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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 <ynorov@caviumnetworks.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Clement Courbet <courbet@google.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Yury Norov 2018-02-06 15:38:31 -08:00 committed by Linus Torvalds
parent dceeb3e7fd
commit 15ff67bf85
1 changed files with 21 additions and 26 deletions
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47
lib/find_bit_benchmark.c
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@ -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");