From 4441fca0a27f5f0e2c652584ae9d7abec6255c1f Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Fri, 17 Nov 2017 15:28:31 -0800 Subject: lib: test module for find_*_bit() functions find_bit functions are widely used in the kernel, including hot paths. This module tests performance of those functions in 2 typical scenarios: randomly filled bitmap with relatively equal distribution of set and cleared bits, and sparse bitmap which has 1 set bit for 500 cleared bits. On ThunderX machine: Start testing find_bit() with random-filled bitmap find_next_bit: 240043 cycles, 164062 iterations find_next_zero_bit: 312848 cycles, 163619 iterations find_last_bit: 193748 cycles, 164062 iterations find_first_bit: 177720874 cycles, 164062 iterations Start testing find_bit() with sparse bitmap find_next_bit: 3633 cycles, 656 iterations find_next_zero_bit: 620399 cycles, 327025 iterations find_last_bit: 3038 cycles, 656 iterations find_first_bit: 691407 cycles, 656 iterations [arnd@arndb.de: use correct format string for find-bit tests] Link: http://lkml.kernel.org/r/20171113135605.3166307-1-arnd@arndb.de Link: http://lkml.kernel.org/r/20171109140714.13168-1-ynorov@caviumnetworks.com Signed-off-by: Yury Norov Signed-off-by: Arnd Bergmann Reviewed-by: Clement Courbet Cc: Alexey Dobriyan Cc: Matthew Wilcox Cc: Rasmus Villemoes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/Kconfig.debug | 9 ++++ lib/Makefile | 1 + lib/test_find_bit.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 154 insertions(+) create mode 100644 lib/test_find_bit.c (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 8ffd891857ab..ce813731269f 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1850,6 +1850,15 @@ config TEST_BPF If unsure, say N. +config TEST_FIND_BIT + tristate "Test find_bit functions" + default n + help + This builds the "test_find_bit" module that measure find_*_bit() + functions performance. + + If unsure, say N. + config TEST_FIRMWARE tristate "Test firmware loading via userspace interface" default n diff --git a/lib/Makefile b/lib/Makefile index e3cb2a241338..d11c48ec8ffd 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -47,6 +47,7 @@ obj-y += hexdump.o obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o obj-y += kstrtox.o obj-$(CONFIG_TEST_BPF) += test_bpf.o +obj-$(CONFIG_TEST_FIND_BIT) += test_find_bit.o obj-$(CONFIG_TEST_FIRMWARE) += test_firmware.o obj-$(CONFIG_TEST_SYSCTL) += test_sysctl.o obj-$(CONFIG_TEST_HASH) += test_hash.o test_siphash.o 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 +#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