Messages in this thread Patch in this message | | | Date | Fri, 11 Dec 2020 17:50:39 +0900 | From | Levi Yun <> | Subject | [PATCH] lib/find_bit_bench: fix the unmatched iterations cnt |
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We should have same iteration count when we walk the same bitmap regardless of using find_next_bit or find_last_bit.
When we run the find_bit_benchmark.ko, we sometime get unmatched iterations count below:
Start testing find_bit() with random-filled bitmap [+...] find_next_bit: 875085 ns, 163755 iterations < [+...] find_next_zero_bit: 865319 ns, 163926 iterations [+...] find_last_bit: 611807 ns, 163756 iterations < [+...] find_first_bit: 1601016 ns, 16335 iterations [+...] find_next_and_bit: 400645 ns, 74040 iterations [+...] Start testing find_bit() with sparse bitmap [+...] find_next_bit: 9942 ns, 654 iterations [+...] find_next_zero_bit: 1678445 ns, 327027 iterations [+...] find_last_bit: 7131 ns, 654 iterations [+...] find_first_bit: 551383 ns, 654 iterations [+...] find_next_and_bit: 3027 ns, 1 iterations
Normally, this is happen when the last bit of bitmap was set.
This patch fix the unmatched iterations count between test_find_next_bit and test_find_last_bit.
Signed-off-by: Levi Yun <ppbuk5246@gmail.com> --- lib/find_bit_benchmark.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-)
diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c index 5637c5711db9..766e0487852b 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); @@ -84,12 +86,11 @@ 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); time = ktime_get() - time; pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt); @@ -99,12 +100,13 @@ static int __init test_find_last_bit(const void *bitmap, unsigned long len) static int __init test_find_next_and_bit(const void *bitmap, const void *bitmap2, 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_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); -- 2.27.0
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