bitmap,135 const void *bitmap2, unsigned long len)136{137 unsigned long i, cnt;138 ktime_t time;139 140 time = ktime_get();141 for (cnt = i = 0; i < BITMAP_LEN; cnt++)142 i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);143 time = ktime_get() - time;144 pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt);145 146 return 0;147}148 149static int __init find_bit_test(void)150{151 unsigned long nbits = BITMAP_LEN / SPARSE;152 153 pr_err("\nStart testing find_bit() with random-filled bitmap\n");154 155 get_random_bytes(bitmap, sizeof(bitmap));156 get_random_bytes(bitmap2, sizeof(bitmap2));157 158 test_find_next_bit(bitmap, BITMAP_LEN);159 test_find_next_zero_bit(bitmap, BITMAP_LEN);160 test_find_last_bit(bitmap, BITMAP_LEN);161 test_find_nth_bit(bitmap, BITMAP_LEN / 10);162 163 /*164 * test_find_first_bit() may take some time, so165 * traverse only part of bitmap to avoid soft lockup.166 */167 test_find_first_bit(bitmap, BITMAP_LEN / 10);168 test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN / 2);169 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);170 171 pr_err("\nStart testing find_bit() with sparse bitmap\n");172 173 bitmap_zero(bitmap, BITMAP_LEN);174 bitmap_zero(bitmap2, BITMAP_LEN);175 176 while (nbits--) {177 __set_bit(get_random_u32_below(BITMAP_LEN), bitmap);178 __set_bit(get_random_u32_below(BITMAP_LEN), bitmap2);179 }180 181 test_find_next_bit(bitmap, BITMAP_LEN);182 test_find_next_zero_bit(bitmap, BITMAP_LEN);183 test_find_last_bit(bitmap, BITMAP_LEN);184 test_find_nth_bit(bitmap, BITMAP_LEN);185 test_find_first_bit(bitmap, BITMAP_LEN);186 test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN);187 test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);188 189 /*190 * Everything is OK. Return error just to let user run benchmark191 * again without annoying rmmod.192 */193 return -EINVAL;194}195module_init(find_bit_test);196 197MODULE_DESCRIPTION("Test for find_*_bit functions");198MODULE_LICENSE("GPL");199