Hi,
在 2025/08/01 8:24, Yu Kuai 写道:
Hi,
在 2025/08/01 0:27, Jan Kara 写道:
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)
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)
Sorry there is a mistake, should use the word_depth here, following is
an example for 4 word sbitmap(64+64+64+32), I do the math manually, and
the results look perfect :)
| shallow_depth | word0 | word1 | word2 | word3 | total |
| ------------- | ------ | ------ | ------ | ----- | ----- |
| 224 | 64 | 64 | 64 | 32 | 224 |
| 112 | 32 | 32 | 32 | 16 | 112 |
| 113 | 32 + 1 | 32 | 32 | 16 | 113 |
| 114 | 32 + 1 | 32 + 1 | 32 | 16 | 114 |
| 115 | 32 + 1 | 32 + 1 | 32 + 1 | 16 | 115 |
| 116 | 33 | 33 | 33 | 16+1 | 116 |
shallow_word_depth++;
Thanks,
Kuai
?
That should accurately distribute the remainder across the remaining
words,
shouldn't it?
shallow_word_depth++;
return shallow_word_depth;
}
Honza
.
