Hi,
在 2025/07/31 2:24, Yu Kuai 写道:
hi, Jan!
在 2025/7/30 21:03, Jan Kara 写道:
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.
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))
shallow_word_depth++;
return shallow_word_depth;
}
and allow depth shallow_per_word + 1 if current index < rounding_index
and
exactly shallow_per_word if current index >= rounding_index. This will
still evenly distribute shallow depth among words and I don't think the
additional overhead of the several arithmetic operations will be visible.
Yes, you're right, I did not get your idea before. Thanks for the
explanation
and the suggestion :） Will follow this idea in the next version.
Thanks
.
