Re: [PATCH] lib/sbitmap: kill 'depth' from sbitmap_word

Jens Axboe
2022-01-10T01:54:26Z

On 1/9/22 6:50 PM, Ming Lei wrote:
> Only the last sbitmap_word can have different depth, and all the others
> must have same depth of 1U << sb->shift, so not necessary to store it in
> sbitmap_word, and it can be retrieved easily and efficiently by adding
> one internal helper of __map_depth(sb, index).
>
> Not see performance effect when running iops test on null_blk.
>
> This way saves us one cacheline(usually 64 words) per each sbitmap_word.

We probably want to kill the ____cacheline_aligned_in_smp from 'word' as
well.

--
Jens Axboe