From 15ff67bf85c6c02ab7d850deea0199516e8f16a0 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Tue, 6 Feb 2018 15:38:31 -0800 Subject: lib/find_bit_benchmark.c: improvements As suggested in review comments: * printk: align numbers using whitespaces instead of tabs; * return error value from init() to avoid calling rmmod if testing again; * use ktime_get instead of get_cycles as some arches don't support it; The output in dmesg (on QEMU arm64): [ 38.823430] Start testing find_bit() with random-filled bitmap [ 38.845358] find_next_bit: 20138448 ns, 163968 iterations [ 38.856217] find_next_zero_bit: 10615328 ns, 163713 iterations [ 38.863564] find_last_bit: 7111888 ns, 163967 iterations [ 40.944796] find_first_bit: 2081007216 ns, 163968 iterations [ 40.944975] [ 40.944975] Start testing find_bit() with sparse bitmap [ 40.945268] find_next_bit: 73216 ns, 656 iterations [ 40.967858] find_next_zero_bit: 22461008 ns, 327025 iterations [ 40.968047] find_last_bit: 62320 ns, 656 iterations [ 40.978060] find_first_bit: 9889360 ns, 656 iterations 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 | 47 +++++++++++++++++++++-------------------------- 1 file changed, 21 insertions(+), 26 deletions(-) (limited to 'lib/find_bit_benchmark.c') diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c index f4394a36f9aa..67b19233c28f 100644 --- a/lib/find_bit_benchmark.c +++ b/lib/find_bit_benchmark.c @@ -43,16 +43,15 @@ static DECLARE_BITMAP(bitmap, BITMAP_LEN) __initdata; static int __init test_find_first_bit(void *bitmap, unsigned long len) { unsigned long i, cnt; - cycles_t cycles; + ktime_t time; - cycles = get_cycles(); + time = ktime_get(); 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); + time = ktime_get() - time; + pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt); return 0; } @@ -60,14 +59,13 @@ static int __init test_find_first_bit(void *bitmap, unsigned long len) static int __init test_find_next_bit(const void *bitmap, unsigned long len) { unsigned long i, cnt; - cycles_t cycles; + ktime_t time; - cycles = get_cycles(); + time = ktime_get(); 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); + time = ktime_get() - time; + pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt); return 0; } @@ -75,14 +73,13 @@ static int __init test_find_next_bit(const void *bitmap, unsigned long len) static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len) { unsigned long i, cnt; - cycles_t cycles; + ktime_t time; - cycles = get_cycles(); + time = ktime_get(); 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); + time = ktime_get() - time; + pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt); return 0; } @@ -90,9 +87,9 @@ static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len) static int __init test_find_last_bit(const void *bitmap, unsigned long len) { unsigned long l, cnt = 0; - cycles_t cycles; + ktime_t time; - cycles = get_cycles(); + time = ktime_get(); do { cnt++; l = find_last_bit(bitmap, len); @@ -100,9 +97,8 @@ static int __init test_find_last_bit(const void *bitmap, unsigned long 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); + time = ktime_get() - time; + pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt); return 0; } @@ -132,13 +128,12 @@ static int __init find_bit_test(void) test_find_last_bit(bitmap, BITMAP_LEN); test_find_first_bit(bitmap, BITMAP_LEN); - return 0; + /* + * Everything is OK. Return error just to let user run benchmark + * again without annoying rmmod. + */ + return -EINVAL; } module_init(find_bit_test); -static void __exit test_find_bit_cleanup(void) -{ -} -module_exit(test_find_bit_cleanup); - MODULE_LICENSE("GPL"); -- cgit v1.2.3-59-g8ed1b