Hi,

在 2025/08/01 0:27, Jan Kara 写道:

On Thu 31-07-25 10:38:58, Yu Kuai wrote:

quoted

Hi,

在 2025/07/31 2:24, Yu Kuai 写道:

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hi, Jan!

在 2025/7/30 21:03, Jan Kara 写道:

quoted

I think having two APIs will be even more confusing than the current
state.
But as I wrote I think you can have API to specify shallow depth in total
size and in sbitmap_queue_get_shallow() do:

shallow_per_word = (shallow_depth << sb->shift) / sb->depth;

In order to consider the last word, I think we should use __map_depth()
here.

Right.

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rounding_index = shallow_depth - shallow_per_word * sb->depth;

And then it's not possible to calculate this rounding index easily. How
about following, although the reminder handling is not perfect.

  static unsigned int __map_depth_with_shallow(const struct sbitmap *sb,
                                              int index,
                                              unsigned int shallow_depth)
  {
         unsigned int word_depth = __map_depth(sb, index);
         unsigned int shallow_word_depth = word_depth * shallow_depth;
         unsigned reminder = do_div(shallow_word_depth, sb->depth);

         if (reminder && !(index & 0x1))

Well, why not:
	if (remainder > index)

Do you mean reminder > index * shallow_depth? This looks correct, and
with the consideration for the last word:

if (index == sb->map_nr - 1)
	shallow_word_depth = max(shallow_word_depth, 1);
else if (reminder > index * shallow_depth)
	shallow_word_depth++;

Thanks,
Kuai

?

That should accurately distribute the remainder across the remaining words,
shouldn't it?

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                 shallow_word_depth++;

         return shallow_word_depth;
  }

								Honza