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- // 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(prandom_u32_max(BITMAP_LEN), bitmap);
- __set_bit(prandom_u32_max(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_LICENSE("GPL");
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