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SubjectRe: [PATCH] lib: test module for find_*_bit() functions
Hi Geert, all

Below the updates proposed in this thread.

Yury


From 959700bd7e7f586171c15a4130a9888acac02daf Mon Sep 17 00:00:00 2001
From: Yury Norov <ynorov@caviumnetworks.com>
Date: Wed, 22 Nov 2017 17:21:40 +0300
Subject: [PATCH] improve lib/test_find_bit

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;
* rename test_find_bit.c to find_bit_benchmark.c.

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

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
lib/Kconfig.debug | 2 +-
lib/Makefile | 2 +-
lib/{test_find_bit.c => find_bit_benchmark.c} | 47 ++++++++++++---------------
3 files changed, 23 insertions(+), 28 deletions(-)
rename lib/{test_find_bit.c => find_bit_benchmark.c} (79%)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 138034cc68a3..1c57c36ad79a 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1838,7 +1838,7 @@ config TEST_BPF

If unsure, say N.

-config TEST_FIND_BIT
+config FIND_BIT_BENCHMARK
tristate "Test find_bit functions"
default n
help
diff --git a/lib/Makefile b/lib/Makefile
index 97ec69d843f2..1688cc84536e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -45,8 +45,8 @@ obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
obj-y += hexdump.o
obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o
obj-y += kstrtox.o
+obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o
obj-$(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/find_bit_benchmark.c
similarity index 79%
rename from lib/test_find_bit.c
rename to lib/find_bit_benchmark.c
index f4394a36f9aa..67b19233c28f 100644
--- a/lib/test_find_bit.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");
--
2.11.0
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