On Thu 31-07-25 10:38:58, Yu Kuai wrote:
> 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.
Right.
> > > 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)
?
That should accurately distribute the remainder across the remaining words,
shouldn't it?
> shallow_word_depth++;
>
> return shallow_word_depth;
> }
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
