From dceeb3e7fd5cdafb6b8f70321fc4d994c95c3554 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Tue, 6 Feb 2018 15:38:27 -0800 Subject: lib/test_find_bit.c: rename to find_bit_benchmark.c As suggested in review comments, rename test_find_bit.c to find_bit_benchmark.c. Link: http://lkml.kernel.org/r/20171124143040.a44jvhmnaiyedg2i@yury-thinkpad Signed-off-by: Yury Norov Tested-by: Geert Uytterhoeven Cc: Alexey Dobriyan Cc: Clement Courbet Cc: Matthew Wilcox Cc: Rasmus Villemoes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/find_bit_benchmark.c | 144 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 lib/find_bit_benchmark.c (limited to 'lib/find_bit_benchmark.c') diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c new file mode 100644 index 000000000000..f4394a36f9aa --- /dev/null +++ b/lib/find_bit_benchmark.c @@ -0,0 +1,144 @@ +/* + * Test for find_*_bit functions. + * + * Copyright (c) 2017 Cavium. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +/* + * 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 +#include +#include +#include +#include +#include + +#define BITMAP_LEN (4096UL * 8 * 10) +#define SPARSE 500 + +static DECLARE_BITMAP(bitmap, 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; + cycles_t cycles; + + cycles = get_cycles(); + for (cnt = i = 0; i < len; cnt++) { + i = find_first_bit(bitmap, len); + __clear_bit(i, bitmap); + } + cycles = get_cycles() - cycles; + pr_err("find_first_bit:\t\t%llu cycles,\t%ld iterations\n", + (u64)cycles, cnt); + + return 0; +} + +static int __init test_find_next_bit(const void *bitmap, unsigned long len) +{ + unsigned long i, cnt; + cycles_t cycles; + + cycles = get_cycles(); + for (cnt = i = 0; i < BITMAP_LEN; cnt++) + i = find_next_bit(bitmap, BITMAP_LEN, i) + 1; + cycles = get_cycles() - cycles; + pr_err("find_next_bit:\t\t%llu cycles,\t%ld iterations\n", + (u64)cycles, cnt); + + return 0; +} + +static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len) +{ + unsigned long i, cnt; + cycles_t cycles; + + cycles = get_cycles(); + for (cnt = i = 0; i < BITMAP_LEN; cnt++) + i = find_next_zero_bit(bitmap, len, i) + 1; + cycles = get_cycles() - cycles; + pr_err("find_next_zero_bit:\t%llu cycles,\t%ld iterations\n", + (u64)cycles, cnt); + + return 0; +} + +static int __init test_find_last_bit(const void *bitmap, unsigned long len) +{ + unsigned long l, cnt = 0; + cycles_t cycles; + + cycles = get_cycles(); + do { + cnt++; + l = find_last_bit(bitmap, len); + if (l >= len) + break; + len = l; + } while (len); + cycles = get_cycles() - cycles; + pr_err("find_last_bit:\t\t%llu cycles,\t%ld iterations\n", + (u64)cycles, 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)); + + test_find_next_bit(bitmap, BITMAP_LEN); + test_find_next_zero_bit(bitmap, BITMAP_LEN); + test_find_last_bit(bitmap, BITMAP_LEN); + test_find_first_bit(bitmap, BITMAP_LEN); + + pr_err("\nStart testing find_bit() with sparse bitmap\n"); + + bitmap_zero(bitmap, BITMAP_LEN); + + while (nbits--) + __set_bit(prandom_u32() % BITMAP_LEN, bitmap); + + test_find_next_bit(bitmap, BITMAP_LEN); + test_find_next_zero_bit(bitmap, BITMAP_LEN); + test_find_last_bit(bitmap, BITMAP_LEN); + test_find_first_bit(bitmap, BITMAP_LEN); + + return 0; +} +module_init(find_bit_test); + +static void __exit test_find_bit_cleanup(void) +{ +} +module_exit(test_find_bit_cleanup); + +MODULE_LICENSE("GPL"); -- cgit