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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-17 16:56:17 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-17 16:56:17 -0800 |
commit | fa7f578076a8814caa5371e9f4949e408140766d (patch) | |
tree | 8021be6f956e8a259523c394a01183797ce04422 /lib/test_find_bit.c | |
parent | 2dcd9c71c1ffa9a036e09047f60e08383bb0abb6 (diff) | |
parent | d1b069f5febc850556cf49e9bb9092d3179c5be5 (diff) |
Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:
- a bit more MM
- procfs updates
- dynamic-debug fixes
- lib/ updates
- checkpatch
- epoll
- nilfs2
- signals
- rapidio
- PID management cleanup and optimization
- kcov updates
- sysvipc updates
- quite a few misc things all over the place
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (94 commits)
EXPERT Kconfig menu: fix broken EXPERT menu
include/asm-generic/topology.h: remove unused parent_node() macro
arch/tile/include/asm/topology.h: remove unused parent_node() macro
arch/sparc/include/asm/topology_64.h: remove unused parent_node() macro
arch/sh/include/asm/topology.h: remove unused parent_node() macro
arch/ia64/include/asm/topology.h: remove unused parent_node() macro
drivers/pcmcia/sa1111_badge4.c: avoid unused function warning
mm: add infrastructure for get_user_pages_fast() benchmarking
sysvipc: make get_maxid O(1) again
sysvipc: properly name ipc_addid() limit parameter
sysvipc: duplicate lock comments wrt ipc_addid()
sysvipc: unteach ids->next_id for !CHECKPOINT_RESTORE
initramfs: use time64_t timestamps
drivers/watchdog: make use of devm_register_reboot_notifier()
kernel/reboot.c: add devm_register_reboot_notifier()
kcov: update documentation
Makefile: support flag -fsanitizer-coverage=trace-cmp
kcov: support comparison operands collection
kcov: remove pointless current != NULL check
kernel/panic.c: add TAINT_AUX
...
Diffstat (limited to 'lib/test_find_bit.c')
-rw-r--r-- | lib/test_find_bit.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/lib/test_find_bit.c b/lib/test_find_bit.c new file mode 100644 index 000000000000..f4394a36f9aa --- /dev/null +++ b/lib/test_find_bit.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 <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; + +/* + * 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"); |