2020-12-06 06:52:34

by Yun Levi

Subject: [PATCH v2 5/8] lib/find_bit_bench.c: Add find_last_zero_bit.

Add bench test of find_last_zero_bit.

Also, this patch fix the unmatched iterations value with
find_next_bit and find_last_bit which happen when
the last bit set or not,
Let suppose, 4096 bitmap size and 4095 bit is set only.
In this case former find_next_bit returns iterations count as 0.
But find_last_bit returns it as 1.
This unmatched return value makes some confusion.
So we fix it.

Signed-off-by: Levi Yun <[email protected]>
---
lib/find_bit_benchmark.c | 51 +++++++++++++++++++++++++++++-----------
1 file changed, 37 insertions(+), 14 deletions(-)

diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c
index 5637c5711db9..007371169008 100644
--- a/lib/find_bit_benchmark.c
+++ b/lib/find_bit_benchmark.c
@@ -35,14 +35,14 @@ static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata;
*/
static int __init test_find_first_bit(void *bitmap, unsigned long len)
{
- unsigned long i, cnt;
+ unsigned long i = 0, cnt = 0;
ktime_t time;

time = ktime_get();
- for (cnt = i = 0; i < len; cnt++) {
+ do {
i = find_first_bit(bitmap, len);
__clear_bit(i, bitmap);
- }
+ } while (i++ < len && ++cnt);
time = ktime_get() - time;
pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt);

@@ -51,12 +51,13 @@ 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;
+ unsigned long i = 0, cnt = 0;
ktime_t time;

time = ktime_get();
- for (cnt = i = 0; i < BITMAP_LEN; cnt++)
- i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;
+ do {
+ i = find_next_bit(bitmap, BITMAP_LEN, i);
+ } while (i++ < BITMAP_LEN && ++cnt);
time = ktime_get() - time;
pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt);

@@ -65,12 +66,13 @@ 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;
+ unsigned long i = 0, cnt = 0;
ktime_t time;

time = ktime_get();
- for (cnt = i = 0; i < BITMAP_LEN; cnt++)
- i = find_next_zero_bit(bitmap, len, i) + 1;
+ do {
+ i = find_next_zero_bit(bitmap, len, i);
+ } while (i++ < BITMAP_LEN && ++cnt);
time = ktime_get() - time;
pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);

@@ -84,27 +86,46 @@ static int __init test_find_last_bit(const void *bitmap, unsigned long len)

time = ktime_get();
do {
- cnt++;
l = find_last_bit(bitmap, len);
if (l >= len)
break;
len = l;
- } while (len);
+ } while (len >= 0 && ++cnt); /**< to find real 0 bit set. */
time = ktime_get() - time;
pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt);

return 0;
}

+static int __init test_find_last_zero_bit(const void *bitmap, unsigned long len)
+{
+ unsigned long l, cnt = 0;
+ ktime_t time;
+
+ time = ktime_get();
+ do {
+ l = find_last_zero_bit(bitmap, len);
+ if (l >= len)
+ break;
+ len = l;
+ } while (len >= 0 && ++cnt); /**< to find real 0 bit set. */
+ time = ktime_get() - time;
+ pr_err("find_last_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
+
+ return 0;
+}
+
+
static int __init test_find_next_and_bit(const void *bitmap,
const void *bitmap2, unsigned long len)
{
- unsigned long i, cnt;
+ unsigned long i, cnt = 0;
ktime_t time;

time = ktime_get();
- for (cnt = i = 0; i < BITMAP_LEN; cnt++)
- i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);
+ do {
+ i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i);
+ } while (i++ < BITMAP_LEN && ++cnt);
time = ktime_get() - time;
pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt);

@@ -123,6 +144,7 @@ static int __init find_bit_test(void)
test_find_next_bit(bitmap, BITMAP_LEN);
test_find_next_zero_bit(bitmap, BITMAP_LEN);
test_find_last_bit(bitmap, BITMAP_LEN);
+ test_find_last_zero_bit(bitmap, BITMAP_LEN);

/*
* test_find_first_bit() may take some time, so
@@ -144,6 +166,7 @@ static int __init find_bit_test(void)
test_find_next_bit(bitmap, BITMAP_LEN);
test_find_next_zero_bit(bitmap, BITMAP_LEN);
test_find_last_bit(bitmap, BITMAP_LEN);
+ test_find_last_zero_bit(bitmap, BITMAP_LEN);
test_find_first_bit(bitmap, BITMAP_LEN);
test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);

--
2.27.0