Re: [PATCH v6 1/2] lib: bitmap: add tests for bitmap_find_next_zero_area_off()

[Yury Norov]

On Thu, Jun 18, 2026 at 09:35:17PM +0800, Yi Sun wrote:
> Add functional and performance tests
> for bitmap_find_next_zero_area_off().
> 
> performance tests partial output:
> Start testing find_bit() with random-filled bitmap
> [    0.310073] bitmap_find_next_zero_area_off:         852731 ns,   1154 iterations
> [    0.311435] find_next_bit:                         1356654 ns, 163975 iterations
> Start testing find_bit() with sparse bitmap
> [    0.316267] bitmap_find_next_zero_area_off:        4426808 ns, 322479 iterations
> [    0.316292] find_next_bit:                           15154 ns,    656 iterations
> 
> Signed-off-by: Yi Sun <yi.sun@xxxxxxxxxx>
> ---
>  lib/find_bit_benchmark.c | 31 ++++++++++++++++++++++++-------
>  lib/test_bitmap.c        | 38 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c
> index 00d9dc61cd46..cde7c09de05c 100644
> --- a/lib/find_bit_benchmark.c
> +++ b/lib/find_bit_benchmark.c
> @@ -46,7 +46,7 @@ static int __init test_find_first_bit(const void *bitmap, unsigned long len)
>  		__clear_bit(i, cp);
>  	}
>  	time = ktime_get() - time;
> -	pr_err("find_first_bit:     %18llu ns, %6ld iterations\n", time, cnt);
> +	pr_err("find_first_bit:                 %14llu ns, %6ld iterations\n", time, cnt);

No need to change the existing code. Just add your test and make sure
it looks aligned with the existing format.

>  
>  	return 0;
>  }
> @@ -66,7 +66,7 @@ static int __init test_find_first_and_bit(const void *bitmap, const void *bitmap
>  		__clear_bit(i, cp);
>  	}
>  	time = ktime_get() - time;
> -	pr_err("find_first_and_bit: %18llu ns, %6ld iterations\n", time, cnt);
> +	pr_err("find_first_and_bit:             %14llu ns, %6ld iterations\n", time, cnt);
>  
>  	return 0;
>  }
> @@ -80,7 +80,7 @@ static int __init test_find_next_bit(const void *bitmap, unsigned long len)
>  	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
>  		i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;
>  	time = ktime_get() - time;
> -	pr_err("find_next_bit:      %18llu ns, %6ld iterations\n", time, cnt);
> +	pr_err("find_next_bit:                  %14llu ns, %6ld iterations\n", time, cnt);
>  
>  	return 0;
>  }
> @@ -94,7 +94,7 @@ static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)
>  	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
>  		i = find_next_zero_bit(bitmap, len, i) + 1;
>  	time = ktime_get() - time;
> -	pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
> +	pr_err("find_next_zero_bit:             %14llu ns, %6ld iterations\n", time, cnt);
>  
>  	return 0;
>  }
> @@ -113,7 +113,7 @@ static int __init test_find_last_bit(const void *bitmap, unsigned long len)
>  		len = l;
>  	} while (len);
>  	time = ktime_get() - time;
> -	pr_err("find_last_bit:      %18llu ns, %6ld iterations\n", time, cnt);
> +	pr_err("find_last_bit:                  %14llu ns, %6ld iterations\n", time, cnt);
>  
>  	return 0;
>  }
> @@ -129,7 +129,7 @@ static int __init test_find_nth_bit(const unsigned long *bitmap, unsigned long l
>  		WARN_ON(l >= len);
>  	}
>  	time = ktime_get() - time;
> -	pr_err("find_nth_bit:       %18llu ns, %6ld iterations\n", time, w);
> +	pr_err("find_nth_bit:                   %14llu ns, %6ld iterations\n", time, w);
>  
>  	return 0;
>  }
> @@ -144,7 +144,22 @@ static int __init test_find_next_and_bit(const void *bitmap,
>  	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
>  		i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);
>  	time = ktime_get() - time;
> -	pr_err("find_next_and_bit:  %18llu ns, %6ld iterations\n", time, cnt);
> +	pr_err("find_next_and_bit:              %14llu ns, %6ld iterations\n", time, cnt);
> +
> +	return 0;
> +}
> +
> +static int __init
> +test_bitmap_find_next_zero_area_off(unsigned long *bitmap, unsigned long len)
> +{
> +	unsigned long i, cnt;
> +	ktime_t time;
> +
> +	time = ktime_get();
> +	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
> +		i = bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN, i, 8, 0, 0) + 1;
> +	time = ktime_get() - time;
> +	pr_err("bitmap_find_next_zero_area_off: %14llu ns, %6ld iterations\n", time, cnt);
>  
>  	return 0;
>  }
> @@ -158,6 +173,7 @@ static int __init find_bit_test(void)
>  	get_random_bytes(bitmap, sizeof(bitmap));
>  	get_random_bytes(bitmap2, sizeof(bitmap2));
>  
> +	test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
>  	test_find_next_bit(bitmap, BITMAP_LEN);
>  	test_find_next_zero_bit(bitmap, BITMAP_LEN);
>  	test_find_last_bit(bitmap, BITMAP_LEN);
> @@ -181,6 +197,7 @@ static int __init find_bit_test(void)
>  		__set_bit(get_random_u32_below(BITMAP_LEN), bitmap2);
>  	}
>  
> +	test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
>  	test_find_next_bit(bitmap, BITMAP_LEN);
>  	test_find_next_zero_bit(bitmap, BITMAP_LEN);
>  	test_find_last_bit(bitmap, BITMAP_LEN);
> diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
> index 69813c10e6c0..8665df77c960 100644
> --- a/lib/test_bitmap.c
> +++ b/lib/test_bitmap.c
> @@ -234,6 +234,43 @@ static void __init test_find_nth_bit(void)
>  	}
>  }
>  
> +static void __init
> +test_bitmap_find_next_zero_area_off(void)
> +{
> +	DECLARE_BITMAP(bmap, 192);
> +
> +	bitmap_set(bmap, 0, 192);
> +
> +	bitmap_clear(bmap, 0, 8);
> +	__clear_bit(50, bmap);
> +	bitmap_clear(bmap, 60, 18);
> +	__set_bit(69, bmap);
> +	__clear_bit(80, bmap);
> +	bitmap_clear(bmap, 100, 10);
> +	__clear_bit(120, bmap);
> +	bitmap_clear(bmap, 145, 8);
> +	bitmap_clear(bmap, 160, 32);
> +
> +	expect_eq_uint(0,
> +		bitmap_find_next_zero_area_off(bmap, 192, 0, 8, 0, 0));
> +	expect_eq_uint(0,
> +		bitmap_find_next_zero_area_off(bmap, 192, 0, 8, 3, 0));
> +	expect_eq_uint(163,
> +		bitmap_find_next_zero_area_off(bmap, 192, 0, 8, 3, 1));
> +	expect_eq_uint(60,
> +		bitmap_find_next_zero_area_off(bmap, 192, 1, 8, 0, 0));
> +	expect_eq_uint(160,
> +		bitmap_find_next_zero_area_off(bmap, 192, 1, 8, 7, 0));
> +	expect_eq_uint(60,
> +		bitmap_find_next_zero_area_off(bmap, 192, 1, 8, 7, 4));
> +	expect_eq_uint(100,
> +		bitmap_find_next_zero_area_off(bmap, 192, 0, 10, 0, 0));
> +	expect_eq_uint(160,
> +		bitmap_find_next_zero_area_off(bmap, 192, 0, 32, 0, 0));
> +	expect_eq_uint(1,
> +		!!(bitmap_find_next_zero_area_off(bmap, 192, 0, 33, 0, 0) >= 192));
> +}
> +
>  static void __init test_fill_set(void)
>  {
>  	DECLARE_BITMAP(bmap, 1024);
> @@ -1559,6 +1596,7 @@ static void __init selftest(void)
>  	test_for_each_clear_bitrange_from();
>  	test_for_each_set_clump8();
>  	test_for_each_set_bit_wrap();
> +	test_bitmap_find_next_zero_area_off();
>  }
>  
>  KSTM_MODULE_LOADERS(test_bitmap);
> -- 
> 2.34.1