145 lines
3.6 KiB
C
145 lines
3.6 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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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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/*
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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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cycles_t cycles;
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cycles = get_cycles();
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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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cycles = get_cycles() - cycles;
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pr_err("find_first_bit:\t\t%llu cycles,\t%ld iterations\n",
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(u64)cycles, 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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cycles_t cycles;
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cycles = get_cycles();
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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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cycles = get_cycles() - cycles;
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pr_err("find_next_bit:\t\t%llu cycles,\t%ld iterations\n",
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(u64)cycles, 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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cycles_t cycles;
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cycles = get_cycles();
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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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cycles = get_cycles() - cycles;
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pr_err("find_next_zero_bit:\t%llu cycles,\t%ld iterations\n",
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(u64)cycles, 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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cycles_t cycles;
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cycles = get_cycles();
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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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cycles = get_cycles() - cycles;
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pr_err("find_last_bit:\t\t%llu cycles,\t%ld iterations\n",
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(u64)cycles, 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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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_first_bit(bitmap, 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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while (nbits--)
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__set_bit(prandom_u32() % BITMAP_LEN, bitmap);
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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_first_bit(bitmap, BITMAP_LEN);
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return 0;
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}
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module_init(find_bit_test);
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static void __exit test_find_bit_cleanup(void)
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{
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}
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module_exit(test_find_bit_cleanup);
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MODULE_LICENSE("GPL");
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