答复: [PATCH v5 1/2] lib: bitmap: add tests for bitmap_find_next_zero_area_off()

[孙毅 (Yi Sun)]

> -----邮件原件-----
> 发件人: Yury Norov <yury.norov@xxxxxxxxx>
> 发送时间: 2026年6月18日 13:48
> 收件人: 孙毅 (Yi Sun) <Yi.Sun@xxxxxxxxxx>
> 抄送: yury.norov@xxxxxxxxx; mina86@xxxxxxxxxx; 279644543@xxxxxx;
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> 主题: Re: [PATCH v5 1/2] lib: bitmap: add tests for
> bitmap_find_next_zero_area_off()
> 
> 
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> 
> On Thu, Jun 18, 2026 at 09:52:51AM +0800, Yi Sun wrote:
> > Add functional and performance tests
> > for bitmap_find_next_zero_area_off().
> >
> > To maintain consistent output format,
> > use "find_next_0_area" instead of
> > "bitmap_find_next_zero_area_off".
> >
> > performance tests partial output:
> > Start testing find_bit() with random-filled bitmap
> > [    0.191166] find_next_0_area:              1521308 ns,   1326 iterations
> > [    0.192552] find_next_bit:                 1382385 ns, 163724 iterations
> > Start testing find_bit() with sparse bitmap
> > [    0.196835] find_next_0_area:              4250307 ns, 322497 iterations
> > [    0.196853] find_next_bit:                   15077 ns,    656 iterations
> >
> > Signed-off-by: Yi Sun <yi.sun@xxxxxxxxxx>
> > ---
> >  lib/find_bit_benchmark.c | 17 +++++++++++++++++
> >  lib/test_bitmap.c        | 38 ++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 55 insertions(+)
> >
> > diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c
> > index 00d9dc61cd46..062a69930d83 100644
> > --- a/lib/find_bit_benchmark.c
> > +++ b/lib/find_bit_benchmark.c
> > @@ -149,6 +149,21 @@ static int __init test_find_next_and_bit(const void
> *bitmap,
> >       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("find_next_0_area:   %18llu ns, %6ld iterations\n", time, cnt);
> 
> Change %18llu to %14llu (or whatever), and keep the name as it should.

ok,  I will make changes in v6.

> 
> > +
> > +     return 0;
> > +}
> > +
> >  static int __init find_bit_test(void)
> >  {
> >       unsigned long nbits = BITMAP_LEN / SPARSE;
> > @@ -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..12aa2ca37fe1 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));
> 
> It should be >= here.

There would be a problem if the return value equals 192.
size = 192;
if (end > size)
	return end;
So the return value must be greater than 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