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197 lines
4.9 KiB
197 lines
4.9 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Test for find_*_bit functions. |
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* |
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* Copyright (c) 2017 Cavium. |
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*/ |
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/* |
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* find_bit functions are widely used in kernel, so the successful boot |
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* is good enough test for correctness. |
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* |
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* This test is focused on performance of traversing bitmaps. Two typical |
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* scenarios are reproduced: |
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* - randomly filled bitmap with approximately equal number of set and |
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* cleared bits; |
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* - sparse bitmap with few set bits at random positions. |
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*/ |
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#include <linux/bitops.h> |
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#include <linux/kernel.h> |
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#include <linux/list.h> |
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#include <linux/module.h> |
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#include <linux/printk.h> |
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#include <linux/random.h> |
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#define BITMAP_LEN (4096UL * 8 * 10) |
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#define SPARSE 500 |
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static DECLARE_BITMAP(bitmap, BITMAP_LEN) __initdata; |
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static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata; |
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/* |
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* This is Schlemiel the Painter's algorithm. It should be called after |
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* all other tests for the same bitmap because it sets all bits of bitmap to 1. |
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*/ |
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static int __init test_find_first_bit(void *bitmap, unsigned long len) |
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{ |
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unsigned long i, cnt; |
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ktime_t time; |
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time = ktime_get(); |
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for (cnt = i = 0; i < len; cnt++) { |
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i = find_first_bit(bitmap, len); |
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__clear_bit(i, bitmap); |
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} |
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time = ktime_get() - time; |
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pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt); |
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return 0; |
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} |
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static int __init test_find_first_and_bit(void *bitmap, const void *bitmap2, unsigned long len) |
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{ |
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static DECLARE_BITMAP(cp, BITMAP_LEN) __initdata; |
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unsigned long i, cnt; |
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ktime_t time; |
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bitmap_copy(cp, bitmap, BITMAP_LEN); |
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time = ktime_get(); |
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for (cnt = i = 0; i < len; cnt++) { |
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i = find_first_and_bit(cp, bitmap2, len); |
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__clear_bit(i, cp); |
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} |
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time = ktime_get() - time; |
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pr_err("find_first_and_bit: %18llu ns, %6ld iterations\n", time, cnt); |
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return 0; |
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} |
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static int __init test_find_next_bit(const void *bitmap, unsigned long len) |
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{ |
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unsigned long i, cnt; |
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ktime_t time; |
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time = ktime_get(); |
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for (cnt = i = 0; i < BITMAP_LEN; cnt++) |
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i = find_next_bit(bitmap, BITMAP_LEN, i) + 1; |
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time = ktime_get() - time; |
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pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt); |
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return 0; |
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} |
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static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len) |
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{ |
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unsigned long i, cnt; |
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ktime_t time; |
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time = ktime_get(); |
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for (cnt = i = 0; i < BITMAP_LEN; cnt++) |
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i = find_next_zero_bit(bitmap, len, i) + 1; |
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time = ktime_get() - time; |
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pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt); |
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return 0; |
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} |
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static int __init test_find_last_bit(const void *bitmap, unsigned long len) |
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{ |
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unsigned long l, cnt = 0; |
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ktime_t time; |
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time = ktime_get(); |
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do { |
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cnt++; |
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l = find_last_bit(bitmap, len); |
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if (l >= len) |
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break; |
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len = l; |
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} while (len); |
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time = ktime_get() - time; |
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pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt); |
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return 0; |
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} |
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static int __init test_find_nth_bit(const unsigned long *bitmap, unsigned long len) |
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{ |
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unsigned long l, n, w = bitmap_weight(bitmap, len); |
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ktime_t time; |
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time = ktime_get(); |
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for (n = 0; n < w; n++) { |
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l = find_nth_bit(bitmap, len, n); |
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WARN_ON(l >= len); |
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} |
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time = ktime_get() - time; |
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pr_err("find_nth_bit: %18llu ns, %6ld iterations\n", time, w); |
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return 0; |
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} |
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static int __init test_find_next_and_bit(const void *bitmap, |
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const void *bitmap2, unsigned long len) |
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{ |
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unsigned long i, cnt; |
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ktime_t time; |
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time = ktime_get(); |
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for (cnt = i = 0; i < BITMAP_LEN; cnt++) |
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i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1); |
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time = ktime_get() - time; |
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pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt); |
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return 0; |
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} |
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static int __init find_bit_test(void) |
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{ |
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unsigned long nbits = BITMAP_LEN / SPARSE; |
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pr_err("\nStart testing find_bit() with random-filled bitmap\n"); |
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get_random_bytes(bitmap, sizeof(bitmap)); |
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get_random_bytes(bitmap2, sizeof(bitmap2)); |
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test_find_next_bit(bitmap, BITMAP_LEN); |
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test_find_next_zero_bit(bitmap, BITMAP_LEN); |
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test_find_last_bit(bitmap, BITMAP_LEN); |
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test_find_nth_bit(bitmap, BITMAP_LEN / 10); |
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/* |
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* test_find_first_bit() may take some time, so |
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* traverse only part of bitmap to avoid soft lockup. |
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*/ |
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test_find_first_bit(bitmap, BITMAP_LEN / 10); |
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test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN / 2); |
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test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN); |
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pr_err("\nStart testing find_bit() with sparse bitmap\n"); |
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bitmap_zero(bitmap, BITMAP_LEN); |
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bitmap_zero(bitmap2, BITMAP_LEN); |
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while (nbits--) { |
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__set_bit(prandom_u32_max(BITMAP_LEN), bitmap); |
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__set_bit(prandom_u32_max(BITMAP_LEN), bitmap2); |
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} |
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test_find_next_bit(bitmap, BITMAP_LEN); |
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test_find_next_zero_bit(bitmap, BITMAP_LEN); |
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test_find_last_bit(bitmap, BITMAP_LEN); |
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test_find_nth_bit(bitmap, BITMAP_LEN); |
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test_find_first_bit(bitmap, BITMAP_LEN); |
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test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN); |
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test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN); |
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/* |
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* Everything is OK. Return error just to let user run benchmark |
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* again without annoying rmmod. |
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*/ |
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return -EINVAL; |
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} |
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module_init(find_bit_test); |
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MODULE_LICENSE("GPL");
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